Preexisting cracks are of great significance for the stability of rocks, they can influence the growth and propagation pattern of cracks. For revealing the failure characteristics of rocks with prefabricated cracks, the mechanical behaviors of red sandstone with two close-collinear-equal length cracks were studied by acoustic emission (AE) monitoring experiment. The results indicated that the stress of red sandstone specimens showed an obvious stepwise growth phenomenon, and AE ring counts can better characterize the growth of microcracks of rocks. Moreover, AE events were mainly distributed near the prefabricated cracks of rocks. Then, a novel modified Kachanov method for analyzing collinear-close cracks was proposed. The influences of crack length and crack spacing on the interaction force of cracks were discussed. Then, it can be found that this modified method had a good applicability for two close-collinear-equal length cracks of rocks under compression.

We analyzed geologic-geophysical data, both from archives and collections in recent expeditions by the Shirshov Institute of Oceanology of Russian Academy of Sciences, and revealed many anomalies in the seismoacoustic wavefield. Anomalies are of two types: horizontal disturbed layers and vertical pipes. Anomalies form associations — pipes (chimneys) are rooted in disturbed layers and go through sediments up to the seafloor and form pockmarks. We consider all specified seismic anomalies and bottom microrelief as a possibility of vertical migration of gas and water via sediments (fluid from sediments to water and from seawater to sediments). It is expected that the fluids form a huge underground hydrosphere below the Caspian Sea. To test the fluid flow, we made a mathematical model of fluid discharge and absorption in bottom sediments. We hypothesize that the Caspian Sea level fluctuates, at least partially, due to cycles of the submarine ground water discharge and sea water absorption back into the sediments. This cyclicity of fluid discharge and absorption correlates with regional seismic events. The earthquakes cause tectonic relaxation, triggering the absorption process, and sea-level drop due to reverse flow into sediments. In other periods, the tectonic tension causes sediment compression and fluid discharge to sea water, which causes sea-level rise. The model was tested on the recent (past 100 years) sea-level change curve. As a result, we got a distribution of the general volume of fluid flows depending on the infiltration coefficient. The real change in the Caspian Sea volume is at the lower range of the calculated values, so we cannot neglect the effect of “gas pipes” (“chimneys”) on the Caspian Sea-level change.

Detailed geological mapping of Phoebe Regio on Venus, located near 10°S, 282°W, at a scale of 1:500,000, provided the basis for the discovery of a linear trend with 12 splotches, herein termed the Phoebe Regio Splotch Chain. The formation of splotches on the surface is associated with an explosion that occurs as a result of the interaction of a cosmic body penetrating through the dense atmosphere of Venus. The shockwave from such an air-blast could affect the surface in different ways, leading to both radar darkening and brightening. It was found that the 12 splotches differ in size but have a similar morphology and include a dark center and a radar-bright ring. The presence of such characteristics makes it possible to distinguish splotches from other geological features such as volcano-tectonic features (volcanic edifices, pyroclastic mantles, portions of lava flows and associated structures), which, when analyzed on a broad scale, can look similar. Splotches are known to be among the youngest geological features on the surface of Venus, and the elongated distribution of 12 splotches is suggested to have been formed by a stream of individual fragments of a parent body that disrupted well before entering the atmosphere of Venus.

The failure process of rocks is usually accompanied by numerous acoustic emission (AE) signals. For evaluating the damage state of rocks, it is important to select key disaster-causing AE signals from massive AE monitoring data. Based on the uniaxial compression test of red sandstone, the failure characteristics of AE signals were analyzed. Then, based on the principal component analysis method, the evolution pattern of key disaster-causing factors of AE signals of red sandstone has been obtained. The results demonstrated that AE parameter signals (AE energy and AE ring counts) and AE waveform signals (AE main frequency) contributed to characterize the precursor of rock failure. The values of AE energy and AE ring counts increased significantly in the critical failure stage of rocks, and there existed a short quiet period phenomenon of AE signals. Similarly, AE main frequency increased densely in the critical failure stage. Moreover, the optimized key disaster-causing signals (AE energy, AE ring counts and AE main frequency) can clearly characterize the stress fluctuation and damage state of rocks. Based on the optimized key disaster-causing AE signals, the primary early warning point and the key early warning point of rockburst were proposed. We hope this method can bring some new ideas for predicting rockburst.

Представлено численное моделирование процесса дробления массива горных пород зарядами взрывчатых веществ в двумерных плоской и осесимметричной постановках с помощью вычислительного комплекса, разработанного на основе лагранжева численного метода “Тензор’'. Результаты сопоставлены с уникальными данными прямых измерений проницаемости массива в ближней зоне подземного ядерного взрыва “Днепр-1”, проведенного в 1972 г. в Хибинах. Показано, что поствзрывную проницаемость массива скальных пород с приемлемой точностью можно оценить на основе расчета интенсивности деформации сдвига. В качестве примера рассмотрены результаты расчета изменения проницаемости вблизи заряда сложной конфигурации. (Будков, А. М. Оценка изменения проницаемости массива горных пород в окрестности подземного взрыва по экспериментальным данным и результатам численного моделирования / А. М. Будков, Г. Г. Кочарян, С. Б. Кишкина // Физико-технические проблемы разработки полезных ископаемых. – 2023. – № 1. – С. 12-21. – DOI 10.15372/FTPRPI20230102. – EDN SGXDFW. Budkov, A.M., Kocharyan, G.G. & Kishkina, S.B. Assessment of Change in Rock Mass Permeability in the Vicinity of Underground Explosion from Experimental Data and Numerical Modeling. J Min Sci 59, 8–16 (2023). https://doi.org/10.1134/S1062739123010027)

Исследование динамики периодических вариаций с периодами от 1 до 27 сут с применением вейвлет-преобразования и анализа скейлинга методом максимумов модулей коэффициентов вейвлет-преобразования выполняется с привлечением результатов инструментальных наблюдений за геомагнитным полем, выполненных на Центральной геофизической обсерватории “Бельск” в 2008 г. и 2018 г. (низкая солнечная активность) и в 2014 г. (высокая солнечная активность). Установлено изменение интенсивности периодических вариаций. Показан близкий к монофрактальному характер суточных геомагнитных вариаций. 27-суточная вариация и ее гармоники имеют более высокую степень мультифрактальности во время максимума солнечной активности по сравнению с минимумом солнечной активности.(Riabova, S.A. Study of the Multifractality of Geomagnetic Variations at the Belsk Observatory. Dokl. Earth Sc. 507 (Suppl 2), S299–S303 (2022). https://doi.org/10.1134/S1028334X22700489)

The article presents the results of monitoring the seismic impact of bulk blasts during explosive breaking of iron ore in the Gubkin mine on the city of Gubkin. The dependence of the maximum oscillation velocity in a seismic explosion wave on the reduced (based on the mass of the explosive in the delay stage) hypocentral distance to the explosive chamber is obtained. For one bulk blast, an isoseist map was constructed, demonstrating the intensity of seismic impact on residential areas of the city. Taking into account the requirements of regulatory documents and duration of seismic and explosion vibrations, estimates of the permissible and maximum permissible velocities of seismic vibrations for the population have been obtained.

Модель абляции для мелких метеороидов используется для оценки физических параметров метеоров в разных предположениях. Метеороид рассматривается в двух модификациях: сплошное и пористое тело. Использован автоматизированный метод оценки параметров по кривым блеска. Обсуждаются ограничения и особенности модели. (Абляция мелких метеорных тел: сравнение модели сплошного и пористого тела / В. В. Ефремов, О. П. Попова, Д. О. Глазачев [и др.] // Вестник Томского государственного университета. Математика и механика. – 2023. – № 81. – С. 110-122. – DOI 10.17223/19988621/81/10. – EDN ZKFUKN.)

Применение специальной методики позволило выделить из измерений вариаций геомагнитного поля на нескольких среднеширотных обсерваториях серию джерков за 17 лет с 2004 по 2020 гг. Показано, что джерки следуют с квазипериодом 3–4 года. Для интерпретации этих экспериментальных результатов предложен возможный механизм возникновения быстрых изменений геомагнитного поля, обусловленный магниторотационной неустойчивостью в ядре Земли. (Рябова, С. А. О короткопериодной динамике в ядре Земли по наземным наблюдениям геомагнитных джерков / С. А. Рябова, С. Л. Шалимов // Физика Земли. – 2023. – № 1. – С. 3-11. – DOI 10.31857/S0002333723010040. – EDN BZPVVG.) Riabova, S.A., Shalimov, S.L. On Short-Period Dynamics in the Earth’s Core according to Ground-Based Observations of Geomagnetic Jerks. Izv., Phys. Solid Earth 59, 41–48 (2023). https://doi.org/10.1134/S1069351323010044

Обсуждается влияние освещенности трассы на амплитуду сверхдлинноволновых радиосигналов при прохождении солнечного терминатора. На основе многолетних измерений (с 2014 по 2020 г.) показано, что в зимний период резкое падение амплитуды сигнала на среднеширотных трассах происходит уже при освещении 15% длины трассы. Анализ вариаций амплитуды сверхдлинноволновых сигналов также позволил оценить высоту их отражения от верхней стенки неосвещенной части волновода hN (D – область ионосферы) и выявить сезонные и годовые вариации этой величины. Экспериментально обнаружен тренд увеличения hN примерно на 4 км за семь лет, вызванный спадом солнечной активности в этот период. (Влияние освещенности трасс на амплитудные характеристики сигналов СДВ-диапазона / Е. Н. Козакова, И. А. Ряховский, Ю. В. Поклад [и др.] // Геомагнетизм и аэрономия. – 2023. – Т. 63, № 2. – С. 154-162. – DOI 10.31857/S0016794022100297. – EDN DMCDNZ.) Kozakova, E.N., Ryakhovsky, I.A., Poklad, Y.V. et al. Influence of Path Illumination on the Amplitude Characteristics of VLF Signals. Geomagn. Aeron. 63, 127–135 (2023). https://doi.org/10.1134/S0016793222600850

For the first time precise measurements of the groundwater level variations in the territory of the Mikhnevo geophysical observatory in an aseismic region (Moscow region, Russia) have been carried out since February 2008 at a sampling rate of 1 Hz. The groundwater level variations under quasi-stationary filtration are considered indicators of the dynamic deformation of a fluid-saturated reservoir represented by carbonate-terrigenous sediments. Both permanent (long-term) factors—atmospheric pressure, lunar-solar tides, and periodic (short-term) ones—seismic impacts from distant earthquakes, are used as probing signals for analyzing the filtration parameters of aquifers of different ages. Hydrogeological responses to the passage of seismic waves from earthquakes with magnitudes of 6.1–9.1 with epicentral distances of 1456–16,553 km was recorded in 2010–2023. Dependences of dynamic variations of the pore pressure in the upper weakly confined and lower confined aquifers on the ground velocity are approximated by different regression functions. Spectral analysis of hydrogeological responses made it possible to identify coseismic and postseismic effects from distant earthquakes. The postseismic effects in the form of an episodic increase in the pore pressure may be caused by a skin effect—clogging of microcracks nearby the wellbore by colloidal particles under intensive seismic impact.

A comprehensive monitoring at the territory of the Korobkovskoe and Lebedinskoe iron ore deposits of the Kursk Magnetic Anomaly (KMA), which are developed using explosive technologies, has been carried out since July 2019 near the town of Gubkin (Belgorod Region, Russia). A unique database of the responses of the system “reservoir–well” to short-delay explosions in a mine and a quarry has been formed with a sampling rate of 200 Hz on the basis of synchronous seismic, barometric, and precision hydrogeological measurements. The research object is groundwater in the zones of exogenous weathering and tectonic fracturing of the ore-crystalline basement of the Archean-Proterozoic. Processing hydrogeological responses to mass explosions in the mine and the quarry made it possible to indicate two types of water level response to seismic impact. In addition to coseismic variations in the pore pressure in the system “reservoir–well” for the first time postseismic hydrogeological effects were established during the exploitation of the iron ore deposits. The observed effects may have been caused by two mechanisms. The first mechanism is represented by the skin effect—a change in the permeability of a fluid-saturated reservoir in the near-wellbore space. The second one is the renewal of existing fracture systems and the formation of technogenic fractures in the zones of lithological-stratigraphic contacts and faults at the interface between weathered and relatively monolithic rocks. The subsequent decrease of the water level in the well is associated with the filling of the fractured zones with water.

Проведены оценки влияния разрушения астероидов на орбитах при их приближении к Земле на последствия их ударов. Определены площади поражения ударной волной, сейсмической волной и излучением при ударе каменных астероидов по суше или при входе в атмосферу над сушей со скоростью 20 км/с для диапазона их размеров 20–500 м. Получено, что произвольное разрушение астероида недалеко от Земли может приводить к увеличению суммарной площади поражения ударными волнами и тепловым излучением при ударах отдельных фрагментов. В общем случае уменьшения ущерба при разрушении астероидов с диаметрами 150–500 м можно добиться, если основную массу фрагментов составляют тела с размерами менее 20–30 м, которые не представляют катастрофической опасности. (Светцов, В. В. Падение на Землю фрагментов разрушенного астероида / В. В. Светцов // Астрономический вестник. Исследования Солнечной системы. – 2023. – Т. 57, № 3. – С. 275-283. – DOI 10.31857/S0320930X2303009X. – EDN BSADIH.) Svetsov V.V. Fall to Earth of Fragments of Destroyed Asteroid. Sol Syst Res 57, 278–285 (2023). https://doi.org/10.1134/S0038094623030097

Изучение связанного с извержением сейсмического процесса и оценка энергетических параметров и структуры волнового поля по сейсмическим данным составляют предмет настоящей работы. В структуре волнового поля выделены три типа возмущений. В первую очередь – это поверхностные волны Рэлея со средним периодом колебаний 23 с, хорошо прослеживаемые на расстояниях до 100 градусов. Групповая скорость волн Рэлея составляет 3.6–3.8 км/с. Рассчитанная по ним магнитуда на станциях в основном с океаническими трассами распространения Ms = 5.52 ± 0.18, а соответствующая ей сейсмическая энергия составила порядка Ec = (1–7) × 1Е13 Дж, а скалярный сейсмический момент Mо = 2.4 × 1Е17 Дж. На сейсмических каналах c полосой частот от 0.0003 до 0.1 Гц обнаружены два других типа колебаний. Для первого кажущаяся скорость распространения возмущения лежит в диапазоне 0.28–0.37 км/с с характерным периодом 268 с. Этот тип возмущений связан с гравитационным откликом сейсмометра на акустическое возмущение (волна Лэмба) в атмосфере. Для второго типа сейсмических возмущений скорость распространения составляет 0.21–0.28 км/с с характерными периодами 450 с на горизонтальных компонентах сейсмоприемников. Этот тип сейсмических возмущений, вероятно, обусловлен взаимодействием гравитационной волны в гидросфере с побережьем островов, на которых расположены сейсмические станции. (Овчинников, В. М. Сейсмические явления, связанные с извержением вулкана в районе архипелага Тонга 15 января 2022 г / В. М. Овчинников, О. А. Усольцева // Физика Земли. – 2023. – № 3. – С. 110-121. – DOI 10.31857/S0002333723030092. – EDN KAKMIE.) Ovtchinnikov, V.M., Usoltseva, O.A. Seismic Phenomena Associated with the Eruption of the Volcano in the Region of the Tonga Archipelago on January 15, 2022. Izv., Phys. Solid Earth 59, 433–443 (2023). https://doi.org/10.1134/S1069351323030096

Показана возможность дистанционного исследования электромагнитных и ионосферных эффектов, вызванных извержением вулкана Тонга 15.01.2022 г. На расстояниях до 15 000 км от источника зарегистрированы вариации геомагнитного поля, связанные с возмущением Шумановского резонанса (ШР), распространением волны Лэмба и акустико-гравитационных волн. Показано, что появление мощного источника грозовой активности, вызванного извержением, вызвало значимый рост (более, чем в три раза) амплитуды геомагнитных возмущений на частотах ШР, коррелирующий с числом молниевых разрядов. Влияния извержения на частотные характеристики ШР не обнаружено. (Дистанционное зондирование электромагнитных эффектов извержения вулкана Тонга 15 января 2022 г / Б. Г. Гаврилов, Ю. В. Поклад, И. А. Ряховский, В. М. Ермак // Физика Земли. – 2023. – № 3. – С. 122-130. – DOI 10.31857/S000233372303002X. – EDN JZNHQD.) Gavrilov, B.G., Poklad, Y.V., Ryakhovsky, I.A. et al. Remote Sensing of the Electromagnetic Effects of the Tonga Volcano Eruption on January 15, 2022. Izv., Phys. Solid Earth 59, 444–451 (2023). https://doi.org/10.1134/S1069351323030023

Приведены результаты трехмерного численного моделирования падения десятикилометровых астероидов под углом 45 градусов на твердую поверхность и в океан глубиной от 1 до 6 км. В расчетах получены максимальные массы выброшенных в атмосферу воды, вещества ударника и грунта, а также массы воды, вещества ударника и грунта, оставшиеся в атмосфере через 10 мин после удара. Определена масса паров в выбросах. Показано, что при косых ударах в атмосферу выбрасывается в 2–5 раз больше вещества ударника и грунта, чем при вертикальных.(Шувалов, В. В. Численное моделирование выброса вещества в атмосферу при наклонном падении десятикилометровых астероидов в океан / В. В. Шувалов // Физика Земли. – 2023. – № 3. – С. 131-138. – DOI 10.31857/S0002333723030122. – EDN KBCVUQ.) Shuvalov, V.V. Numerical Simulation of Material Ejection into the Atmosphere Induced by Oblique Impacts of Ten-Kilometer-Diameter Asteroids into the Ocean. Izv., Phys. Solid Earth 59, 452–459 (2023). https://doi.org/10.1134/S1069351323030126

Созданная в ИДГ РАН установка для исследования процесса сдвига по контакту между блоками горной породы метрового размера использована для изучения деформационных процессов на разломе с гетерогенной структурой поверхности скольжения, содержащей прочные контактные области – аналоги зон “asperity” в известной модели Х. Канамори [Kanamori, Stewart, 1978]. Показано, что при реализации крупной подвижки, которая начинается в зоне максимального дефицита межблокового смещения, происходит разрыв тех областей разлома, эффективная прочность которых снижена предыдущими деформационными событиями. При этом эти, более ранние, события могут быть “медленными” подвижками, имеющими низкую сейсмическую эффективность. В природе события, “подготавливающие” поверхность разлома к крупной подвижке, могут быть зарегистрированы в виде более слабых землетрясений – форшоков, либо являться низкочастотными землетрясениями или событиями медленного скольжения, слабо проявляющимися на сейсмических записях. В этой связи перспективным диагностическим признаком подготовки крупной подвижки является эффект смещения спектра сейсмического шума в сторону более низких частот, вызванного снижением жесткости разлома. (Развитие процесса скольжения по гетерогенному разлому. Крупномасштабный лабораторный эксперимент / Г. А. Гридин, Г. Г. Кочарян, К. Г. Морозова [и др.] // Физика Земли. – 2023. – № 3. – С. 139-147. – DOI 10.31857/S0002333723030043. – EDN JZVXSK.) Gridin, G.A., Kocharyan, G.G., Morozova, K.G. et al. Evolution of Sliding Along a Heterogeneous Fault. A Large-Scale Laboratory Experiment. Izv., Phys. Solid Earth 59, 460–467 (2023). https://doi.org/10.1134/S1069351323030047

Приведены результаты лабораторных экспериментов по совместному активному акустическому и деформационному мониторингу трещины гидроразрыва. Эксперименты проводились в модельном материале на основе гипса. Для сравнения были проведены эталонные эксперименты по исследованию прохождения ультразвуковых волн через заполненную жидкостью щель контролируемой ширины между двумя прецизионными стеклянными пластинами. Целью экспериментов было исследование зависимости амплитуды ультразвуковой волны, прошедшей через трещину от величины ее раскрытия. В этих экспериментах создавалась круговая трещина гидроразрыва, плоскость которой была перпендикулярна оси цилиндрического образца. Вдоль этой же оси располагалась обсаженная нагнетательная скважина, заканчивающаяся на середине его высоты. Образец располагался между двумя дисками из алюминиевого сплава, оснащенных вмонтированными в них пьезокерамическими преобразователями, работающими как в режиме излучателя, так и режиме приемника. Через канал в нижнем диске осуществлялась подача рабочей жидкости в трещину...(Совместный акустический и деформационный мониторинг трещины гидроразрыва в лабораторном эксперименте / Е. В. Зенченко, П. Е. Зенченко, В. А. Начев [и др.] // Физика Земли. – 2023. – № 3. – С. 148-157. – DOI 10.31857/S0002333723030134. – EDN KBGNNF.) Zenchenko, E.V., Zenchenko, P.E., Nachev, V.A. et al. Concurrent Active Acoustic and Deformation Monitoring of a Hydraulic Fracture in Laboratory Experiments. Izv., Phys. Solid Earth 59, 468–476 (2023). https://doi.org/10.1134/S1069351323030138

В статье представлен концептуальный обзор состояния исследований сопротивления разломных зон сдвигу. Публикации последних лет проанализированы в контексте подходов, сформулированных в нескольких докладах, сделанных авторами на 6-й конференции “Триггерные эффекты в геосистемах”. Анализ результатов, полученных различными группами исследователей в последние два–три десятилетия, демонстрирует, что определяющее значение для закономерностей инициирования и распространения разрыва, играют фрикционные свойства материала-заполнителя зоны скольжения. Совершенствование методов обработки данных регистрации параметров слабой сейсмичности, направленных на оценку “медленности” микроземлетрясений, приуроченных к зоне разлома, может привести к созданию новых подходов к мониторингу разломных зон для получения косвенной информации о материальном составе зоны скольжения разлома, а, следовательно, и о его потенциальной “сейсмогенности”. В настоящее время подобные методы могут оказаться востребованы при решении задач снижения ущерба от землетрясений, инициированных техногенной деятельностью. (Трение как фактор, определяющий излучательную эффективность подвижек по разломам и возможность их инициирования. Состояние вопроса / Г. Г. Кочарян, А. Н. Беседина, Г. А. Гридин [и др.] // Физика Земли. – 2023. – № 3. – С. 3-32. – DOI 10.31857/S0002333723030067. – EDN JZZKZN.) Kocharyan, G.G., Besedina, A.N., Gridin, G.A. et al. Friction as a Factor Determining the Radiation Efficiency of Fault Slips and the Possibility of Their Initiation: State of the Art. Izv., Phys. Solid Earth 59, 337–363 (2023). https://doi.org/10.1134/S1069351323030060

В статье приведён обзор текущего состояния дел в области повышения эффективности и безопасности основных направлений взрывных работ. Положительные качества эмульсионных взрывчатых веществ (ЭВВ) послужили основанием их широкого распространения при добыче твердых полезных ископаемых во всем мире. Высококонцентрированные эмульсии характеризуются значительной поверхностной энергией раздела фаз, поэтому могут быть получены и сохранены только с применением поверхностно-активных веществ (ПАВ). На стабильность эмульсии также большое влияние оказывает качество окислителя, горючего и эмульгатора. В настоящее время в рамках импортозамещения осуществляется переход исключительно на отечественные компоненты взрывчатых составов, что может сказаться на их физико-химических свойствах. В России наибольшее распространение среди средств инициирования получили неэлектрические системы, состоящие из ударно-волновой трубки, соединенной с капсюлем-детонатором. Их применение с учетом необходимости импортозамещения, сталкивается с рядом проблем, которые успешно решаются. Вопросы повышения эффективности взрывных работ в промышленности невозможно решить без подготовки квалифицированных научных и инженерных кадров.(Адушкин, В. В. О повышении эффективности и безопасности взрывных работ / В. В. Адушкин, В. А. Белин, С. А. Горинов // Взрывное дело. – 2023. – № 138-95. – С. 32-50. – EDN QYLXZO.)

На основе результатов инструментальных наблюдений за геомагнитными вариациями в обсерватории Михнево ИДГ РАН и данных каталога IERS установлено, что выделяемая в спектрах вариаций магнитного поля частота F основной сфероидальной моды собственных колебаний Земли 0S2 изменяется со временем, причем значения F выше в периоды уменьшения скорости вращения Земли и ниже при ее увеличении. Получена эмпирическая зависимость между вариациями F и скоростью вращения Земли. (О связи частоты фундаментальной моды 0S2 и скорости вращения Земли / А. А. Спивак, Д. Н. Локтев, А. В. Тихонова, В. А. Харламов // Доклады Российской академии наук. Науки о Земле. – 2023. – Т. 508, № 2. – С. 265-269. – DOI 10.31857/S2686739722602472. – EDN SWWHWA.) Spivak, A.A., Loktev, D.N., Tikhonova, A.V. et al. Relationship between the Frequency of the Fundamental Mode 0S2 and the Speed of the Earth’s Rotation. Dokl. Earth Sc. 507 (Suppl 3), S442–S445 (2022). https://doi.org/10.1134/S1028334X22601729

С использованием результатов инструментальных наблюдений, выполненных в приземной атмосфере, анализируется отклик микробарического фона, вариаций магнитного и электрического полей Земли на параксизмальную активность вулкана Стромболи (09.10.2022 г., Италия). Показано, что активная стадия вулканического извержения сопровождалась генерацией акустического сигнала и выраженными вариациями геомагнитного и атмосферного электрического поля на значительных расстояниях как в период активности вулкана, так и в период прихода в точку наблюдений инфразвуковой волны. Также отмечено, что вулканическое извержение вызвало отклик в ионосфере в виде изменения критической частоты F2-слоя. (Геофизические эффекты активной стадии извержения вулкана Стромболи 09.10.2022 г / А. А. Спивак, Д. Н. Локтев, Ю. С. Рыбнов [и др.] // Доклады Российской академии наук. Науки о Земле. – 2023. – Т. 509, № 2. – С. 237-242. – DOI 10.31857/S2686739722602757. – EDN NYZVFG.) Spivak, A.A., Loktev, D.N., Rybnov, Y.S. et al. Geophysical Effects of the Active Stage of the Stromboli Volcano Eruption on October 9, 2022. Dokl. Earth Sc. 509, 217–221 (2023). https://doi.org/10.1134/S1028334X22602061

Представлен анализ вариаций микробарического фона, магнитного и электрического поля в приземном слое атмосферы, сопутствующих сильным землетрясениям 06.02.2023 г. в Турции. Для анализа привлекались результаты инструментальных наблюдений, выполненных в Центре геофизического мониторинга Москвы и обсерватории “Михнево” ИДГ РАН, а также данные, полученные рядом магнитных обсерваторий сети INTERNAGNET. Показано, что землетрясения, помимо сейсмического эффекта, сопровождались вариациями магнитного и электрического полей, а также генерацией инфразвуковых волн, зарегистрированных на значительном расстоянии от источников. (Серия катастрофических землетрясений в Турции 06.02.2023 г. и возмущение геофизических полей / В.В. Адушкин, А.А. Спивак, Ю.С. Рыбнов, А.В. Тихонова // Доклады Российской академии наук. Науки о Земле. – 2023. – Т. 510, № 2. – С. 227-232. – DOI 10.31857/S2686739723600327. – EDN UKVRGG.) Adushkin, V.V., Spivak, A.A., Rybnov, Y.S. et al. The Series of Catastrophic Earthquakes of February 6, 2023, in Turkey and Variations in the Geophysical Fields. Dokl. Earth Sc. 510, 481–486 (2023). https://doi.org/10.1134/S1028334X23600287

This work presents an analysis of data obtained through unique laboratory experiments on hydraulic fracturing. In the experiments, sufficiently large artificial samples were used to model a reservoir. Thus, it was possible to simulate several wells simultaneously, given that hydraulic fracture was initiated in one of them. In addition, the setup construction provided a true triaxial stress–strain state. The setup allowed us to investigate parameters that are difficult to access in real conditions. The data processing based on six laboratory experiments on hydraulic fracturing showed discrepancies between the values of the minimum stresses calculated from the fracture closure pressure and the actual values known based on the experimental conditions. There was also a discrepancy between the theoretical values of the fracture breakdown pressure and those obtained through the experiments. This paper examines phenomena such as backstress as the main reasons for this discrepancy. Backstress is stress acting on the walls of a fracture or well and is caused by the filtered hydraulic fracturing fluid. The authors demonstrated that by taking into account this phenomenon, one can significantly reduce the differences between calculated and experimental values. Therefore, the authors call for the careful use of the standard theory when determining the stress state in real fields. (Novikova, E.V.; Trimonova, M.A.; Turuntaev, S.B.; Zenchenko, E.V.; Zenchenko, P.E. Backstress Influence on the Formation Stress Field in Hydraulic Fracturing Experiments. Geosciences 2023, 13, 153. https://doi.org/10.3390/geosciences13060153)

Subsea permafrost stability is the key to whether pre-performed methane sequestered in hydrate deposits escapes to the overlying strata. By making use of the 1D numerical modeling and field data, we analyze the capabilities of the time-domain (transient) electromagnetic method (TDEM) when being applied for subsea permafrost mapping, and study the effect of the background resistivity structure on the inversion models’ accuracy for a series of settings typical for the East Siberian Arctic Shelf—the broadest and shallowest shelf in the world ocean, which represents more than 70% of the subsea permafrost. The synthetic response analysis included the construction of a series of resistivity models corresponding to different settings (presence/absence of ice-bonded permafrost layer, different position of its top and bottom boundaries, different width and thickness of thawed bodies or taliks, variable seawater depth and its resistivity), and calculation of synthetic apparent resistivity responses used to assess their sensitivity to changes in the target parameters of the resistivity structure. This was followed by regularized inversion of synthetic responses and comparing resulting models with original (true) ones, which allowed us to understand the possible uncertainties in the geometry and resistivity of the reconstructed permafrost layer, depending on seawater depth and unfrozen layer thickness, as well as confirm the overall efficacy of TDEM technology for the subsea permafrost imaging. That is crucially important for understanding the current state of the subsea permafrost-hydrate system and possible future dynamics. (Alekseev, D.A.; Koshurnikov, A.V.; Gunar, A.Y.; Balikhin, E.I.; Semiletov, I.P.; Shakhova, N.E.; Palshin, N.A.; Lobkovsky, L.I. Time-Domain Electromagnetics for Subsea Permafrost Mapping in the Arctic: The Synthetic Response Analyses and Uncertainty Estimates from Numerical Modelling Data. Geosciences 2023, 13, 144. https://doi.org/10.3390/geosciences13050144)

The software for visualization of the scattering diagrams (phase functions) of monochromatic visible range laser radiation that scatters on the spherical dielectric particles is developed. The comparative analysis of the angle characteristics of the Mie and Henyey–Greenstein phase functions is provided. (I. Galaktionov, V. Toporovsky, J. Sheldakova et al., Visscat: The software for scattering diagrams visualization and comparison, Software Impacts (2023) 100552, https://doi.org/10.1016/j.simpa.2023.100552)

С использованием данных магнитных наблюдений, выполненных в обсерваториях сети INTERMAGNET в период двойного землетрясения 16.03.2022 г. (Япония), продемонстрирован глобальный характер вызванных геомагнитных вариаций. Их синхронность и сопоставимая амплитуда в широком диапазоне расстояний от 210 до ~10 000 км, время запаздывания относительно рассматриваемых сейсмических событий (~55 мин) и преимущественный период вариаций ~30 мин свидетельствуют о том, что источником является геодинамо, возмущенное воздействием сейсмических волн, распространяющихся вглубь Земли. (В.В. Адушкин, А.А. Спивак ЭФФЕКТ ВЛИЯНИЯ СИЛЬНЫХ ЗЕМЛЕТРЯСЕНИЙ НА ГЕОДИНАМО // Доклады Российской академии наук. Науки о Земле, 2023, T. 511, № 1, стр. 61-64 EDN: RXCQLYDOI: 10.31857/S268673972360008X) Adushkin, V.V., Spivak, A.A. Effect of Strong Earthquakes on the Geodynamo. Dokl. Earth Sc. 511, 563–565 (2023). https://doi.org/10.1134/S1028334X23600494

The results of instrumental observations of acoustic oscillations and geomagnetic variations during the bolide-fall event on April 19, 2023 in the region of Kyiv (Ukraine) are presented. It is shown that the bolide explosion was accompanied by an acoustic signal recorded at a great distance from the epicenter of the event (~755 km) and was manifested in variations in the magnetic field. According to acoustic observations, four explosions of the largest fragments of the bolide were recorded. The total energy of the event was 4.2 × 1E11 J, which corresponds to about 0.1 kt in trinitrotoluene (TNT) equivalent. The maximum amplitude of geomagnetic variations caused by the bolide explosion at distances in the range of 454–909 km was 2.5 to 4 nT. (Adushkin, V.V., Rybnov, Y.S. & Spivak, A.A. Acoustic and Magnetic Effects of the Bolide Fall on April 19, 2023. Dokl. Earth Sc. (2023). https://doi.org/10.1134/S1028334X23601001)

Metamorphic transformations in felsic and mafic rocks in a zone of intense tectonic movements were compared. The object of study is the exhumed part of damage zone of Primorsky fault—main collision suture, which connects the Siberian Craton and the Olkhon Terrane. The studied area is located near the Khorga River. Collected metamorphic rock samples are represented by both “felsic” (plagiogranite-gneiss) and more “mafic” (amphibole–biotite plagiogneiss) rocks. The samples present two different parent rocks contacting each other but differ in chemical composition. The formation of identical metamorphic minerals of the garnet and epidote groups, associated with the processes of high-pressure regional metamorphism and, possibly, later collisional events, is detected in both rock types. The study of the chemical composition of rock-forming minerals provided estimates of the P–T conditions of metamorphism of these rocks by the method of multimineral thermobarometry. It was established that conditions of early metamorphism retain in amphibole-biotite plagiogneiss. Early metamorphism is characterized by high-pressure amphibolite facies of medium temperature next to eclogite facies. The parameters of later metamorphism are recorded in plagiogranite-gneiss, which occurred at higher pressure, but at a lower temperature, within the paragonite–kyanite–zoisite subfacies of the eclogitic facies, bordering on the greenschist facies. Associations of early metamorphism are poorly preserved in plagiogneiss.(Grigor’eva, A.V., Kozlovskiy, V.M., Gridin, G.A. et al. Metamorphic Transformations of Rocks in the Central Part of the Primorsky Fault, Western Baikalia. Dokl. Earth Sc. (2023). https://doi.org/10.1134/S1028334X23600962)

The hybrid model for analyzing distortions of a laser beam passed through a moderately scattering medium with the number of scattering events up to 10 is developed and investigated. The model implemented the Monte Carlo technique to simulate the beam propagation through a scattering layer, a ray-tracing technique to propagate the scattered beam to the measurements plane, and the Shack–Hartmann technique to calculate the scattered laser beam distortions. The results obtained from the developed model were confirmed during the laboratory experiment. Both the numerical model and laboratory experiment showed that with an increase of the concentration value of scattering particles in the range from 1E5 to 1E6 mm−3, the amplitude of distortions of laser beam propagated through the layer of the scattering medium increases exponentially. (Galaktionov I, Sheldakova J, Nikitin A, Toporovsky V, Kudryashov A. A Hybrid Model for Analysis of Laser Beam Distortions Using Monte Carlo and Shack–Hartmann Techniques: Numerical Study and Experimental Results. Algorithms. 2023; 16(7):337. https://doi.org/10.3390/a16070337)

The peculiarities of waveforms of the P and S receiver functions, constructed from the records of three closely located broadband seismic stations, are studied. The stations are located in the Avacha Bay area, near the subducting part of the Pacific Plate. This is an inclined slab, which is characterized by higher seismic velocities and can cause complex patterns of seismic waves, thus distorting the waveforms of receiver functions. In order to reveal the degree of such influence, we calculated two pairs of receiver functions. To calculate the first pair, we used the seismic events where seismic waves traveled through the subducting oceanic slab; in the case of the second pair, the waves did not travel through the slab. It is shown that converted and multiple waves formed at the boundaries of the high-velocity layer considerable distort the shapes of P receiver functions beginning approximately 30 seconds after the main arrival. The subducting slab does not show any considerable effect on the records of the S receiver function. This fact empirically supports the applicability of local one-dimensional models for interpreting the receiver functions. The seismic noise, generated by the oceanic slab, limits the maximum depth of these models at around 200 km in the study area. (Goev, A.G., Reznichenko, R.A. & Aleshin, I.M. Applicability of Receiver Functions in a Subduction Zone: Case Study of the Avacha Bay Area. Dokl. Earth Sc. 511, 698–702 (2023). https://doi.org/10.1134/S1028334X23600743)

Статья посвящена изучению строения земной коры и верхней мантии района Авачинской бухты полуострова Камчатка. Представлены полученные в ходе исследования одномерные разрезы зависимости сейсмических скоростей от глубины, построенные по данным станций “Петропавловск” (PET), “Дальний” (DAL), “Институт” (IVS) и “Карымшина” (KRM) за период с 2000 по 2019 гг. Станции входят в состав постоянной наблюдательной сети сейсмических станций Камчатского филиала Федерального исследовательского центра “Единая геофизическая служба РАН”. Разрезы построены до глубины 300 км, что позволяет дать характеристику строения среды в районе залива, а именно, выделить структурные слои в земной коре, границу Мохоровичича и оценить степень отклонения скоростей сейсмических волн в верхней мантии от соответствующих значений глобальной модели Земли IASP91. Усреднённые значения скоростей, рассчитанные по полученным разрезам, в земной коре и верхней мантии оказались заметно ниже по сравнению с глобальной моделью. Среднее отклонение наблюдённых скоростей от модельных составляет 0.5-1.0 км/с в коре, а затем постепенно уменьшается вплоть до глубины порядка 180 км. На бóльших глубинах скорости в полученных моделях совпадают со стандартными значениями. Следует отметить, что в местах расположения сейсмических станций нижняя граница погружающейся Тихоокеанской плиты проходит на глубинах около 180 км. Поэтому, вероятно, основная причина расхождения скоростей связана с существенным нагревом вещества и сложной флюидодинамической обстановкой в области мантийного клина. (Глубинные скоростные разрезы района Авачинской бухты полуострова Камчатка, полученные методом функций приёмника / Р. А. Резниченко, А. Г. Гоев, И. М. Алешин [и др.] // Геофизические исследования. – 2023. – Т. 24, № 2. – С. 25-38. – DOI 10.21455/gr2023.2-2. – EDN KBYGPJ.)

В основе предлагаемого подхода лежит известное из лабораторных экспериментов положение о том, что текущие фрикционные свойства поверхности скольжения отражаются и на очаговых параметрах отдельных индуцированных микросейсмических событий, и в характеристиках сейсмоакустического шума, источники которого локализованы в зоне разлома. Методика основана на оценке величины приведенной сейсмической энергии, что позволяет судить о вероятности реализации накопленной в массиве упругой энергии в виде динамических событий. На примере данных, зарегистрированных на Коробковском железорудном месторождении Курской магнитной аномалии, проведена оценка очаговых параметров сейсмических событий, индуцированных взрывами. На основе полученных результатов показано, что на шахте «КМА-руда» зарегистрирован рой инициированных массовым взрывом микроземлетрясений с низкой скоростью распространения разрыва. Показана перспективность применения методов машинного обучения для определения времени и магнитуды готовящегося динамического события в режиме реального времени на основе данных лабораторных экспериментов с АЭ. Полученные результаты могут быть использованы для краткосрочного прогноза крупных динамических событий в условиях работающего рудника. Проведенный анализ показал перспективность создания новых методов мониторинга напряженных массивов при ведении горных работ с целью предупреждения инициирования крупных землетрясений, связанных с динамическим смещением по тектоническим разломам. (А.Н. Беседина, Г.Г. Кочарян Новый подход к снижению риска крупных техногенных землетрясений, основанный на результатах микросейсмического мониторинга // Горная промышленность. – 2023. – № S1. – С. 28-34. – DOI 10.30686/1609-9192-2023-S1-28-34. – EDN FFYZQQ.)

Рассмотрены возможные механизмы, вызывающие деградацию и катастрофические отказы микроэлектронной элементной базы в полях мощного электромагнитного излучения. Проанализированы результаты экспериментальных исследований и модели, используемые для анализа механизмов повреждения современных интегральных микросхем при воздействии радиоизлучения. Определены критериальные уровни функционального поражения полупроводниковых приборов сверхкороткими видеоимпульсами 0,1-1,0 нс при плотности потока от 2 до 5 Вт/см2. Установлено, что снижение критериальных уровней поражения находится в прямой зависимости от увеличения длины волны воздействующего излучения, так как основной механизм пробоя связан с поглощением энергии квантов электромагнитного излучения, энергия которых прямо пропорциональна частоте излучения. (Дмитриев, В. Г. Влияние сильных электромагнитных полейна устойчивость элементной базы радиоэлектронных систем / В. Г. Дмитриев, А. И. Куприянов, Ю. М. Перунов // Ракетно-космическое приборостроение и информационные системы. – 2023. – Т. 10, № 2. – С. 89-95. – DOI 10.30894/issn2409-0239.2023.10.2.89.95. – EDN PXOKOP.)

Холодная плазма ионосферы, в основном влияющая на условия распространения радиоволн в околоземном пространстве, образуется вследствие ионизации нейтральных атомов и молекул атмосферных газов жестким солнечным и космическим излучением. Но современные технологии позволяют управлять параметрами ионосферы. Прежде всего - коэффициентом преломления. Для активного воздействия на ионосферу и целенаправленного изменения условий распространения радиосигналов в околоземном пространстве используются нагревные стенды - мощные передатчики с фазированными антенными системами. Энергия излучаемых электромагнитных полей резонансно поглощается ионосферой, повышая степень замагниченности магнитоактивной плазмы. В результате создаются условия для генерации сигналов очень низких частот, пригодных для организации связи с подземными и подводными объектами; обеспечение сверхдальней связи за счет использования специфических волноводов, образованных ионосферными слоями F 1 и F 2 ; создание локальных областей пространства с высокой ионизацией для деструктивного воздействия на космические объекты; формирование активных помех радиоэлектронным системам связи, передачи данных, радиолокации и радионавигации; генерации биологически активных сигналов. Использование нагревных стендов для управления состоянием ионосферы также открывает возможности и других как практических, так и научно-исследовательских применений. (Дмитриев, В. Г. Техногенные воздействия на среду распространения радиосигнала / В. Г. Дмитриев, А. И. Куприянов, Ю. М. Перунов // Техника средств связи. – 2023. – № 1(161). – С. 2-12. – DOI 10.24412/2782-2141-2023-1-2-12. – EDN BGZLZX.)

Here, we present a numerical model for simulating the formation and evolution of the gas and dust cloud that forms after the detonation of high explosive charges in boreholes. This model provides a possible method for converting a substance ejected from an explosion funnel into discrete particles (smaller particles and stones) and calculating the movement of these condensed particles and their interaction with the air–gas flow; this method uses the framework of equations for multiphase media motion. For modeling of borehole explosion, we focused on the parameters of commercial blasting that are carried out at the Lebedinsky open pit. The results of simulating the initial stage of a borehole explosion with a mass of 1000 kg are presented in this paper. These results demonstrate the evolution of a gas and dust cloud, the change in the mass of particles of different sizes in the air over time, and their spatial distribution. (Shuvalov V, Khazins V, Krasheninnikov A, Soloviev S. Formation and Evolution of a Dust Cloud as a Result of TNT Detonation in a Borehole: Numerical Simulation. Mining. 2023; 3(2):261-270. https://doi.org/10.3390/mining3020016)

This paper presents a FPGA-based closed-loop adaptive optical system with a bimorph deformable mirror for correction of the phase perturbation caused by artificial turbulence. The system’s operating frequency of about 2000 Hz is, in many cases, sufficient to provide the real-time mode. The results of the correction of the wavefront of laser radiation distorted by the airflow formed in the laboratory conditions with the help of a fan heater are presented. For detailed consideration, the expansion of the wavefront by Zernike polynomials is used with further statistical analysis based on the discrete Fourier transform. The result of the work is an estimation of the correction efficiency of the wavefront distorted by the turbulent phase fluctuations. The ability of the bimorph adaptive mirror to correct for certain aberrations is also determined. As a result, it was concluded that the adaptive bimorph mirrors, together with a fast adaptive optical system based on FPGA, can be used to compensate wavefront distortions caused by atmospheric turbulence in the real-time mode.

A option of the methodology for observing PM2.5 and PM10 particle mass concentrations based on an Arduino UNO board and Sensirion SPS30 laser sensor has been developed. The measuring system built according to the technique was used in a field experiment, as well as in continuous observations at a stationary point: the Moscow Geophysical Monitoring Center of the Institute of Dynamics of Geospheres, Russian Academy of Sciences (IDG RAS). Examples of variations in the observed characteristics are given, which indicate the possibility of using the instrumental system in addition to already existing devices when observing the geophysical environment. Continuous monitoring of microparticle concentrations at the Geophysical Monitoring Center will make it possible not only to assess the degree of atmospheric pollution in the megalopolis, but also highlight certain trends, frequencies, and patterns. Such monitoring will also make it possible to reveal the contribution of various sources to the increase in microparticle concentrations, as well as the effect of pollution on different geophysical fields.

Tectonic faults show rheological heterogeneity in interfaces, and the spectrum of their sliding regimes span a continuum from the slow-slip events to dynamic ruptures. The heterogeneity of the fault interface is crucial for the mechanics of faulting. By using the earthquake source locations, the complex structure of a fault interface can be reproduced at a resolution down to 50–100 m. Here, we use a declustered seismic catalog of Northern California to investigate structures of 11 segments of San Andreas, Calaveras, and Hayward faults. The cumulative length of all the segments is about 500 km. All the selected segments belong to subvertical strike–slip faults. A noticeable localization of sources near the fault cores is observed for all segments. The projection of earthquake sources to the fault plane shows severe inhomogeneity. Topologically dense clusters (seismogenic patches (SPs)) can be detected in fault planes. The longer the observation are, the more distinct are the clusters. The SPs usually cover about 10%–20% of the fault interface area. It is in the vicinity of SPs that earthquakes of magnitudes above 5 are usually initiated. The Voronoi tessellation is used to determine the orderliness of SPs. Distributions of areas of Voronoi cells of all the SPs obey the lognormal law, and the value of Voronoi entropy of 1.6–1.9 prevails. The findings show the informativeness of the background seismicity in revealing the heterogenous structure of a tectonic fault interface.

The low-frequency component of the distortions caused by both the atmospheric turbulence and the behavior of the telescope itself has been studied. A corrector for the position of the center of the star image has been developed and is being used in front of the high-resolution Echelle spectrograph on the 6 m telescope of the Special Astrophysical Observatory, Russian Academy of Sciences. To speed up the calculations and to increase the bandwidth, a laser beam angular stabilization system based on an FPGA platform is considered. The system consists of two tip-tilt mirrors and two quadrant photodiodes. The FPGA analyzes the signals from the photodiodes, calculates and then applies the voltages to the piezo-driven tip-tilt mirrors to minimize the displacement of the beam on the photodiodes. The stabilization system was developed as a part of the adaptive optical system to improve the efficiency of the high-resolution Echelle spectrograph.

It is the first time when we present a significant amount of two-channel (north-south and west-east) absolute magnetic field data in the extremely low frequency (ELF) band for the European Russia. The measurements are evaluated at Mikhnevo geophysical observatory of the Sadovsky Institute of Geosphere Dynamics. We start with a recently proposed unified processing procedure by Rodriguez-Camacho et al. (2018, https://doi.org/10.1029/2018jd029462) and further elaborate an ELF spectrum calculation technique. The true sequence of the spectrum calculation is presented, including the proper parameters, software requirements, and the use of third-party libraries. We receive an optimal set of processing parameters for Mikhnevo observatory and discuss the long-term (2016–2020) Schumann Resonance variations.

Представлены результаты сопоставления трех различных плазмохимических моделей D-области ионосферы во время рентгеновских вспышек C- и X-классов. Рассмотрены четырех-, пяти- и восьмикомпонентная модели, описывающие динамику заряженных составляющих среды. Для верификации результатов были использованы данные наземных радиофизических измерений, полученных в Геофизической обсерватории Михнево. Полученные по трем моделям высотные профили концентрации электронов использовались для описания среды распространения радиоволн на четырех среднеширотных СДВ-трассах (3–30 кГц). В результате верификации было получено, что четырех- и пятикомпонентная модели описывают экспериментальные данные лучше, чем восьмикомпонентная модель, как в спокойных гелиогеофизических условиях, так и во время естественных возмущений.(БЕККЕР С.З. ВЕРИФИКАЦИЯ ПЛАЗМОХИМИЧЕСКИХ МОДЕЛЕЙ D-ОБЛАСТИ ИОНОСФЕРЫ ПО РАДИОФИЗИЧЕСКИМ ДАННЫМ ГЕОФИЗИЧЕСКОЙ ОБСЕРВАТОРИИ МИХНЕВО // ГЕОМАГНЕТИЗМ И АЭРОНОМИЯ. Т.62, №3 2022 С.365-373 DOI: 10.31857/S001679402202002X EDN: AKWARD)

An experimental study was made of the dependence of the electron-density perturbations in the D‑regions of the midlatitude ionosphere during solar flares on the spectral composition of X-ray radiation in the wavelength range from 0.01 to 0.4 nm, i.e., outside the measurement range of the GOES satellite. For this, the variation in the brightness temperature of the emission of six flares in 2014–2017 were calculated, and the composition of their radiation was determined. It is shown that, although only a small percent of the total flash radiation energy is in the 0.01–0.2 nm wavelength range, it is the hard components that are the main factor leading to a change in the reflection height of very low frequency (VLF) radio waves. It is shown that the efficiency of solar flares significantly depends on the previous solar activity, not only for class-C flares but also for powerful class-M and -X flares. (ГАВРИЛОВ Б.Г., ПОКЛАД Ю.В., РЯХОВСКИЙ И.А., ЕРМАК В.М. ЗАВИСИМОСТЬ ВОЗМУЩЕНИЙ D-ОБЛАСТИ СРЕДНЕШИРОТНОЙ ИОНОСФЕРЫ ОТ СПЕКТРАЛЬНОГО СОСТАВА РЕНТГЕНОВСКОГО ИЗЛУЧЕНИЯ СОЛНЕЧНЫХ ВСПЫШЕК ПО ЭКСПЕРИМЕНТАЛЬНЫМ ДАННЫМ // ГЕОМАГНЕТИЗМ И АЭРОНОМИЯ, 2022, т.62, №2, с.239-244 DOI: 10.31857/S0016794022020080, EDN: GQFRIC)

A complex prognostic feature of dangerous atmospheric phenomena like hurricanes, squalls, and strong thunderstorms is proposed. It is based on the analysis of joint variations in the electric field and the vertical current of the surface atmosphere, magnetic field, and atmospheric pressure micropulsations in the period preceding the most intensive manifestations of these phenomena. The data obtained can help to improve the reliability of short-term predictions of dangerous consequences of strong atmospheric phenomena. (СПИВАК А.А., РЫБНОВ Ю.С., РЯБОВА С.А. КОМПЛЕКСНЫЙ ПРОГНОСТИЧЕСКИЙ ПРИЗНАК ОПАСНЫХ АТМОСФЕРНЫХ ЯВЛЕНИЙ // ДОКЛАДЫ РОССИЙСКОЙ АКАДЕМИИ НАУК. НАУКИ О ЗЕМЛЕ. Т.504, №1, 2022 С.69-74 , EDN: UGIUPC DOI: 10.31857/S2686739722050152)

The parameters and peculiarities of a catastrophic rockburst that occurred at the Umbozero rare-metal mine located in the Lovozero massif (central Kola Peninsula), at a distance of about 50 km from the Khibiny massif, are presented. According to the seismic network of the United Geophysical Survey, Russian Academy of Sciences, the magnitude of this seismic event was ML = 5.1; the data from Norwegian seismic stations showed mb = 5.9. The energy released at the source was E = 1.02 × 1Е12 J. The source with such value of elastic energy was several tens of kilometers in size, and the source depth was 4–7 km, which reached the working of the mine. As a result of the rockburst, intensive destruction of mine workings occurred, ore mining was stopped, and the mine was closed. The paper also calculated the released energy not only by the parameters of seismic waves of various types, but also by the magnitude of the seismic moment, using the experimental data on the slip in the source (0.16 m) and the area of the slip along the fault (about 3 × 105 m2). As a result, the values of the seismic moment M0 = 11.5 × 1Е12 t m of energy class K = 11.8 and the energy released in the source E = 1Е12 J were obtained, and all these data are consisted with the results calculated from the parameters of the seismic waves. (АДУШКИН В.В., ЛОВЧИКОВ А.В., ГОЕВ А.Г. О ВОЗНИКНОВЕНИИ КАТАСТРОФИЧЕСКОГО ГОРНО-ТЕКТОНИЧЕСКОГО УДАРА НА РУДНИКЕ “УМБОЗЕРО” В ЛОВОЗЁРСКОМ МАССИВЕ В ЦЕНТРАЛЬНОЙ ЧАСТИ КОЛЬСКОГО ПОЛУОСТРОВА // ДОКЛАДЫ РОССИЙСКОЙ АКАДЕМИИ НАУК. НАУКИ О ЗЕМЛЕ Т.504, №1, 2022, С.85-90 EDN: PZXFEP DOI: 10.31857/S2686739722050036)

This paper presents an attempt to reconstruct the Campo del Cielo (CdC) impact event, that is, to estimate the preatmospheric mass and velocity of the iron meteoroid and pre-impact parameters of its fragments allowing formation of funnels and impact craters. The goal of this study is to improve the understanding of the effects small-scale iron meteoroids can have on the Earth's surface. We model the meteoroid's atmospheric flight taking deceleration, ablation, and fragmentation into account, and then compare the results with available observations. We found that a fragment's velocity near the surface should be <1 km/s in order to form a funnel with an intact meteorite inside. The estimates of preatmospheric (at an altitude of 100 km) parameters of the CdC impact event are as follows: minimal mass of 7500–8500 t, which corresponds to a diameter range of 12.2–12.8 m; maximum entry angle above the atmosphere of ~16.5° and velocities of 14.5–18.4 km/s, which is close to the one most frequently reached by near-Earth objects (NEOs). Near the surface, the largest fragments with a mass of 400–1500 t and velocities of 4–7 km/s form impact craters whereas fragments with a mass <31 t and velocities <1 km/s form funnels. Masses <3 t are not included in our simulations. Their total mass is 280–460 t at the point of disruption but <110 t on the Earth's surface. These numerous small fragments are dispersed over a large area and are very popular among meteorite hunters and dealers. In spite of all the observed crater location/size data and impactor velocity limits from the models, there are far more free parameters than constraints. As a result, any values for preatmospheric mass, velocity, and entry angle are merely representative or limitative as opposed to true values.

A study is performed of the possibility of using nanotechnology to produce bimorph wavefront correctors. Results are presented for the laser ablation of a conductive layer from the surface of a piezodisk using a pulsed Nd:YAG laser. Split-tip welding technology is used to create reliable copper wire–silver layer electrical contacts.(ТОПОРОВСКИЙ В.В., КУДРЯШОВ А.В., СКВОРЦОВ А.А., САМАРКИН В.В., ШЕЛДАКОВА Ю.В., РУКОСУЕВ А.Л. НАНОТЕХНОЛОГИЧЕСКИЕ МЕТОДЫ В ЗАДАЧАХ СОЗДАНИЯ СОВРЕМЕННЫХ ПЬЕЗОЭЛЕКТРИЧЕСКИХ КОРРЕКТОРОВ ВОЛНОВОГО ФРОНТА // ИЗВЕСТИЯ РОССИЙСКОЙ АКАДЕМИИ НАУК. СЕРИЯ ФИЗИЧЕСКАЯ. Т.86, №6, 2022. С.873-878. DOI: 10.31857/S0367676522060308 EDN: FSOCIW)

The results of instrumental observations for meteoparameters, microbaric variations, and variations in an electric field are analyzed at the Mikhnevo Observatory and the Center for Geophysical Monitoring, Moscow of the Institute of Geospheric Dynamics, Russian Academy of Sciences, as are geomagnetic variations from observatories of the INTERMAGNET network during the explosive eruption of Hunga–Tonga–Hunga–Ha’apai volcano on January 15, 2001. It is shown that the volcanic explosion was accompanied by wave disturbances of the atmosphere and strong variations in the magnetic and electric fields at significant epicentral distances. Together with Lamb waves caused at the explosion epicenter, we registered waves caused by a virtual source located in the antipode, as well as secondary and tertiary direct (from the explosion epicenter) and antipode waves indicating that the wave atmospheric signal skirts the Earth three times. The source energy estimated by the typical frequency in the signal spectrum is ~1018 J, which corresponds to a ~200 Mt TNT explosion with recalculation to the explosive source. It is shown that the volcanic explosion was responsible for the global variations in the electric and magnetic fields.(АДУШКИН В.В., РЫБНОВ Ю.С., СПИВАК А.А. ГЕОФИЗИЧЕСКИЕ ЭФФЕКТЫ ИЗВЕРЖЕНИЯ ВУЛКАНА ХУНГА-ТОНГА-ХУНГА-ХААПАЙ 15.01.2022 Г. // ДОКЛАДЫ РОССИЙСКОЙ АКАДЕМИИ НАУК. НАУКИ О ЗЕМЛЕ // Т.504, №2, 2022. С.156-162. DOI: 10.31857/S2686739722060032 EDN: MXHQEV)

The results of instrumental observations of acoustic oscillations and geomagnetic variations during the fall of the bolide on November 17, 2021, near the town of Izhevsk (Russia) are presented. It is shown that the bolide explosion was accompanied by an acoustic signal and manifested itself in magnetic field variations. Based on the data of acoustic observations performed at three observatories, the probable region of destruction of the bolide was determined and the energy of the acoustic source was estimated. It is noted that the geomagnetic effect caused by the bolide explosion had a nonlocal character and was observed at epicentral distances of up to ~4000 km.(РЫБНОВ Ю.С., РЯБОВА С.А., СПИВАК А.А. АКУСТИЧЕСКИЙ И МАГНИТНЫЙ ЭФФЕКТ ПАДЕНИЯ БОЛИДА 17.11.2021 Г. // ДОКЛАДЫ РОССИЙСКОЙ АКАДЕМИИ НАУК. НАУКИ О ЗЕМЛЕ. Т.504, №2, 2022. С.183-188 DOI: 10.31857/S2686739722060135 EDN: LTKTZN)

The deep structure of the crust and the upper mantle of the Kola Peninsula and adjacent territories is studied using representative data on the dispersion of group velocities of surface waves in the period range of 10–250 s. The distributions of group velocities of Rayleigh and Love waves with their estimated horizontal resolution are calculated by surface wave tomography. The velocity sections of SV- and SH-waves to a depth of 500 km are calculated from the maps for the western and eastern parts of the Kola Peninsula. The results of this study are characterized by higher horizontal resolution relative to the current surface wave models and allow tracing the main peculiarities of the structure of the crust and the upper mantle of the study territory. Our results indicate possible differences in the structure of the crust and the value of radial anisotropy of the upper mantle for the western and eastern parts of the Kola Peninsula.(ФИЛИППОВА А.И., СОЛОВЕЙ О.А. ПОВЕРХНОСТНО-ВОЛНОВАЯ ТОМОГРАФИЯ КОЛЬСКОГО ПОЛУОСТРОВА И СОПРЕДЕЛЬНЫХ ТЕРРИТОРИЙ ПО ДАННЫМ ДИСПЕРСИИ ГРУППОВЫХ СКОРОСТЕЙ ВОЛН РЭЛЕЯ И ЛЯВА // ДОКЛАДЫ РОССИЙСКОЙ АКАДЕМИИ НАУК. НАУКИ О ЗЕМЛЕ. Т.504, №2, 2022. С.177-182 DOI: 10.31857/S2686739722060068 EDN: SYWFMP)

The results of numerical simulation of the generation and the initial stage of tsunami wave propagation during the impacts of asteroids with sizes of about 10 km into an ocean with a depth of 1 to 6 km are presented. The calculations obtained the amplitudes and wavelengths at a distance of 2000 km from the impact point. Approximate formulas are given that make it possible to estimate the amplitudes and wavelengths with an accuracy of 10–20%. The conclusion is confirmed that when an asteroid with a size of about ten kilometers falls into the ocean, long tsunami waves are generated, similar to those that occur during earthquakes. (ШУВАЛОВ В.В. ГЕНЕРАЦИИЯ ВОЛН ЦУНАМИ ПРИ ПАДЕНИИ ДЕСЯТИКИЛОМЕТРОВЫХ АСТЕРОИДОВ В ОКЕАН // АСТРОНОМИЧЕСКИЙ ВЕСТНИК. ИССЛЕДОВАНИЯ СОЛНЕЧНОЙ СИСТЕМЫ. Т.56 №4 2022. С.285-292 DOI: 10.31857/S0320930X22030069 EDN: KHWUQA)

Disturbances of seismic noise, magnetic field, electrical characteristics of the surface atmosphere and microbaric variations caused by the passage of cold atmospheric fronts of the 2nd kind are discussed. A new approach to a complex prognostic sign of strong atmospheric fronts, potentially dangerous by their effects such as hurricanes, squalls and severe thunderstorms, based on the analysis of joint variations of the electric field and vertical current of the surface atmosphere, magnetic field and micropulsations of atmospheric pressure in the period preceding the onset of the most intense manifestations of these phenomena, is proposed. The data obtained can contribute to improving the reliability of the short-term forecast of dangerous atmospheric phenomena. (СПИВАК А.А., ОВЧИННИКОВ В.М., РЫБНОВ Ю.С., РЯБОВА С.А., ХАРЛАМОВ В.А. СЕЙСМИЧЕСКИЕ, АТМОСФЕРНО-ВОЛНОВЫЕ, ЭЛЕКТРИЧЕСКИЕ И МАГНИТНЫЕ ЭФФЕКТЫ МОЩНЫХ АТМОСФЕРНЫХ ФРОНТОВ // ФИЗИКА ЗЕМЛИ. 2022, №4 С.56-70 DOI: 10.31857/S0002333722040111 EDN: DKGUFT)

The intensification of geomagnetic variations due to a number of strong remote earthquakes is studied using a chain of ground-based midlatitude magnetic stations located a few thousand km away from each other. It is shown that the spectral peaks of the variations at periods between 5 and 13 min (the range of magnetic pulsations Pc5–Pc6) can be caused by the corresponding variations in the components of the interplanetary magnetic field. Geomagnetic variations with periods longer than 13 min are interpreted as the result of the propagation of slow magnetohydrodynamic (MHD) waves excited in the ionosphere by acoustic pulse after earthquakes or as the result of the passage of traveling ionospheric disturbances. (РЯБОВА С.А., ШАЛИМОВ С.Л. О ГЕОМАГНИТНЫХ ВАРИАЦИЯХ, НАБЛЮДАЕМЫХ НА ПОВЕРХНОСТИ ЗЕМЛИ И ПРИУРОЧЕННЫХ К СИЛЬНЫМ ЗЕМЛЕТРЯСЕНИЯМ // ФИЗИКА ЗЕМЛИ. 2022. №4 С.30-45 DOI: 10.31857/S0002333722040081 EDN: NWTDXO)

The formation of supershear rupture (with a slip front propagation velocity higher than S-wave velocity in the material) along a model fault with homogeneous and heterogeneous surface is analyzed based on the results of numerical simulation. Heterogeneity of the properties is specified by friction spots weakening at shear, interspersed with stable friction segments between them. This problem statement goes back to the well-known asperity model (Kanamori and Stewart, 1978). In this paper, we use seismological and geodetic data to estimate characteristic sizes of the fault-zone segments that are locked during interseismic period. Calculations show that the characteristic sizes of inhomogeneities on the slip plane largely determine the pattern of dynamic rupture propagation. A necessary condition for rupture to pass into supershear is a sufficiently rapid frictional weakening. The observed wavefield features (relatively weak attenuation, an increase in the amplitude of oscillations at some distance from the hypocenter, the predominant motion in the direction parallel to the fault, etc.) do not necessarily need nonlinear medium and are not the result of generation of a “shock wave,” as assumed in some publications, but are only a result of wavefront interference. Interaction between regions with different frictional properties can cause rupture transition to supershear, induce dynamic slip pulses which re-fracture the fault segments previously displaced by the creep process, and slowdown rupture propagation. Judging by the results of calculations, rupture is more likely to accelerate into supershear on rough/undulating segments of contact surfaces with closely spaced frictional weakening zones. At the same time, propagation of such a rupture with a decaying displacement amplitude can be stable on locally smoother segments. (БУДКОВ А.М., КИШКИНА С.Б., КОЧАРЯН Г.Г. МОДЕЛИРОВАНИЕ СВЕРХСДВИГОВОГО РЕЖИМА РАСПРОСТРАНЕНИЯ РАЗРЫВА ПО РАЗЛОМУ С ГЕТЕРОГЕННОЙ ПОВЕРХНОСТЬЮ // ФИЗИКА ЗЕМЛИ. 2022, №4, С.135-150 DOI: 10.31857/S0002333722040019 EDN: WHLNMX)

The article describes the lab-scale testing of dynamic instability in a block placed on a rough slope surface and subjected to small-amplitude vibrations. It is shown that the macroscopic sliding evolution is well-presented using equations of creep with the properly selected constants. According to the testing data, the necessary condition of the dynamic failure is the critical displacement along the slope and the certain creep rate. The critical displacement appears to exceed greatly the typical value when the sliding surface transits to the residual shear resistance. It is found that the landslide body instability develops at the late stage due to the phenomenon of reduction in friction at increasing sliding velocity. (КОЧАРЯН Г.Г., ШАРАФИЕВ З.З., КИШКИНА С.Б., ЧЕН ЧЖИ ЦИ ЭФФЕКТ СНИЖЕНИЯ ТРЕНИЯ В ОСНОВАНИИ ГРАВИТАЦИОННОГО ОПОЛЗНЯ ПОД ДЕЙСТВИЕМ СЕЙСМИЧЕСКИХ КОЛЕБАНИЙ // ФИЗИКО-ТЕХНИЧЕСКИЕ ПРОБЛЕМЫ РАЗРАБОТКИ ПОЛЕЗНЫХ ИСКОПАЕМЫХ. 2022, №2, С.3-14 DOI: 10.15372/FTPRPI20220201 EDN: HLLKXJ)

Product miniaturization of micro-engineering technology with energy consumption at the level of milli- and microwatts requires a corresponding reduction in the characteristic dimensions of personal energy sources and an increase in the duration of their operation, otherwise it will not be possible to ensure the proper autonomy and service life of the promising developments. The most actual problem manifests itself in the field of information technology, medicine, and space activities. According to this need, there is a constant improvement of traditional (chemical, piezoelectric, etc.) sources within significant objective limitations. Significant new prospects are associated with the use of the energy released during radioactive decay as an energy source. The power density reserve (per unit mass) of radionuclides exceeds that of the best chemical sources by hundreds of thousands of times. The known radionuclides, which meet the relevant requirements and can be used to solve the problem of development and mass production of long-term radiation-safe betavoltaic atomic batteries are considered in the study. 360-366 (Л.А. Цветков, С.Л. Цветкова, А.А. Пустовалов, В.Н. Вербецкий, Н.Н. Баранов, А.А. Мандругин РАДИОНУКЛИДЫ ДЛЯ Β-ВОЛЬТАИЧЕСКИХ АТОМНЫХ БАТАРЕЙ (МИНИАТЮРНЫХ, ЭНЕРГОЕМКИХ, С МНОГОЛЕТНИМ СРОКОМ СЛУЖБЫ) // РАДИОХИМИЯ, 2022, vol. 64, No. 3, p. 281-288 DOI: 10.31857/S00338311210300X)

This paper discusses the data of instrumental observations conducted at the Mikhnevo Observatory, at INTERMAGNET observatories, and at the Geophysical Monitoring Center of the Institute of Geosphere Dynamics (IGD), Russian Academy of Sciences (RAS) during the explosive eruption of Hunga Tonga-Hunga Ha’apai Volcano of January 15, 2022. It is shown that the explosion of the volcano produced a series of wave disturbances in the atmosphere, as well as electrical and magnetic variations at large epicentral distances. The atmospheric disturbances were recorded as Lamb waves emitted by a source at the center of the explosion, as well as by a virtual source situated at the antipode. The latter source was formed by convergence and summing of signals propagating on the terrestrial sphere. In addition to primary waves, the recorded phenomena also include secondary and tertiary waves due to multiple passage of the explosion-produced signal around the terrestrial sphere. We evaluated the source energy based on the characteristic frequency in the spectrum of the signal, resulting in the value ~1018 J, which corresponds to ~200 MT of TNT, when converted to an explosive source. It is shown that a volcanic explosion is accompanied by electrical and magnetic variations both at the time of the explosion and at the time when the recording site receives atmospheric wave disturbances. (АДУШКИН В.В., РЫБНОВ Ю.С., СПИВАК А.А. ВОЛНОВЫЕ, ЭЛЕКТРИЧЕСКИЕ И МАГНИТНЫЕ ЭФФЕКТЫ КАТАСТРОФИЧЕСКОГО ИЗВЕРЖЕНИЯ ВУЛКАНА ХУНГА-ТОНГА-ХУНГА-ХААПАЙ 15.01.2022 Г. // ВУЛКАНОЛОГИЯ И СЕЙСМОЛОГИЯ. 2022, №4, С.17-30. EDN: DDQKBQ DOI: 10.31857/S0203030622040022)

The results of the analysis of the aftershock sequences initiated by the underground nuclear tests conducted in North Korea in 2016 and 2017 are presented. Waveform cross-correlation and a multi-master method applied to phase association allowed us to find and analyze almost 100 aftershocks and divide them into two clusters related to the underground explosions conducted on 09.09.2016 (DPRK-5) and on 03.09.2017 (DPRK-6). The duration, intensity, and sporadic nature of these two sequences indicate specific mechanisms of seismic energy release, probably related to the interaction of the destruction zones of the DPRK-5 and DPRK-6 explosions and the collapse of their cavities with the gradual advance of the collapse column to the free surface. The after-shock activity in 2021 allows assuming the collapse process is not yet completed and expecting new aftershocks in the near future, which could end in the collapse column reaching the free surface. These assumptions were confirmed - during the preparation of the article, on 11.02.22, a strong aftershock with a magnitude of 3.85 was recorded, which, according to preliminary estimates, indicates the beginning of the final stage of the collapse, the probability of which is discussed in this study. (КИТОВ И.О., САНИНА И.А. АНАЛИЗ ПОСЛЕДОВАТЕЛЬНОСТЕЙ АФТЕРШОКОВ, ИНИЦИИРОВАННЫХ ПОДЗЕМНЫМИ ЯДЕРНЫМИ ИСПЫТАНИЯМИ, ПРОВЕДЕННЫМИ В СЕВЕРНОЙ КОРЕЕ 09.09.2016 Г. И 03.09.2017 Г. // СЕЙСМИЧЕСКИЕ ПРИБОРЫ. 2022, Т.58, №3, С.25-42 DOI: 10.21455/si2020.3-2 EDN: PEBNXV)

The interference of electromagnetic signals from lightning discharges in the frequency range below 100 Hz is the source of a global electromagnetic phenomenon in the Earth's atmosphere known as the Schumann resonance (SR). Changes in the parameters of SR signals caused by geophysical disturbances make it possible to study the state and dynamics of the lower ionosphere. When calculating the SR parameters, there are problems associated with the impact of electromagnetic interference of natural and anthropogenic origin. The main natural sources of interference are signals associated with the radiation of nearby lightning discharges, as well as the influence of the Alfvén ionospheric resonator. The paper presents a new method for calculating the SR parameters, which makes it possible to find the spectra distorted by interference, mention above, and exclude them from further processing. The developed technique significantly increased the temporal resolution of the obtained data on the frequency and amplitude of the SR. Due to this, it became possible to study the influence of fast heliogeophysical disturbances (such as solar X-ray flares) on the lower ionosphere and, as a consequence, on the parameters of the SR. An analysis of the experimental data made it possible to establish a linear dependence of the SR frequency on the logarithm of the X-ray flux in the range up to 0.2 nm during a class X solar flare.

В работе представлены результаты численного моделирования напряженно-деформированного состояния самоподъемных плавучих буровых установок, использующихся для освоения шельфовых месторождений углеводородов. Изучены равновесное напряженное состояние установки, погруженной в донный грунт, и его изменение, вызванное внешним механическим воздействием. Рассмотрена частная задача, в рамках которой в роли внешнего воздействия выступает поверхностная сейсмическая волна от удаленного землетрясения. Исследован отклик системы «самоподъемная плавучая буровая установка – донный грунт» на такое воздействие: проанализировано перераспределение полей напряжений и деформаций в системе, вызванное сейсмическим воздействием. Рассмотрен вопрос устойчивости установки: продемонстрировано, что приход сейсмической волны приводит к резкому росту напряжений в определенных элементах опорных колонн, что может привести к потере устойчивости. Для численного моделирования рассмотренной контактной задачи теории упругости использован метод конечных элементов. Проверка корректности постановки задачи и сходимости ее решения была выполнена путем рассмотрения известной задачи о вдавливании жесткого цилиндра в упругое полупространство. Показано, что использующаяся для анализа устойчивости самоподъемной буровой установки численная схема дает верные результаты для рассмотренной модельной задачи при условии корректного построения сетки конечных элементов. В рамках работы были исследованы роли различных факторов, определяющих условия достижения напряжениями в самоподъемной плавучей буровой установке критических значений: рассмотрены степень выраженности сейсмического воздействия, механические свойства донного грунта и глубина погружения опорных колонн установки в грунт. Сделаны предварительные выводы о необходимости заглубления опорных колонн в донный грунт с учетом его механических свойств и характерной для региона сейсмичности. Представленный в работе подход может быть использован в качестве инструмента для прогноза рисков, связанных с освоением месторождений углеводородов, расположенных на континентальном шельфе, а использованная схема численного моделирования — для решения класса контактных задач теории упругости, требующих анализа динамических процессов. (Vasiliev I.A., Dubinya N.V., Tikhotskiy S.A., Nachev V.A., Alexeev D.A. Numerical model of jack-up rig’s mechanical behavior under seismic loading // Computer Research and Modeling, 2022, vol. 14, no. 4, pp. 853-871)

Time dependences of gasdynamic parameters of the high-speed aluminum plasma jets injected into the ionosphere at altitudes 140–300 km plasma jet explosive type generators (ETG) were obtained. The results of numeric simulations of the initial stage of jet dynamics agree with measurement data of gasdynamic and radiation characteristics of the plasma in laboratory and ionospheric experiments. (ЛОСЕВА Т.В., КОСАРЕВ И.Б., ПОКЛАД Ю.В., ЛЯХОВ А.Н., ЗЕЦЕР Ю.И., УРВАЧЕВ Е.М.ЧИСЛЕННОЕ МОДЕЛИРОВАНИЕ НАЧАЛЬНОЙ СТАДИИ ДИНАМИКИ ВЫСОКОСКОРОСТНОЙ ПЛАЗМЕННОЙ СТРУИ В АКТИВНЫХ ГЕОФИЗИЧЕСКИХ РАКЕТНЫХ ЭКСПЕРИМЕНТАХ “ФЛАКСУС” И “СЕВЕРНАЯ ЗВЕЗДА”//ФИЗИКА ПЛАЗМЫ, 2022. Т.48, №10, С.956-961 2EDN: JNRBUADOI: 10.31857/S0367292122600583)

A semiempirical method for studying the photochemistry of the D-region is proposed. It is based on the well-known five-component approximation (two species of positive ions, two species of negative ions, and electrons) in the stationary case. The main advantage of the method is the ability to determine the ionization rate of the ionosphere using the only parameter, the height distribution of electron density Ne(h), as experimental data on the ionosphere. The method includes a procedure for calibrating results based on solutions of forward and inverse ionospheric problems, because not all components of chemical reactions are known with sufficient accuracy. It is noted that the method can be used at different latitudes under quiet and disturbed conditions. (КОЗЛОВ С.И., БЕККЕР С.З, ЛЯХОВ А.Н., НИКОЛАЙШВИЛИ С. Ш. ПОЛУЭМПИРИЧЕСКИЙ ПРИБЛИЖЕННЫЙ МЕТОД ИССЛЕДОВАНИЯ НЕКОТОРЫХ ВОПРОСОВ АЭРОНОМИИ ОБЛАСТИ D ИОНОСФЕРЫ. I. ОСНОВНЫЕ ПРИНЦИПЫ РАЗРАБОТКИ МЕТОДА И БАЗОВЫЕ УРАВНЕНИЯ// ГЕОМАГНЕТИЗМ И АЭРОНОМИЯ/ Т.62, №5, с.653-660 (DOI: 10.31857/S0016794022050078 EDN: DGFZBD)

The use of a special technique for processing variations of the geomagnetic field at several mid-latitude observatories allowed us to identify a series of jerks over more than a decade, from 2004 to 2020. To interpret the experimental results showing that jerks follow with a quasi-period of 3–4 years, a mechanism for the occurrence of rapid changes in the geomagnetic field caused by unstable processes in the Earth’s core is proposed. (РЯБОВА С.А., ШАЛИМОВ С.Л. О ПОВТОРЯЕМОСТИ ГЕОМАГНИТНЫХ ДЖЕРКОВ ПО НАБЛЮДЕНИЯМ НА СРЕДНЕШИРОТНЫХ ОБСЕРВАТОРИЯХ // ДОКЛАДЫ РОССИЙСКОЙ АКАДЕМИИ НАУК. НАУКИ О ЗЕМЛЕ. Т.506,№2, 2022. С.214-218 DOI: 10.31857/S2686739722600813 EDN: CNMCKR)

New data are presented on the characteristics of the upper mantle transition zone of the Kola Peninsula (the northeastern part of the Fennoscandian Shield) at a depth of about 410–660 km. The studies were carried out on the basis of a new broadband seismic network. Converted waves from the boundaries of 410 and 660 km were identified for all stations. The arrival times of these phases are recorded and analyzed. It has been established that the lithosphere of the studied region has some higher seismic velocities relative to the IASP91 global model. For the first time, a phase has been identified for this region, which may indicate the presence of a layer of lower velocities in the upper mantle at a depth of about 350 km.(ГОЕВ А.Г. О НЕКОТОРЫХ ОСОБЕННОСТЯХ ГРАНИЦ ЗОНЫ ФАЗОВЫХ ПЕРЕХОДОВ В ВЕРХНЕЙ МАНТИИ ЦЕНТРАЛЬНОЙ ЧАСТИ КОЛЬСКОГО ПОЛУОСТРОВА // ДОКЛАДЫ РОССИЙСКОЙ АКАДЕМИИ НАУК. НАУКИ О ЗЕМЛЕ. Т.506, №2, 2022. С.243-247 DOI: 10.31857/S2686739722600928 EDN: YXBJNY)

A numerical model of the influence of a strong earthquake on disturbances to the geomagnetic field is proposed. The impact on the epicentral region of the Earth’s ionosphere of wave atmospheric disturbances caused by a seismic event is considered as the main mechanism of the magnetic effect. The estimates made on the basis of the proposed model using the example of a strong earthquake on March 11, 2011 (Japan, M = 9.1), are consistent with the results of instrumental observations. (АДУШКИН В.В., КУЗЬМИЧЕВА М.Ю., СПИВАК А.А. ВОЗМУЩЕНИЕ ГЕОМАГНИТНОГО ПОЛЯ ПРИ ЗЕМЛЕТРЯСЕНИЯХ // ДОКЛАДЫ РОССИЙСКОЙ АКАДЕМИИ НАУК. НАУКИ О ЗЕМЛЕ. Т.506, №2, 2022. С.243-247 DOI: 10.31857/S2686739722700025 EDN: KCUSHB)

The use of the post-compression technique ensures gain in laser pulse peak power but at the same time degrades beam focusability due to the nonlinear wavefront distortions caused by a spatially nonuniform beam profile. In this paper a substantial focusability improvement of a post-compressed laser pulse by means of adaptive optics was demonstrated experimentally. The Strehl ratio increase from 0.16 to 0.43 was measured. Simulations showed that the peak intensity in this case reaches 0.52 of the theoretical limit.

We present a generalization of the mathematical model of gas discharge from frozen rocks containing gas-saturated ice and gas hydrates in a metastable state (due to the self-preservation effect) caused by the drop in external stress associated with various geodynamic factors. These factors can be attributed, for example, to a decrease in hydrostatic pressure on a gas-bearing formation due to glacier melting, causing an isostatic rise, or to the formation of linear depressions in the bottom topography on the shelf due to iceberg ploughing. A change in external pressure can also be associated with seismic and tectonic deformation waves propagating in the lithosphere as a result of ongoing strong earthquakes. Starting from the existing hydrate destruction model, operating at the scale of individual granules, we consider a low-permeable hydrate and ice-saturated horizontal reservoir. Generalization is associated with the introduction of a finite threshold for the external pressure drop, which causes the destruction of the gas hydrate and gas-saturated microcavities of supramolecular size. This makes it possible to take into account the effect of anomalously high pressures occurring in the released gas as a result of partial hydrate dissociation. Numerical and approximate analytical solutions to the problem were found in the self-similar formulation. A parametric study of the solution was carried out, and regularities of the hydrate decomposition process were revealed.

Изучено развитие пылегазовых облаков массовых взрывов на Ситовском карьере в Липецкой области и их влияние на загрязнение окрестностей ближайших населенных пунктов. В режиме реального времени с помощью современного оборудования определена концентрация твердых частицы размером менее 2.5 мкм в пунктах наблюдения. Результаты видеосъемки массового взрыва и переноса облака пыли ветром в пределах карьера позволили рассмотреть теоретически частную задачу о распространении частиц мелкодисперсной пыли из верхней части облака с высоты 50 - 100 м к пунктам фиксации на поверхности вне пределов карьера. Методами вычислительной гидродинамики смоделировано течение, которое развивается в нижней части атмосферного пограничного слоя, возмущенного взаимодействием ветра с рельефом карьера. Показано, что турбулентная диффузия способна обеспечить вертикальную дисперсию микрочастиц вплоть до пунктов фиксации, предложено объяснение обнаруженной при измерениях немонотонности максимальной концентрации пыли вдоль поверхности при удалении от карьера.(Хазинс В.М., Соловьев С.П., Локтев Д.Н., Крашенинников А.В., Шувалов В.В. ЗАГРЯЗНЕНИЕ ПРИПОВЕРХНОСТНОГО СЛОЯ АТМОСФЕРЫ ЧАСТИЦАМИ ПЫЛИ МИКРОННОГО РАЗМЕРА В РЕЗУЛЬТАТЕ МАССОВЫХ ВЗРЫВОВ НА ОТКРЫТЫХ КАРЬЕРАХ // Физико-технические проблемы разработки полезных ископаемых. 2022. № 4. С. 170-185. DOI: 10.15372/FTPRPI20220416 EDN: GOTGPM )

Установлена возможность использования волоконно-оптической структуры "одномод--многомод--одномод" для удаленного измерения температуры с помощью оптического рефлектометра. Проведены эксперименты по измерению температуры с помощью структуры с длиной многомодового волокна 10 mm в диапазоне температур от 30 до 70oC на длинах волн 1310 и 1550 nm. Общая длина одномодовой оптоволоконной линии для рефлектометрических измерений составляла 20 km.

Time dependences of gasdynamic parameters of the high-speed aluminum plasma jets injected into the ionosphere at altitudes 140–300 km plasma jet explosive type generators (ETG) were obtained. The results of numeric simulations of the initial stage of jet dynamics agree with measurement data of gasdynamic and radiation characteristics of the plasma in laboratory and ionospheric experiments. (ЛОСЕВА Т.В., КОСАРЕВ И.Б., ПОКЛАД Ю.В., ЛЯХОВ А.Н., ЗЕЦЕР Ю.И., УРВАЧЕВ Е.М. ЧИСЛЕННОЕ МОДЕЛИРОВАНИЕ НАЧАЛЬНОЙ СТАДИИ ДИНАМИКИ ВЫСОКОСКОРОСТНОЙ ПЛАЗМЕННОЙ СТРУИ В АКТИВНЫХ ГЕОФИЗИЧЕСКИХ РАКЕТНЫХ ЭКСПЕРИМЕНТАХ “ФЛАКСУС” И “СЕВЕРНАЯ ЗВЕЗДА”// ФИЗИКА ПЛАЗМЫ/ 2022, Т. 48, №10, С.956-961 EDN: JNRBUA DOI: 10.31857/S0367292122600583)

Dissociation of methane hydrates in the Arctic permafrost may lead to explosive gas emission. Methane blowout may be triggered by increasing gas flow rate at a certain depth. The mechanism of rock failure and blowout under the effect of pressurized gas was studied numerically and in laboratory experiments. The problem was formulated for the unsteady flow of compressed gas depending on the flow rate at a given depth, and pore gas pressure variations were calculated as a function of depth and time. The model parameters were chosen with reference to field data. According to the model, the input of gas to friable material at an increasing rate may lead to gas blowout and density loss propagating downward as the gas pressure exceeds the overburden pressure at some depth. The laboratory system was of the type of a Hele-Shaw cell, with small glass balls as friable material confined between two glass panels. The results of physical modeling and calculations show good agreement.

This study presents the results of a comparison and verification of three plasma-chemical models of the lower ionosphere, which describe the dynamics of 4, 5, and 8 charged components under calm conditions and during X-ray flares of different classes. As a result of verification of the constructed schemes for the ionization-recombination cycle using data on the propagation of very low frequency signals during 12 X-ray flares, the best agreement with experimental measurements was obtained with the eight-component model of the ionospheric D-region. On two of the four paths, this model successfully simulated the qualitative and quantitative response of the amplitude-phase characteristics to solar flares in the C, M, and X classes. In contrast to the eight-component model, four- and five-component models are of limited accuracy which could not be noticeably increased by correcting the ionization rate calculation or the input values of the neutral parameters of the atmosphere.

The study is devoted to the analysis of geomagnetic field disturbances and the response of the Schumann resonance (SR) during the eruption of the Tonga volcano in 2022. The data on geomagnetic field variations at distances from 800 to 15,000 km from the volcano according to the INTERMAGNET network and parameters of SR signals recorded at Mikhnevo Observatory in Russia were used. The source of global geomagnetic disturbances are acoustic–gravity waves (AGWs), which caused changes in ionospheric conductivity, values of ionospheric currents, and the geomagnetic field. The propagation velocity of magnetic disturbances 263 ± 5 m/s, corresponding to the AGWs velocity, was determined and an independent estimate of the time of the eruption phase that caused the generation of the atmospheric wave (4:14 ± 10 UT) was obtained. A new method of processing the results of measurements of SR disturbance with a time resolution of 5 min instead of the usual 10–15 min allowed not only to detect but also to study this phenomenon in detail. The peculiarities of signals related to the number and energy of lightning discharges were revealed. Synchronous measurements of SR signals and geomagnetic field variations in a single observatory for the first time allowed to obtain an independent estimate of the eruption time and the electromagnetic disturbance propagation rate.

Frictional slip along faults and large fractures is the predominant mechanism behind crustal earthquakes. Laboratory experiments in formulating a slider model are an effective tool for obtaining information about the origination patterns of laboratory earthquakes. This paper presents the results of laboratory acoustic emission (AE) experiments to stud various modes of frictional slip of a model crack and establish a unified evolutionary law for the preparation of fast and slow slip events based on synchronous continuous recording of AE and cumulative displacement of blocks. A new parameter for the state of a crack is introduced, generalized deficit, which makes it possible to monitor the stage of its loading cycle with high accuracy. Generalized deficit takes into account variations in the AE energy flux and displacement of the crack’s edges, thereby taking into account the processes occurring at the micro- and macrolevels, respectively. The rate of change in generalized deficit has a single evolutionary pattern for all occurring slip modes and can be used as an indicator for a crack’s transition to the limiting state. In the experiments, a functional relationship was established between the frictional strength of a crack, its deformation rate, and the flux of AE energy, which indicates the relatedness of processes occurring at the micro- and macrolevels. (МОРОЗОВА К.Г., ОСТАПЧУК А.А. СВЯЗЬ СОСТОЯНИЯ СДВИГОВОЙ ТРЕЩИНЫ В ГРАНУЛИРОВАННОМ МАТЕРИАЛЕ И АКУСТОЭМИССИОНННЫХ И ДЕФОРМАЦИОННЫХ ДАННЫХ // АКУСТИЧЕСКИЙ ЖУРНАЛ. 2022, Т.68, №5, С.543-549 DOI: 10.31857/S0320791922050082 EDN: UNHTXK)

The paper presents a brief analysis of the accumulated data on fast dynamics of earthquake ruptures and their qualitative comparison with the numerical results on supershear rupture propagation along homogeneous and heterogeneous fault surfaces. Calculation methods and parameters are described. The numerical results indicate that the rupture velocity in strong earthquakes can vary in a wide range, exceeding significantly the Rayleigh wave velocity treated as the maximum possible crack velocity in conventional fracture mechanics. It is shown that a necessary condition for the transition to supershear rupture propagation along the heterogeneous contact surface is the presence of a sufficient number of asperity contact spots that experience rapid frictional weakening during shear. The rupture velocity can periodically decrease or increase in the case of a heterogeneous fracture surface. Systematic variation in fault properties along strike increases the probability of supershear rupture in old contact segments. (Г.Г. Кочарян, А.М. Будков, С.Б. Кишкина. Влияние структуры зоны скольжения разлома на скорость распространения разрыва при землетрясении // Физическая мезомеханика 25, 4 (2022) 84–93, DOI: 10.55652/1683-805X_2022_25_4_84 EDN: PYOBXV)

Представлено описание уникальной научной установки ИДГ РАН «Среднеширотный комплекс геофизических наблюдений "Михнево"». Описан состав измерительного комплекса, используемая аппаратура и применяемые методики. Кратко перечислены некоторые научные результаты, полученные на УНУ СКГН «Михнево» в последние годы. (Кочарян Г.Г., Локтев Д.Н., Ряховский И.А., Санина И.А. УНИКАЛЬНАЯ НАУЧНАЯ УСТАНОВКА «СРЕДНЕШИРОТНЫЙ КОМПЛЕКС ГЕОФИЗИЧЕСКИХ НАБЛЮДЕНИЙ «МИХНЕВО». Геодинамика и тектонофизика. 2022;13(2). https://doi.org/10.5800/GT-2022-13-2-0590)

The paper introduces a new, unique for Russia, meter-scale laboratory setup created in the Institute of Geosphere Dynamics of the Russian Academy of Sciences (IDG RAS) to study the development of different sliding regimes on rock discontinuities. The experimental procedure is described and the results of the first series of tests aimed at studying the formation of different sliding regimes on rock faults are presented. The laboratory fault was a loaded contact of two 75-cm long blocks made of diabase. The fault was filled with granular material (a fault gouge). Normal stresses on the fault can reach 10 MPa. By varying fault gouge composition and loading rate, we reproduced a wide range of sliding regimes: sliding with constant velocity, regular stick-slip, and aperiodic slow slip episodes. It is shown that a variation in the loading rate can cause a significant change in the sliding regime. Intense frictional crushing of gouge grains is detected in the experiments at relatively low normal pressure of 2 MPa. In the case of high-amplitude stick-slip, besides crushing of the gouge material, also structural phase transformations of quartz grains corresponding to a local temperature increase up to 700°C are revealed. A possible set of the problems related to deformation processes in seismogenic fault zones that can be addressed by modeling on such setups—the pre-seismic stage of inelastic behavior of the main fault zone at critical stress—is outlined. (КОЧАРЯН Г.Г., ОСТАПЧУК А.А., ПАВЛОВ Д.В., ГРИДИН Г.А., МОРОЗОВА К.Г., HONGWEN J., ПАНТЕЛЕЕВ И.А. ЛАБОРАТОРНЫЕ ИССЛЕДОВАНИЯ ЗАКОНОМЕРНОСТЕЙ ФРИКЦИОННОГО ВЗАИМОДЕЙСТВИЯ БЛОКОВ СКАЛЬНОЙ ПОРОДЫ МЕТРОВОГО МАСШТАБА. МЕТОДИКА И ПЕРВЫЕ РЕЗУЛЬТАТЫ//ФИЗИКА ЗЕМЛИ. 2022. №6. DOI: 10.31857/S0002333722060060 EDN: YSAGVJ)

The extraction and movement of rock during mining operations is considered a possible trigger for slip along the fault. In this study, possible anthropogenic causes were analyzed for triggering the earthquake with the local magnitude of ML = 6.1 (at a depth of 4 km just beneath the quarry), in the vicinity of the large coal open-pit mine in Russia. This event was the largest earthquake associated with a quarry (an open pit). A sufficiently deep occurrence of the source testified that seismic vibrations were produced in a dynamic slip along a preexisting and prestressed tectonic fault. Analytical calculations were conducted of increments of normal and shear stresses at fault planes with several dip angles at depths corresponding to the probable location of the hypocenter of the Bachat earthquake. As the results show, long-term rock excavations bring a prestressed thrust fault closer to the ultimate Coulomb strength, and stress variations at those depths may suffice to initiate a movement along the fault. By measuring seismic vibrations at different quarries and mines in Russia, the dynamic effect at the supposed depth of the source occurrence could be reliably estimated. As is shown, the ultimate anticipated dynamic deformations are noticeably lower than corresponding values produced by seismic waves of distant earthquakes in the case when the effects of dynamic triggering were observed. Accordingly, the seismic effect of explosions cannot trigger a large earthquake with deep source occurrence. Operations in open-pit mines can only bring forward the moment of an earthquake at a potentially seismogenic fault. At the same time, the numerical calculations reveal that a branching network of underground tunnels located at several horizons can noticeably reduce the effective shear modulus of the host rock. This effect can even provoke a dynamic movement at a previously aseismic fault.

Many researchers note a nonlinearity of flow in tight rock samples at low rates. The effects include changes in apparent permeability with pore pressure gradient and so-called threshold gradients, below which low flow or no flow occurs. It is believed that these effects may be related to the influence of adhesive layers with altered properties at the interfaces between liquid and solid phases. For low-permeable rocks, the estimation of reservoir permeability without taking into account the nonlinearity of the flow can lead to significant errors. An account of the flow nonlinearity also can downgrade the reservoir productivity estimation and may result in underestimation of stationary oil zone appearances. Conventional methods for studying fluid flows in porous rocks are poorly suited for studying their permeability when approaching zero flow rates because of the lack of accuracy. Such studies also require a special approach for the interpretation of the data obtained. At the same time, there is a lack of discussion of the appropriate experimental technique in the publications known. Our goal was to develop a technique suitable for studying the flow nonlinearity at extremely low flow rates. Using the developed experimental technique, we carried out three series of consecutive tests on three similar limestone core samples. The samples were taken from the aquifer; however, their porosity and permeability are similar to the typical parameters of a tight oil reservoir. During the test series, we observed the change in the deviation from the linear Darcy’s law over a long time. We realized that in the sample with the most pronounced deviation from linear flow, there was a most significant decrease in net permeability in the entire series. We believe that our method can provide more precise evaluation of the permeability of tight rocks at the near real flow rate.

We analyzed geologic-geophysical data, both from archives and collections in recent expeditions by the Shirshov Institute of Oceanology RAS (SIO RAS), and revealed many anomalies in the seismoacoustic wavefield. Anomalies are of two types: horizontal disturbed layers and vertical pipes. Anomalies form associations — pipes (chimneys) are rooted in disturbed layers and go through sediments up to the seafloor and form pockmarks. We consider all specified seismic anomalies and bottom microrelief as a possibility of vertical migration of gas and water via sediments (fluid from sediments to water and from seawater to sediments). It is expected that the fluids form a huge underground hydrosphere below the Caspian Sea. To test the fluid flow, we made a mathematical model of fluid discharge and absorption in bottom sediments. We hypothesize that the Caspian Sea level fluctuates, at least partially, due to cycles of the submarine ground water discharge and sea water absorption back into the sediments. This cyclicity of fluid discharge and absorption correlates with regional seismic events. The earthquakes cause tectonic relaxation, triggering the absorption process, and sea-level drop due to reverse flow into sediments. In other periods, the tectonic tension causes sediment compression and fluid discharge to sea water, which causes sea-level rise. The model was tested on the recent (past 100 years) sea-level change curve. As a result, we got a distribution of the general volume of fluid flows depending on the infiltration coefficient. The real change in the Caspian Sea volume is at the lower range of the calculated values, so we cannot neglect the effect of “gas pipes” (“chimneys”) on the Caspian sea-level change

The probability of capturing preplanetary bodies into the protolunar swarm is considered in the dependence on the distance of a collision point to the center of the growing Earth and on the mass ratio of colliding bodies. The formulas and diagrams in our work allowed us to determine the rate of mass gain per unit area of the disk of the protolunar swarm due to pair collisions of preplanetary bodies in the Hill sphere of the Earth. It has been shown that, if the masses of colliding bodies differ by more than two, the capture probability is substantial (exceeds 0.05) at distances less than eight current radii of the Earth. It has been found that pair collisions of preplanetary bodies result in forming a near-Earth swarm, the mass of which is about 10−5 times the present-day mass of the Moon. This process may serve as a trigger for further accretion due to collisions of the protolunar-swarm bodies with bodies from the feeding zone of the planet and the ejecta produced by impacts of large bodies on the growing Earth. In future, our results may be used to confirm the coaccretion hypothesis of the formation of the Earth−Moon system. (АФАНАСЬЕВ В.Н., ПЕЧЕРНИКОВА Г.В. О ВЕРОЯТНОСТИ ЗАХВАТА ДОПЛАНЕТНЫХ ТЕЛ В ПРОТОЛУННЫЙ РОЙ ПРИ ФОРМИРОВАНИИ СИСТЕМЫ ЗЕМЛЯ–ЛУНА // АСТРОНОМИЧЕСКИЙ ВЕСТНИК. ИССЛЕДОВАНИЯ СОЛНЕЧНОЙ СИСТЕМЫ. 2022. Т.56, №6 С.389-409 DOI: 10.31857/S0320930X22060019 EDN: NNDNXP)

This article presents the results of a lineament analysis of the Baikal region (the southwestern part) using the methods of visually interpreting digital elevation models (DEMs), topographic maps with a scale of 1 : 100 000 and 1 : 25 000, and the formalized (computer) processing of space images and DEMs using the Lineament Extraction and Stripe Statistical Analysis (LESSA) software. The results of the visual and computer analysis of extended lineaments and statistical fields of small lineaments in digital images are compared in detail to the features of the fault-block structure within the Baikal region. We show the information value of the combination of used remote sensing methods of the study area in the mapping of faults of different ranks in regions characterized by different tectonic activity. Based on the results of the lineament analysis, we propose methods for processing remote sensing materials and topographic maps that make it possible to specify the position of faults of different ranks during the geological mapping of both geodynamically active areas (the Baikal rift system) and relatively stable areas (the Siberian platform). The main parameters of faults of different ranks are verified by field observations at key sites. (ИВАНЧЕНКО Г.Н., ГОРБУНОВА Э.М., ЧЕРЕМНЫХ А.В. НЕКОТОРЫЕ ВОЗМОЖНОСТИ ЛИНЕАМЕНТНОГО АНАЛИЗА ПРИ КАРТИРОВАНИИ РАЗНОРАНГОВЫХ РАЗЛОМОВ (НА ПРИМЕРЕ ПРИБАЙКАЛЬЯ) // ИССЛЕДОВАНИЕ ЗЕМЛИ ИЗ КОСМОСА, 2022, No. 3, p. 66-83 DOI: 10.31857/S020596142203006X)

This paper considers the results of registering geophysical field variations by the large-scale research facilities “Mid-Latitude complex of geophysical observations “Mikhnevo”” at the Sadovsky Institute of Geospheres Dynamics, Russian Academy of Sciences, caused by the catastrophic Tonga volcanic eruption in the period from December 19, 2021, to January 18, 2022. Atmospheric–ionospheric waves associated with the Tonga volcanic activity were a source of global geomagnetic disturbances. An independent estimate of the eruption time and propagation velocity of electromagnetic disturbances is made based on synchronous measurements of Schumann resonance signals, atmospheric pressure, and geomagnetic field variations. The background data obtained during the observation period of December 2021 to January 2022 are compared with the results of registering the Tonga volcanic eruption and two passages of Lamb’s surface wave around the Earth. The ranges of atmospheric pressure variations and the amplitudes of hydrogeological responses of the weakly confined and confined aquifers have been determined. Experimental data obtained by the Mikhnevo large-scale research facilities confirm the relationship between different geospheres and add the global database of geophysical parameters recorded at different epicentral distances from catastrophic events. (Горбунова Э.М., Ряховский И.А., Гаврилов Б.Г., Поклад Ю.В., Петухова С.М., Беседина А.Н. Вариации геофизических полей при извержении вулкана Тонга по данным уникальной научной установки «Михнево» // Геофизические процессы и биосфера. 2022. Т. 21. № 4. С.5-22 DOI: 10.21455/GPB2022. 4-1)

Based on the results of instrumental observations of geomagnetic variations at the Mikhnevo Observatory of the Institute of Geosphere Dynamics, Russian Academy of Sciences, and the data from the IERS catalog, it is found that the frequency F of the fundamental spheroidal mode 0S2 of the Earth’s free oscillations, distinguished in the spectra of magnetic field variations, changes with time; the values of F are higher when the speed of the Earth’s rotation decreases and are lower when it increases. An empirical relationship between the variations in F and the speed of the Earth’s rotation is obtained.

The article presents a new method of classifying acoustic and microseismic emission (KLASI-k), which analyzes waveform parameters (the rise time amplitude RA, average frequency AF, and the waveform index WI). The method is based on k-means clustering, which makes it possible to separate subsets of events differing in scaled seismic energy (the ratio of emitted seismic energy to released seismic moment) and source duration. In classifying seismic events, there is the fundamental possibility of using the source parameters (seismic energy Es, seismic moment M0, and corner frequency f0) as the features of the KLASI-k algorithm. Good correspondence is observed between the classified subsets of events in the transition from waveform parameters {RA, AF, WI} to source parameters {Es, M0, f0}. The KLASI-k method was applied to the data on mining seismicity induced by two ripple-fired blasts in the Gubkin Mine of the KMAruda Mining Enterprise at the Korobkovskoe iron ore deposit. The analyzed catalogs include 77 microevents recorded after the blast on July 6, 2019 and 259 microevents after the blast on October 24, 2020. Applying the KLASI-k method has made it possible to separate two subsets in the seismic catalogs. The events in the first subset show a scaled seismic energy (Es/M0) higher than 10–7 J/(N m), while those in the second subset, lower than 10–7 J/(N m). The first type of events have a smaller source duration than those of the second type; the released seismic moment is the same. ( К. Г. Морозова, А. А. Остапчук, А. Н. Беседина, Д. В. Павлов Классификация сейсмических событий, сопровождающих взрывной способ разработки массива горных пород // Сейсмические приборы. – 2022. – Т. 58, № 4. – С. 97-110. – DOI 10.21455/si2022.4-6. – EDN AGCKFJ)

Динамика фрикционного скольжения по тектоническому разлому определяется процессами самоорганизации среды, протекающими в его узкой центральной зоне. На гетерогенной поверхности блоков горных пород выделяются особые зоны локальных контактов неровностей разного размера. В зависимости от структурных и фрикционных свойств этих зон может быть реализован полный спектр режимов скольжения по разлому: от непрерывного крипа и событий медленного скольжения до динамического разрыва. В силу невозможности прямых наблюдений на сейсмогенных глубинах, критически важным является получение достоверной информации о характеристиках зон локальных контактов на поверхности скольжения разлома. В настоящей работе были использованы данные высокоточного сейсмического каталога Северной Калифорнии, позволившие выявить структурные особенности зон скольжения различных сегментов разломов Сан-Андреас и Калаверас на масштабах от 0.1 до 10 км. Показано, что в контактной области формируются линейно вытянутые кластеры, характерное расстояние между которыми составляет от 4 до 9 км. Кластеры представляют собой систему локальных контактов со статистически самоподобной структурой и коэффициентом самоподобия от 0.7 до 1.6. Проведенный анализ показал, что характерный размер самоподобных кластеров составляет порядка 1 км, при этом косейсмический разрыв, зарождаясь на одном и том же локальном контакте кластера, может охватывать различный пространственный масштаб от метров до километров. (Kocharyan G.G., Ostapchuk A.A. Mesostructure of a Tectonic Fault Slip Zone // Physical Mesomechanics, 2023, vol. 26 , p. 82-92 DOI: 10.1134/S1029959923010095)

Построен скоростной разрез до глубины около 250 км восточной окраины протократона Сарматия (Восточно-Европейская платформа) на основе P-функций приемника (PRF). В качестве исходных данных использованы сейсмограммы новой широкополосной станции «Александровка». В разрезе выявлены основные сейсмические границы, а также показано наличие среднелитосферной неоднородности в верхней мантии (MLD). (Гоев, А. Г. Первые результаты моделирования глубинного скоростного строения восточной окраины протократона Сарматия по данным сейсмической станции "Александровка" методом продольных функций приемника / А. Г. Гоев // Вестник Московского университета. Серия 4: Геология. – 2022. – № 6. – С. 88-94. – EDN DSUCZS.) Goev, A.G. Early Results of Modeling the Deep Velocity Structure of the Eastern Margin of the Sarmatian Protocraton Based on the Aleksandrovka Seismic Station Data from the Receiver Function Technique. Moscow Univ. Geol. Bull. 78, 87–94 (2023). https://doi.org/10.3103/S0145875223010052

Обобщены результаты многолетних наблюдений за природной и техногенной сейсмичностью на Восточно-Европейской платформе (ВЕП) по данным малоапертурной сейсмической группы (МСГ) «Михнево» ИДГ РАН. Показано, что на этой территории доминирует техногенная сейсмичность. Приведены описания волновых форм от взрывов на крупнейших карьерах Белгородской и Курской областей. Особое внимание уделено оценке энергии от взрывов, производимых на многочисленных сравнительно небольших карьерах, расположенных в центральной части ВЕП. Дана энергетическая оценка суммарного техногенного воздействия на среду. Показаны результаты регистрации и локации природно-тектонических событий, произошедших на территории центральной части ВЕП, ранее считавшейся асейсмичной. Отмечено отрицательное воздействие на территории, расположенные вблизи действующих карьеров, от образующихся пылегазовых выбросов при проведении буровзрывных и иных работ по добыче полезных ископаемых. (Константиновская, Н. Л. Возможные последствия техногенных сейсмических событий на геологическую среду центральной части Восточно-Европейской платформы по данным малоапертурной сейсмической группы "Михнево" / Н. Л. Константиновская, А. Г. Гоев, Т. В. Данилова // Вестник Московского университета. Серия 4: Геология. – 2022. – № 6. – С. 95-109. – EDN JJVEUV.) Konstantinovskaya, N.L., Goev, A.G. & Danilova, T.V. The Possible Consequences of the Technogenic Seismic Impact on the Geological Environment in the Central Part of the East European Platform Based on Data from the Small-Aperture Mikhnevo Seismic Group. Moscow Univ. Geol. Bull. 78, 95–109 (2023). https://doi.org/10.3103/S014587522301009X

Reaction of confined and unconfined aquifers to propagation of seismic waves from distant earthquakes registered on the territory of geophysical observatory IDG RAS “Mikhnevo” is considered as dynamic deformation regime indicator. The reference point of measurements is located to the South of Moscow at the 80 km distance within the East–European platform. Based on the results of precision monitoring of groundwater levels, carried out from 2010 to 2018, database of seismic and hydrogeological data is formed, which includes registration of responses to 61 earthquakes with MW 6.3–9.1 at epicentral distances in the range between 1863 and 16,507 km. On the basis of spectral analysis of a sample of experimental data series with duration of 6 h (3 h before and 3 h after the earthquake) the principal features of fluid–saturated reservoir reaction to seismic waves propagation and types of hydrogeological effects have been determined. In some cases the relative deformation of fluid saturated reservoir reaches (1.59–5.95)·1E–7 at maximum amplitude of ground velocity 1.01–3.78 mm/s and exceeds by one or two orders of magnitude calculated poroelastic deformation of reservoir from tidal waves

In this paper, we report a study of the seismic noise measured in the underground Baksan neutrino observatory in the framework of the site qualification for third generation Gravitational Wave detectors like the Einstein Telescope (Einstein gravitational wave telescope conceptual design study, ET-0106C-10. http://et-gw.eu/etdsdocument, 2011) and Cosmic Explorer (https://cosmicexplorer.org/). The main spectral feature below 1 H z is the oceanic microseism, while for greater frequencies the measured horizontal and vertical accelerations approach the Peterson low noise model. Using two synchronized seismometers, we also studied the coherence in the microseismic band (0.1–0.5Hz) between three underground stations located at 0.3 km, 1.4 km and 3.7 km from the tunnel entrance. Finally, on the base of our measurements, we evaluate the Newtonian noise contribution from the seismic noise background of body waves.

The bimorph deformable mirror with a diameter of 320 mm, including 127 control electrodes, has been developed and tested. The flatness of the initial mirror surface of about 1 µm (P-V) was achieved by mechanically adjusting the mirror substrate fixed in the metal mount. To correct for the aberrations and improve the beam focusing in the petawatt Ti:Sa laser, the wide-aperture adaptive optical system with the deformable mirror and Shack–Hartmann wavefront sensor was developed. Correction of the wavefront aberrations in the 4.2 PW Ti:Sa laser using the adaptive system provided increases the intensity in the focusing plane to a value of 1.1 × 10^23 W/cm2.

A new method for estimating the self-noise of the measuring channel of a seismometer is proposed, taking into account the linear relationship between the signal and noise. The method extracts noise using records of two identical measuring channels on the example of the SM-3KV short-period seismometer with an operating frequency range of 0.5-40 Hz. The method was tested on model signals for channel noise with a normal distribution, as well as microseismic noise records recorded on a pedestal by seismometers with locked and free inertial masses. Work with the model signals demonstrated that the accuracy of the numerical result when assessing the level of isolated noise depends on the value of the cross-correlation of the initial seismograms. Consideration of this dependence when calculating the self-noise of real measuring channels yields a noise level similar to the standard method based on separation of the incoherent component of the initial signals. The noise values in the 0.5-40 Hz range with a locked mass of the seismometer are 2.1 +/- 0.3 nm/s according to the standard method and 2.2 +/- 0.4 nm/s according to the new methods. The obtained values do not contradict the manufacturer's data of the SM-3KV seismometer, which state that the self-noise level does not exceed 2 nm/s in the operating frequency range. (БЕСЕДИНА А.Н., КАБЫЧЕНКО Н.В., ВОЛОСОВ С.Г. МЕТОД ОЦЕНКИ СОБСТВЕННОГО ШУМА ИЗМЕРИТЕЛЬНОГО КАНАЛА НА ПРИМЕРЕ КОРОТКОПЕРИОДНОГО СЕЙСМОМЕТРА СМ-3КВ // СЕЙСМИЧЕСКИЕ ПРИБОРЫ Т.57, №3, 2021. С.5-18. DOI: 10.21455/si2021.3-1)

This paper reports a large-aperture adaptive optical system with a bimorph deformable mirror and Shack – Hartmann wavefront sensor for aberration correction and beam focusing improvement in state-of-the-art petawatt Ti : sapphire lasers. We consider methods for providing feedback to the wavefront sensor and obtaining an objective wavefront that optimises beam focusing onto a target. The use of an adaptive system with a controlled 127-channel 320-mm-aperture mirror in a Ti : sapphire laser with an output power of 4.2 PW has made it possible to obtain a record high laser beam intensity: 1.1 × 10 ²³ W cm ⁻².

Considered is triggering landslides with seismic vibrations produced by earthquakes and explosions. Laboratory investigations have been performed of the effect of impulsive actions on slopes at a vertical and a horizontal impact set-ups designed and constructed in IDG RAS. The ultimate parameters of dynamic effects obtained in laboratory have been compared to the critical accelerations estimated on the basis of the quasi-static approach. Estimations of critical parameters of the effects of earthquakes of various magnitudes have been also performed. The results show that the minimal peak acceleration that could trigger a landslide noticeably exceeds the estimate of critical acceleration that uses the static coefficient of stability. The critical Newmark's displacements under the action of seismic vibrations of earthquakes can be reached in the case when the maximal acceleration exceeds 5–10 times the critical acceleration calculated using the quasi-static approach.

The presented research provides an analysis of electric parameter anomalies during magnetic storms in 2018 selected from weather data. As the initial data, we used the time series of instrumental observations of vertical components of the electric field strength and atmospheric current, carried out at the Center for Geophysical Monitoring in Moscow of Sadovsky Institute of Geosphere Dynamics of Russian Academy of Sciences and Mikhnevo Geophysical Observatory of Sadovsky Institute of Geosphere of Russian Academy of Sciences. The changes in the parameters of the electric field during the one of strongest magnetic storm (August 25–26, 2018) in solar cycle No. 24 are discussed in more detail.

The presented research provides a comparative analysis of the features of the amplitude and spectral characteristics of acoustic noise in the conditions of Moscow during the quarantine period for COVID-19 in 2020 and during the period preceding the quarantine. As the initial data, we used the time series of instrumental observations of micropulsations of atmospheric pressure, carried out at the Center for Geophysical Monitoring in Moscow of Sadovsky Institute of Geosphere Dynamics of Russian Academy of Sciences from February to May 2020. Data plots were analyzed during periods characterized by calm meteorological conditions: the absence of strong atmospheric disturbances in the form of hurricanes and squalls, as well as atmospheric fronts.

В статье представлены результаты совместной обработки гидрогеологических и сейсмических данных, полученных на уникальной научной установке «Среднеширотный комплекс геофизических наблюдений "Михнево"» ИДГ РАН за 12-летний период наблюдений. В сформированной базе данных выделены отклики системы «пласт – скважина» на прохождение сейсмических волн от удаленных землетрясений с магнитудой 6.3–9.0, зарегистрированных на эпицентральных расстояниях от 1863 до 16507 км. Определены максимальные значения вариаций уровня подземных вод и скорости смещения грунта при сейсмическом воздействии. Установлена степенная зависимость амплитуд уровней напорного и слабонапорного водоносных горизонтов от максимальной скорости смещения грунта по вертикальной компоненте. Выполнен спектральный анализ выборки 6-часовых интервалов (3 ч до и 3 ч после землетрясения) сейсмических и гидрогеологических данных. На нормированных спектрах определены частоты, соответствующие максимальным значениям скорости смещения грунта и вариациям уровня подземных вод. В низкочастотной области выделены интервалы, в пределах которых прослежены экстремумы гидрогеологических откликов при фоновых значениях скорости смещения грунта. Амплитудно-частотные характеристики систем «пласт – скважина» при сейсмическом воздействии на эпицентральных расстояниях до 4901 км различаются. При регистрации землетрясений на эпицентральных расстояниях 11024–14026 км реакция систем подобна (Горбунова Э.М., Беседина А.Н., Санина И.А., Константиновская Н.Л. РЕАКЦИЯ СИСТЕМ «ПЛАСТ – СКВАЖИНА» НА УДАЛЕННЫЕ ЗЕМЛЕТРЯСЕНИЯ. Геодинамика и тектонофизика. 0;. https://doi.org/10.5800/GT-2022-13-2s-0630).

The paper proposes a special technique for microstructural analysis (STMA) of rock samples based on two provisions. The first one is an algorithm for the automatic detection and digitalization of microstructures in images of oriented thin sections. The second one utilizes geographic information system (GIS) tools for an automatized analysis of objects at the micro scale. Using STMA allows the establishment of geometric features of fissure and pore space of rock samples to determine the parameters of stress–strain fields at different stages of rock massif deformation and to establish a relationship between microstructures and macrostructures. STMA makes it possible to evaluate the spatial heterogeneity of physical and structural properties of rocks at the micro scale. Verification of STMA was carried out using 15 rock samples collected across the core of the Primorsky Fault of the Baikal Rift Zone. Petrographic data were compared to the quantitative parameters of microfracture networks. The damage zone of the Primorsky Fault includes three clusters characterized by different porosity, permeability, and deformation type. Findings point to the efficiency of STMA in revealing the spatial heterogeneity of a tectonic fault.

Results from instrumental observations of geomagnetic variations and variations in the electrical characteristics of the surface atmosphere (electric field, atmospheric current), carried out at the Mikhnevo Geophysical Observatory of the Institute of Geosphere Dynamics of Russian Academy of Sciences (IDG RAS) and at the Center for Geophysical Monitoring in Moscow of IDG RAS during periods of cold atmospheric fronts, are presented. It is shown from the example of 34 events that occurred in the period 2015–2021 that atmospheric fronts are accompanied by variations in the magnetic field, electric field, and atmospheric current. The main characteristics of the induced variations are presented. (А.А. Спивак, С.А. Рябова Геофизические эффекты сильных атмосферных фронтов // Доклады Российской академии наук. Науки о Земле, 2022, T. 502, № 1, стр. 26-31 DOI: 10.1134/S1028334X22010081, EDN: UXHGRM)

Subsurface injection of fluids inside tectonically active areas is in some cases followed by a seismic response. This paper examines an example of seismic activation on the northeast coast of Sakhalin Island (in the area of the North American tectonic plate) in 2013–2014, which coincides with the start of the pilot operation of injection wells designated for the disposal of drilling fluids and co-produced and domestic wastewater from nearby oil and gas operations. Hypothesizing that the recorded seismicity is entirely induced by the fluid disposal, and considering injection rates of 105 m3/year, we estimate a seismogenic index of Σ =  −3.98 ± 0.06. Assuming a total injection volume of VC = 107 m3 until 2041, the probability of occurrence of at least one earthquake with a magnitude M 5.5 was calculated to be PE = 0.99. The obtained results are of practical interest for developing seismic risk management strategies and using numerical tools to quantify seismic hazards.

The registration possibilities of the recently installed "Aleksandrovka" broadband seismic station are considered. It is established that its hardware and installation conditions enable monitoring of the central part of the East European Craton in order to identify small-magnitude events and to clarify the coordinates of the located events. It is shown that the approach for discriminating the nature of seismic events that was developed earlier for the "Mikhnevo" small-aperture seismic array can be applied to the records of a single seismic station.(ГОЕВ А.Г., САНИНА И.А., КОНСТАНТИНОВСКАЯ Н.Л., ОВЧИННИКОВА О.В.ВОЗМОЖНОСТИ ИЗУЧЕНИЯ СЛАБОЙ СЕЙСМИЧНОСТИ В ЦЕНТРАЛЬНОЙ ЧАСТИ ВОСТОЧНО-ЕВРОПЕЙСКОЙ ПЛАТФОРМЫ С ПОМОЩЬЮ НОВОЙ ШИРОКОПОЛОСНОЙ СЕЙСМИЧЕСКОЙ СТАНЦИИ "АЛЕКСАНДРОВКА" // ВЕСТНИК МОСКОВСКОГО УНИВЕРСИТЕТА. СЕРИЯ 4: ГЕОЛОГИЯ №: 6, 2021 С.142-149 EDN: JPCITF)

The rarely considered case of laser beam propagation and focusaing through the moderately scattering medium was researched. A phase-only spatial light modulator (SLM) with 1920×1080 pixel resolution was used to increase the efficiency of focusing of laser radiation propagated through the 5 mm layer of the scattering suspension of 1 µm polystyrene microbeads in distilled water with the concentration values ranging from 1E5 to 1E6 mm−3. A CCD camera with micro-objective was used to estimate the intensity distribution of the far-field focal spot. A Shack-Hartmann sensor was used to measure wavefront distortions. The conducted experimental research demonstrated the 8% increase in integral intensity and 16% decrease in diameter of the far-field focal spot due to the use of the SLM for laser beam focusing.

In this work, two advanced technologies were applied for manufacturing a bimorph wavefront corrector: laser ablation, to vaporize conductive silver coating from piezoceramic surface, and parallel-gap resistance microwelding, to provide a reliable electrical contact between the piezodisk surface silver electrodes and copper wires. A step-by-step guide for bimorph mirror production is presented, together with the ‘bottlenecks’. Optimization of the laser ablation technique was carried out using an Nd:YAG laser with an output power of 4 W and a frequency of 20 kHz. A comparison of the ultrasonic welding and parallel-gap resistance microwelding methods was performed. The tensile strength in the first case was in the range of 0.2…0.25 N for the system ‘copper wire–silver coating’. The use of resistance welding made it possible to increase the value of this parameter for the same contact pair by almost two times (0.45…0.5 N).

В работе приведены результаты сейсмического мониторинга массовых взрывов на шахте имени Губкина. Получена зависимость максимальной скорости колебаний от приведенного гипоцентрального расстояния. Для каждого массового взрыва была определена интенсивность сейсмического действия взрыва на застройку города Губкин и его население. Для одного из взрывов приведена карта изосейст, демонстрирующая сейсмическое воздействие на регион. По данным сейсмического мониторинга технологического взрыва одной скважины проведены численные эксперименты по определению оптимального замедления для КЗВ. Определена зависимость интенсивности колебаний от массы ВВ в ступени замедления (скважине) и от числа скважин.

В июле 2021 г. сеть сейсмологического мониторинга Кольского филиала ФИЦ ЕГС РАН была расширена за счёт открытия новой сейсмостанции, установленной в южной части Кольского полуострова в посёлке Умба (код UMBA). Насущность развития сейсмологической сети в южном направлении продиктована необходимостью повышения детальности мониторинга Кандалакшской зоны возникновения очагов землетрясений (ВОЗ). Согласно современным представлениям, Кандалакшская зона ВОЗ, состоящая из Колвицкого и Кандалакшского грабенов, является потенциально наиболее опасным геологическим объектом в восточной части Балтийского щита. Для выбора места установки новой сейсмической станции проведены рекогносцировочные работы, включавшие оценку уровня фонового сейсмического шума. Приведён анализ шумов в выбранной точке установки сейсмической станции. Показан хороший уровень фоновых шумов в сравнении с моделями NHNM и NLNM. В качестве регистрирующей аппаратуры на новой сейсмической станции используются аналоговый сейсмометр Guralp CMG-6T с диапазоном регистрации 30 с - 50 Гц и регистратор сейсмических сигналов «Ермак-5». Данные в режиме, близком к реальному времени, передаются в Кольский региональный информационно-обрабатывающий центр по каналам мобильного интернета. На примере слабого землетрясения показано, что в новой конфигурации сейсмическая сеть КоФ ФИЦ ЕГС РАН позволяет более уверенно регистрировать и определять координаты эпицентров слабых сейсмических событий локальной магнитудой менее двух в районе Кандалакшской зоны ВОЗ.(EDN: QSUMPP )

Рассмотрены особенности локации и идентификации массовых взрывов, производимых на карьерах в центральной части Восточно-Европейской платформы, связанных с изменением регламента проведения взрывных работ, по данным наблюдений на малоапертурной сейсмической группе «Михнево» ИДГ РАН. Приведены описания волновых форм от взрывов на крупнейших карьерах Белгородской и Курской областей. Дан анализ выявленных «аномальных» массовых взрывов на карьерах. Рассмотрены «нетипичные» волновые формы и время проведения взрывных работ. Указаны возможные негативные последствия для расположенных в непосредственной близости объектов народного хозяйства и особо ответственных зданий и сооружений.

Описаны комплексные инструментальные наблюдения за развитием пылегазовых облаков при промышленных взрывах на карьере Лебединского ГОКа и обусловленного этим процессом выноса микрочастиц разрушенной горной породы в приземный слой атмосферы. В период с июня по октябрь 2021 г. на Лебединском карьере было произведено четыре массовых взрыва. Проводились непрерывные наблюдения за вариациями концентрации микрочастиц и за метеорологическими параметрами в приземном слое атмосферы в районе карьера. В целом проведенные измерения позволили получить оценки значений концентрации твердых частиц во времени и пространстве. (EDN: VEIDAM)

The results of the analysis of the aftershock sequences initiated by the underground nuclear tests conducted in North Korea in 2016 and 2017 are presented. Waveform cross-correlation and a multi-master method applied to phase association allowed us to find and analyze almost 100 aftershocks and divide them into two clusters related to the underground explosions conducted on 09.09.2016 (DPRK-5) and on 03.09.2017 (DPRK-6). The duration, intensity, and sporadic nature of these two sequences indicate specific mechanisms of seismic energy release, probably related to the interaction of the destruction zones of the DPRK-5 and DPRK-6 explosions and the collapse of their cavities with the gradual advance of the collapse column to the free surface. The after-shock activity in 2021 allows assuming the collapse process is not yet completed and expecting new aftershocks in the near future, which could end in the collapse column reaching the free surface. These assumptions were confirmed - during the preparation of the article, on 11.02.22, a strong aftershock with a magnitude of 3.85 was recorded, which, according to preliminary estimates, indicates the beginning of the final stage of the collapse, the probability of which is discussed in this study. (КИТОВ И.О., САНИНА И.А. АНАЛИЗ ПОСЛЕДОВАТЕЛЬНОСТЕЙ АФТЕРШОКОВ, ИНИЦИИРОВАННЫХ ПОДЗЕМНЫМИ ЯДЕРНЫМИ ИСПЫТАНИЯМИ, ПРОВЕДЕННЫМИ В СЕВЕРНОЙ КОРЕЕ 09.09.2016 Г. И 03.09.2017 Г. // СЕЙСМИЧЕСКИЕ ПРИБОРЫ. 2022, Т.58, №3, С.25-42 DOI: 10.21455/si2020.3-2 EDN: PEBNXV)

В работе представлены результаты численного моделирования напряженно-деформированного состояния самоподъемных плавучих буровых установок, использующихся для освоения шельфовых месторождений углеводородов. Изучены равновесное напряженное состояние установки, погруженной в донный грунт, и его изменение, вызванное внешним механическим воздействием. Рассмотрена частная задача, в рамках которой в роли внешнего воздействия выступает поверхностная сейсмическая волна от удаленного землетрясения. Исследован отклик системы «самоподъемная плавучая буровая установка – донный грунт» на такое воздействие: проанализировано перераспределение полей напряжений и деформаций в системе, вызванное сейсмическим воздействием. Рассмотрен вопрос устойчивости установки: продемонстрировано, что приход сейсмической волны приводит к резкому росту напряжений в определенных элементах опорных колонн, что может привести к потере устойчивости. Для численного моделирования рассмотренной контактной задачи теории упругости использован метод конечных элементов. Проверка корректности постановки задачи и сходимости ее решения была выполнена путем рассмотрения известной задачи о вдавливании жесткого цилиндра в упругое полупространство. Показано, что использующаяся для анализа устойчивости самоподъемной буровой установки численная схема дает верные результаты для рассмотренной модельной задачи при условии корректного построения сетки конечных элементов. В рамках работы были исследованы роли различных факторов, определяющих условия достижения напряжениями в самоподъемной плавучей буровой установке критических значений: рассмотрены степень выраженности сейсмического воздействия, механические свойства донного грунта и глубина погружения опорных колонн установки в грунт. Сделаны предварительные выводы о необходимости заглубления опорных колонн в донный грунт с учетом его механических свойств и характерной для региона сейсмичности. Представленный в работе подход может быть использован в качестве инструмента для прогноза рисков, связанных с освоением месторождений углеводородов, расположенных на континентальном шельфе, а использованная схема численного моделирования — для решения класса контактных задач теории упругости, требующих анализа динамических процессов. (Vasiliev I.A., Dubinya N.V., Tikhotskiy S.A., Nachev V.A., Alexeev D.A. Numerical model of jack-up rig’s mechanical behavior under seismic loading // Computer Research and Modeling, 2022, vol. 14, no. 4, pp. 853-871)

This article presents the results of geological, structural, and hydrogeological investigations carried out before and after a large-scale explosion of an object located within the Semipalatinsk Test Site. The obtained data are compared with published information on aftershock emissions registered in an epicentral area after an explosion. Zones with irreversibly changed mechanical and filtrational parameters of geological media are compared with a spatiotemporal distribution of high-amplitude aftershocks in plan and cross-sectional views. The cone of depression formed in the potentiometric surface coincides with the area of registered microseismic events. The general trend of decreasing microseismicity intensity induced by underground large-scale explosion is synchronic with stabilization of the hydrogeodynamic situation.

The spectrum of fault slip modes spans a continuum from fast ruptures to slow slip events. The nucleation of a certain slip mode is governed by the frictional heterogeneity of fault interface and the rheological fault stiffness. There is a mounting evidence that a single fault can host multiple slip modes. In laboratory experiments we study acoustic emission (AE) initiated by a sliding frictional fault and focus our attention on gouge-filled faults hosting multiple slip modes. Deformation experiments were performed on a slider model setup with a precise control of mechanical parameters and monitoring the acoustic signal in the frequency range of 20-80 kHz. We have shown that the cumulative AE energy linearly depends on block displacement. Besides that, there is a high inverse correlation (-0.94) between fault friction and b-value of frequency-amplitude distribution of AE in the performed experiments. Provided that velocity weakening is specific for the fault interface, the self-organization of a gouge-filled fault at the micro scale is the key parameter that controls the frictional behavior of fault hosting multiple slip modes. Resting on a quantitative categorization of AE waveforms, two AE subpopulations have been distinguished. One of them manifests as AEs with harsh onsets. The second one exhibits a gradual amplitude rise and tremor-like waveforms. A longer duration of the intergrain rupture is specific for the second AE subpopulation. During a laboratory seismic cycle, the first AE subpopulation retains parameters, while the second one exhibits a pronounced cyclic recurrence of b-value. The b-value of the second subpopulation gradually decreases before slip events and recovers after them. Two AE subpopulations, probably, point to the coexistence of two dynamic subsystems. The revealed precursory changes of AE subpopulations are common for the entire spectrum of slip modes. We speculate on the unity of underlying mechanisms of different slip modes.

The results of numerical modeling of the vertical fall of ten-kilometer asteroids onto a solid surface and into an ocean with a depth of 1 to 7 km are presented. The calculations obtained the maximum masses of water and soil emitted into the atmosphere, as well as the masses of water and soil remaining in the atmosphere 30 minutes after the impact. It is concluded that that when asteroids about ten kilometers in size fall into the ocean, the impact on the Earth's atmosphere will, apparently, be no less strong than when asteroids fall on land. (В. В. Шувалов ВЫБРОС ВЕЩЕСТВА В АТМОСФЕРУ ПРИ ПАДЕНИИ ДЕСЯТИКИЛОМЕТРОВЫХ АСТЕРОИДОВ В ОКЕАН // Астрономический вестник, 2021, T. 55, № 2, стр. 114-123 DOI: 10.31857/S0320930X21010072)

Variations in the electric field and atmospheric current in the surface atmosphere at middle latitudes during 58 strong magnetic storms that occurred from 2016 to 2019 are examined based on instrumental observations made by the Mikhnevo Geophysical Observatory of the Sadovsky Institute of Geosphere Dynamics of Russian Academy of Sciences (MHV). It is shown that geomagnetic disturbances characterized by a station magnetic activity K-index exceeding five are accompanied by changes in the vertical component of the Earth's electric field. It is found that the changes have different patterns: sometimes a bay-like increase/decrease in the electric field and sometimes a sign-alternating increase in the magnitude of the electric field. In general, the range of electric field variations varies from 5 to 580 V/m. At the same time, magnetic storm periods are characterized by greater atmospheric current variations the magnitude of which goes up to 80 pA/m(2). The findings presented enrich the database on these phenomena and may be useful in improving existing models of interaction and transformation of geophysical fields as well as in developing new ones. (С.А. Рябова, А.А. Спивак ВАРИАЦИИ ЭЛЕКТРИЧЕСКИХ ХАРАКТЕРИСТИК ПРИЗЕМНОЙ АТМОСФЕРЫ В ПЕРИОДЫ МАГНИТНЫХ БУРЬ // Доклады Российской академии наук. Науки о Земле, 2021, T. 497, № 1, стр. 71-77 DOI: 10.31857/S2686739721030099)

This study presents the results obtained from modeling the lower ionosphere response to C-, M- and X-class solar X-ray flares. This model is based on a 5-component scheme for the ionization-recombination cycle of the ionospheric D-region. Input parameters for the plasma-chemical model under different heliogeophysical conditions corresponding to selected X-ray flares were determined by using data received from the AURA, SDO, and GOES satellites. Verification of the obtained results was carried out with use of ground-based radiophysical measurements taken at the geophysical observatory Mikhnevo. The results obtained from a comparison of the calculated and experimental radio wave amplitude variations along six European very low frequency (VLF) paths show that the average normalized root mean square error is similar to 7%, 14%, and 18% for C-, M-, and X-class flares, respectively. Qualitative and quantitative analysis of the verification results for the VLF signal amplitude show good predictive capability of the model built for describing weak and moderate ionospheric disturbances.

Large airbursts, the most frequent hazardous impact events, are estimated to occur orders of magnitude more frequently than crater-forming impacts. However, finding traces of these events is impeded by the difficulty of identifying them in the recent geological record. Here, we describe condensation spherules found on top of Walnumfjellet in the Sor Rondane Mountains, Antarctica. Affinities with similar spherules found in EPICA Dome C and Dome Fuji ice cores suggest that these particles were produced during a single-asteroid impact ca. 430 thousand years (ka) ago. The lack of a confirmed crater on the Antarctic ice sheet and geochemical and O-18-poor oxygen isotope signatures allow us to hypothesize that the impact particles result from a touchdown event, in which a projectile vapor jet interacts with the Antarctic ice sheet. Numerical models support a touchdown scenario. This study has implications for the identification and inventory of large cosmic events on Earth.

Fast adaptive optical system usually used in atmosphere tasks—for wavefront correction of the laser beam passed through a turbulent atmosphere. As a rule, the frequency of waveform distortions is about 100 Hz (roughly). Consequently, the frequency of discreet system should be about 1500 frames per second. Achieving such performance is possible by FPGA using for full closed-loop cycle: image receiving from wavefront sensor, voltages array for deformable mirror calculation the and provision fast applying these voltages to deformable mirror. Main aspects of FPGA using to minimize the whole cycle of adaptive optical system are considered.

The method and corresponding optical scheme for the registration and reconstruction of digital volume holograms are considered. It is shown that a set of digital holograms recorded with a scanning reference beam makes it possible to reconstruct the complex amplitude of the object field. The proposed method for registering digital holograms is considered a digital analog of Denisyuk's holography. In particular, a condition is obtained connecting the number of steps (number of holograms) with the quantity of the phase step, when the background and conjugate image are eliminated after the reconstruction procedure of an object field according to the suggested algorithm. Experimental results are presented validating the proposed approach

DOI: 10.1134/S0016793221010047 The paper presents the results of a study of the relationship of seismic events with geomagnetic disturbances arising from the acoustic impact on the lower ionosphere, which are caused by vibrations of the Earth's surface at distances of several thousand kilometers from the earthquake source. The measurements were carried out at Mikhnevo Observatory, which is equipped with an instrumental complex, including seismic, acoustic, electromagnetic, and ionospheric means of observation. It is also equipped with a time-reference system that uses GPS receivers, which ensures an accuracy of the measurement data synchronization of no worse than 20 ns. The regularities of the formation of atmospheric and geomagnetic effects of distant earthquakes and the dependence of the time of their occurrence on the distance to the seismic source are shown on the example of five seismic events. It is demonstrated that the difference in the nature and time of the occurrence of geomagnetic pulsations associated with the impact of acoustic waves on the ionosphere differ from the signals caused by the seismomagnetic effect. (Б.Г. Гаврилов, Ю.В. Поклад, Ю.С. Рыбнов, И.А. Ряховский, И.А. Санина ГЕОМАГНИТНЫЕ ЭФФЕКТЫ УДАЛЕННЫХ ЗЕМЛЕТРЯСЕНИЙ // Геомагнетизм и аэрономия, 2021, T. 61, № 1, стр. 115-123 DOI: 10.31857/S0016794021010041)

Stacked-array deformable mirror is one of the most popular tools for correction of wavefront aberrations. We manufactured the stacked-array deformable mirror with small diameter by using piezoceramic combs with few actuators on them. In this case the aperture of mirror will be equal to 30 mm. The stroke of such mirror would be about 5 microns. The thickness of the mirror substrate is 1 mm. Developed deformable mirrors will be suitable for fast adaptive optical systems for optical radiation transferring through turbulent atmosphere tasks.

The results of experiments conducted on a laboratory setup of a fast adaptive optical system based on the use of FPGA as the main control element and a bimorph mirror as a wavefront corrector are presented. The adaptive system bandwidth ranged from a dozen Hertz to 2,000 Hertz. For independent control of the quality of correction the intensity distribution in the far field was recorded. It is shown that for a good correction of the wavefront the system bandwidth should be an order of magnitude higher than the upper boundary of the spectrum of wavefront distortions caused by turbulence. A comparison of the model and experimental data is also presented.

Bimorph and stacked actuator deformable mirrors were used to increase the efficiency of focusing of partially coherent laser radiation propagated through the scattering suspension that was equivalent to the middle-density fog layer with the length ranging from 300–500 meters up to 5 kilometers. We used Shack-Hartmann sensor to measure the averaged wavefront distortions and CCD camera to estimate the intensity distribution of the focal spot in the far-field. Numerical and experimental investigations of focusing improvement demonstrated that it is possible to increase the peak intensity of the focal spot by more than 60 %.

The article discusses the use of stacked-actuator adaptive mirrors to improve the focusing of laser radiation. The criterion of focusing efficiency is the fraction of the energy of the laser radiation passing through the pinhole located in the focal plane of the focusing lens.

Adaptive system for wavefront correction based on 240-mm bimorph deformable mirror and Shack-Hartmann wavefront sensor is presented. The dynamic characteristics of the deformable mirror and the performance of the wavefront correction in various operating modes of the PEARL facility as well as the features of phase distortion compensation in a single-shot generation regime are studied. An improvement in the quality of focusing that led to an increase in the Strehl ratio to 0.6 is demonstrated.

The spectra of geomagnetic variations calculated in the period range close to planetary waves-5, 10, and 16 days-are analyzed. The records of the geomagnetic field at the Geophysical Observatory "Mikhnevo" of the Institute of Geosphere Dynamics of Russian Academy of Sciences are used. Spectral estimation based on parametric approach is carried out for the winter and summer periods of 2009 (low solar activity) and 2015 (high solar activity). For the first time, it is established that the harmonics directly related to the manifestation of the atmospheric planetary waves in the entire period range from 4 to 17 days are only observed in winter and, irrespective of solar activity; the changes in the atmospheric pressure are about a month ahead of the changes in the geomagnetic field. In the spectra of geomagnetic variations in the period range of 4-17 days, the harmonics of the 27-day geomagnetic periodicity and the harmonics associated with their modulation by the 11-year solar cycle, annual and semiannual variations are revealed. In the spectra for the period range from 12 to 17 days, harmonics with periods close to tidal waves \M-f and M-sf are identified. (С.А. Рябова, С.Л. Шалимов О ГЕОМАГНИТНЫХ ВАРИАЦИЯХ, НАБЛЮДАЕМЫХ НА ПОВЕРХНОСТИ ЗЕМЛИ В ДИАПАЗОНЕ ПЕРИОДОВ ПЛАНЕТАРНЫХ ВОЛН // Физика Земли, 2021, № 1, стр. 51-60 DOI: 10.31857/S0002333721010075)

The structure of seismic wavefield at distances close to antipodal is analyzed using two numerical methods-DSM and AXISEM-for calculating full waveforms. The obtained empirical estimates of the amplitude ratio of PKIIKP and PKIKP phases indicate that the S-wave velocity in the upper 40 km of the inner core may not be higher than 3.1 km/s. The properties of the PKPc-dif waves suggest a lower P-wave velocity in the lower 100 km of the outer core. (О.А. Усольцева, В.М. Овчинников, Д.Н. Краснощеков ОБ ОСОБЕННОСТЯХ ПЕРЕХОДНОЙ ЗОНЫ ОТ ВНЕШНЕГО К ВНУТРЕННЕМУ ЯДРУ ЗЕМЛИ ИЗ ХАРАКТЕРИСТИК ВОЛН PKIIKP И PKPC-DIF // Физика Земли, 2021, № 1, стр. 95-108 DOI: 10.31857/S0002333721010105)

The results of instrumental observations of acoustic effects from a number of strong earthquakes in Albania, Greece, Iran, and Turkey with magnitudes from 5.1 to 6.9 are presented. The observations were carried out at three sites-at the Geophysical observatory "Mikhnevo" (54.94 degrees N; 37.73 degrees E), at the Center for Geophysical Monitoring in Moscow (CGM) (55.70 degrees N; 37.57 degrees E) of the Sadovsky Institute of Geosphere Dynamics of the Russian Academy of Sciences, and at the observation site in Zvenigorod, Moscow region (55.69 degrees N; 36.77 degrees E). This observation geometry provided the directions to the sources of acoustic perturbations. It is shown that earthquakes with the sources located at distances from similar to 1845 to similar to 2815 km from recording points cause perturbations in the atmosphere in the form of acoustic oscillations in infrasound range propagating in the stratospheric waveguide and in the form of acoustic oscillations caused by seismic waves. The characteristic periods of the acoustic signals caused by the earthquakes are presented. The energies of the acoustic source and the earthquake are estimated from the spectral characteristics of infrasonic signals propagating in the stratospheric waveguide. (А.А. Спивак, Ю.С. Рыбнов АКУСТИЧЕСКИЕ ЭФФЕКТЫ СИЛЬНЫХ ЗЕМЛЕТРЯСЕНИЙ // Физика Земли, 2021, № 1, стр. 41-50 DOI: 10.31857/S0002333721010099)

In this work, we study the splitting of the lowest frequency 0S2 of the Earth’s free oscillations in the Earth’s electromagnetic field during large earthquakes. The work analyzes the results of electromagnetic monitoring at the Mikhnevo geophysical observatory of Sadovsky Institute of Geosphere Dynamics of Russian Academy of Sciences (54.96° N, 37.77° E), carried out using a LEMI-008 magnetometer (magnetic field components) and INEP fluxometer (vertical component of electric field). The estimates of the 0S2 singlet frequencies, obtained from experimental data on the detection of magnetic and electric fields, are determined with sufficiently high accuracy and have values rather close to theoretical ones. The theoretical frequencies are calculated by the Earth model 1066A.

In the course of this study, we used the results of geomagnetic field monitoring at the Mikhnevo Geophysical Observatory of Sadovsky Institute of Geosphere Dynamics of Russian Academy of Sciences, Russian Federation, Moscow region, Mikhnevo village (its geographic coordinates are 54.96° N, 37.77° E). It has been established that for all three components the diurnal geomagnetic variations show a similar tendency, that is, two hours before the climax of the Sun, a minimum is observed, and approximately three and a half hours after noon, a maximum is observed. In addition, the time of the beginning of the quiet interval approximately coincides with the time of sunset, and the time of the end of the quiet interval is close to the time of sunrise. The latest beginning of the quiet interval is observed in summer, and the earliest in winter, this result is to some extent predictable, because the start of a quiet interval approximately corresponds to the time of sunset. Spectral analysis of time series of geomagnetic field monitoring demonstrates the presence of variations with periods of 6, 8, 12, and 24 h.

This paper addresses the results of instrumental observation of acoustic oscillations in the atmosphere above the city of Moscow during the COVID-19 quarantine period. Instrumental observations made by the Geophysical Monitoring Center (GMC) at the Institute of Geosphere Dynamics (IGD), Russian Academy of Sciences, show that the quarantine-related decrease in production activity caused significant changes in the amplitude and spectral characteristics of acoustic noise above the city, as compared to the long-term averages. During the quarantine period, the amplitude of the main spectral components and the average amplitude of acoustic noise decreased by more than two times. The diurnal variation of the amplitude of noise caused by production activities in the daytime was much less evident. Our findings can be useful in determining the characteristics of technogenic noise sources and assessing its contribution to the total acoustic noise level of the city. (А.А. Спивак, Д.Н. Локтев, Ю.С. Рыбнов, В.А. Харламов АКУСТИЧЕСКИЙ ШУМ В МОСКВЕ В ПЕРИОД КАРАНТИНА ПО COVID-19 В 2020 Г. // Доклады Российской академии наук. Науки о Земле, 2021, T. 496, № 1, стр. 67-70 DOI: 10.31857/S2686739721010230)

The results of data analysis of instrumental observations of microbaric variations in the atmospheric pressure carried out at the Mikhnevo Geophysical Observatory and at the Center for Geophysical Monitoring in Moscow of Sadovsky Institute of Geosphere Dynamics of Russian Academy of Sciences (IDG RAS) during periods of strong geomagnetic disturbances are presented. It was shown from the example of 57 events that, during magnetic storms (index of geomagnetic activity K-p >= 5), increased microbaric variations with amplitudes from 2 to 20 Pa in the range of periods of 20-80 min and frequencies close to the Brunt-Vaisala frequency have been observed. It is shown that the spectrum of microbaric variations caused by magnetic storms contains several quasi-harmonic components. The maximum amplitudes of acoustic vibrations fall in the range from 2 to 20 Pa with the maximum amplitudes of the magnetic disturbance from 15 to 200 nT. (А.А. Спивак, Ю.С. Рыбнов, С.А. Рябова, В.А. Харламов ВОЛНОВЫЕ ВОЗМУЩЕНИЯ В ПРИЗЕМНОЙ АТМОСФЕРЕ ПРИ МАГНИТНЫХ БУРЯХ // Доклады Российской академии наук. Науки о Земле, 2021, T. 498, № 2, стр. 158-162 DOI: 10.31857/S2686739721060165)

Despite extensive research, it is still unclear, to what extent studying the parameters of weak seismicity facilitates the interpretation of the data obtained from moderate and strong earthquakes. In this paper, we analyze seismic events initiated by mine explosions at the Korobkovskoe iron ore deposit of the Kursk Magnetic Anomaly, central East European platform. The study region is distinguished by the excess of horizontal stresses over vertical stresses and is declared as a potentially rock-burst prone massif although mining-induced rock bursts have not been observed so far. In this analysis, we use the data from a seismic network of four one-component horizontal accelerometers installed in the mine. After the detection and location of weak seismic events, their source parameters were estimated based on the Brune model spectrum approximation. It was established that the sources of the recorded seismic events are densely clustered in space in the vicinity of the closest explosion room and most sources are located within a domain with a level of the explosion-induced dynamic strains higher than 10(-6). The calculated moment magnitudes vary from -2.7 to -1.4. The stress drop is estimated to range from 0.002 to 0.25 MPa with the apparent stress values varying from 0.0003 to 0.017 MPa. The scaled seismic energy E-s/M-0 increases from 10(-8) to 10(-7) J/(N m) as the seismic moment changes from 1.5 x 10(5) to 1.5 x 10(6) N m. This trend is not observed in the interval of moments from 106 to 107 N m. In our opinion, this effect can probably be associated with the decrease in the shear modulus of the rock with the increase of the event size. The calculated values of the scaled energy and rupture propagation velocity indicate that the industrial explosion has probably initiated a series of microearthquakes with low radiation efficiency. (А.Н. Беседина, С.Б. Кишкина, Г.Г. Кочарян ПАРАМЕТРЫ ИСТОЧНИКОВ РОЯ МИКРОСЕЙСМИЧЕСКИХ СОБЫТИЙ, ИНИЦИИРОВАННЫХ ВЗРЫВОМ НА КОРОБКОВСКОМ ЖЕЛЕЗОРУДНОМ МЕСТОРОЖДЕНИИ //Физика Земли, 2021, № 3, стр. 63-81 DOI: 10.31857/S0002333721030030)

Deformable mirrors in adaptive system for high power lasers should have high damage threshold and thermally stabilized surface. The cooling is required for average beam power above 100W. In this paper, the problem of the thermo-stabilizing of the deformable mirrors is studied. Bimorph deformable mirrors (BDM) and stack actuator deformable mirrors (SADM) are considered. For BDMs the active and passive cooling designs have been implemented. In active design, the waffle-type cooling system for circulation of the cooling liquid was made inside of the thin substrate. In passive design, the periphery surface is thermally contacted with the condenser which temperature is constant. Such BDMs not damaged at CW power density 20kW/cm2 when the beam fills full surface of the mirror and can be used in powerful solid state ceramic YAG lasers. SADM is most suitable to correct for small-scale and high-speed aberrations. We developed SADM where reflecting substrate is cooled through the actuator bodies. Individual actuators are housed in metal holders and can be replaced if they fail due to electrical breakdown. SADM has the diameter 120 mm and included 121 actuators. The deformation stroke of the actuator was 7μ. The first resonant frequency was 18.5 kHz, which allowed operating in adaptive system in kHz range.

It is known that the electrodynamic coupling of plasma flows with a magnetic field and background plasma leads to the generation of field-aligned currents that cause many effects in the auroral regions of the Earth during magnetic storms and sub-storms. Much less is known about the influence of field-aligned currents on the dynamics and evolution of plasma flows themselves. The study of this effect in space is complicated by the scale of the phenomenon and requires simultaneous measurements in various regions of the magnetosphere and ionosphere using a large number of satellites. In addition, taking into account the non-stationary nature of these processes, an extremely complex and expensive experiment must be carried out over a long time period. At the same time, such studies can be quite effective in controlled laboratory and ionospheric plasma experiments. This review is devoted to exploring how the generation and evolution of field-aligned currents influences the state and dynamics of plasma flows moving in the magnetic field.

We present the results of the aberration correction of laser radiation wavefront using a dynamic method for determining the reference wavefront. The method, which is based on the processing of synchronously obtained data on the near- and far-field zones, significantly improves the focusing quality with active wavefront correction, especially under conditions of dynamic aberrations. An increase in the Strehl number S from 0.7 to 0.86 is demonstrated when a beam 18 cm in diameter is focused by an F/2.5 parabolic mirror. (А. В. Котов, С. Е. Перевалов, М. В. Стародубцев, Р. С. Земсков, А. Г. Александров, И. В. Галактионов, А. В. Кудряшов, В. В. Самаркин, А. А. Соловьев Адаптивная система коррекции оптических аберраций излучения мощных лазеров с динамическим определением эталонной формы волнового фронта // Квантовая электроника, 51:7 (2021), 593–596)

This paper is a brief review of the main recent results obtained by studying fault slip processes. The published hypotheses and data are analyzed within the approach proposed by Panin, according to which the subsurface is considered as a multilevel hierarchically organized system where all processes evolve consistently at the nano-, micro-, meso- and macroscale levels. The review focuses on the hierarchy of structures that, according to modern concepts, form the seismogenic fault slip zone. The relationship of the structures with the mechanical characteristics of localized slip surfaces and microcontacts determining the slip dynamics of fault zones at the macrolevel is discussed. It is shown that the evolution of the contact properties of filler particles in the slip zone determines not only the occurrence of instability, but also the ability of a fault to recover strength with time. The simplest scheme of the hierarchy of macroscopic asperities is described to support the important principle that the initiation, evolution and arrest of a seismogenic fault depend on the size and relative position of regions with different dynamics of frictional characteristics during slip. The performed analysis of the results of field observations shows that because of the insufficient accuracy of observations and the ambiguous interpretation of the inverse problem solution, it is impossible to correctly identify fault segments with the velocity weakening property. The size and location of these zones can be more accurately determined from the analysis of records of high-frequency oscillations in the vicinity of an earthquake rupture. The basic principles of physical mesomechanics provide a good basis for the interpretation of such results. (Кочарян Г.Г., Кишкина С.Б. Физическая мезомеханика очага землетрясения // Физическая мезомеханика т.23, №6 (2020), с.9–24 DOI: 10.24411/1683-805X-2020-16001)

To correct for phase distortions in high-power laser setups a stacked-actuator deformable mirror with water cooling was developed. The main characteristics of the mirror such as the initial surface profile, response functions of the actuators, maximal stroke and amplitude frequency characteristic were shown. The quality of initial surface was equal to 0.14 µm (P-V). The maximal stroke of the mirror was about 7 µm. The first resonant frequency was found at 18.5 kHz, that would allow to exploit such wavefront corrector in high-speed adaptive optical systems. The measured hysteresis of the deformable mirror was equal to 12%. Experimental investigations of proposed cooling method of the mirror surface through actuators were performed.

Positioning and synchronization of seismic stations using GPS receivers is convenient and has sufficiently high accuracy for subsequent processing and adequate interpretation of the obtained seismic data. However, it is impossible to synchronize a seismic station at the time of data acquisition if it is outside the access area of GPS satellites, e.g., in a deep mine, such that the receiver itself cannot be extracted from the mine and remains connected to the seismic station. This situation is relevant, e.g., for seismological studies conducted by the IGD RAS in Gubkin. This study is aimed at solving the problem of positioning and synchronizzing seismic stations directly inaccessible to the signals of satellites of this system. (ВОЛОСОВ С.Г., КОРОЛЁВ С.А., НЕСТЁРКИН В.Н., ТАРАСОВ С.А. МЕТОДЫ И СРЕДСТВА СИНХРОНИЗАЦИИ СЕЙСМОСТАНЦИЙ, РАБОТАЮЩИХ В УСЛОВИЯХ НЕДОСТУПНОСТИ СИГНАЛОВ СПУТНИКОВ GPS // СЕЙСМИЧЕСКИЕ ПРИБОРЫ Т.57, №2, 2021, С.5-22 DOI: 10.21455/si2021.2-1)

A review is presented of the state-of-the-art publications concerning the nucleation and evolution of fault slip in the Earth's crust. The review covers various aspects of the problem, from the structure of the slip localization zones to the triggering of dynamic rupture by exogenous factors. The publications show a clear current trend from investigating individual effects to studying interactions between subsets of the relevant processes on several spatial and time scales to establish probable correlations between different phenomena. The efforts of many research teams in the field of earthquake source physics and faulting are focused towards creating a computational model that relies on physical principles and successfully fulfils forecasting tasks. The review demonstrates multi-aspect and multi-scale character of the discussed problem and provides coverage of recent results and challenges in achieving the objectives. Some promising lines of development in geomechanics of faults, as they are seen from the author's standpoint, are formulated. (Г.Г. Кочарян ВОЗНИКНОВЕНИЕ И РАЗВИТИЕ ПРОЦЕССОВ СКОЛЬЖЕНИЯ В ЗОНАХ КОНТИНЕНТАЛЬНЫХ РАЗЛОМОВ ПОД ДЕЙСТВИЕМ ПРИРОДНЫХ И ТЕХНОГЕННЫХ ФАКТОРОВ. ОБЗОР СОВРЕМЕННОГО СОСТОЯНИЯ ВОПРОСА // Физика Земли, 2021, № 4, стр. 3-41 DOI: 10.31857/S0002333721040062)

The possibility of jointly inverting the receiver function waveforms and the seismic noise horizontal-to-vertical spectral ratio to study the Earth's structure is substantiated. Both data types are widely used for constructing a velocity model beneath a single seismic station. The main difference between the methods is associated with the different frequency content of input data which is 0.02-0.2 Hz in receiver functions and 0.5-20 Hz in seismic noise. It is shown that notwithstanding these differences, the joint inversion approach more effectively reconstructs the model of the medium in case when a station is underlain by a complexly structured sedimentary cover. In the practical implementation, the parameters of both seismic methods are described in a flat-layer representation of the medium. Besides, both methods are most sensitive to the depth distribution of S-wave velocities. In this work, we use records from the Monakovo seismic station, Nizhny Novgorod region, Russia, to construct a model of the medium consistent with both data types. It is shown that the allowance for the H/V spectral curve in the receiver function interpretation provides additional constraints on the small-scale structure of the upper part of the velocity section thus stabilizing the reconstruction procedure. (И.М. Алешин, А.Г. Гоев, Г.Л. Косарев, Д.А. Преснов СПЕКТР ОТНОШЕНИЯ H/V СЕЙСМИЧЕСКОГО ШУМА МОЖНО ОБРАЩАТЬ СОВМЕСТНО С ПРИЕМНЫМИ ФУНКЦИЯМИ // Физика Земли, 2021, № 4, стр. 133-141 DOI: 10.31857/S0002333721040013)

Variations in the vertical electric field and atmospheric current in the near-surface atmosphere, accompanying strong earthquakes, are analyzed. The analysis is based on the data of the Center for Geophysical Monitoring in Moscow (CGM) and Geophysical observatory "Mikhnevo" of the Sadovsky Institute of Geosphere Dynamics of Russian Academy of Sciences (IDG RAS). We considered seismic events that occurred when the electric field and atmospheric current were not disturbed by anthropogenic sources and natural impacts unrelated to earthquakes. It is noted that the earthquakes are accompanied by the increased local variations in the electric field in the period of arrival of seismic waves at the observation point and variations associated with the source region of the seismic event. In the latter case, the effect appears as a bay-like decrease and increase and as alternating variations in the vertical gradient of the electric potential. Simultaneously, the earthquakes are accompanied by the increased variations in the atmospheric current. For the first time it is shown that the main shock is accompanied by the increased variations in the electrical characteristics of the near-surface atmosphere at significant distances from the seismic source. (С.А. Рябова, А.А. Спивак ВАРИАЦИИ ЭЛЕКТРИЧЕСКИХ ХАРАКТЕРИСТИК ПРИЗЕМНОЙ АТМОСФЕРЫ ПРИ СИЛЬНЫХ ЗЕМЛЕТРЯСЕНИЯХ. РЕЗУЛЬТАТЫ НАБЛЮДЕНИЙ // Физика Земли, 2021, № 4, стр. 120-132 DOI: 10.31857/S0002333721040074)

Reconstruction of the Campo del Cielo impact event, i.e., to estimate the minimal pre-atmospheric mass and velocity of the meteoroid, its fragmentation during the atmospheric entry and to compare the resulting strewn field with the observed one.

A mechanism for the appearance of anomalous variations in the vertical component of the electric field strength recorded at the Mikhnevo Geophysical Observatory of Sadovskii Institute of Geosphere Dynamics, Russian Academy of Sciences, during strong remote earthquakes is proposed. It is shown that intensification of radon emanations in the observational area stimulated by the seismogravitational oscillations and subsequent modulation of radon and aerosol concentrations by atmospheric internal waves may result in these electric field variations. (С.Л. Шалимов, С.А. Рябова О возможном механизме вариаций электрического поля приземной атмосферы при сильных удаленных землетрясениях // Доклады Российской академии наук. Науки о Земле, 2021, T. 499, № 2, стр. 164-167 DOI: 10.31857/S2686739721080144)

The article presents the results of precision hydrogeological monitoring, carried out within the operating iron ore deposit near the city of Gubkin, Belgorod region. The organization of an autonomous instrumentation-measuring complex at the wellhead areas of observation wells is described in detail. The methods of processing the series of synchronous recording of seismic, hydrogeological, and barometric data are considered. The proposed scientific and methodological approach to analyzing the obtained experimental data is oriented towards the background parameters of water-saturated reservoirs of pore and fractured-porous types (including the coefficients of barometric efficiency and tidal sensitivity) and studying the response of the well–aquifer system to mass explosions. (ГОРБУНОВА Э.М., БЕСЕДИНА А.Н., КАБЫЧЕНКО Н.В., БАТУХТИН И.В., ПЕТУХОВА С.М. ПРЕЦИЗИОННЫЙ ГИДРОГЕОЛОГИЧЕСКИЙ МОНИТОРИНГ В ТЕХНОГЕННО-НАРУШЕННЫХ УСЛОВИЯХ: ОРГАНИЗАЦИЯ, ПРОВЕДЕНИЕ И ОБРАБОТКА ЭКСПЕРИМЕНТАЛЬНЫХ ДАННЫХ // СЕЙСМИЧЕСКИЕ ПРИБОРЫ, Т.57, №2, 2021, С.62-80 DOI: 10.21455/si2021.2-4)

Fractionation effects related to evaporation and condensation had a major impact on the current elemental and isotopic composition of the Solar System. Although isotopic fractionation of moderately volatile elements has been observed in tektites due to impact heating, the exact nature of the processes taking place during hypervelocity impacts remains poorly understood. By studying Fe in microtektites, here we show that impact events do not simply lead to melting, melt expulsion and evaporation, but involve a convoluted sequence of processes including condensation, variable degrees of mixing between isotopically distinct reservoirs and ablative evaporation during atmospheric re-entry. Hypervelocity impacts can as such not only generate isotopically heavy, but also isotopically light ejecta, with δ56/54Fe spanning over nearly 5‰ and likely even larger variations for more volatile elements. The mechanisms demonstrated here for terrestrial impact ejecta modify our understanding of the effects of impact processing on the isotopic evolution of planetary crusts.

Abundances of the highly siderophile elements (HSEs) in silicate portions of Earth and the Moon provide constraints on the impact flux to both bodies, but only since similar to 100 Myr after the beginning of the Solar System (hereafter t(CAI)) The earlier impact flux to the inner Solar System remains poorly constrained. The former dwarf planet Vesta offers the possibility to probe this early history, because it underwent rapid core formation similar to 1 Myr after t(CAI) and its silicate portions possess elevated chondritic HSE abundances. Here we quantify the material accreted into Vesta's mantle and crust and find that the HSE abundances can only be explained by the bombardments of planetesimals from the terrestrial planet region. The Vestan mantle accreted HSEs within the first 60 Myr; its crust accreted HSEs throughout the Solar System history, with asteroid impacts dominating only since similar to 4.1 billion years ago. Our results indicate that all major bodies in the inner Solar System accreted planetesimals predominantly from the terrestrial planet region. The asteroid belt was either never significantly more massive than today, or it rapidly lost most of its mass early in the Solar System history.

A brief summary of fundamental results obtained in the IDG RAS on the mechanics of sliding along faults and fractures is presented. Conditions of emergence of different sliding regimes, and regularities of their evolution were investigated in the laboratory, as well as in numerical and field experiments. All possible sliding regimes were realized in the laboratory, from creep to dynamic failure. Experiments on triggering the contact zone have demonstrated that even a weak external disturbance can cause failure of a “prepared” contact. It was experimentally proven that even small variations of the percentage of materials exhibiting velocity strengthening and velocity weakening in the fault principal slip zone may result in a significant variation of the share of seismic energy radiated during a fault slip event. The obtained results lead to the conclusion that the radiation efficiency of an earthquake and the fault slip mode are governed by the ratio of two parameters—the rate of decrease of resistance to shear along the fault and the shear stiffness of the enclosing massif. The ideas developed were used to determine the principal possibility to artificially transform the slidding regime of a section of a fault into a slow deformation mode with a low share of seismic wave radiation. (DOI: 10.1007/978-3-030-60124-9_15)

The work is devoted to the study of the influence of external mechanical impacts on the stability of jack-up floating drilling rigs. Ensuring safety when working on jack-up floating drilling rigs (jack-up rigs) is one of the most important tasks at the initial stages of offshore hydrocarbon field development. The aim of the work is simulation of the stability of the rigs, which is in the operating mode, both in the absence of external effects acting on it, and when it is affected by various geodynamic processes. Calculation of jack-up rig stability in sea soil with complex viscoelastoplastic rheology under external mechanical influences was carried out using the finite element method. As a result of the work, the spatial distributions of stress and strain fields were determined both in the jack-up rig itself and in the area of the soil in the vicinity of its supports, in an equilibrium and disturbed state. The results of equilibrium static calculations made it possible to analyze the zones of localization of stresses and deformations in the jack-up rig with respect to stability: the structural elements that are most dangerous from the perspective of stability loss were identified. The analysis of the soil area in the vicinity of the jack-up rig supports made it possible to estimate the typical dimensions of the stress concentration zones arising during the jack-up installation and draw conclusions about the requirements on details and scalability of the model of mechanical properties needed for geomechanical modeling at specific objects. The obtained results of dynamic calculations - the response of theconsidered system to external influences simulating remote seismic processes - made it possible to study the process of loss of jack-up rig stability. The critical values of the parameters describing external influences were determined: in particular, the amplitudes of surface seismic waves leading to the loss of stability of the jack-up rig were found. The obtained results made it possible to formulate an algorithm for predicting seismic hazard during drilling in offshore conditions, based on numerical modeling of mechanical processes at specific locations. Copyright 2021, Society of Petroleum Engineers.

The analysis of the instrumentally observed variations in the error of determining coordinates by the GPS navigation satellite system, performed at the Mikhnevo Geophysical Observatory of Sadovsky Institute of Geosphere Dynamics of Russian Academy of Sciences, during periods of magnetic storms, is carried out. Using a sample of 50 events that occurred in the period 2016-2019, it is shown that magnetic storms (geomagnetic activity index Kp >= 5) cause a noticeable increase in the GPS positioning error. The data obtained suggests that positioning error can be used as an indicator of the disturbed state of the ionosphere and atmosphere during magnetic storms, as well as a parameter that characterizes the degree of disturbance of the environment and the conditions for the propagation of GPS signals. (СПИВАК А.А., РЯБОВА С.А., РЫБНОВ Ю.С., ХАРЛАМОВ В.А. ОШИБКИ ПОЗИЦИОНИРОВАНИЯ GPS В ПЕРИОДЫ МАГНИТНЫХ БУРЬ // ДОКЛАДЫ РОССИЙСКОЙ АКАДЕМИИ НАУК. НАУКИ О ЗЕМЛЕ, Т.500. №2, 2021 С.173-177 DOI: 10.31857/S2686739721100169)

The effects of the strong natural events on the acoustic fields in the atmosphere, geomagnetic field, and electrical characteristics of atmospheric surface layer—atmospheric current and electric field—are discussed. The extreme events analyzed in the paper are volcanic eruptions, earthquakes, and impacts of outer space bodies falling to the Earth. These natural phenomena are considered as local indicators of the enhancement of interactions between the geospheres in the lithosphere–atmosphere near-surface system with active involvement of the ionosphere. It is shown that in these cases, the induced effects in the geophysical fields are observed at quite a distance from an event source and have similar amplitudes, probably suggesting a special role of the ionosphere in a rapid long-distance transfer of the disturbances. The effect of the acoustic-gravity waves generated by the strong natural events in their epicentral zone is considered as the main excitation mechanism of the ionosphere. The objectives and tasks of the research aimed at establishing the main regularities and interaction mechanisms between the geospheres in the environment are formulated. (В.В. Адушкин, А.А. Спивак ВОЗДЕЙСТВИЕ ЭКСТРЕМАЛЬНЫХ ПРИРОДНЫХ СОБЫТИЙ НА ГЕОФИЗИЧЕСКИЕ ПОЛЯ В СРЕДЕ ОБИТАНИЯ // Физика Земли, 2021, № 5, стр. 6-16 DOI: 10.31857/S0002333721050033)

Based on the alpha-shape computer-graphics analysis of coda envelope of the waves from nuclear explosions reflected from the inner core boundary (PKiKP), the estimates of the mechanical Q-factor are obtained for nine reflection regions beneath the Arctic, Central, and Southeast Asia with the average Q = 447 ± 43. The coda formation mechanism can be associated with the heterogeneities in the upper inner core with a characteristic linear size of 1–4 km and variations in P-wave velocity on the order of 1–3%. (Д.Н. Краснощеков, В.М. Овчинников, О.А. Усольцева МЕХАНИЧЕСКАЯ ДОБРОТНОСТЬ В ВЕРХНЕЙ ЧАСТИ ВНУТРЕННЕГО ЯДРА ЗЕМЛИ ПО ДАННЫМ КОДЫ ВОЛН РКIКP // Физика Земли, 2021, № 5, стр. 17-29 DOI: 10.31857/S0002333721050148)

The velocity structure of the lithosphere is studied beneath the Khibiny and Lovozero massifs in the northeastern part of the Baltic shield. The massifs belong to the world’s eight largest alkaline intrusions and are widely known for their unique mineralogy. The crustal and upper-mantle velocity structure beneath these two rock blocks is reconstructed down to a depth of ~300 km from P- and S-receiver functions (PRF and SRF, respectively) based on the data on the remote earthquakes recorded by broadband seismic sensors of the Apatity (APA) and Lovozero stations (LVZ). For identifying the probable differences in the velocity structure of the Khibiny and Lovozero massifs and the distinction of this structure of Baltic Shield, the data for each station were divided into two groups containing records of the converted waves formed (a) within a closest intrusive body to a station and (b) outside the intrusive body, i.e. within the shield. The four resulting data sets were processed separately. The modeling results do not show significant differences between the analyzed structures. A sharp crust–mantle boundary is established at a depth of 40 km for the models corresponding to the shield’s structure; a similar structure of the Moho zone is established for the region of the Khibiny massif. A gradient crust-mantle transition zone with Moho at a depth of ~48 km is established in the region of ​​the Lovozero massif. In all the studied structures, the S-wave velocities in the upper mantle are somewhat higher than standard IASP91 model values; a low-velocity zone in the upper mantle is observed at the depths from 90 to 140 km. For identifying the probable anomalies at the 410- and 660-km phase transition boundaries, the calculated PRFs were stacked. The estimated delays of the converted waves from these boundaries are somewhat shorter than standard delays ​​relative to the IASP91 model and lie within the expected limits ​for paleotectonic structures. (А.Г. Гоев, И.А. Санина, С.И. Орешин, Р.А. Резниченко, С.А. Тарасов, А.В. Федоров СКОРОСТНОЕ СТРОЕНИЕ ЛИТОСФЕРЫ ХИБИНСКОГО И ЛОВОЗЕРСКОГО МАССИВОВ (СЕВЕРО-ВОСТОЧНАЯ ЧАСТЬ БАЛТИЙСКОГО ЩИТА) МЕТОДОМ ФУНКЦИИ ПРИЕМНИКА // Физика Земли, 2021, № 5, стр. 30-40 DOI: 10.31857/S0002333721050069)

We present the results of laboratory studies of slope failure criteria by dynamic impulse loading in the range of peak ground velocities (PGV) between 0.003 and 1.3 m/s and peak ground accelerations (PGA) between 0.01 to above 170g. Critical parameter values of the dynamic loads acting on model slopes are established. The minimum PGA value at which landslide initiation was observed is significantly higher than critical acceleration calculated in the quasi static approach. At the same time, with close static factors of safety, critical parameters for underwater and dry slopes are comparable notwithstanding the fact that the character of the ground motion after initiation in the experiments under water strongly differs from that on the dry slopes. It is shown that there are minimal PGA and PGV values ​​at which irreversible slope deformations take place. If acceleration is lower than the minimum PGA value PGAmin, no significant irreversible deformations occur at any PGV. If mass velocity is below PGVmin, than at PGA > PGAmin, irreversible deformations are observed, and a repeated impact may cause a slope to fail. Using Newmark approximation, slope stability is calculated for various impact types: earthquakes of different magnitudes, ripple-fired explosions, and high-yield underground explosions. (Г.Г. Кочарян, А.Н. Беседина, С.Б. Кишкина, Д.В. Павлов, З.З. Шарафиев, П.А. Каменев ИНИЦИИРОВАНИЕ ОБРУШЕНИЯ СКЛОНА СЕЙСМИЧЕСКИМИ КОЛЕБАНИЯМИ ОТ РАЗНЫХ ИСТОЧНИКОВ // Физика Земли, 2021, № 5, стр. 41-54 DOI: 10.31857/S0002333721050112)

Numerical modeling of induced seismicity resulting from fluid injection into the subsurface is considered. One of important factors determining the slip dynamics of a tectonic fault during fluid injection loading is the form of the law of friction acting on the fault sides. The numerical analysis in the context of a slider model compared to the results of laboratory experiments has shown that a two-parameter rate-and-state friction law describes the widest spectrum of the observed sliding modes. A double porosity model and a slider model for fracture are used to simulate the induced seismicity in ​​the region of Basel, Switzerland, caused by geothermal stimulation. A physically complete model of embedded fractures which allows for calculating fluid flow in a rock with fractures or faults taking into account changes in the hydraulic properties of the latter is presented. Fault deformation process is described based on the displacement discontinuity method. Based on the model, the results of the field experiment on water injection into a fault in the southern France are analyzed. The development of fault slips is studied as a function of a number of parameters characterizing a fault, filtration properties of a rock, and injection pattern. The conditions for the emergence of seismic slip in the context of the proposed model are established. (В.Ю. Рига, С.Б. Турунтаев МОДЕЛИРОВАНИЕ ИНДУЦИРОВАННОЙ СЕЙСМИЧНОСТИ НА ОСНОВЕ ДВУХПАРАМЕТРИЧЕСКОГО ЗАКОНА RATE-AND-STATE //Физика Земли, 2021, № 5, стр. 55-73 DOI: 10.31857/S000233372105015X)

Deformation regimes of water-saturated reservoirs under dynamic impact are studied using groundwater-level monitoring by precision measurements. As a quasi-stationary factor responsible for background poroelastic groundwater-level fluctuations in the reservoir–well system, the Earth’s tides are considered. Hydrogeological responses to the passage of seismic waves from remote earthquakes and mass blasts produced during iron ore mining are used for estimating relative deformation of water-saturated reservoirs. The study objects are located both outside the zone of active manmade impact on geological environment (in the territory of Geophysical observatory “Mikhnevo” of the Institute of Geosphere Dynamics of the Russian Academy of Sciences) and in the technogenically disturbed conditions—in the industrial region near Gubkin, Belgorod region. Integrated processing of seismic, barometric, and hydrogeological data synchronously recorded by the instrumental-measuring systems installed in the observation wells and at the near-head sites is aimed at revealing common regularities in the responses of water-saturated reservoirs to a dynamic impact. The comparative analysis of the amplitudes of groundwater level fluctuations and pressure variations in the reservoir–well system is carried out with the allowance for ground motion velocities and reduced distances from the remote earthquakes and mass explosions. The response of water-saturated porous- and fractured-porous type reservoirs is different. Alongside with the coseismic hydrogeological effects, the analysis revealed a postseismic groundwater-level rise and increase in pressure indicating a local change in the poroperm properties of a water-saturated reservoir. The maximum values of seismic-wave ground velocities and pressure in the reservoir–well system at which deformation regimes change from a poroelastic to quasi reversible response are established. (Э.М. Горбунова, А.Н. Беседина, Н.В. Кабыченко, И.В. Батухтин, С.М. Петухова РЕАКЦИЯ ВОДОНАСЫЩЕННЫХ КОЛЛЕКТОРОВ НА ДИНАМИЧЕСКОЕ ВОЗДЕЙСТВИЕ (ПО ДАННЫМ ПРЕЦИЗИОННОГО МОНИТОРИНГА УРОВНЯ ПОДЗЕМНЫХ ВОД // Физика Земли, 2021, № 5, стр. 74-90 DOI: 10.31857/S0002333721050070)

Granular media determine the dynamics of many natural systems including faults in the Earth’s crust. The paper addresses the laboratory study of shear deformation of a model fault simulated by a layer of granular material located between rock blocks. A model fault is a complex dynamic system characterized by the presence of bifurcations and fast and slow slips may take turn aperiodically during deformation. The sliding of the rock blocks is accompanied by the generation of acoustic emission pulses (AEs) which are identified based on the Akaike information criterion. The dynamics of AEs reflects the evolution of mechanical properties of the fault. In the flow of AEs, the subsets with different rise time/amplitude values (RA-values) and different scaling relations are identified. Applying the random forest machine learning algorithm to the analysis of AE catalogue demonstrates the possibility of determining the velocity of fault sliding and the time to both fast and slow slips. The nucleation of a certain slip mode is predetermined by the self-organization processes taking place in the central zone of a fault, and the characteristics of the AE reflect these processes. The proposed approach to the estimation of fault sliding parameters can be promising for the design of new methods for monitoring stressed massifs at mining. (А.А. Остапчук, Г.Г. Кочарян, К.Г. Морозова, Д.В. Павлов, Г.А. Гридин ОСОБЕННОСТИ ФОРМИРОВАНИЯ ДИНАМИЧЕСКОГО СДВИГА В ТОНКОМ СЛОЕ ГРАНУЛИРОВАННОГО МАТЕРИАЛА // Физика Земли, 2021, № 5, стр. 91-103 DOI: 10.31857/S0002333721050136)

There is a brief overview of technogenic sources of microparticles associated with the extraction of mineral raw materials and fuel from the lithosphere. The overview focuses on the emissions of rock particles during the open-pit mining process. Assessments of microparticle emission into the surface layer of the atmosphere are obtained using the example of coal mining. The analysis was carried out on the basis of data on dust emission during various technological operations in mining activities and their total volume. The obtained assessments of microparticle emissions from open-pit coal mining in the world should be taken into account when analyzing the total aerosol balance of the atmosphere in the technogenic sources section, since these assessments are very close to the mass of emissions from motor vehicles and exceed the emissions of aviation and marine fleet. The dynamics of microparticle emission assessments from coal mining in the world for the period from 2010 to 2019 show that emissions increased by about 12% compared to 2010—this also corresponds to the growth of global open-pit coal mining. (В.В. Адушкин, С.П. Соловьев МИКРОЧАСТИЦЫ В АТМОСФЕРЕ ОТ ЛИТОСФЕРНЫХ ИСТОЧНИКОВ ТЕХНОГЕННОГО ПРОИСХОЖДЕНИЯ // Физика Земли, 2021, № 5, стр. 120-132 DOI: 10.31857/S0002333721050021)

Modeling the relative motion of large crustal blocks vitally depends on an adequate description of the forces acting between the blocks. To describe motion at high strain rates, it proved necessary to assume a dry friction to depend on the shear strain rate and, in some cases, on the amplitude of fault side displacement. The best known examples of large-scale motions with dynamically decreasing friction are long-runout rock avalanches and gravity-driven collapsing of the transitional cavities of large impact craters. In this work, the experience is discussed of using the model of acoustic fluidization as a factor of a temporary decrease in friction to quantitatively simulate impact crater shape on the Earth and other planetary bodies. Immediate promising ways to find more adequate models are outlined. (Б.А. Иванов ЧИСЛЕННОЕ МОДЕЛИРОВАНИЕ ФОРМЫ УДАРНЫХ КРАТЕРОВ С УЧЕТОМ АНОМАЛЬНОГО ДИНАМИЧЕСКОГО РАЗУПРОЧНЕНИЯ // Физика Земли, 2021, № 5, стр. 146-154 DOI: 10.31857/S0002333721050094)

Studying the spatiotemporal dynamics of the disturbances in the atmosphere, upper, and lower ionosphere requires integrated investigation of interrelated processes at different heights in the different solar-geophysical conditions. The radiophysical complex at the Geophysical observatory “Mikhnevo” of the Institute of Geosphere Dynamics of the Russian Academy of Sciences (IDG RAS) which includes magnetic and electrophysical equipment, radio receiving systems, acoustic instruments, and ionospheric sounders provides data on the structure and dynamics of the ionospheric plasma in the midlatitude European part of Russia. The data from ULF/VLF receivers and measurements of GNSS signals are used to study synchronous variations caused in the lower and upper ionosphere by the magnetic storms, solar X-ray flares, and experiments on artificial modification of the ionosphere. The techniques are developed for processing the multi-instrumental measurements of the variations in the physical fields. They include the methods for reconstructing the absolute ionospheric total electron content (TEC) and electron density profile in the lower ionosphere. The obtained data are used for verifying the IDG RAS models of the lower ionosphere. (И.А. Ряховский, Б.Г. Гаврилов, Ю.В. Поклад, С.З. Беккер, В.М. Ермак ИССЛЕДОВАНИЯ СОСТОЯНИЯ И ДИНАМИКИ ИОНОСФЕРЫ ПО ДАННЫМ СИНХРОННОЙ РЕГИСТРАЦИИ РАДИОСИГНАЛОВ КНЧ/ОНЧ И ВЧ/УВЧ ДИАПАЗОНАХ В ГЕОФИЗИЧЕСКОЙ ОБСЕРВАТОРИИ “МИХНЕВО” // Физика Земли, 2021, № 5, стр. 155-168 DOI: 10.31857/S0002333721050173)

The occurrence and evolution of plasma fluxes in the ionosphere is one of the factors that have a significant impact on the dynamics and state of the geophysical environment. The study of plasma and magnetohydrodynamic effects arising from the motion of plasma jets in real space is complicated by the scale of the phenomenon and the complex nature of the background environment, which is a non-stationary system of interacting neutral and partially or completely magnetized charged particles. The creation of theoretical models of this phenomenon is also completely unsolved scientific task. Under these conditions, controlled ionospheric plasma experiments are of great importance. The results of active rocket experiments obtained over the past few decades have made it possible to study the processes of magnetohydrodynamic interaction between a high-velocity plasma and the geomagnetic field, the generation of electromagnetic and MHD waves, optical radiation in the visible, UV and IR ranges, background gas ionization, the emergence of complex systems of electric fields and currents, the acceleration of charged particles, and other phenomena. The article discusses the current physical concepts developed from the analysis of the available experimental data, as well as the tasks and possibilities of new active experiments. (Б.Г. Гаврилов, Ю.В. Поклад ФИЗИЧЕСКИЕ ЭФФЕКТЫ, ВОЗНИКАЮЩИЕ ПРИ ДВИЖЕНИИ ПЛАЗМЕННЫХ ПОТОКОВ В ИОНОСФЕРЕ // Физика Земли, 2021, № 5, стр. 169-183 DOI: 10.31857/S0002333721050045)

Dynamics of complex plasma structures, that drive precipitation and current systems into the ionosphere, produce a multitude of physical and geophysical effects that present unresolved mysteries in our understanding of the cross-geospace coupling. High-altitude active experiments that produce high-speed plasma injections play a crucial role in solving this outstanding mystery. In particular, the experiments at various ionospheric heights give an insight into the spatial and temporal effects triggered by plasma flows. Such effects include optical radiation in a broad range of wavelength that give an insight into hydrodynamic and physical-chemical effects. Due to early active experiments as “Fluxus” and “North Star” much data had being acquainted, processed and and actively discussed. In the present paper we revision these data, acquired with ground based measurements, a satellite, and geophysical rockets. (Ю.И. Зецер, Ю.В Поклад, R.E. Erlandson АКТИВНЫЕ ЭКСПЕРИМЕНТЫ В ИОНОСФЕРЕ НА ВЫСОТАХ 140–360 КМ. РЕАНАЛИЗ РЕЗУЛЬТАТОВ ОПТИЧЕСКИХ НАБЛЮДЕНИЙ // Физика Земли, 2021, № 5, стр. 184-201 DOI: 10.31857/S0002333721050227)

A comparative analysis is presented of the approaches and methods for estimating the energy of the sources of acoustic-gravity waves (AGW) in the Earth’s atmosphere from the records of these waves. A number of known relationships linking the parameters of the recorded infrasonic signals and the source energy are considered. A phenomenological model of the propagation of infrasonic signals from high-yield explosive sources in the stratospheric waveguide is discussed. Based on the model and principle of energy similarity of AGW spectra, a new approach is developed to determine the source energy, in which the key parameter is the dominant frequency of the signal propagating in the atmosphere. It is shown that the source energy estimates obtained by the developed approach agree well with the instrumental data. The errors of AGW source energy estimates obtained by the existing approaches and the new approach are determined. (Ю.С. Рыбнов, А.А. Спивак, В.А. Харламов АНАЛИЗ МЕТОДОВ ОЦЕНКИ ЭНЕРГИИ ИСТОЧНИКОВ АКУСТИКО-ГРАВИТАЦИОННЫХ ВОЛН В АТМОСФЕРЕ ЗЕМЛИ // Физика Земли, 2021, № 5, стр. 202-209 DOI: 10.31857/S0002333721050185)

Destruction on the Earth’s surface caused by a shock wave is one of the most important and dangerous effects from asteroid and comet impacts. The overpressure and wind speed behind the shock wave front, leading to various dangerous effects, can be estimated on the basis of specially developed models of the interaction of cosmic objects with the atmosphere and the Earth’s surface. The shock wave is also the cause of seismic effects, but this work only considers the direct effect of the shock wave. A serial numerical modeling of the interaction of cosmic objects with the atmosphere has previously been performed for a large number of different scenarios under the hydrodynamic model. Analysis of the modeling results provides scaling relations that allow you to estimate the overpressure, wind speed behind the shock wave and their distribution on the surface, if you know the impactor’s parameters, its velocity and trajectory inclination angle. These relations take into account the spatial inhomogeneity of the overpressure distribution on the Earth’s surface. The suggested scaling relations were tested on the data of the Chelyabinsk and Tunguska events, which showed a good correspondence with the observed destruction data. The obtained scaling relations are used in the online calculator (http://www.AsteroidHazard.pro), which allows you to quickly and quite accurately estimate the various effects of impacts.(Д.О. Глазачев, О.П. Попова, Е.Д. Подобная, Н.А. Артемьева, В.В. Шувалов, В.В. Светцов ЭФФЕКТЫ УДАРНОЙ ВОЛНЫ, ГЕНЕРИРУЕМОЙ НА ПОВЕРХНОСТИ ЗЕМЛИ ПРИ ПАДЕНИИ КОСМИЧЕСКИХ ТЕЛ РАЗМЕРОМ ОТ 20 М ДО 3 КМ // Физика Земли, 2021, № 5, стр. 133-145 DOI: 10.31857/S0002333721050057)

The application of special sensor correction methods may allow the use of short-period seismometers with an extended frequency range in the absence of broadband sensors to solve a wide range of problems associated with recording low-frequency signals. The paper considers an instrumental correction circuit that uses integrating elements to broaden the frequency range of the SM-3KV seismometer to the low-frequency region. In laboratory conditions, the modified seismometer was calibrated and the device was tested on microseismic noise, explosion, and earthquake records. Our analysis of microseismic noise shows the possibility of using this device for recording and analyzing microseismic noise at frequencies above 0.07 Hz. Analysis of explosion and earthquake records demonstrated that the circuit can be used for seismic monitoring, taking into account the features of the frequency and phase responses of the modified seismometers. (Э.М. Горбунова, А.Н. Беседина, Н.В. Кабыченко, И.В. Батухтин, С.М. Петухова Прецизионный гидрогеологический мониторинг в техногенно-нарушенных условиях: организация, проведение и обработка экспериментальных данных // Сейсмические приборы, Т.57, №2, 2021, с.62-80 DOI: 10.21455/si2021.2-4)

Cometary impacts on Earth, as comets themselves, especially aperiodic ones, have been much less studied compared to asteroids. Nevertheless, despite the rarity of such impacts, they occurred in the past and cannot be ruled out in the near future. Moreover, the impacts of interstellar and, in principle, even intergalactic objects with hyperbolic orbits are possible. One such comet 2I/Borisov has been discovered quite recently. To assess the influence of such objects on Earth, we carried out numerical simulations of the impacts of cometary nuclei with diameters of 1 and 3 km on solid Earth at speeds of 70 and 170 km/s at an angle of 45° to the surface. Modeling was carried out using a hydrodynamic computer code with allowance for thermodynamic properties of a dusty core and shell of a comet and Earth’s crust in solid and molten state. Fluxes of thermal radiation on Earth’s surface were determined based on an approximate solution of the radiation transfer equation, taking into account optical properties of vapors and air. We estimated areas affected by air shock waves, masses of material ejected into the atmosphere and atmospheric pollution, magnitudes of earthquakes, areas of potential fires. The most dangerous direct effect is associated with the possibility of fires in areas that are much larger than both the size of an impact crater and the area of low-velocity ejecta from a crater, ranging in diameter from 3000 km with the minimum of considered impact energies up to 14 000 km with the maximum impact energy. Long-term effects of the impacts are associated with air pollution by fine dispersed ejecta, chemical components, darkening of the atmosphere.(В.В. Светцов, В.В. Шувалов ОЦЕНКИ ВОЗДЕЙСТВИЯ НА ЗЕМЛЮ УДАРОВ АПЕРИОДИЧЕСКИХ КОМЕТ // Физика Земли, 2021, № 5, стр. 210-222 DOI: 10.31857/S0002333721050197)

The paper is devoted to the identification and study of active neotectonic structures using a formalized (computerized) analysis of linear elements (lineaments) in the southern part of the junction of the Siberian Platform with the Baikal Rift Zone (BRZ). The time-varying movements of the Amurian subplate, the development of the mantle diapir, and the remote effect of the Indo-Eurasian collision combine to determine structure formation and neotectonic activity of the study region. The geodynamic features of the region are reflected in the system of small and extended lineaments. The issue is considered on the regional and local scale levels. Some details of the method and interpretation of the results are discussed. It is shown that a statistical relationship exists between the parameters of lineament formal identification in satellite images and kinematics and activation age of the corresponding Cenozoic faults. The lineament analysis (LESSA technology) is used to assess the effect of BRZ tectonic stresses on the Pliocene-Quaternary movements of the southern part of the Siberian Platform and on the formation of morphostructures in the region. The stages of stress-state evolution, fault activity, terrain formation, and some geodynamic models of the development of the Baikal region are discussed.(Г.Н. Иванченко, Э.М. Горбунова ФОРМАЛИЗОВАННЫЙ ЛИНЕАМЕНТНЫЙ АНАЛИЗ ГЕОЛОГИЧЕСКИХ СТРУКТУР ПРИБАЙКАЛЬЯ // Физика Земли, 2021, № 5, стр. 223-234 DOI: 10.31857/S0002333721050082)

Atmospheric turbulence has been simulated under laboratory conditions, where a household heat fan has been used as a source of air flows of different temperatures. The wavefront distortions of laser radiation passing through a heated air flow have been studied by means of a Shack-Hartmann wavefront sensor, which is part of a fast adaptive optical system that has a correction rate of up to 2000 Hz (frames per second). The energy spectra of laser radiation wavefront disturbances are presented, which help determine the frequency bandwidth of the disturbing effect. Based on the calculated Fried parameter, a graph is plotted for the turbulent flow, which compares the results of the laboratory simulation with the real conditions of the Earth’s atmosphere.(А.Л. Рукосуев, В.Н. Белоусов, А.Н. Никитин, Ю.В. Шелдакова, И.В. Сиверцева, А.В. Кудряшов ЛАБОРАТОРНОЕ МОДЕЛИРОВАНИЕ АТМОСФЕРНОЙ ТУРБУЛЕНТНОСТИ В ЗАДАЧЕ КОРРЕКЦИИ ИСКАЖЕНИЙ ВОЛНОВОГО ФРОНТА ЛАЗЕРНОГО ИЗЛУЧЕНИЯ С ПОМОЩЬЮ БЫСТРОЙ АДАПТИВНОЙ ОПТИЧЕСКОЙ СИСТЕМЫ // Физика Земли, 2021, № 5, стр. 235-241 DOI: 10.31857/S0002333721050161)

The formation of impact craters on the Earth’s surface is accompanied by the effect of shock waves on rocks. The shock wave compression results in rocks heating up to the point of melting and evaporation during unloading. The direct mechanical action of shock compression and residual heating change the magnetic properties of rocks. Geophysical modeling is used to determine the sources of the magnetic anomaly by interpreting the fields measured on the surface, but such modeling does not take into account the impact demagnetization of rocks. This work gives an example of analysis of the magnetic anomaly over the well-studied Bosumtwi crater (Ghana, 10.5 km diameter, 1 million years old), including the numerical modeling of the crater formation process and the construction of a magnetic anomaly model based on the simulated shock compression parameters and crater drilling data. It is shown that the morphological features of the crater— the crater rim and the central uplift—form positive magnetic anomalies around and inside the crater. (М.Ю. Кузьмичева, Б.А. Иванов МОДЕЛИРОВАНИЕ МАГНИТНОЙ АНОМАЛИИ СЛОЖНОГО МЕТЕОРИТНОГО КРАТЕРА БОСУМТВИ (ГАНА) С УЧЕТОМ УДАРНОГО РАЗМАГНИЧИВАНИЯ И МОРФОЛОГИЧЕСКИХ ОСОБЕННОСТЕЙ // Физика Земли, 2021, № 5, стр. 242-253 DOI: 10.31857/S0002333721050124)

Mass industrial explosions on extended benches of open pits are the most effective way to crush rock. Such explosions are accompanied by the rise of a gas and dust cloud. Three-dimensional numerical experiments are used to study the interaction of ascending gas and dust clouds generated by three, five, and multiple linearly arranged explosions in open pit mines. We examine both the initial stage of formation of a hot rarefied dust and gas cloud after the scattering of detonation products and the subsequent rise of thermals caused by buoyancy forces. We have obtained the dependences of the rise altitude and the size of the gas and dust clouds on the distance between adjacent explosions. (В.М. Хазинс, В.В. Шувалов, С.П. Соловьев ДИНАМИКА ВЫБРОСОВ МЕЛКОДИСПЕРСНЫХ ЧАСТИЦ В ОТКРЫТЫХ ГОРНОРУДНЫХ КАРЬЕРАХ // Физика Земли, 2021, № 5, стр. 254-266 DOI: 10.31857/S0002333721050100)

We report the results of the analysis of experiments on dynamic phase correction of laser radiation distorted by a turbulent airflow in an adaptive optical system (AOS) with a Shack - Hartmann wavefront sensor (WFS). A field-programmable gate array is used as the main AOS control element, which provides a closed loop AOS bandwidth of up to 2000 Hz. The WFS is used to estimate the characteristic bandwidth of the generated turbulence nturb. Changes in the spatial and temporal spectra of the laser radiation phase, as well as the quality of the beam during its dynamic phase correction at various AOS frequencies, are analysed. It is shown experimentally and by calculation that to ensure a high efficiency of the wavefront correction, the AOS frequency should be at least 20 times higher than nturb. (В.Н. Белоусов, В. А. Богачев, М.В. Волков, С.Г. Гаранин, А.В. Кудряшов, А.Н. Никитин, А.Л. Рукосуев, Ф.А. Стариков, Ю.В. Шелдаковa, Р.А. Шнягин Исследования пространственно-временных характеристик искаженного турбулентностью лазерного излучения при его динамической фазовой коррекции в адаптивной оптической системе // Квантовая электроника, 2021, т.51, №11, с.992–999)

Conventional Shack-Hartmann sensor uses Zernike polynomials in order to approximate the wavefront of the light. Zernike approximation is well-known, well-established and widely used technique. And in most cases the quality of approximation is good enough, especially if the measured light beam has circular aperture. But when the light beam is rectangular or ringshaped (for example, if one need to measure the surface flatness of the detail that is ring-shaped), the approximation using Zernike polynomials fails. In this work we implemented the approach of the approximation of the wavefront using Bspline polynomials. We present the results of approximation of a complex simulated wavefront (Franke surface) and an experimentally measured wavefront of the ring-shaped detail using B-Spline polynomials.

Bimorph deformable mirrors can be successively used to improve focusing of a laser beam passed through a moderately scattering medium with optical density in the range of 1. 10. In this paper we investigate the efficiency of the stacked actuator deformable mirror with 61 piezo stacks and clear aperture of 60 mm. We demonstrate that such kind of mirrors also can be used to optimize the focal spot in the far-field. Shack-Hartmann sensor was used to measure the averaged wavefront distortions and CCD camera was used to estimate the intensity distribution of the focal spot in the far-field.

The spectral characteristics of laboratory turbulence obtained from the Shack-Hartmann wavefront sensor focal spot coordinates dynamics are presented. The limits of applicability of a fast adaptive optical system in a real atmosphere are determined/

The paper presents the review of the conceptually most important results of seismological studies of the Earth’s core and their interpretation from the standpoint of geodynamics in three directions: anisotropy of seismic velocities and seismic attenuation, structural features of the transition zone between the outer and inner core, and differential rotation of the inner core. (В.М. Овчинников, Д.Н. Краснощеков СЕЙСМИЧЕСКИЕ ИССЛЕДОВАНИЯ ЯДРА ЗЕМЛИ // Физика Земли, 2021, № 2, стр. 3-26, DOI: 10.31857/S0002333721020083)

The implemented research aimed to assess the impact of open pit coal mining in Gorlovka deposit on the seismicity in the Iskitim area of the Novosibirsk Region. The seismic vibrations induced by large-scale blasting are analyzed, the seismic event potential is estimated, and the strain accumulation at a high-stress fault under seismic load is assessed. A key potential trigger was assumed as the change of the stress field parameters. Relaxation of rock mass from stresses due to formation of a pit and the extra loading of rock mass by dumps are calculated numerically and estimated analytically as two major factors of induced effect on static stresses. For the correct selection of computation parameters, the geology and the main physical/mechanical properties of rocks mass in the coal mining area are analyzed, and the main mechanical parameters of the most significant structural faults are selected. (КИШКИНА С.Б., КОЧАРЯН Г.Г., БУДКОВ А.М., ИВАНЧЕНКО Г.Н., ЛОКТЕВ Д.Н. ВОЗДЕЙСТВИЕ ГОРНЫХ РАБОТ РАЗРЕЗОВ ГОРЛОВСКОГО БАССЕЙНА НА ОЧАГИ ЗЕМЛЕТРЯСЕНИЙ ЗНАЧИТЕЛЬНОЙ МАГНИТУДЫ // ФИЗИКО-ТЕХНИЧЕСКИЕ ПРОБЛЕМЫ РАЗРАБОТКИ ПОЛЕЗНЫХ ИСКОПАЕМЫХ, 2021 , No. 4, p. 11-24 DOI: 10.15372/FTPRPI20210402)

Deformable mirrors are vital components of any adaptive optical system. Considering such a crucial role in compensation of incident wavefront distortions, the main requirements are imposed on these elements that determine performance of the entire system. To correct for phase distortions in high-power laser complexes a stacked-actuator deformable mirror with water cooling was developed. The main characteristics of the mirror, such as the initial surface profile (flatness), response functions of the actuators, maximal stroke, and amplitude-frequency characteristics are presented in this paper. Experimental investigations of the proposed cooling method of the mirror surface through actuators were performed.

Acoustic transmission data obtained in the laboratory experiment are used to identify stages of hydraulic fracture initiation, growth, and filling with a fracturing fluid. The laboratory setup allows for performing experiments with porous saturated samples made of artificial materials, with a diameter of 430 mm and height 70 mm. The model material was a mixture of gypsum and cement; the sample was saturated with water solution of gypsum and loaded by vertical and two independent horizontal stresses. Fracture was created by constant-rate injection of a viscous fluid through a cased hole in the center of the sample. Hydraulic fracture (HF) was monitored using ultrasonic pulses transmitted through the sample. The comparison of amplitude variations of ultrasonic pulses and injection pressure indicates that HF crack propagation initiates at lower pressure than maximum; HF crack grows faster than is filled with a fluid; after the crack volume is filled up with a fluid, fracture aperture expands. Once the injection stops, the crack closes when pressure in the wellbore decreases due to fluid leakage into the sample. It is shown that if the principal compressive stresses reorient, a secondary hydraulic fracture can appear provided that the primary fracture is perpendicular and secondary parallel to the well axis. (С.Б. Турунтаев, Е.В. Зенченко, П.Е. Зенченко, М. А. Тримонова, Н. А. Барышников, Е.В. Новикова ДИНАМИКА РОСТА ТРЕЩИНЫ ГИДРОРАЗРЫВА ПО ДАННЫМ УЛЬТРАЗВУКОВОГО ПРОСВЕЧИВАНИЯ В ЛАБОРАТОРНЫХ ЭКСПЕРИМЕНТАХ // Физика Земли, 2021, № 5, стр. 104-119 DOI: 10.31857/S0002333721050215)

During the study, four laboratory experiments on hydraulic fracturing were conducted. The experiments were carried out using a special laboratory setup with triaxial loading of the model sample. The pressure-time dependences were recorded during the experiments and analyzed using the Nolte method. The main purpose of this study was to investigate the fluid loss properties of model samples for different flow regimes, in particular, permeability. Another purpose of the study was to compare the obtained values with the real value of the permeability.

Variations of the geomagnetic field and F2-layer critical frequency in the range of periods of planetary waves in winter season are analyzed. The measurements were conducted by a magnetometer and a vertical radio sounding ionosonde at the nearby Belsk and Warsaw stations and provided the records of the ionospheric current variations in the lower ionosphere and plasma density variations in the upper ionosphere, respectively. Spectral estimation is carried out for the winter seasons of 2018-2019 and 2014-2015 when solar activity was low and high, respectively. It is established that practically synchronous variations in the above range of period are present in the records by the ground magnetic station and in the ionosonde measurements of the F2 layer critical frequency. The spectra of the time variations of the geomagnetic field and F2-layer critical frequency in the period range of planetary waves in winter season contain the harmonic components associated with solar activity and with quasi-16-day and quasi-10-day planetary waves. The mechanism of the formation of the 16- and 10-day variations in the upper ionosphere is proposed. (РЯБОВА С.А., ШАЛИМОВ С.Л. О ВАРИАЦИЯХ ПАРАМЕТРОВ ПЛАЗМЫ ИОНОСФЕРЫ, НАБЛЮДАЕМЫХ ПОСРЕДСТВОМ ИОНОЗОНДА И НА МАГНИТНОЙ СТАНЦИИ В ДИАПАЗОНЕ ПЕРИОДОВ ПЛАНЕТАРНЫХ ВОЛН // ФИЗИКА ЗЕМЛИ, 2021. №6 С.122-130 DOI: 10.31857/S0002333721060065)

This article summarizes the observations of the Mikhnevo small-aperture seismic array (SSA) for seismic events within the East European Platform based on analysis of a large number of experimental data. A method for recognizing earthquakes and short-lived group blasts, which is based on discriminating the nature of slope for the curve of distribution of the ratio between amplitude spectra of P and Lg waves log(A(P)/A(Lg)) relative to the frequency of oscillation, is proposed. It is shown that the curve has a certain trend, whose slope is different for explosions and earthquakes. A new criterion, that is, the sign of the coefficient in the equation that connects the values of log(A(P)/A(Lg)) and the frequency, is proposed. A negative trend with the increase in frequency is typical of short shots, while a positive trend is typical of earthquakes. The method has been tested based on the records of 405 industrial explosions and 24 earthquakes, with epicenters located 350-900 km from the Mikhnevo SSA. (САНИНА И.А., НЕСТЕРКИНА М.А., КОНСТАНТИНОВСКАЯ Н.Л., ГАБСАТАРОВА И.П. РАСПОЗНАВАНИЕ ПРИРОДЫ СЕЙСМИЧЕСКИХ ИСТОЧНИКОВ НА ВОСТОЧНО-ЕВРОПЕЙСКОЙ ПЛАТФОРМЕ, РЕГИСТРИРУЕМЫХ МАЛОАПЕРТУРНОЙ СЕЙСМИЧЕСКОЙ ГРУППОЙ “МИХНЕВО” НА РЕГИОНАЛЬНЫХ РАССТОЯНИЯХ // СЕЙСМИЧЕСКИЕ ПРИБОРЫ, 2020, Т.56, №2. С.56-76 DOI: 10.21455/si2020.2-5)

New results are presented on the features of the deep velocity structure of two of the three main tectonic blocks that make up the Kola region-Murmansk and Belomorskii-by the P receiver function technique. The research is based on data from the broadband seismic stations Teriberka and Kovda. The results are compared with the models obtained by mutual inversion of PRF and SRF using the data from the stations Apatity and Lovozero. It is shown that the crust has a two-layer structure with the border at a depth of 11 km under the Murmansk block and at a depth of 15 km under the Kola and Belomorskii blocks. The crust thickness of the Murmansk, Belomorskii, and Kola blocks are 35, 33, and 40 km, respectively. The presence of the MLD was revealed in all tectonic structures analyzed for the first time, with a top at a depth of about 70 km for the Murmansk and Belomorskii blocks and 90 km for the Kola block and a bottom at 130-140 km for all structures. (АДУШКИН В.В., ГОЕВ А.Г., САНИНА И.А., ФЕДОРОВ А.В. DOI: ОСОБЕННОСТИ ГЛУБИННОГО СКОРОСТНОГО СТРОЕНИЯ ЦЕНТРАЛЬНОЙ ЧАСТИ КОЛЬСКОГО ПОЛУОСТРОВА МЕТОДОМ ФУНКЦИЙ ПРИЕМНИКА // ДОКЛАДЫ РОССИЙСКОЙ АКАДЕМИИ НАУК. НАУКИ О ЗЕМЛЕ. Т.501, №2, 2021 С.180-183 DOI:10.31857/S268673972112001X)

Worldwide maps of lightning activity have been obtained from the ground-based World Wide Lightning Location Network (WWLLN) for 2007-2009. We have compiled these maps separately for different seasons and UT periods, using WWLLN data on the time and coordinates of each of the recorded lightning. The total number of flashes of lightning in WWLLN data is by an order of magnitude smaller than in satellite data from Optical Transient Detector and the Lightning Imaging Sensor satellites. However, the key features of the spatial distribution and seasonal trends coincide well. The main difference observed is the absence of diurnal variation (similar to Carnegie curve) in WWLLN data against the satellite one. This concerns the global lightning number as well as its density in major thunderstorm regions. The solar local time dependence is also weak in WWLLN data. We show that in 2007-2009 the mean latitude of lightning observation is shifted to the summer hemisphere up to 10 degrees from the annual mean value. From the beginning of 2007 to the end of 2009, the global monthly average number of flashes of lightning increased threefold. We attribute this fact primarily to improved processing techniques in WWLLN. The constructed maps are necessary for numerical simulation of the Global Electric Circuit. (Денисенко В.В., Ляхов А.Н. СРАВНЕНИЕ НАЗЕМНЫХ И СПУТНИКОВЫХ ДАННЫХ О ПРОСТРАНСТВЕННО-ВРЕМЕННОМ РАСПРЕДЕЛЕНИИ ГРОЗОВЫХ РАЗРЯДОВ ПРИ НИЗКОЙ СОЛНЕЧНОЙ АКТИВНОСТИ // СОЛНЕЧНО-ЗЕМНАЯ ФИЗИКА Том 7 № 4, 2021, с.111-119 DOI: 10.12737/szf-74202112)

We study the process of meteoroid interaction with the Earth's atmosphere, in particular, the effect of ablation. An ablation model is used, where mass loss of a meteoroid is determined using the saturated vapor pressure of the assumed meteoroid's substance. An automated method is suggested, where we estimate the physical parameters of a meteoroid by comparing data from observations and models of known parameters. Model constraints and features of the models are discussed.

Exploration of small craters and craters clusters on Mars allows one to study meteoroid fragmentation details that cannot be detected in terrestrial conditions. It was suggested earlier that the description of a cluster with a scattering ellipse allows one to estimate the meteoroids' trajectory, which is connected with orbital parameters of the impactor. Independent construction of scattering ellipses and comparison with crater ejecta demonstrate the accuracy and find out some problems of this approach.

The paper presents the parameters of seismic wave travel times for three artificially induced events obtained from the archive of the Institute of Geosphere Dynamics (IDG RAS). For the study, we chose underground nuclear tests (Long Shot, Milrow, and Cannikin) with magnitudes 6.1 < m(b) < 6.8 conducted by the United States of America from 1965 to 1971 on Amchitka Island in the Aleutian Arc. The study contains the results of observations obtained with various types of seismic channels. Travel time curves were constructed, and the linear functions of body wave propagation were obtained for epicentral distances of Delta similar to 8 degrees-85 degrees and similar to 134 degrees-160 degrees. The integral velocity of the Earth's upper mantle and outer core is estimated. The wave travel times are intended for further research of seismic waves from shallow artificially induced sources (701-1791 m) and for refining the Earth's structure. (НЕПЕИНА К.С., АН В.А. ГОДОГРАФЫ СЕЙСМИЧЕСКИХ ВОЛН ОТ ПОДЗЕМНЫХ ВЗРЫВОВ НА ОСТРОВЕ АМЧИТКА // АКУСТИЧЕСКИЙ ЖУРНАЛ. 2021, Т.67, №6, С.650-658 DOI: 10.31857/S0320791921060125)

The authors discuss the lab-scale studies into sub-horizontal effect of a low-frequency seismic wave on a slope. Acceleration transducers enabled tracing relative slope sliding even in case of invisible straining. It is found that if the maximum acceleration in the momentum is below a certain value governed by the soil strength, the slope keeps stable even at high displacement velocities. A single impact at high acceleration but low mass velocity is also incapable to initiate landslide. However, in this case, residual strains arise, accumulate and can make the slope unstable. Under multiple impacts, the critical parameters are markedly lower as compared with the single impact. This is particularly true for steep slopes having small stability factors. The parameters of vibrations generated by different-magnitude earthquakes which initiate slope failures in the form of landslides are analyzed. (Г.Г. Кочарян, С.Б. Кишкина, З.З. Шарафиев ЛАБОРАТОРНОЕ ИССЛЕДОВАНИЕ УСТОЙЧИВОСТИ ГОРНЫХ СКЛОНОВ ПРИ ДИНАМИЧЕСКИХ ВОЗДЕЙСТВИЯХ // ФТПРПИ №6, 2021.DOI: 10.15372/FTPRPI20210609)

В статье рассмотрены результаты системного анализа в области воздействий на различные слои атмосферы. Даны общая классификация воздействий и характеристика антропогенного непреднамеренного и преднамеренного (целевого) воздействий. В работе приведен перечень основных источников таких видов воздействий.

Выполнен сравнительный анализ методов калибровки датчика волнового фронта Шэка-Гартмана по плоскому волновому фронту (калибровка по наклону датчика) и сферическому волновому фронту (абсолютная калибровка). Для сравнения был проведен общий анализ достоинств и недостатков методов калибровки. Показано, что калибровка датчика включает в себя следующие этапы: создание опорного волнового фронта и определение точных проектных параметров датчика. Значения проектных параметров используются в реконструкции измеряемого волнового фронта и определяют такие параметры датчика Шэка-Гартмана, как динамический диапазон и чувствительность. Также для численного сравнения был проведен анализ погрешностей динамического диапазона, определяемого по аберрациям типа наклон и дефокусировка, и построены зависимости этих погрешностей от погрешности проектных параметров датчика.

Рассматривается действие нагревных стендов на ионосферу и влияние этих воздействий на условия работы радиоэлектронных систем.

Using the results of geomagnetic monitoring at the Mikhnevo geophysical observatory and spectral analysis methods, the spectral harmonics of geomagnetic variations were studied in the period range from 12 to 17 days. We have highlighted: harmonics associated with a variation in solar activity; harmonics due to the modulation of shorter-period variations by the long-period ones; harmonics close to periods of tidal waves, and harmonics close to the period of the atmospheric planetary 16-day wave. Comparative analysis of the spectral composition in summer and winter for a period of low solar activity were carried out.

We consider the disturbances of the magnetic field, electrical characteristics, and microbaric variations in the surface atmosphere caused by a strong earthquake that occurred in Turkey on January 24, 2020. The effects were recorded at the Mikhnevo observatory of Sadovsky Institute of Geosphere Dynamics of Russian Academy of Sciences which is located at distance of ~ 1900 km from the earthquake focus. It is shown that the acoustic effects accompanying the earthquake are caused by two sources: acoustic signal produced by arrival of seismic waves and acoustic signal propagating in the stratospheric waveguide. Using the data of the Mikhnevo observatory, we present the amplitudes of the induced variations in the electric field and atmospheric current. Also geomagnetic variations at different distances from the earthquake focus are presented.

Using the results of instrumental observations, it was shown that the explosion of the Stromboli volcano on July 3, 2019, caused variations in the atmospheric electric field and the amplitude of the atmospheric current at the Mikhnevo geophysical observatory and at the Geophysical Monitoring in Moscow of IDG RAS located at distances of ~ 2450 km and ~ 2500 km from the source, respectively. Anomalous variations in the electric field were also recorded during the period of arrival of the acoustic signal at electric monitoring points.

Based on the analysis of instrumental observational data, it was shown that large fires manifest themselves in local variations of the electric field and the amplitude of acoustic vibrations. Above the fire area, the formation of the zone with altered thermodynamic characteristics causes the formation of acoustic-gravitational waves with a Brent-Väisälä frequency during the most intense burning. The examples of the strong fires in Moscow are considered.

This paper is devoted to the problem of studying the rheological properties of seafloor sediments during the sampling process with the use of a gravity corer. The problem of gravity corer penetration through the soil with a complicated visco-elasto-plastic rheology is considered. Estimation of the mechanical properties of bottom sediments is among the most important problems emerging during the exploration of the hydrocarbon fields located on the Arctic shelf. Proper evaluation of the reaction of infrastructure objects to external effects (earthquakes, large waves) is needed to reduce the risks of serious accidents on the shelf. This paper presents a new approach to determining the parameters governing the stability of the infrastructure: static elastic moduli of seafloor sediments and their plastic and viscous properties. The dynamics of gravity corer penetration, with a measurable dependency of its acceleration, acts as a source of information regarding these parameters. The inverse problem of reconstructing the mechanical properties of seafloor sediments from the characteristics of this dependency has to be solved. This paper presents the results of solving the corresponding direct problem with the use of the finite element method. The possibility to estimate the mechanical properties of seafloor sediments from data on parameters such as time passed until the complete cessation of the tube sampler and the depth of its penetration is demonstrated.

Today it is necessary to continue to improve the methods of remote monitoring of volcanic processes, including the analysis of anomalies in geophysical fields caused by volcanic eruption. The presented research is aimed at analyzing geophysical effects accompanying eruption of Stromboli volcano in the summer of 2019. We researched variations in acoustic vibrations, geomagnetic field and electrical characteristics of near-surface layer of the Earth’s atmosphere. As initial data, we used results of observations of geophysical fields at Geophysical observatory «Mikhnevo» and at Center for geophysical monitoring of Moscow of Sadovsky Institute of Geosphere Dynamics of Russian Academy of Sciences; results of magnetic monitoring at a number of Intermagnet network magnetic observatories. We found that, along with the known local effects accompanying strong volcanic activity (emission of heated material, formation of an air wave and lava flow etc.), disturbances of physical fields at significant distances from the volcano are recorded. It is important to note that variations in the magnetic field and electrical characteristics of the atmosphere are observed not only during a volcanic eruption at its various stages, but also during periods of disturbance of the atmosphere by an acoustic signal arriving at the registration point caused by volcanic activity.

In this work, we study the parameters of microseismic noise in the vicinity of the Chilean subduction zone in order to detect oscillations of a block-fault system, similar to those identified by processing the results of the previous laboratory experiment. The analysis is based on the data recorded by the broadband seismic stations of the international seismic network IRIS. We calculated the spectral parameters of microseismic noise before and after several earthquakes. It is established that before the earthquakes with M-w >= 8, the calculated value of spectral centroid decreases by 0.12-0.26 Hz. The decrease in the value of spectral centroid in the range from 0.008 to 0.45 Hz can be as long as up to two days. The proposed approach can be a new instrument useful for real-time monitoring of active faults of various scales.

To solve various engineering problems, it is often necessary to record signals in the 0.1-2000 Hz range. The lower limit of this range is beyond the operating band of geophones. This article considers extending of geophone frequency responses in two ways: multiplication of the transfer functions and introduction of negative resistance. The applicability limits of these methods are estimated. The upper limit of the velocity recorded by the geophone is determined by the gap in which the coil is shifted relative to the sensor frame. The lower limit depends on the total instrument noise of the measurement channel, the main contribution to which is the Brownian noise of the mechanical oscillatory system and the noise of the measuring circuit. A prototype was constructed using multiplication of the transfer functions. Laboratory measurements on a shaking table and microseismic noise recordings demonstrated that the modified geophone operates as a velocity sensor with an eigenfrequency of 2 Hz. This value depends on the microseismic conditions of where of the measurement system is placed. Recording seismicity with the modified geophone made it possible to record massive blasts in mines and quarries in the frequency range up to 2 Hz. Thus, the research demonstrates that the modified geophone can be used to monitor local and regional seismicity as a counterpart to short-period seismometers.

Dynamics of granular media is the key to understanding behavior of many natural systems. In this work we concentrate on studying regularities of deformation of a gouge-filled fault. Confined granular layer - model fault - subjected to an external stress may display sudden slip owing to rearrangement of the granular layer. In nature fast slip along a fault results in an earthquake. To understand fault behavior better, we have conducted a comprehensive analysis of acoustic emission (AE) data that accompany stick-slip in granular media. Here we reveal and trace the emergence of two populations of AE. The first one is characterized by a waveform with a harsh onset, while the second one exhibits a gradual amplitude rise and a tremor-like waveform. During a regular stick-slip the statistical properties of the first population remains intact. The second one is very sensitive to alterations of stress conditions, and its scaling parameters correlate with the change of mechanical characteristics of the fault. Probably, AE populations were identified corresponding to two gouge-filled fault subsystems - a load-bearing granular network and an ensemble of relatively unloaded grains in the granular layer. The detected regularities point to a compound self-organization processes in fault zones and suggest that the final stage of earthquake preparation can be revealed in analyzing the scaling characteristics of seismic-acoustic data.

Frictional instability is the most likely mechanism of shallow earthquakes. For better understanding fault behavior we have conducted field experiments on shear deformation of a model fault. This study has focused on revealing the seismic-acoustic signatures of fault behavior. The entire spectrum of sliding regimes has been realized in the course of 1-m scale experiments-from a stable creep to a regular stick-slip, and their seismic-acoustic characteristics were investigated. It is shown that seismic pulses with characteristic frequencies less than 500 Hz are emitted only during slip events. The acoustic emission (AE) is observed both during slip events and at the stage of their preparation. Statistical analysis has shown that the AE distribution is generally a superposition of a power law distribution for low-energy pulses and a peak-like distribution for the largest pulses. The distribution with a characteristic peak prevails in regular stick-slip, while (quasi)stable creep is characterized by the power law distribution over the entire range of amplitudes. Both distributions-"with peak" and "without peak"-are observed for irregular sliding regime (random slip events with various amplitudes). Applying the nonlinear Grassberger-Procaccia algorithm to the analysis of time-series of AE data has allowed to rank the fault sliding regimes. The calculated correlation dimension characterizes the dynamics of the fault. The highest dimension is typical for stable sliding. A decrease of the correlation dimension indicates an enhanced probability of high-amplitude slip events. Nucleation of largest slip events is observed for the regular stick-slip with the least correlation dimension.

Block-granular geological objects and rock volumetric mobility indicators are described. The mechanisms of structural and material reworking of rocks are considered in relation to the formation of a discrete tectonic structure of rocks and changes in the shapes of the geological bodies, which take place without rupturing the rock surfaces bounding these bodies and provide for the volumetric tectonic flow of solid rocks. Based on the study of natural objects and their comparison with the theoretical and experimental data on solid mechanics and geomechanics, it is suggested that one of the triggers for the volumetric disintegration of rock masses is rock fatigue damage (a fundamental phenomenon of solid-state physics). The disintegrated rocks behave according to the laws of mechanics of granular materials and mesomechanics. This study is of both theoretical and pragmatic importance as it contributes to the understanding of the regional geological features and provides new knowledge on the formation of crystalline protrusions known among the main hydrocarbon reservoirs within the basements of various geologic structures.

Pore-scale modeling is a rapidly evolving area of research because modeling multiphase flow directly on 3D pore geometries is of utmost importance in wide variety of research areas, including oil and gas development, hydrology and material sciences. Although there are numerous methods to model flow, only so-called pore-network models are computationally effective enough to perform simulations in large modeling domains, and they are orders of magnitude faster than direct modeling approaches. However, pore-network models require a simplification of the 3D pore geometry to perform simulations, which are usually referred to as pore-network extraction. Such extraction poses a separate problem because it must provide an accurate description of the pore space geometry and topology. Different methods have been proposed in the literature. Recently, watershed-based approaches have been popular due to their effectiveness in working with porous media images of any porosity. A watershed algorithm requires seed placement to segment the space into distinct pores. We propose a hybrid algorithm combining the power of watersheds in finding intersections between pores with the advantages of the maximum inscribed ball technique, which is very effective in finding pore centers. We rigorously verify and test our novel methodology on artificial and X-ray microtomography images of wide variety of porous materials: sphere packings, carbonate, soil, ceramic and sandstone samples. Comparison against a purely watershed-based method and results based solely on the maximum inscribed balls-based method (in terms of pore/throat total number, pore size distributions and connection statistics, and multiphase flow properties including capillary curves and relative permeabilities) revealed the accuracy of our novel technique, consistency with existing classical techniques and great potential in analysing 3D pore images of any complexity. On the other hand, comparison of extracted pore-network topology (as based on Euler number) revealed significant differences between different methodologies, which is rather surprising considering the similarities in two-phase flow properties. While analysing permeability results, we also compared two popular pore-throat partitioning models and advocated in favor of the weight model usually utilized within watershed-based extracted pore networks. Our results illuminate problems in current pore-network models and outline some potential ways to improve their accuracy in future research.

The work is devoted to mathematical simulation of laboratory experiments on the single-phase fluid displacement in synthetic porous samples. The basis of the mathematical model used is the system of poroelasticity equations in terms of the Biot's model, which implies that the processes of fluid filtration and the dynamics of changes in the stress-strain state of a continuous medium are considered together in the framework of a single coupled statement. For simulation, the software package developed at the Keldysh Institute of Applied Mathematics, Russian Academy of Sciences, was used. The laboratory experiments considered in this work were performed at the Institute of Geosphere Dynamics, Russian Academy of Sciences. The mathematical model used is briefly presented; the main computational algorithms and the features of their software implementation are described. A detailed description of the laboratory set-up, laboratory experiments themselves and their results are given. A significant part of the work is devoted to the problem statement description in terms of mathematical simulation. The results of calculations are presented; the calculated and experimentally observed dependencies are compared. The possible causes of the observed deviations are analyzed

Based on the results of instrumental observations carried out at a number of mid-latitude observatories of the INTERMAGNET network and at the Mikhnevo Geophysical Observatory (Institute of Geospheres Dynamics, Russian Academy of Sciences), it is shown that strong earthquakes are accompanied by increased variations in the Earth's magnetic field. In this case, the short-period (period of similar to 0.5-0.8 min) and long-period (similar to 5-20 min) stages of increased geomagnetic variations are clearly distinguished. The maximum amplitudes of induced geomagnetic variations for short-period and long-period variations are 1.5-2 and 2-4 nT, respectively. Induced geomagnetic disturbances of similar morphology and almost synchronous nature are noted at observatories located at significantly different distances from the earthquake source.

The response of atmospheric pressure to the Tohoku earthquake on February 11, 2011 (magnitude M similar to 9), is analyzed using the results of instrumental observations made at the Mikhnevo Geophysical Observatory, Institute of Geosphere Dynamics, Russian Academy of Sciences (IDG RAS). It is shown that the earthquake gave rise to atmospheric pressure fluctuations with periods as long as 8.5, 9.4, 10, and 10.4 h. Waves in an isothermal atmosphere with a source at the earthquake epicenter are considered as a possible cause of excitation of these basic variations.

Based on instrumental observations made at a number of the INTERMAGNET network observatories, at the Mikhnevo Geophysical Observatory, and at the Center for Geophysical Monitoring (Institute of Geospheric Dynamics, Russian Academy of Sciences, Moscow), the acoustic, magnetic, and electrical effects accompanying the November 26, 2019, earthquake in Albania are analyzed. It is shown that this seismic event was accompanied by disturbances in the physical fields at considerable distances from the epicenter. At the same time, the parameters of induced variations in the atmospheric current and magnetic and electric fields allowed them to be recorded confidently by the available instrumentation. The results of recording infrasound signals caused by vertical movements of the Earth's crust in Rayleigh waves, as well as of recording the signal propagating along a stratospheric waveguide, are presented.

We consider the ionospheric models that are suitable for over-the-horizon HF and UHF band radars. Namely, there are three such models: the numerical model developed by IZMIRAN and Fedorov Institute of Applied Geophysics, the numerical model designed by ISTP SB RAS and IDG RAS, and the probabilistic model worked out by IDG RAS. We briefly describe these models and report the results of the analysis of their compliance with radar requirements. Probabilis- tic models are shown to be most promising; hence, they must be placed at the frontier of ionosphere simulation.

An adaptive optical system is developed to correct the wavefront of laser radiation distorted by a turbulent air flow. The use of a field-programmable gate array as the main control element makes it possible to achieve a system bandwidth of 2 kHz. The results of experiments on dynamic correction of the phase of a laser beam distorted by a flow of heated air are presented and analysed

The results of numerical simulation of kilometer-sized asteroid impacts on different types of terrain (a flat surface, a mountain, and a depression) are presented. The results show that terrain features significantly affect the amplitude of the shock wave propagating along the surface, the fireball size, the radiation fluxes on the surface, and the distribution of ejecta around the crater. This effect is significant if terrain inhomogeneities are equal to or larger than the impactor in size.

A scanning full-field interferometer is a key device in the optical scheme of digital hyperspectral hologram registration. Behind the theory of hyperspectral holography is Fourier transform spectroscopy, wherein the set of spectrally resolved complex amplitudes of the object's hyperspectral field is obtained via the Fourier transform of a series of interferograms registered in incoherent radiation. Several established approaches in digital holography, based on discrete phase-shifting techniques as well as continuous phase modulation of the reference signal by a scanning mirror, are special cases of Fourier transform spectroscopy, where a coherent light source is used for hologram registration. The proposed algorithm was found to apply to processing holograms registered by various phase-shifting techniques and can give a greater signal-to-noise ratio

Libyan Desert Glass contains meteoritic material and, therefore, its origin is most likely associated with an impact event. However, the impact crater has not been found. We performed numerical simulations of impacts of stony and cometary bodies in order to confirm the version that this glass was formed from silica heated by radiation from aerial bursts near the ground. Asteroids were treated as strengthless bodies from dunite with a density of 3.3 g cm(-3), and comets as icy bodies with a density of 1 g cm(-3). The simulations based on hydrodynamic equations included the equations of radiation transfer. Melting and vaporization of a silica target under action of radiation incident on a planar surface were modeled using a one-dimensional hydrodynamic equation of energy and equations of radiation transfer in two-flux approximation. We selected those variants of simulations in which a crater is not formed, a fireball touches the earth surface, and the area of a molten target corresponds to the area of the Libyan Desert Glass strewn field. Appropriate options include the impact of an asteroid with a diameter of 300 m, an entry speed of 35 km s(-1), and an entry angle of 8 degrees, and cometary bodies with diameters from 150 to 300 m, speeds of 50-70 km s(-1), and entry angles from 15 degrees to 45 degrees. Impact options with crater formation are also discussed. The maximum depth of molten silica at ground zero reaches 10 cm with the cometary impacts and 3-4 cm with the asteroidal impact. Melting occurs during a period of time from 50 to 400 s.

We review modern HF-X band radars including over-the-horizon systems. The ionosphere significantly affects wave propagation in all the bands. We describe available correction techniques, which use additional evidence on the ionosphere, as well as models of different degrees of complexity. The fact that the field of view cannot be covered by ground-based instruments as well as the growing requirements to the precision and stability of the radars result in the impossibility of ionospheric correction with up-to-date models, hence the latter require further elaboration. We give a virtually full classification of the models. The article summarizes the requirements to the models for the radars depending on their task

Based on the analysis of data from the Geophysical Observatory "Mikhnevo" and the Center for Geophysical Monitoring of Moscow of the Institute of Geosphere Dynamics of the Russian Academy of Sciences, the response of the atmospheric boundary layer to the strong earthquakes with magnitudes starting from >= 7 is considered. It is shown that the Tohoku earthquake (March 11, 2011, Japan) can be associated with the variations in atmospheric pressure with periods ranging from 8 to 11 h that emerged after this event, whereas a series of the strong earthquakes discussed in the work are accompanied by the variations in the atmospheric pressure with periods close to the singlets of the fundamental free oscillation of the Earth(0)S(2). Another effect after the earthquakes is the presence of the acoustic-gravity waves in the atmosphere with a period close to the Brunt-Vaisala period at large distances from the epicenter.

The article analyzes statistics on micro-solid emissions in mineral mining and discusses features of micro-emission in atmosphere in large-scale blasting in open pit mines. The gas-dynamic calculations of dust and gas cloud elevation after blasting for localization of solid micro particles and determination of their concentration in the troposphere are presented. The influence of large-scale blasting on regional seismicity is illustrated in terms of the Kuznetsk Coal Basin

On the basis of the data on perturbations in the Earth's atmosphere recorded before and after 52 significant earthquakes that occurred during the period from 1997 to 2018 in the Asian region, it is shown that the amplitudes of internal gravity waves that originated from seismically active regions can be used at the saturation threshold level for a short-term indication of upcoming seismic events.

The results of recording and determining the locations of seismic events triggered by industrial explosions conducted by OJSC Kombinat KMAruda at the Korobkovskoe iron ore deposit (Belgorod Region) are presented. Seismic signals were recorded by a small-aperture seismic array located on the surface in the immediate vicinity of the mine workings. The confinement of induced seismicity to the fault zone and the migration of seismic sources along its strike have been established. Such studies on the territory of the Korobkovskoe iron ore deposit have been performed for the first time.

The response of the Earth's magnetic field and electrical parameters of the atmosphere to the eruption of Stromboli (July 3, 2019, Italy) is studied using the results of instrumental observations carried out at several observatories of the INTERMAGNET network and the Mikhnevo Geophysical Observatory, Institute of Geosphere Dynamics, Russian Academy of Sciences. It is shown that the beginning of the eruption of Stromboli volcano had an explosive character and was accompanied by pronounced geomagnetic variations as well as variations in the electric field intensity and the amplitude of the atmospheric current at a considerable distance from the disturbance sources.

In this paper, we consider the problem of recording and processing the microseismic data with their subsequent interpretation and making the decisions concerning the probable threats associated with the violation of integrity of terrestrial environment due to mining activity. These decisions are made based on the detection of microseismic sources and recognition of their types by processing the multichannel seismograms from small-aperture seismic arrays. The procedures of seismogram processing include the algorithms for detecting the signals of microseismic sources in the noisy seismograms from the array sensors and the procedures for estimating various parameters of these sources. In this paper, we propose a new detection algorithm which is based on evaluating multiple coherence of the array seismograms and is capable of identifying the waves radiated from microseismic sources with complex focal mechanisms against the diffuse seismic noise. In contrast to the widely used STA/LTA array detector which is aimed at separating plane seismic waves, the proposed detector is intended for the recognition of waves from local seismic events in the complexly structured subsurface environment. Based on the numerical experiments with model and real seismic array data containing signals from the sources with complex focal mechanisms, it is shown that the types of microseismic sources can be recognized with the use of various algorithms of seismic array data analysis: with new algorithms for estimating the coordinates of microseismic sources and with traditional algorithms of space-time spectral analysis

The article presents the analysis of seismic observations in mine roadways. The recorded seismic signals are connected with dynamic deformation of rock mass under massive blasting. The source of induced seismicity are dynamic movements deformation of rocks with an amplitude of 3-30 mu m along fractures 1-15 m long. These events feature low values of reduced energy, probably, due to shallow depth of mining. Distribution of induced seismicity events in time and space agreed with patterns of larger seismic events due to remote earthquakes, which implies weak probability of nasty geodynamic phenomena in the course of mining in the Korobkov Field.

The impact crater formation on the surface of the Earth and other planetary bodies is accompanied by the action of shock waves on rocks and their displacement into a new position. The shock-wave compression results in the occurrence of the remanent heating of rocks (up to melting and evaporation during the unloading). The direct mechanical action of the shock compression and the remanent heating change the magnetic properties and magnetization, which leads to arising of the magnetic anomaly above the crater area. This work presents an example of the complex analysis of the magnetic anomaly above the well-studied impact crater Bosumtwi (Ghana, a diameter of about 10 km), including the numerical simulation of the crater formation process and the magnetic anomaly model on the basis of simulated parameters of shock compression. The complex model demonstrates a good agreement with data of direct measurements.

We compare the number of lunar craters larger than 15 km across and younger than 1.1 Ga to the estimates of the number of craters that could have been formed for 1.1 Ga if the number of near-Earth objects and their orbital elements during that time were close to the corresponding current values. The comparison was performed for craters over the entire lunar surface and in the region of the Oceanus Procellarum and maria on the near side of the Moon. In these estimates, we used the values of collision probabilities of near-Earth objects with the Moon and the dependences of the crater diameters on the impactor sizes. According to the estimates made by different authors, the number density of known Copernican craters with diametersD >= 15 km in mare regions is at least double the corresponding number for the remaining lunar surface. Our estimates do not contradict the growth in the number of near-Earth objects after probable catastrophic fragmentations of large main-belt asteroids, which may have occurred over the recent 300 Ma; however, they do not prove this increase. Particularly, they do not conflict with the inference made by Mazrouei et al. (2019) that 290 Ma ago the frequency of collisions of near-Earth asteroids with the Moon increased by 2.6 times. The number of Copernican lunar craters with diameters not smaller than 15 km is probably higher than that reported by Mazrouei et al. (2019). For a probability of a collision of an Earth-crossing object (ECO) with the Earth in a year equaled to 10(-8), our estimates of the number of craters agree with the model, according to which the number densities of the 15-km Copernican craters for the whole lunar surface would have been the same as that for mare regions if the data by Losiak et al. (2015) forD< 30 km were as complete as those forD > 30 km. With this collision probability of ECOs with the Earth and for this model, the cratering rate may have been constant over the recent 1.1 Ga.

When it is said about the danger of orbital debris for space activities and the ecology of the Earth, it most often means large orbital debris. In contrast to large orbital debris, the influence of small ones to space activities and ecology of the Earth and near-Earth space is often underestimated. As will be shown in this paper, it is unfair. New data on the dynamics of contamination of near-Earth space with small debris in low Earth orbit were obtained. The number, mass, and dynamics of the small orbital debris population in low Earth orbit are estimated as well as the consequences of the deployment of multi-satellite communication satellite systems are estimated. It makes the study of this area particularly relevant. The various aspects of the consequences of technogenic contamination of near-Earth space are considered. The comparison of the danger of small orbital particles and large satellite fragments for space activity and the ecology of the Earth and near-Earth space is also provided.. significant lack of reliable information on small space debris is proved to be one of the main limiting factors for our knowledge about the population of space debris in low Earth orbits.

A LED-based optical detection circuit and a principle of analysis of diffraction patterns of wet blood smears are proposed. A compact computerized optical device based on the principles of ektacytometry (diffractometry) has been designed to measure the width of the size distribution of red blood cells

The results of evaluating the accuracy of determining coordinates of the epicenters of seismic events that are registries by small-aperture array Mikhnevo are given. Quarry blasts located in the central part of the East European platform were used as a source of the events. With confident identification of seismic wave arrivals (signal to noise ratio ≥ 2), the small-aperture group independently provides high location accuracy and subsequent association of the event with the nearest quarry in coordinates. It is shown that the accuracy of the location strongly depends on the microseismic level, i.e. from signal to noise ratio. With a low signal to noise ratio (R≤2), the accuracy of the location decreases and in this case, the data received from the additional seismic stations can be useful.

The emission of dust particles into the atmosphere during rock mass breaking by blasting in ore mining open-pits is one of the factors that determine the ground-level air pollution in the vicinity of pits. The data on dust concentration in the cloud, which is extremely difficult to obtain experimentally for large-scale explosions, is required to calculate the dust dispersion in the wind stream. We have elaborated a Eulerian model to simulate the initial stage of dust cloud formation and rising, and a Navier-Stokes model to simulate thermal rising and mixing with the ambient air. The first model is used to describe the dust cloud formation after a 500 t TNT (Trinitrotoluene equivalent) explosion. The second model based on the Large Eddy Simulation (LES) method is used to predict the height of cloud rising, its mass, and the evolution of dust particles size distribution for explosions of 1-1000 t TNT. It was found that the value of the turbulent eddy viscosity coefficient (Smagorinsky coefficient) depends on both the charge mass and the spatial resolution (grid cell size). The values of the Smagorinsky coefficient were found for charges with a mass of 1-1000 t using a specific grid

The relationship between electric field variations and microparticle concentrations in the atmospheric surface layer has been studied using the example of the Moscow region. Synchronous field observations of the electric field strength obtained at two stations (the Moscow Center of Geophysical Monitoring and the Mikhnevo Geophysical Observatory of the Institute of Geosphere Dynamics, Russian Academy of Sciences) have been used. Under megacity conditions, the amplitudes of electric field signals have been found to increase relative to their values outside the region. The ratios of average electric field strengths at the observation stations to the values obtained outside the region have been estimated using the model that is developed. Variations in the electric field have been compared with changes in the concentrations of CO, NOx, SO2, and fine particulate matter (PM2.5 and PM10); the electric field strength and the concentration of microparticles under megacity conditions have been found to be correlated.

The paper presents the results of the reconstruction of the effective height h' and the slope of the profile beta of the electron concentration in the D layer of the ionosphere during X-ray flares of M- and X-classes at the midlatitudes. The reconstruction was carried out with data from measurements at the observatory of the Institute of Geospheres Dynamics of the Russian Academy of Sciences at the Mikhnevo observatory of amplitudes and the phases of signals from VLF transmitters GQD (19.6 kHz) and GBZ (22.1 kHz) that propagate along one mid-latitude path. Based on the calculations, the empirical dependencies of the parameters h' and beta on the flare energy according to the X-ray flux measurements on the GOES satellite are in the range 0.05-0.4 nm. Criteria are proposed for the selection of solar flares for the verification of theoretical computational models

Methods of description of ion-acoustic shock waves in dusty plasma are presented. A new type of dust ion-acoustic shock waves related to anomalous dissipation is described. The main dissipative processes related to charging of dust particles, absorption of ions by dust particles, Coulomb collisions between ions and dust particles, and Landau damping are analyzed. Proposed methods of theoretical analysis enable explaining all major specific features of dust ion-acoustic shock waves observed in the laboratory experiments. The shock waves of this type are present in the near-Earth plasma and the universe. Their investigation is possible in active ionospheric experiments of the Fluxus type. Important astrophysical problems in which the appearance of shock waves under consideration should be taken into consideration are the shock waves of supernovas, evolution of Local Interstellar medium, etc

Possibilities of studies of the geomagnetic effects produced by the interaction of a cosmic bodies with the magnetosphere-ionosphere-atmosphere system are very limited due to extremely small number of examined events. Here we present geomagnetic observations at an array of magnetometers during Bering Sea Bolide event on December 18, 2018 when a space body entered the Earth's atmosphere and exploded at the altitude of similar to 25 km near Kamchatka. It has been found that the short-lived electromagnetic signal appeared before the explosion and, consequently, was trigged by the passage of a meteoroid through the inner magnetosphere. Geomagnetic disturbances of the same duration and frequency of oscillations were detected both in the area adjacent to the explosion site in the Northern hemisphere and in the magnetically conjugated area in the Southern hemisphere. These observations may be provisionally interpreted as a triggered excitation of resonant field line oscillations in the inner magnetosphere by the fast-moving meteoroid. The magnetosphere is often in a metastable state, when even a weak external trigger can stimulate an internal instability and wave generation. The appearance of a diamagnetic effect during partial ablation of a meteoroid could cause a local disturbance of the geomagnetic field and its propagation in the magnetic force tube

We present a device using Shack-Hartmann wavefront sensor for measuring concave optical parts. A technique based on the device makes it easy to measure the main parameters of the aspherical equation of concave aspherical mirrors, radius of closest sphere R-v and eccentricity epsilon. The described method allows you to reconstruct the shape of the controlled surface in the form of an equation specified during its manufacture.

An adaptive optical system that implements a phase conjugation algorithm designed to compensate for the effect of atmospheric turbulence the propagating laser beam is presented. The system allows compensating for the influence of atmospheric disturbances up to 200 Hz (in terms of sine). To achieve the compensation effect system operates at a frequency of 2000 Hz (in terms of fps - frames per second). Such high performance can be achieved only when using FPGA as the master control element of the system. The results of correction of disturbances obtained by using a heat fan, simulating the turbulence to frequencies of 200 Hz, are presented.

Bimorph deformable mirror with 63 electrodes on a 20 mm aperture is discussed. Methods of dividing all-round electrodes into sectors with a square of 2-4 mm(2) are described. Results of flat-top beam formation using a 50 mm bimorph deformable mirror with 48 electrodes and a 20 mm miniature bimorph mirror with 27 electrodes are presented and compared.

The results of numerical simulations and experiments on the correction of turbulent distortions of a laser beam are presented. The experiments were carried out using an adaptive optical system with a bandwidth of 2000 Hz. It was shown that for effective correction the bandwidth of the adaptive optical system should be an order of magnitude larger than the bandwidth of turbulent distortions.

The results of numerical simulations and experiments on the correction of turbulent distortions of a laser beam are presented. The experiments were carried out using an adaptive optical system with a bandwidth of 2000 Hz. It was shown that for effective correction the bandwidth of the adaptive optical system should be an order of magnitude larger than the bandwidth of turbulent distortions.

The article discusses the use of stacked-actuator adaptive mirrors to improve the focusing of laser radiation. The criterion of focusing efficiency is the fraction of the energy of the laser radiation passing through the pinhole located in the focal plane of the focusing lens.

Laser beam shaping technology nowadays requires as small diameter of the adaptive optics as possible. In our lab we usually control for laser radiation by means of bimorph deformable mirrors with a typical size of more than 50 mm. To fit the most of industrial and scientific applications the aperture of the corrector should be reduced because the use of extra optics instead makes the whole optical scheme more complicated and introduces extra distortions. But in a bid to reduce the size of the mirror we should care of the response of the mirror electrodes which obviously should not decrease drastically. Here we present 20 mm bimorph mirror with high density of electrodes which is manufactured using laser engraving technology to divide the electrode on the piezoceramic disc into a large number of the controlled sectors. The ability of laser beam formation by means of this mirror is discussed, the results are compared with the ones obtained using 50 mm bimorph deformable mirror.

As well known, the quality of radiation of laser beam is reduced during propagation along optical trace, because of various reasons (for example, atmospheric turbulence, scattering, thermal fluctuations etc.). We propose small-size deformable mirrors with high spatial resolution of control elements, that will allow to compensate for wavefront aberrations in wide range. Developed wavefront corrector could be used in different scientific areas: free-space communications, destruction of space debris, etc.

The results of instrumental observations of acoustic oscillations, geomagnetic variations, and variations in the electric field and atmospheric electric current during the activation of the Stromboli volcano, Italy, in 2019 are presented. Separately considered are the periods of explosive activity and the interval marked by intense emission of incandescent ash-and-gas mixture. It is shown that volcanic activity is accompanied by acoustic signal generation at the explosive stages of the eruption and by the emergence of internal gravity waves at the stage of intense effusion of ash and gas ("purging"). The characteristic variations in the Earth's magnetic field and in the electrical parameters of the atmospheric surface layer are observed during different periods of volcanic eruption. The presented results expand the existing database and can be useful for improving the existing models and developing the new models describing the effect of volcanic activity on the geophysical environment as well as for verifying these models

The azimuthal elastic anisotropy of the upper mantle of the Voronezh uplift is estimated from the data of three three-component broadband stations of the Voronezh seismic network: "Storozhevoe" (VSR), "Novokhopersk" (VRH), and "Galichia Gora" (LPSR) from SKS/SKKS splitting. Two parameters were calculated-the time shift between two quasi-shear waves (delta t), which are formed when a shear wave (for example, SKS) passes through an anisotropic medium, and the azimuth of the axis of maximum speed alpha (axis of symmetry), along which a "fast" quasi-shear wave propagates. According to the data from different station, the anisotropic parameters are alpha = 40 degrees, delta t = 0.6 s (VSR); alpha = 40 degrees, delta t = 0.1 s (VRH); alpha = 40 degrees, delta t = 0.4 s (LPSR). Taking into account the relatively close location of the stations, all the data were summed up to yield alpha = 40 degrees, delta t = 0.4 s. As all obtained results are similar to each other and coincide with the direction of movement of the Eurasian plate, it is concluded that the anisotropy of the upper mantle in the region is relatively weak, has a northeast azimuth, and is caused by modern tectonic processes.

The article discusses application of the passive seismic method MOVSR by the single channel seismic sounding technology (SCSS) using the software/hardware single channel seismic station in geological engineering survey on the Mikhnevo test ground of of the Institute of Geosphere Dynamics, Russian Academy of Sciences. The specifications of the sing channel seismic station, field operation technology, mathematical calculation algorithm and its results in the form of the velocity profile plot are described. The technology SCSS features simplicity and operational efficiency. Its implementation needs 3 seismic detectors. Two detectors are installed at a distance from the test site and serve as the reference stations which operate continuously and are used to eliminate temporal variations. The third movable seismic detector is used to obtained data at the test point. The simultaneous operation of two reference detectors accelerates field works. A feature of the data processing procedure is the calculation of the Fourier transform by the coordinate along the profile and the use of the almost periodic functions at resonance frequencies. The calculations revealed deceleration of SV-component of the Rayleigh wave due to the presence of a vertical shaft and two adits in the test ground. The capabilities of the method are illustrated from the comparison with the borehole data obtained nearby the Mikhnevo settlement. It is concluded on applicability of the software/hardware single channel seismic station with the single channel seismic sounding technology in geological engineering surveys.

The Earth's crystalline inner core (IC) solidifies from the liquid Fe alloy of the outer core (OC), which releases latent heat and light elements sustaining the geodynamo. Variability in solidification regime at the inner core boundary (ICB) may result in compositional and thermal multi-scale mosaic of the IC surface and dissimilarity of its hemispheres. Both the mosaic and hemisphericity are poorly constrained, not least due to a lack of available sampling by short-period reflected waves. Measured amplitude ratio of seismic phases of PKiKP and PcP reflected, respectively, off the inner and outer boundary of the liquid core, yields direct estimate of the ICB density jump. This parameter is capable of constraining the inner-outer core compositional difference and latent energy release, but is not well known (0.2-1.2 g/cub. cm), and its distribution is obscure. Travel time measurements of PKiKP and PcP waveforms can be useful in terms of getting an insight into fine structure of ICB and its topography. We analyse a new representative sample of pre-critical PKiKP/PcP differential travel times and amplitude ratios that probe the core's spots under South-eastern Asia and South America. We observe a statistically significant systematic bias between the Asian and American measurements, and carefully examine its origin. Separating the effects of core-mantle boundary and ICB on the measured differentials is particularly challenging and we note that a whole class of physically valid models involving D '' heterogeneities and lateral variation in lower mantle attenuation can be employed to account for the observed bias. However, we find that variance in PKiKP-PcP differential travel times measured above the epicentral distance of 16 degrees is essentially due to mantle heterogeneities. Analysis of data below this distance indicates the ICB density jump under Southeastern Asia can be about 0.3 g/cub. cm, which is three times as small as under South America where also the thickness of the above liquid core can be by 1-3 km in excess of the one in the East. The findings preclude neither IC hemispherical asymmetry (whereby crystallization dominates in the West and melting in the East) nor patchy IC surface, but provide an improved and robust estimate of the ICB density jump in two probed locations.

Recently, with the growth of the shale non-traditional hydrocarbon field developments, the need for refinement of the models of hydraulic fracturing increases. One of the main components of any model is the problem of fluid flow in the fracture. There are several approaches to this problem. One approach is based on the assumption that the fracture grows faster than the fluid front in it. That is, a dry tip appears between the end of the fracture and the front of the fluid. An experiment on hydraulic fracturing, confirming this fact, is presented in this paper.

In the morning of June 21, 2018 (1:16 Universal Time (UTC)) the space body entered the Earth atmosphere in the Lipetsk region, Russia. This event was detected by a number of registration systems in cars, satellite observations of bolide light curve and subsequent dust trail. The videos, photos, satellite data allow us to calculate the trajectory and the orbit of the Ozerki bolide. The atmospheric entry velocity is 14. 9 +/- 1 km/s. The height of the depression point is 32.8 +/- 0.9 km and that of the maximum brightness is 27.2 +/- 0.9 km. The pre-atmospheric orbit of the Ozerki meteoroid was also calculated: q = 0.67 +/- 0.04 AU, a = 0.84 +/- 0.02 AU, e = 0.199 +/- 0.030, i = 18.44 degrees +/- 3.05 degrees, Omega = 89.6561 degrees and omega = 335.29 degrees +/- 5.15 degrees. The geocentric radiant position is RA = 307.51 degrees +/- 3 degrees and DEC = 43.11 degrees +/- 3.degrees The found material was called Ozerki meteorite and it is classified as an ordinary chondrite (L6). The estimated: mass of the meteoroid is 94 +/- 20 tons, the energy is 2.5 +/- 0.5 kt TNT, diameter is 3.7 +/- 0.5 m.

The paper is devoted to the verification method of results of the lower ionosphere models during solar flares. The verification is based on radio physical measurements of VLF signals. Radio wave amplitude values are normalized according to the difference between experimental and theoretical results, obtained during the calm heliogeophysical day, which is followed by the observed solar flares. This method allows to compare absolute values of radiophysical characteristics without knowing transmitter power. Such an approach makes it possible to evaluate the predictive capabilities of the ionosphere model during flares not only qualitatively, but also quantitatively. As a result of the D-region model verification, it was found that the standard deviation of the difference between experimental and theoretical amplitude of VLF signal is less than 1 dB in ~ 80% of cases.

The work is devoted to an effective method of radiation transfer equations (multi-group diffusion equations) solving used in the numerical simulations of strong perturbations in the atmosphere. The finite-difference approximations of these equations based on the conservative properties of finite difference schemes are presented. In this scheme the analytical solutions of diffusion equations (both for the energy density and for the flux density) are determined inside each layer of a difference grid under the assumption of constancy of the gas-dynamic parameters. The results of test calculations of a number of problems are presented

The paper presents the variations in the parameters of the ionosphere D-layer during X-ray flares of M and X classes on the propagation path of signals from the superluminal waves of the GQD and GBZ transmitters, as well as those adopted by the Mikhnevo State Educational Center. It is shown that, within the framework of the two-parameter Ferguson-White model, the effective reflection height of the VLF signal h' and the gradient of increase in the electron concentration β at the leading edge of the flare are related to the X-ray energy in the range 0.05-0.4 nm

The experimental data of active ionosphere experiment “North-star” are revisited.During the experiment, the plasma jet was injected into the ionosphere plasma transverse to geomagnetic field. A prolonged glow of the plasma cloud was observed. Anomalous ionization, low frequency waves and plasma heating were detected. The asymmetric azimuthal distribution of superthermal electrons indicates the presence of an intense transverse DC electric field. A change in the dynamics of a plasma jet under the influence of this factor is considered in this paper. The external DC electric field and electrostatic ion-cyclotron drift waves on density/temperature gradient along the transverse DC electric field play a role in plasma heating.

The paper presents the results of measurements of the electric field and vertical atmospheric currents in conditions of "fair weather" and their comparison with the Carnegie curve. The features of the measurement data associated with the detection of the evening maximum of the electric field strength are shown.

Based on the analysis of instrumental observation data, it is shown that large fires on gas pipelines manifest themselves in local variations in the amplitude of acoustic vibrations. The formation of a highly heated convective stream of gaseous products over a stationary combustion center provides an intensive supply of cold air into it. In this case, the formation of pressure and temperature gradients near the flame leads to the formation of vortex structures in the atmosphere and the generation of infrasound. An example of a severe fire on a gas pipeline in Moscow on May 10, 2009 is considered.

Verification of the lower ionosphere models on VLF evidence requires robust radio wave propagation code. It, in turn, must handle inhomogeneous, disperse, anisotropic medium. We present results for FDTD, FVFD and complete mode sum methods for homogeneous and inhomogeneous model ionospheres. The quantitative results are presented on required memory, achievable precision and stability. The fastest, easiest and most suitable for ionosphere model verification problem method is FVFD. FDTD is general but it requires supercomputer resources in the problem of the lower ionosphere model verification.

Pollution of the atmosphere and territories adjacent to opencast mine by mineral particles during explosive breaking of rock mass is one of the factors affecting the environmental situation in the vicinity of quarries and reducing the transparency of the surface layer of the atmosphere. A significant effect of wind on particle transfer begins after the completion of the rise of a dust-gas cloud formed by an explosion on the surface of the earth. Numerical simulation was used to determine the characteristics of a dust cloud starting from the moment of formation of the fireball until the cloud reaches hydrostatic equilibrium. The numerical model was improved in order to calculate the dynamics of the dust cloud for charges with a mass of 1 to 1000 tons of TNT. The fireball parameters were set based on the data of theoretical and experimental studies. Based on numerical calculations, a qualitative and quantitative analysis of the dynamics of the dust-gas cloud for an explosion with a mass of 500 tons of TNT is carried out. The obtained relations allow one to determine the height of the upper edge and the radius of the cap of dust-gas clouds depending on the energy of the explosion with a mass of 1 to 1000 tons of TNT.

A wavefront corrector has been designed in the form of a cooled stacked-actuator deformable mirror for the correction of aberrations of laser radiation propagating through the turbulent atmosphere. The main parameters of this mirror are theoretically estimated. A technique for cooling the reflecting surface of the wavefront corrector through piezo actuators is suggested and experimentally tested. The main parameters of the deformable mirror are measured: the initial shape of the surface, the response functions of the actuators, the mirror stroke, and the frequency-amplitude characteristic of optical surface.

The rarely considered case when the optical radiation passes through the weakly scattering medium, e.g. mid-density atmospheric fog with the number of scattering events up to 10 was investigated in this paper. We demonstrated an improvement of focusing of a laser beam (lambda=0.65 mu m) passed through the 5 mm-thick layer of scattering suspension of 1 mu m polystyrene microbeads diluted in a distilled water. For the first time the low-order aberration corrector wide aperture bimorph deformable mirror with 48 electrodes configured in 6 rings was used to optimize a far-field focal spot. We compared efficiencies of the algorithm that optimized the positions of the focal spots on Shack-Hartmann type sensor and the algorithm that optimized the peak brightness and the diameter of the far-field focal spot registered with a CCD. We experimentally demonstrated the increase of the peak brightness of the far-field focal spot by up to 60% due to the use of the bimorph deformable mirror for beam focusing through the scattering medium with concentration values of scatterers ranged from 10(5) to 10(6) mm(-3).

Problems of constructing an adaptive optical system intended for correcting the wavefront of laser radiation that has passed through a turbulent atmosphere are considered. To ensure high-quality wavefront correction, the frequency of the discrete system should be at least 1 kHz or more. This performance can be achieved by using FPGA as the main control element of the system. The results of a laboratory experiments of the laser beam phase fluctuations caused by turbulence, produced by the airflow of a fan heater, correction by means of the FPGA-based adaptive optical system are presented. The system efficiency was evaluated at various correction frequencies up to 1875 Hz.

The results of the operation of a wavefront correction system based on a deformable bimorph mirror of the PEARL subpetawatt laser facility are presented. An improvement in the quality of focusing of laser radiation, which led to an increase in the Strehl ratio from 0.3 to 0.6, is demonstrated. The features of the compensation for phase distortions of the wavefront in the case of a low pulse repetition rate, as well as the correct allowance for the noise of the CCD camera when calculating the Strehl ratio are investigated.

A method and an optical scheme for recording digital hyperspectral holograms in the light of an incoherent source are considered. The optical scheme includes an interferometer with a scanning mirror for generating reference waves. The set of complex amplitudes of the object field is calculated by Fourier transform of the interferograms in each pixel of the recording matrix. Experimental data on holographic images of microobjects obtained with different optical schemes (transmission and reflection) are presented. A scheme of the common path interferometer is considered where the reference wave is part of the object field.

The operation of a powerful source of optical radiation based on explosion of spherical HE charges in metal tubes filled with xenon was investigated. The velocity and radiative characteristics of the shock wave propagating through the tube were determined. It is shown that reflective coating of pipe walls makes it possible to increase the density of the energy flux by more than an order of magnitude as well as to improve the shape of its time dependence. A three-dimensional numerical simulation of the formation and propagation of a shock wave was performed, and a simplified method for estimating the radiation intensity was proposed.

In this paper microseismic ambient noise analysis is based on cross-correlation of seismic noise components and cross-spectral analysis in a sliding window in time. The velocity changes were estimated at small aperture in the high frequency range (hundreds of Hz) at the section of the fault zone of the Korobkovskoye ore deposit. The analysis carried out made it possible to determine the propagation velocity and estimate coseismic velocity changes associated with ripple-fired explosion and further relaxation.

The amplitude-frequency characteristics of a water-saturated reservoir under pressure head and non-pressure conditions were estimated for 2017-2018. The measuring wells are located at the territory of the geophysical observatory “Mikhnevo” of IDG RAS. A comparative analysis of the average monthly amplitudes of volumetric strain and groundwater level was performed. Volumetric strain and water level were calculated for period range of 0.5-28 hours in the sliding window of 0.5 hour without overlapping and for periods of semidiurnal and diurnal tidal waves.

The paper considers a laboratory study of fracture development in a porous medium as applied to hydraulic fracturing. The experiments were carried out on a Hele-Shaw cell. In the first case, the cell was filled with a compressible permeable medium into which glycerin was injected, in the second case with a compressible impermeable medium into which water was injected under pressure. As a result, the conditions for the formation of cracks were obtained, as well as the conditions for maintaining their geometry. The dependences of the fracture growth rate on the pressure of the injected fluid were obtained. Comparison of the obtained dependences showed that the rate of crack propagation does not depend on the pressure of the injected fluid, but the pressure affects its length

The paper presents results of numerical calculation of displacement of a geomedium block along the inclined plain in the presence of a round friction spot. Modeling reveals differences in processes for the elastic and elastoplastic media. In the elastic medium, displacement is symmetric from the spot edges. In the elastoplastic medium, gradual slip and displacement within the friction spot proceed from the edge subjected to the pushing force. Maximum increase in plastic strain is from the edge subjected to the pulling force. The calculations are performed in a 3D statement within the elastic and elastoplastic Drucker-Prager model with the nonassociated flow rule.

The vertical component of the electric field strength and atmospheric current variations accompanying strong earthquakes with a magnitude of more than six are analyzed on the basis of instrumental observations carried out at the Mikhnevo Geophysical Observatory and at the Center for Geophysical Monitoring in Moscow (Sadovsky Institute of Geosphere Dynamics, Russian Academy of Sciences). It is shown that the strong earthquakes cause alternating sign-time variations of the electric field or its baylike variations of positive or negative sign at significant distances from the earthquake source. In the same time, earthquakes cause variations in the atmospheric current in the form of an increase in it or alternating sign-time variations of the averaged amplitude. The present results supplement the corresponding database and may be of interest in improving the known and developing new models of the effect of earthquakes on the environment and their verification.

Contemporary 3D dynamical atmosphere models include the mesosphere as an essential element of simulation framework. Though thousands of elementary chemical processes are included as well as horizontal and vertical transport processes the quality of models is unsatisfied from the radiowave propagation point of view. Below we consider additional physical mechanism to be included in simulation. It is of solar-terrestrial links nature, namely the background processes caused by X-rays, hard X-rays and gamma rays fluxes from Sun. The reanalysis of satellite data proves that within the period of high solar activity the aforementioned fluxes exceed the C-flare level in a continuous manner. We present the satellite evidence and compare the present ionizing block with additional data from solar radiation.

This paper presents the perennial results of ionospheric vertical total electron content (TEC) variations using the Global Navigation Satellite System (GNSS) data from the Geophysical Observatory «Mikhnevo». TEC long data analysis revealed a TEC annual variations and TEC decreasing trend caused by the decline in solar activity during the observation period. Spectral analysis allowed to identify 27 TEC daytime variations, which can be directly related to the period of sun rotation around its axis. Also the TEC distribution from the UV solar radiation flux was made. The linear dependence of the TEC value on the UV flux can be explained by the fact, that UV solar radiation is the main ionization agent of the F region ionosphere.

The first particulate matter PM2.5 and PM10 measurement results obtained in Moscow Geophysical monitoring center of IDG RAS are presented. The results are compared with the data from open sources - Mosecomonitoring and independent station network of Luftdaten project

The study of the near-surface electric field strength variations was conducted on the basis of experimental data obtained at the Geophysical Monitoring Center of IDG RAS in Moscow and the Geophysical Observatory 'Mikhnevo'. This paper features the results of analysis of electric field variations in Moscow and in GO 'Mikhnevo' registered for the period 2015 - 2019, and specifics of daily electric field strength variations depending on the season.

The paper presents a numerical study of hydraulic fracture propagation in a naturally fractured reservoir. Instead of using discrete fracture network in the current study natural fractures are considered from the perspective of effective medium theory: natural fractures are related to inelastic strain accumulated in the medium during its deformation. Although there is no way to implement such a method to construct a specific network of fractures involved in stimulated volume, it becomes possible to evaluate some effective parameters of this network. In this particular study spatial orientation of fractures which provides potential fluid flow paths. Usage of critically stressed fracture concept makes it possible to predict the spatial orientations of hydraulically conductive natural fractures based on calculated stress tensor. In the current study stress state and spatial orientations of hydraulically conductive fractures were modeled for the problem of hydraulic fracture propagation using the extended finite element method.

Efficient hydraulic fracturing operations in unconventional reservoirs rocks require an extensive network of secondary fractures in addition to the primary fractures. In the current work, we study the fracture propagation at the microscale in the unconventional reservoir rocks for searching and determination of optimal stress-strain conditions leading to the most extensive network of secondary fractures at the microscale. This work describes a workflow to create a digital rock model accounting for mechanical and petrophysical features of the pore space and the constituent mineral phases in a geometry mimicking rock’s real microstructure. We applied the described method to one of the most promising gas formations in Russia’s West Siberia. Here we present the results of a model based on the 2D QEMSCAN region containing nine minerals with elastic properties, and we studied the initiation and propagation of fractures in/between elastic-plastic minerals.

The paper describes an application of critically stressed fractures concept to study activation and reactivation of natural shear fractures existing in rock masses surrounding a hydraulic fracture during its propagation. A simplified numerical model of hydraulic fracture propagation is used to obtain stress fields near a hydraulic fracture. These stress fields are used to determine spatial orientations of natural fractures becoming critically stressed in different points of observation near the hydraulic fracture. The main tendencies of these spatial orientations are analyzed: it is shown that the greatest variation of natural fractures becomes activated at the moment of hydraulic fracture being in the closest vicinity of considered point of observation. The preferable spatial orientation of critically stressed fractures is shown to be in a close connection to the current position of hydraulic fracture's tip. The main parameters governing the natural fractures' activation are discussed providing an opportunity to use the proposed algorithm to optimize hydraulic fracturing in naturally fractured reservoirs.

Increasing the efficiency of hydraulic fracturing operations in complex reservoir rocks requires creating an extensive network of fractures to improve the drainage zone of the field development. The research aims at understanding the stress-strain conditions required the initiation and propagation of mechanical fractures during well-bore zone stimulation in tight reservoir rocks. We investigate at the microscale, taking into account the mineral heterogeneity, matrix structure, elastic-plastic properties of minerals, and their intergranular contacts. The research relies on experimental data performed on modern laboratory equipment and the use of applied simulation software. We propose an integral physico-mathematical model of the propagation of three-dimensional fractures at the microscale. The model accounts for the granular composition and structure of the sample, its elastic-plastic properties, and conditions at the intergranular contacts. We discuss a set of experimental methods and research necessary for numerical simulation of fracture propagation at the microscale, taking into account the heterogeneous mineral composition of the reservoir rock. The paper shows the results of mathematical elastic-plastic modeling of stress-strain state and fracture propagation in two-dimensional and three-dimensional models with the complex geometry of contacts between minerals. Finally, we make conclusions about the possibility of using the results obtained in optimizing the parameters of hydraulic fracturing.

This paper presents a study of processing the pressure-time curves obtained during a series of laboratory hydraulic fracturing experiments. The purpose of the study was to determine the time and pressure of the fracture closure using the G-function method, as well as to determine the permeability of model reservoir samples that were used in the laboratory experiments designed to create the fracture in the reservoir sample. The closure pressure values obtained during analysis were compared with the minimum stress applied to the sample in a laboratory experiment with the help of specially constructed setup. The calculated permeability values of the model sample, that was created from special mixture of gypsum and cement, were compared with the actual permeability of the model sample estimated using a special laboratory permeability test. The observed difference in the obtained values justifies the relevance of this work.

The development of laser technique and various applications of laser radiation requires the use of devices that can modify as well as correct for the wavefront of laser beams. In these cases, the use of deformable mirrors is simply very important. In the high-power laser setups, the task of correction of laser aberrations assumes the use of thermally stabilized optical elements. We consider that two types of wavefront correctors are the most well-suitable for such an application: bimorph deformable mirrors and stacked-actuator (SADM) ones. Bimorph deformable mirrors proved their reliability and could be used in high-power industrial lasers. They can perfectly correct for low-order and are simple in manufacturing. On the contrary stacked-actuator mirror can reproduce high-order wavefront aberrations and thus have high spatial resolution of control elements and might be applied in fast adaptive optical systems to correct for laser radiation distributed through turbulent media.

Experiments and numerical simulations of the phase correction of laser beam turbulent distortions have been carried out by using the adaptive optical system with the bandwidth of 1500 Hz. It has been shown that the bandwidth of adaptive optical system should be an order of magnitude greater than the bandwidth of the turbulent distortions for the effective correction.

Stacked-actuator deformable mirrors (SADM) allow to compensate for wide range of wavefront distortions. They are distinguished for their large stroke of control elements, high operational speed, the possibility of correction for small-scale aberrations. The SADM with 6x6 actuators placed on the aperture 30x30 mm was developed. The thickness of mirror substrate was 1 mm. The maximal deformation stroke of the SADM was about 5 microns.

Many atmospheric applications based on the laser beam passed through the Earth's atmosphere are exposed the distortion of the laser beam wavefront, which ultimately leads to a decrease in their efficiency. Such tasks include the transmission of powerful laser radiation over a distance (recharging batteries of drones and low-orbit satellites, delivering energy to hard-to-reach places, destroying fragments of space debris in low orbits), creating protected optical communication lines, increasing the resolution of telescopes, etc. One of the methods to improve the efficiency of such systems is the use of adaptive optics methods and tools that allow the wavefront correction in real time. The features of constructing such a system using FPGA as the main control element are considered.

An express method, based on principles of laser diffractometry, for measuring the parameters of red blood cells size distribution, such as mean size and its dispersion, is proposed. The compact mobile device has been developed for registering diffraction patterns form blood smears and their automatic analysis

Presented are the results of measuring variations of water level in an observation well during a ripple-fired explosion in a mine. Measurements were held in a well at the territory of one of the mining enterprises in the Belgorod district, Russia. The well is 141m deep. It penetrates to the Archean- Proterozoic complex of complicatedly dislocated rock, in which mining operations take place. The water level at the moment when the measurements started was 83.41m from the free surface. The measurements were held with sensors of two types - a sensor of water level and a 3-component seismometer, which was installed at the surface near the well head. An explosion at the mine was chosen for measurements, when one of the chambers was located extremely close to the observation well. The distance from the water level sensor, which was sunk into the well to the depth of 85.5m, to the ceiling of the chamber, in which about 10 tons of explosive was blasted, was only about 240m. The results of measurements showed that the maximal amplitude of dynamic oscillations of water level was 12mm. The main frequency of oscillations was in the range of 15-20Hz, which coincided with the frequency of the signal recorded by the seismometer. No residual changes of the water level accompanying the passage of seismic waves produced by the explosion were observed.

The paper presents the parameters of digital seismograms of artificial seismic events observed in from 1967 to 1990. The data were provided to the authors from the archive of the Sadovsky Institute of Geosphere Dynamics (IDG RAS). Seismograms were obtained after reformatting digital records. The archived data were analyzed to obtain a posteriori information on P-wave travel times, determined from the moment of the first arrival on the record of the vertical component (Z) of the short-period channel. The practice has shown that combining these data is sufficient to compile a map of signal arrival times from seismic sources. We present the regional travel-time curve for three test sites and linear trends of P-wave travel times by calendar date, as well as an isochron map for one of the sites.

The results of instrumental observations of geomagnetic variations caused by eruption of Taal Volcano on January 12, 2020 are given. Its geographical coordinates is 14.002ºN, 120.993ºE. Taal volcano is located within the Macolod Corridor in the large convergence zone between the Eurasian and Philippine tectonic plates which is characterized by active volcanism, crustal thinning, extensive faulting and block rotations. The data in the form of one-minute interval means which are available on web-site of the INTERMAGNET network are used. It is should note that low magnetic activity is observed (the geomagnetic planetary Kp-index did not exceed 2). Moreover, in presented research geomagnetic anomalies are analysis in period of seismic events which are identified by using catalogs of Geophysical Service of the Russian Academy of Sciences (Russia, Obninsk, Kaluzhskaya obl.), the US Geological Survey (Earthquake Hazards Program, USGS) and the Philippine Institute of Volcanology and Seismology. It was found that geomagnetic anomalies are observed in the Earth's magnetic field at different distances from the volcano both during the period of its active eruption and during the period of volcanic tectonic earthquakes. It should be noted that the extraction of geomagnetic anomalies is difficult, since magnetic recordings made at the INTERMAGNET observatories contain anomalies caused by a series of earthquakes in Puerto Rico and other seismic events. In general, amplitudes of geomagnetic anomalies do not exceed tens of nT.

The results of instrumental observations of the acoustic effects caused by stronger earthquake with the magnitude mb = 5.7 which occurred in Iran on July 08, 2019 are given. The observations were carried out at three pointes: Geophysical observatory "Mikhnevo" (54.94° N; 37.73° E), Center for geophysical monitoring in Moscow (55.70° N; 37.57° E) of Sadovsky Institute of Geosphere Dynamics of Russian Academy of Sciences and at a point located in Zvenigorod town, Moscow Region (55.69° N; 36.77° E), which provided the bearing to the source of acoustic signals. Digital series of atmospheric pressure and microbaric variations are obtained by measurements using a Davis Vantage Pro 2 automated digital weather station and MB-03 microbarometer are used as intimal data. In order to isolate useful signals in the analysis of microbaric variations, we used the Multi-Channel Correlation Method which made it possible to isolate low-amplitude coherent wave signals against incoherent microbaric noise. It is shown that the earthquake caused atmospheric disturbances in the form of propagating in the stratospheric waveguide acoustic vibrations in infrasonic frequency band which were registered at distances exceeding 2700 km, as well as microbaric variations caused by seismic waves that came to the point of acoustic detection. The characteristic periods of acoustic signals caused by earthquakes are given. The energies of the acoustic source and the earthquake are estimated from the spectral characteristics of the infrasound signal propagating in the stratospheric waveguide.

Предложены соотношения подобия, позволяющие быстро оценить опасные последствия ударов крупных космических тел. По материалам доклада на XI международной конференции «Околоземная астрономия и космическое наследие» (30 сентября - 4 октября 2019 г., Казань).

Рассмотрены способ и оптическая схема регистрации цифровых гиперспектральных голограмм в свете некогерентного источника. В состав оптической схемы входит интерферометр со сканирующим зеркалом для генерации опорных волн. Набор комплексных амплитуд объектного поля вычисляется путём фурье-преобразования интерферограмм в каждом пикселе матрицы регистрации. Приведены экспериментальные результаты голографических изображений микрообъектов, полученных на различных оптических схемах: на просвет и на отражение. Рассмотрена схема интерферометра общего пути, в которой опорная волна является частью объектного поля.

Появление изделий микросистемной техники с энергопотреблением на уровне нано-, микро- и милливатт требует миниатюризации индивидуальных источников энергии с увеличенной продолжительностью действия, способных обеспечить должную автономность и длительность эксплуатации перспективных разработок. Преобразование энергии радиоактивного распада в электрическую - один из возможных путей решения этой задачи. В работе анализируется, какие из известных радионуклидов удовлетворяют соответствующим требованиям. Внимание сосредоточено на выборе радионуклидов, пригодных для крупносерийного, рентабельного выпуска промышленностью долгоживущих источников энергоснабжения (атомных батарей), оставляя в стороне многочисленные эксклюзивные варианты единичного изготовления.

Представлены результаты исследований верхней части осадочного чехла центральной части Восточно-Европейской платформы (ВЕП) по данным новой сети широкополосных сейсмических станций ИДГ РАН. Используя записи сейсмического шума для каждой станции, были рассчитаны доминирующие частотные пики методом Накамуры. Для станций «Михнево» и «Шатура», опираясь на данные глубокого бурения, установлено, что резонансный пик отвечает границе верхнедевонских – нижнекаменноугольных отложений. Полученные результаты позволяют проследить залегание указанной границы по всем станциям сети субширотного профиля, проходящего вдоль коллизионной зоны ВЕП.

Проведено сравнение количества лунных кратеров с диаметром, большим 15 км, и возрастом менее 1.1 млрд лет с оценками числа кратеров таких размеров, которые могли образоваться за 1.1 млрд лет, если бы количество объектов, сближающихся с Землей, и элементы их орбит за это время были бы близки к их современным значениям. Сравнение проводилось для кратеров на всей поверхности Луны и для области в районе Океана Бурь (Oceanus Procellarum) и морей видимой стороны Луны. При этих оценках использовались значения вероятностей столкновений объектов, сближающихся с Землей, с Луной, а также зависимости диаметров кратеров от диаметров ударников. Число известных коперниканских кратеров с диаметром D ≥ 15 км на единице площади на морях по оценкам различных авторов не менее, чем в двое, превышает аналогичное число для остальной поверхности Луны. Наши оценки не противоречат увеличению количества объектов, сближающихся с Землей, после возможных катастрофических разрушений больших астероидов главного пояса, которые могли произойти в течение последних 300 млн лет, но и не доказывают это увеличение. В частности, они не противоречат выводу работы (Mazrouei и др., 2019) о том, что число столкновений околоземных астероидов с Луной за единицу времени возросло в 2.6 раза 290 млн лет назад. Число коперниканских лунных кратеров с диаметром, не меньшим 15 км, возможно больше, чем по данным (Mazrouei и др., 2019). При вероятности столкновения с Землей за год объекта, пересекающего орбиту Земли, (ОПОЗ), равной 10–8, наши оценки числа кратеров соответствуют модели, в которой число 15-км коперниканских кратеров на единице площади для всей поверхности Луны было бы таким же, как и для области морей, если бы данные (Losiak и др., 2015) для D < 30 км были бы такими же полными, как и для D > 30 км. При такой вероятности столкновения ОПОЗ с Землей и для такой модели темп кратерообразования за последний 1.1 млрд лет мог быть постоянным.

В статье приведен краткий обзор основных результатов, полученных в последние годы при исследовании процессов скольжения по разломам. Опубликованные гипотезы и данные проанализированы на основе подхода, предложенного В.Е. Паниным, согласно которому геосреда рассматривается как многоуровневая иерархически организованная система, в которой все процессы самосогласованно эволюционируют на нано-, микро-, мезо- и макромасштабном уровнях. Основное внимание в обзоре уделено иерархии структур, которые, согласно современным представлениям, формируют зону скольжения сейсмогенного разлома, а также их взаимосвязи с механическими характеристиками поверхностей локализации скольжения и микроконтактов, которые определяют динамику скольжения разломных зон на макроуровне. Показано, что эволюция свойств контактов частиц заполнителя зоны скольжения определяет не только возможность возникновения неустойчивости, но и способность разлома к восстановлению прочности со временем. Описана простейшая схема иерархии макрошероховатостей, которая позволяет отразить важное положение о том, что старт, эволюция и остановка сейсмогенного разрыва определяются размерами и взаимным расположением областей, обладающих разной динамикой фрикционных характеристик в процессе скольжения. Выполненный анализ результатов натурных наблюдений показывает, что точность наблюдений и неоднозначность интерпретации решения обратной задачи не позволяют пока уверенно идентифицировать участки разломов, обладающих свойствами скоростного разупрочнения. Более достоверно установить размеры и расположение этих зон может позволить анализ результатов регистрации высокочастотных колебаний в окрестности разрыва землетрясения. При этом хорошую основу для интерпретации таких результатов создают базовые представления физической мезомеханики.

The problem of modeling the injection of an aluminum jet of a plasma generator into the upper atmosphere during an Active Geophysical experiment is considered. The high-speed jet is a calibrated source of exposure. The gas-dynamic parameters of the jet are calculated. It is shown that in a rapidly expanding jet a violation of thermodynamic equilibrium occurs, causing to "freezing" of the ionic composition. The plasma jet interacts with the atmosphere and the geomagnetic field, causing the glow, the formation of a "diamagnetic cavity", and the generation of electromagnetic waves.

A review of available data on the impact cratering in the Solar System is presented. Most of data have been collected during robotic space missions to the Moon and other terrestrial planets. The main attention is attracted to morphology and morphometry of impact craters, comparable is size with the Puchezh-Katunki structure. All these craters have clearly visible central mound. Crater’s depth-diameter relations on planetary bodies with various surface gravity accelerations demonstrate that the simple-to-complex transitional crater diameter increases with decreasing of the surface gravity. The original depth of the Puchezh-Katunki structure and the presence of the central uplift well fit general trends, observed for impact craters on all planetary bodies of the terrestrial type.

The numerical model of the Puchezh-Katunki formation processes is described. The model results are preceded with a short description of all model components: the concept of hydrocodes, rock equation of states, brittle/ductile rock damaging, and the acoustic fluidization (AF) model.

This research is aimed at the study of the numerical simulation of the laboratory experiment results. Namely, this work shows the results of numerical modeling the filtration process that takes place in the laboratory experiment on a gypsum/cement sample. Numerical simulator is three-dimensional and based on the Biot poroelastic theory. The laboratory experiments are aimed at the study of hydraulic fracturing with account of the fracturing fluid leak-off. This study is the first part of the total numerical-experimental simulation of the hydraulic fracturing and its aim is to test the assumptions in which both the laboratory model and the numerical one were created. As a result of the research, a great influence of the gas presence on the filtration was found. Because of the gas presence, the fluid filtration was much slower in the experiment than in the numerical simulation. Although the numerical model of the filtration process is single-phase, we have invented a method for counting the gas phase presence in the sample. Thanks to this, we were able to reproduce the results of the experiment.

The objective of this research was to study the long-term response of filtration properties of a porous rock sample to external confining pressure. An experimental dependence of the ultra-low-permeable limestone sample permeability on time during the loading-unloading cycle with duration of 29 days was obtained. As a result of the loading, the sample permeability decreased by more than one and a half times. The decrease was linear with time, while there was practically no visible permeability elastic reaction to an abrupt change in external load. An experimental study of the flow stabilizing process in the sample was also conducted. It is shown that the characteristic time of stabilization, both theoretically estimated and measured, is much less than the characteristic time at which the permeability change occurred during the main loading experiment. This allows us to conclude that the observed change in the permeability of the sample is related with its viscous deformation.

The results of a study aimed at optimization of heat methods of hydrocarbon extractions. These methods give the possibility of mining the shale solid minerals at great depths. This paper reviews the heat flow effect on the unconventional hydrocarbon reservoir model. The mechanism of filtration and propagation of exothermic reaction in a gap is considered. The results of measuring the gas-dynamic parameters in the gap during the melting and evaporation of its walls, obtained during laboratory studies are presented. The fracture of a shale layer was simulated by a gap with constant cross section area which was created in poly methyl methacrylate (PMMA or Plexiglas) previously. The gap was blown through the gas flow; its speed was measured by experiments. The gas flow was created by continuously working turbine driven pump. The pressure in the flow was determined by manometer. The values of flow rates, evaporation and entrainment of the mass of material from the surface of the gap are recorded.

Frictional instability is the most likely mechanism of shallow earthquakes. For better understanding fault behavior we have conducted field experiments on shear deformation of a model fault. This study has focused on revealing the seismic-acoustic signatures of fault behavior. The entire spectrum of sliding regimes has been realized in the course of 1-m scale experiments-from a stable creep to a regular stick-slip, and their seismic-acoustic characteristics were investigated. It is shown that seismic pulses with characteristic frequencies less than 500 Hz are emitted only during slip events. The acoustic emission (AE) is observed both during slip events and at the stage of their preparation. Statistical analysis has shown that the AE distribution is generally a superposition of a power law distribution for low-energy pulses and a peak-like distribution for the largest pulses. The distribution with a characteristic peak prevails in regular stick-slip, while (quasi)stable creep is characterized by the power law distribution over the entire range of amplitudes. Both distributions-"with peak" and "without peak"-are observed for irregular sliding regime (random slip events with various amplitudes). Applying the nonlinear Grassberger-Procaccia algorithm to the analysis of time-series of AE data has allowed to rank the fault sliding regimes. The calculated correlation dimension characterizes the dynamics of the fault. The highest dimension is typical for stable sliding. A decrease of the correlation dimension indicates an enhanced probability of high-amplitude slip events. Nucleation of largest slip events is observed for the regular stick-slip with the least correlation dimension.

The results of the study of the gas-dust cloud of solid fuel combustion products dynamics formed under a rocket stages separation are presented. The sequence of the digital images obtained in the twilight condition at a distance of similar to 1500 km from the missile trajectory was analyzed. The height of the cloud center reaches up to similar to 900 km, and its diameter is similar to 2000 km. The glow of the cloud is determined by the scattering of sunlight on dispersed particles of the combustion products. The obtained data allow to specify the dispersed composition of the cloud and dynamic parameters of its development. The proposed methodology can be used to clarify the physical picture of the interaction of the combustion products of solid propellant with the environment, as well as environmental conditions and processes in the upper atmosphere.

Calcium-aluminum-rich inclusions (CAIs) are the oldest Solar System solids dated that formed by evaporation, condensation, aggregation and, sometimes, melting processes near the protoSun, and were subsequently dispersed throughout the protoplanetary disk by still poorly-understood mechanism(s). Here we report on the discovery of disk- and bowl-shaped centimeter-sized igneous CAIs in CV (Vigarano type) carbonaceous chondrites. Igneous CAIs of these shapes are not expected for crystallization of melt droplets in a low gravity field of the protoplanetary disk. We have tested several models for the formation of disk- and bowl-shaped igneous CAIs including: collision, aerodynamic deformation and shock flattening. We conclude that these CAIs resulted from aerodynamic deformation of CAI-like melt droplets and propose the following multistage formation scenario: (1) nearly complete melting and acceleration of CAIs at < 30 km/s in the CAI-forming region having approximately solar dust/gas ratio; (2) aerodynamic deformation, ablation, deceleration, solidification at similar to 30-40 K/min, Wark-Lovering rims formation, and deceleration of the CAIs entering a dust-rich inner disk wall; (3) radial drift of the solidified deformed CAIs towards the Sun; (4) heating and partial melting of the deformed CAIs by solar radiation that preserve their morphology; (5) cooling and crystallization of CAIs at similar to 2 K/h; (5) radial transport of CAIs from their formation region to the outer disk.

The airburst events at Chelyabinsk and Tunguska in Russia are the best-documented asteroid impacts of recent times. Models that assess the potential danger from such events rely on an accurate picture of their aftermath. Here, we re-examine the most critical eyewitness accounts of the Tunguska airburst, namely those that describe injuries and casualties, and those that paint a picture of what events were responsible. Not all relevant information has survived in the written record and there are contradictions that create some ambiguity. We find that inside and near the tree-fall area were at least 30 people. Many lost consciousness and at least 3 passed away (immediately or later) as a direct consequence of the Tunguska event. The airburst created a butterfly-shaped pattern of glass damage extending 4-5 times wider than that seen at Chelyabinsk. At these larger distances, any injuries from falls, shattering glass cuts, or from UV radiation exposure were not reported.

In this paper we present the results of numerical modeling of the Chelyabinsk dust train during the first 3 min after the meteoroid entry which are in qualitative agreement with observations. Then we analyze the possibility of plume formation after impacts of small cosmic bodies and make some calculations for the Tunguska event which, unfortunately, cannot be compared directly with observations. We also estimate long-lasting disturbances in the upper atmosphere caused by the plume formation.

Hundreds of new impact craters have been observed to form on Mars since spacecraft began imaging that planet. New impact craters produced visible ejecta deposits and many of them also have visible rays, similar to lunar and mercurian craters. However, some of the new martian impact craters have a circular feature of relatively low reflectance that we call a "halo." This feature is distinct from the usual visible ejecta deposits or ray patterns. In this paper we present an observational study of this halo feature and we discuss the results of this study with respect to the nature of the halos: what they are and how they may have formed. To address these questions, we measured diameters of both halos and their central craters. We found a strong correlation between halo diameter and crater diameter, which indicates that the nature of the halos is fundamentally governed by the amount of impact energy available at their formation. Specifically, halo size is controlled by impact energy according to the non-linear relationship D-H proportional to E-2/3, where D-H is the diameter of the halo and E is the impact energy. We also found that certain factors may influence the formation of the halos: a thicker dust layer and lower elevations are both correlated with larger halos. From these correlations we conclude that the local surface characteristics as well as local atmospheric pressure influence the formation of the halos. Our description and analysis of the martian halo features provide a framework upon which specific halo formation mechanisms can be developed and tested in the future.

Fine dust from impact ejecta settles slowly in an atmosphere, whereas large chunks of ejecta easily traverse the surrounding gas on nearly parabolic trajectories. In order to study the effects of the interaction of impact ejecta with an atmosphere, we implemented a "representative particle" approach into the iSALE-2D shock physics code. We verify the modelling approach using analytical equilibrium sedimentation velocities, and successfully benchmark the results against simulations with the shock physics code SOYA. We study vertical dust settling scenarios of different initial mass and dust size (100 mu m - 10 cm), and find three different regimes of settling - sedimentation, formation of density currents, and the free-fall. Based on this, we model natural ejecta curtains for craters from 200 m - 4 km in radius, and small craters in the laboratory for different atmospheric pressures from 1 kPa - 6 MPa. We assess the range of ballistic ejecta deposition within an atmosphere in terms of ejecta thickness and deposition velocity.

We used statistical correlation functions (CFs) to describe food microstructure and to reconstruct their 3121 complexity by using limited information coming from single 213 microtomographic images. Apple fleshy parenchyma tissue and muffin crumb were chosen to test the ability of the reconstructions to mimic structural diversities. Several metrics based on morphological measures and cluster functions were utilized to analyze the fidelity of reconstructions. For the apple, reconstructions are accurate enough proving that lineal, L-2, and two-point, S-2, functions sufficiently describe the complexity of apple tissue. Muffin structure is isotropic but statistically inhomogeneous showing at least two different porosity domains which reduced the fidelity of reconstructions. Further improvement could be obtained by using more CFs as input data and by implementation of the techniques dealing with statistical non-stationarity. Novel stochastic reconstruction and CF-based characterization methods could improve the fidelity of reconstruction and future advances of this technology will allow estimating macroscopic food properties based on (limited) 2/3D input information.

Resolving topography of the inner core boundary (ICB) and the structure and composition of the nearby region is key to improving our understanding of solidification of the Earth's inner core. Observations of travel times and amplitudes of short-period seismic phases of PKiKP and PcP reflected, respectively, off the inner and outer boundary of the liquid core, provide essential constraints on the properties of this region. We revisit heterogeneities of ICB using a total of more than 1,300 new differential travel times and amplitude ratios of PKiKP and PcP measured at 3.2-35.2 degrees and reflected off the core's boundaries under Northeastern Asia and South America. We observe a statistically significant systematic bias between the measurements collected in the two spots. We carefully examine its origin in terms of contributions by various Earth's shells and find that most of variance in PKiKP-PcP differential travel times measured above the epicentral distance of 16.5 degrees in Northeastern Asia can be accounted for by mantle corrections. We find slight disparity of about 1-3 km between the outer core thickness under Asia and America; the ICB density jump under Northeastern Asia is about 0.3 g/cm(3), which is three times as small as under South America. The findings are interpretable either as evidence for inner core hemispherical asymmetry, whereby crystallization dominates in the West and melting in the East (not vice versa), or in terms of two disconnected mosaic patches with contrasting properties.

The importance of highly siderophile elements (HSEs; namely, gold, iridium, osmium, palladium, platinum, rhenium, rhodium and ruthenium) in tracking the late accretion stages of planetary formation has long been recognized. However, the precise nature of the Moon's accretional history remains enigmatic. There is a substantial mismatch in the HSE budgets of the Earth and the Moon, with the Earth seeming to have accreted disproportionally more HSEs than the Moon(1). Several scenarios have been proposed to explain this conundrum, including the delivery of HSEs to the Earth by a few big impactors(1), the accretion of pebble-sized objects on dynamically cold orbits that enhanced the Earth's gravitational focusing factor(2), and the 'sawtooth' impact model, with its much reduced impact flux before about 4.10 billion years ago(3). However, most of these models assume a high impactor-retention ratio (the fraction of impactor mass retained on the target) for the Moon. Here we perform a series of impact simulations to quantify the impactor-retention ratio, followed by a Monte Carlo procedure considering a monotonically decaying impact flux(4), to compute the impactor mass accreted into the lunar crust and mantle over their histories. We find that the average impactor-retention ratio for the Moon's entire impact history is about three times lower than previously estimated(1,3). Our results indicate that, to match the HSE budgets of the lunar crust and mantle(5,6), the retention of HSEs should have started 4.35 billion years ago, when most of the lunar magma ocean was solidified(7,8). Mass accreted before this time must have lost its HSEs to the lunar core, presumably during lunar mantle crystallization(9). The combination of a low impactor-retention ratio and a late retention of HSEs in the lunar mantle provides a realistic explanation for the apparent deficit of the Moon's late-accreted mass relative to that of the Earth.

In the paper, we present results of numerical investigation of the formation of the main fault and feathering fault structures in the sedimentary layer in strike slip of the base blocks. Main stages of the strike slip process are distinguished. The initial stage is characterized by the most gradual development of deformation, resulting in multiple discontinuities in the fault tip at the bottom of the sedimentary layer as well as in localization bands in surface layers. At the next stage the geomedium blocks are further displaced along feathering faults, with the displacement velocity considerably increasing at the moment of the fault arrival at the surface. The final stage is the coalescence of faults in the upper and lower parts and main faulting. During the process, displacements of different velocity and direction appear at the surface depending on the site and stage of faulting. The high-frequency component of surface vibrations is related to the medium fracture, arrival of discontinuities at the surface, their coalescence and main cracking. The low-frequency component is related to the development of plastic deformation and block motion. Thus, the analysis of displacement velocity and direction at different surface points can be useful for the estimation of a stage of faulting and its hazard.

The ability to identify the preparation process of seismic events using spectral analysis of microseismic noise was earlier shown in laboratory experiment in the form of reduction of natural frequency of oscillations during the transition of the system to a metastable state. Field studies of the Chilean subduction zone allowed us to identify large earthquakes with the same effects before them. In this paper investigation of the natural frequencies of block oscillations, which can be detected in the spectrum of seismic noise, was performed at a lower scale. Measurements were performed near Gubkin (Belgorod region, Russia), where the development of iron ore deposits and explosive works are carried out regularly. We used the data of the high-frequency accelerometer that was installed at the depth of 300 m from the surface. Spectral centroid reduction in the frequency range of 20-1200 Hz was identified before small seismic events with the amplitude of more than 10 mm/s(2).

In this paper we use the data of precision monitoring of confined aquifer at the territory of the Mikhnevo geophysical observatory in 2017-2018. New approach for identifying tidal waves in noisy initial data was applied. Comparative analysis of the main types of tidal waves in underground water level and theoretical volumetric strain of water-saturated reservoir was carried out. Such technique can be used for detection the main direction of water-bearing cracks, which can change in dependence on filtration mode of reservoir.

Radio waves of extremely low frequencies (5-40Hz) propagate in a special way. Since their wavelengths correspond to the Earth's radius, global resonances are found inside the cavity bounded by the Earth's surface and the lower ionosphere. These so-called Schumann resonances form a system of standing waves around the planet. They can be a powerful tool for investigating the electrical processes occurring in the lower ionosphere. This paper describes finite element method (FEM) simulations in the frequency domain of Schumann eigenmodes in 3D inhomogeneous Earth-ionosphere cavity. Such an approach provides result independence from source configuration and allows to separate ionosphere configuration influence on Schumann resonances. Also the approach visually reproduces line splitting in the global resonances. The ionosphere was modeled by a simple conventional vertical conductivity profile and by means of a complex 22-species plasmachemical model. Obtained simulation results are compared with the experiment and discussed.

We present a modified Linnik microinterferometer that can register image-plane hyperspectral holograms in reflection of various microobjects in incoherent light. A voice coil was integrated into the reference arm of the interferometer to enable mirror displacement. A set of interferograms is registered in each pixel of a high-speed CMOS camera. Post processing yields spectrally resolved image-plane holograms of the object. Quantitative phase images of red blood cells are obtained for each spectral component sigma = 1\lambda.

Atmospheric tides refer to those oscillations in the atmosphere whose periods are integral fractions of a lunar or solar day. Atmospheric tides are, in small measure, gravitationally forced, they are primarily forced by daily variations in solar insolation. Based on the results of instrumental observations of micropulsations of atmospheric pressure, the main waves of the lunar-solar tide in the Earth's atmosphere are identified. The registration of micropulsations is obtained in the range from 0.1 MHz to 10 Hz in the Geophysical observatory Mikhnevo of Institute of Geosphere Dynamics of Russian Academy of Sciences located in the Moscow region in period 2008-2016. An estimate of the spectral characteristics of micropulsations was carried out using the maximum entropy method. In order to increase the level of discrimination related to the frequencies of tidal waves, the adaptive rejection filtering method was applied. It is shown that the spectral amplitudes with frequencies that coincide with the frequencies of the tidal waves change with time with a periodicity of about 29 days. The characteristics of modulation of the solar elliptic wave S-1 and the main solar wave S-2 by periods of 13.66, 27.55 days are obtained; as well as similar to 0.3, 0.5 and 1 year.

While it is well known that permeability is a tensorial property, it is usually reported as a scalar property or only diagonal values are reported. However, experimental evaluation of tensorial flow properties is problematic. Pore-scale modeling using three-dimensional (3D) images of porous media with subsequent upscaling to a continuum scale (homogenization) is a valuable alternative. In this study, we explore the influence of different types of boundary conditions on the external walls of the representative modeling domain along the applied pressure gradient on the magnitude and orientation of the computed permeability tensor. To implement periodic flow boundary conditions, we utilized stochastic reconstruction methodology to create statistically similar (to real porous media structures) geometrically periodic 3D structures. Stochastic reconstructions are similar to encapsulation of the porous media into statistically similar geometrically periodic one with the same permeability tensor. Seven main boundary conditions (BC) were implemented: closed walls, periodic flow, slip on the walls, linear pressure, translation, symmetry, and immersion. The different combinations of BCs amounted to a total number of 15 BC variations. All these BCs significantly influenced the resulting tensorial permeabilities, including both magnitude and orientation. Periodic boundary conditions produced the most physical flow patterns, while other classical BCs either suppressed crucial transversal flows or resulted in unphysical currents. Our results are crucial to performing flow properties upscaling and will be relevant to computing not only single-phase but also multiphase flow properties. Moreover, other calculation of physical properties such as some mechanical, transport, or heat conduction properties may benefit from the technique described in this study.

A study of appearance and spatio-temporal dynamics of disturbances of the atmosphere, the upper and lower ionosphere, require of integrated investigations of interrelated processes at different altitudes and in different geophysical conditions. In the observatory of IDG RAS "Mikhnevo" created the unique radiophysical complex, allowing to carry out of coordinated measurements of variations of the geomagnetic field, propagation of SW, LW and VLF radio signals, variations of electric fields and atmospheric currents. Analysis of the data of measurements of the total electron content of the ionosphere with phase and amplitude of the signals of LF-VLF range on global and regional routes allows to obtain data on the features of the structure and dynamics of the ionospheric plasma in the mid-latitude zone of the European part of the Russian Federation. The coordinated analysis of GNSS and VLF signals makes it possible to study the mechanisms of the relationship between the perturbations of the upper and lower ionosphere and the dynamics of the ionosphere in the horizontal and vertical directions

The analysis of atmospheric pressure and electric field strength variations field observations in GPhO 'Mikhnevo' was carried out. It is shown that during the development of auroras, synchronous variations in pressure and electric field strength in the surface layer of the atmosphere, as well as changes in the electric field characteristic for the development of a magnetic storm, can occur. The cross-correlation of these values was investigated, which showed a link between them.

The paper presents a technique for recovery of the electron concentration profile, based on the two-parameter model of the D-layer of the ionosphere from measurements of the amplitude and phase variations of the VLF radio signal at two frequencies during a solar X-ray flash. Solar X-ray flash of the X8.2 class was processed in accordance with this technique. It was shown that the parameters of the ionosphere during the X-ray flash mainly depend on the radiation flux in the range of 0.05-0.4 nm. The dependence of the parameters of the ionosphere on the flow in the range of 0.1-0.8 nm is expressed to a much lesser extent.

Plumes produced by the impacts of asteroids and comets consist of rock vapor and heated air. They emit visible light, ultraviolet, and infrared radiation, which can greatly affect the environment. We have carried out numerical simulations of the impacts of stony and cometary bodies with a diameter of 0.3, 1, and 3 km, which enter the atmosphere at various angles, using a hydrodynamic model supplemented by radiation transfer. We assumed that the cosmic object has no strength, and deforms, fragments, and vaporizes in the atmosphere. After the impact on the ground, the formation of craters and plumes was simulated, taking the internal friction of destroyed rocks and the trail formed in the atmosphere into account. The equation of radiative transfer, added to the equations of gas dynamics, was used in the approximation of radiative heat conduction or, if the Rosseland optical depth of a radiating volume of gas and vapor was less than unity, in the volume-emission approximation. We used temperature and density distributions obtained in these simulations to calculate radiation fluxes on the Earth's surface by integrating the equation of radiative transfer along rays passing through a luminous region. We used tables of the equation of state of dunite and quartz (for stony impactors and a target) and air, as well as tables of absorption coefficients of air, vapor of ordinary chondrite, and vapor of cometary material. We have calculated the radiation impulse on the ground and the impact radiation efficiency (a ratio of thermal radiation energy incident on the ground to the kinetic energy of a body), which ranges from similar to 0.5% to similar to 9%, depending on the impactor size and the angle of entry into the atmosphere. Direct thermal radiation from fireballs and impact plumes, poses a great danger to people, animals, plants, and economic objects. After the impacts of asteroids at a speed of 20 km s(-1) at an angle of 45 degrees, a fire can occur at a distance of 250 km if the asteroid has a diameter of 0.3 km, and at a distance of 2000 km if the diameter is 3 km.

The results of numerical modeling of meteoroids' interaction with Earth's atmosphere are presented. We model the entry in two dimensions and then interpolate the results into a 3-D model to calculate interaction of shock waves with the surface. Maximum shock pressures, wind speeds, and areas subjected to substantial overpressure are calculated for oblique impacts of asteroids and comets. We show that vertical impacts produce a smaller damage zone on the surface than oblique ones. Damage caused by shock waves covers an order of magnitude larger area than any other hazardous effects. The function of energy release in the atmosphere, which is traditionally used in meteoritics, has a limited application if cosmic bodies are larger than tens of meters in diameter: at each time moment energy is smoothed along a substantial length of the trajectory; both emitted radiation (routinely used for calibration of semi-analytical models) and shock wave amplitude are complex functions of temperature-density distributions in atmosphere.

Several Snowball Earth periods, in which the Earth has been (almost) totally glaciated, are known from Earth history. Neither the trigger for the initiation, nor the reason for the ending of such phases, are well understood. Here we discuss some mechanical effects of the impact of asteroids 5-10 km in diameter on the Snowball Earth environment. An impact of this scale is the largest impact that is statistically predictable for 10-60 Myr time periods. The impact cratering itself (shock waves, impact crater formation) is not powerful enough to change the natural climate evolution path on Earth. However, the products of impact (mainly-water vapor) can be quickly distributed over a substantial part of the globe, influencing the global circulation (e.g., facilitating cloud formation). It is a question for future studies to confirm if such an event (which is possible statistically during this interval) may or may not have influenced the global climate of the Snowball Earth, and/or contributed to deglaciation.

High entry speed (>25kms(-1)) and low density (<2500kgm(-3)) are the two factors that lower the chance of a meteoroid to drop meteorites. The 26g carbonaceous (CM2) meteorite Maribo recovered in Denmark in 2009 was delivered by a bright bolide observed by several instruments across northern and central Europe. By reanalyzing the available data, we confirmed the previously reported high entry speed of (28.3 +/- 0.3) kms(-1) and trajectory with slope of 31 degrees to the horizontal. In order to understand how such a fragile material survived, we applied three different models of meteoroid atmospheric fragmentation to the detailed bolide light curve obtained by radiometers located in Czech Republic. The Maribo meteoroid was found to be quite inhomogeneous with different parts fragmenting at different dynamic pressures. While 30-40% of the (2000 +/- 1000) kg entry mass was destroyed already at 0.02 MPa, another 25-40%, according to different models, survived without fragmentation up to the relatively large dynamic pressures of 3-5 MPa. These pressures are only slightly lower than the measured tensile strengths of hydrated carbonaceous chondrite (CC) meteorites and are comparable with usual atmospheric fragmentation pressures of ordinary chondritic (OC) meteoroids. While internal cracks weaken OC meteoroids in comparison with meteorites, this effect seems to be absent in CC, enabling meteorite delivery even at high speeds, though in the form of only small fragments.

We present our latest research results on intensity distribution transformation from Gaussian to a flattop and doughnut. The theoretical calculations and experimental results of the efficiency of different types of deformable mirrors are given. During the experiments the wavefront was measured with Shack-Hartmann sensor and then modified with bimorph deformable mirror to reach the desired intensity distribution in the far-field. Then the bimorph mirror was substituted with the stacked-actuators deformable mirror to confirm the simulations.

The ability to focus laser beam with wavelength 0.65 um through the multiply scattering suspension of polystyrene microspheres, diluted in distilled water, was investigated. Experimental setup, contained the Shack-Hartmann sensor for measurements of the local slopes of the Poynting vector, the CCD camera for estimation of the far-field focal spot's intensity and the bimorph mirror with 48 electrodes was built. Numerical and experimental investigations of focusing efficiency was carried out also.

A high-quality flat wave front is usually used to calibrate the Shach-Hartmann wave-front sensors. The article discusses the possibility of calibrating sensors with spherical wave fronts. Special attention is paid to the consideration of calibration in standard laboratory conditions. The mathematical apparatus and the scheme of the experiment are considered.

As it is well-known, the laser radiation, propagated through different mediums, is affected by wavefront distortions and thus the quality of the radiation is significantly decreased. To compensate for the wavefront aberrations adaptive optics means are used. We developed miniature bimorph mirror with 37 electrodes. To manufacture this type of mirrors two technologies were used. Those are laser engraving technology for drawing electrode grid on the piezoceramic disc, and ultrasonic welding technology to connect wires to the control electrodes. Main parameters of such a deformable mirror were investigated and presented in this paper.

The article discusses the use of bimorph adaptive mirrors to improve the focusing of laser radiation. The criterion of focusing efficiency is the fraction of the energy of the laser radiation passing through the pinhole located in the focal plane of the focusing lens.

Thermal effects in the active laser medium influence on the quality of the laser beam in high-power laser systems. Temperature fluctuations lead to refractive index modulation in the medium, thus the intensity of the radiation is significantly reduced. Historically, to solve this task an adaptive optics technique is used. It allows to compensate for the wavefront aberrations. Stacked-actuator deformable mirror is a traditional technology that is used in order to improve the quality of the incident wavefront. This type of wavefront correctors has one significant shortcoming - the impossibility of the replacement of broken actuators. We developed a stacked-actuator deformable mirror with aperture of 120 mm and 121 control actuators to correct for the high-power laser radiation. Actuator arrangement was hexagonal. In our design, the broken piezoactuators could be easily replaced.

Registration of two types of digital holograms is considered: digital hyperspectral holograms and Denisyuk volume holograms (holograms in colliding beams). Hyperspectral holograms are considered as an analogue of thin holograms, in which zero order and a conjugate image are suppressed. Previously proposed principles are developed for the case of thick holograms in their digital representation. It is shown that the displacement of a scanning mirror in the process of hyperspectral holograms capturing is analogous to registering of the blackening function of layers of the volume hologram. The position of the mirror corresponds to the layers in a thick hologram, where the interference pattern is recorded in layers. An analogy is drawn between the restoration of a hologram by a light beam and its processing of its digital analog.

The most important part of any adaptive optical system is a deformable mirror. One of the most widely used type of such mirrors are the bimorph ones. In fact, there is no problem to manufacture a wide aperture bimorph wavefront correctors that perfectly can compensate low-order laser aberrations. But if one needs a tiny deformable mirror to correct for high order aberrations with reasonable amplitude, he usually will use stacked actuator mirror or a MEMS one. In this presentation we suggest the new design and technology of production of a small size bimorph mirrors to be used to correct for atmospheric phase fluctuations. Our mirror has the diameter of 30 mm and 37 control electrodes (mirror with 20 mm and 63 control electrodes is being developed). The resonance frequency of 13.2 kHz is due to its small diameter. At the same time, large number of electrodes allows to reproduce high order aberrations. To manufacture this device two modern technologies are used: ultrasonic welding and laser engraving technology.

High-power laser systems are widely used for technological purposes or laser fusion experiments, but also to deliver the energy to some remote places here on the Earth as well as in space. Probably the only instrument to improve the phase structure of the laser beam is to use methods and elements of adaptive optics. The heart of any adaptive optical system is of course the deformable mirror. That is why the research and development of such optical elements continues for many years already. Here we propose a new stacked actuator mirror to be used to correct for not just the turbulent phase fluctuations, but also it should work with high CW power laser beams. Therefore, our mirror is a water-cooled one. Another important feature of this device is that each actuator could be easily substituted in case of failure. The mirror is 120 mm in diameter and has 121 control elements. Main characteristics of a mirror are presented in this work.

Bimorph deformable mirror with the clear aperture of 50 mm and 48 control electrodes and spatial light modulator with resolution of 1920x1080 pixels were used to increase the efficiency of focusing of partially coherent laser radiation, propagated through the 5 mm layer of the scattering suspension of 1 um polystyrene microspheres, diluted in distilled water, with the concentration values ranging from 10(5) to 10(6) mm(-3). Medium with such parameters can be considered as an equivalent to the mid-dense fog layer with the length ranging from 300-500 meters up to 5 kilometers. Shack-Hartmann sensor was used to measure the distortions of averaged wavefront of laser beam, and CCD camera was used to estimate the intensity distribution of the focal spot in the far-field. Numerical and experimental investigation of the focusing improvement showed that it is possible to increase the peak intensity of the focal spot up to 45-60 %.

In this work, we investigate the efficiency of the use of the bimorph deformable mirror to focusing laser beam in the pinhole. Pinholes of different diameters are used as an instrument for focusing verification. Different algorithms are discussed and analyzed for the investigation of the process of the beam focusing. It is shown that tip-tilt correction is an essential condition for increasing the focusing efficiency.

Instrumental observation data on acoustic oscillations in Moscow for 2014-2017 have been analyzed. The difference in amplitude and spectral characteristics of acoustic noise between the megalopolis and an outside area has been demonstrated. Data testifying to an increase in acoustic noise during strong atmospheric phenomena such as hurricanes and squalls are presented. Specific features of infrasound oscillations and acoustic-gravity waves have been considered separately.

This is a study of the spatiotemporal distribution of midlatitude disturbances of the upper and lower ionosphere in the European zone during a strong geomagnetic storm and strong X-ray flare using data of synchronous measurements of the parameters of global navigation satellite system (GNSS) signals and very low-frequency (VLF) radio signals. It has been shown that the contribution of electron concentration at different altitudes to the total electron content of the ionosphere can vary significantly depending on the type of heliogeophysical disturbances. A combined analysis of GNSS signals and VLF radio signals makes it possible to study the mechanisms of coupling between the upper and lower ionospheric disturbances and the dynamics of ionospheric disturbances in the horizontal and vertical directions.

The data from observation of the geomagnetic field variations at the Midlatitude Mikhnevo Geophysical Observatory of Institute of Geosphere Dynamics of the Russian Academy of Sciences, Mikhnevo village, Moscow oblast, Russia (coordinates 54.959 degrees N; 37.766 degrees E) and at the INTERMAGNET international magnetic network station of the Belsk Geophysical Observatory of Geophysical Institute of the Polish Academy of Sciences, Belsk, Poland (coordinates 51.837 degrees N, 20.792 degrees E) in 2008-2016 are analyzed. A long-term trend related to secular variation in the magnetic field of the Earth is studied by the daily-mean values. Annual variation is distinguished in the north horizontal component of the magnetic field. The reliability of the recent version of the International Geomagnetic Reference Field (IGRF-12) model, which was released in December 2014 to describe variations in the main magnetic field at the Mikhnevo and Belsk observatories, is estimated. The 2011 and 2014 jerks are identified.

The paper quantitatively compares the results of calculations of the electron density Ne by the International Reference Ionosphere model IRI-2016 with experimental data obtained from the DE-2 satellite. It considers 648 variants of heliogeophysical conditions. The deviation of theoretical estimates from experimental values is within the instrumental accuracy of satellite data in an average of 27% of cases. It is concluded that the IRI-2016 model, the approximation coefficients of which in functional dependences are associated with heights of the F-region, gives negative values of the efficiency coefficient of the predicted electron density in 73% of cases in the outer ionosphere at altitudes over 500 km.

The paper presents the field observation data on variations in the pressure and electric field intensity in the near-surface atmospheric layer during the passage of the morning solar terminator in several regions of the Russian Federation: on Kamchatka, Kola Peninsula, and in Vladimir oblast. Analysis of the data shows that the pressure and electric field intensity undergo synchronous variations during the passage of the solar terminator. An isolated series of events has a mutual correlation coefficient of variations in the pressure and electric field intensity in the period of passage of the solar terminator that exceeded 0.9 with a subsequent decrease to the background values of approximate to 0.2-0.3.

A sequence of digital images of a gas-dust cloud of combustion products of solid fuel that formed during the separation of rocket stages is analyzed. The images were obtained in twilight conditions from a distance of similar to 1500 km. The height of the cloud center reaches similar to 900 km, and its diameter is similar to 2000 km. The obtained data make it possible to estimate the dispersed composition of the cloud and the dynamic parameters of its development. The practically constant expansion velocity of the cloud, similar to 2 km/s, indicates that it consists of rather large, dispersed particles that do not slow down in the upper atmosphere. The proposed method can be used to clarify the physical picture of the interaction of solid-fuel combustion products with the environment.

The results of instrumental observations of the electric-field strength in the conditions of Moscow in 2014-2018 are presented and analyzed. The spectral characteristics of the electric-field variations and its daily variation are discussed. The effect of cold atmospheric fronts, hurricanes, squalls and thunderstorms, as well as technogenic phenomena (large fires), on the electric-field variation is demonstrated. It is shown that hurricanes, squalls, and thunderstorms are preceded by periods of 1 to 4 h characterized by specific electric-field variations, which can be considered a possible prognostic sign of strong atmospheric phenomena.

Changes in the state of the D and E ionospheric regions lead to variations in the amplitude-phase characteristics of VLF radio signals. The existing theoretical and empirical models of the propagation of low-frequency electromagnetic waves qualitatively describe the relative variations in the parameters of the lower ionosphere associated with strong heliogeophysical disturbances; however, these models do not allow estimation of the absolute value and distribution of the electron concentration. We used the measurement data for the amplitude-phase characteristics of VLF radio signals with different frequencies propagating along two closely spaced paths. This made it possible not only to quantify the parameters of the D region of the ionosphere on a spatial scale of thousands of kilometers during the powerful solar flare of September 10, 2017 but also to restore the electron concentration profile before the onset of X-ray radiation.

The results of instrumental observations of variations in the Earth's magnetic field conducted at a number of observatories of the INTERMAGNET network and the Mikhnevo geophysical observatory of Institute of Geosphere Dynamics of Russian Academy of Sciences, during the fall of meteorites have been analyzed. The Vitim (September 24, 2002), Chelyabinsk (February 15, 2013), Romania (January 7, 2015), Buryatia (October 25, 2016), Khakassia (December 6, 2016), St. Petersburg (September 11, 2017), and Lipetsk (June 21, 2018) events have been used to show the geomagnetic effect of falling cosmic bodies. The effect has a nonlocal character, occurs simultaneously, and is observed at distances up to 7000 km from the location of falling cosmic bodies. The amplitude of induced geomagnetic variations has been found to depend weakly on the distance to the event location. The resulting data can be used to verify theoretical and computational models of the geophysical processes accompanying the fall of meteorites.

Based on the Chelyabinsk (February 13, 2013) and Lipetsk (June 21, 2018) events, disturbances in the Earth's geomagnetic field, which were induced by the fall of these meteorites, were studied. Based on the data provided by geomagnetic observatories of the INTERMAGNET network and the mid-latitude Mikhnevo geophysical observatory (IGD RAS), it was established that the fall of meteorites through the Earth's atmosphere, in general, induces geomagnetic disturbances of up to 5 nT at distances up to 2700 km from the impact point of a cosmic body; the maximum effect is reached with a delay time ranging from 5 to 10 min, and the duration of the period of the induced geomagnetic field disturbances varies from 5 to 20 min. The estimation dependencies of the amplitude and duration of induced geomagnetic disturbances from a distance from the meteorite impact points are proposed.

Based on the data of experimental studies of wave disturbances in the Earth's atmosphere before and after the earthquakes in Uzbekistan (May 26, 2013) and Kyrgyzstan (January 8, 2007), earlier unknown changes in the parameters of internal gravity waves are revealed. These changes were manifested during the period of five days before the earthquake and in certain cases can be used for short-term prediction of the time when seismic events are to occur.

Based on the results of instrumental observations carried out at a number of mid-latitude observatories of the INTERMAGNET network and at the Mikhnevo Geophysical Observatory (Institute of Geospheres Dynamics, Russian Academy of Sciences), it is shown that strong earthquakes are accompanied by increased variations in the Earth's magnetic field. In this case, the short-period (period of similar to 0.5-0.8 min) and long-period (similar to 5-20 min) stages of increased geomagnetic variations are clearly distinguished. The maximum amplitudes of induced geomagnetic variations for short-period and long-period variations are 1.5-2 and 2-4 nT, respectively. Induced geomagnetic disturbances of similar morphology and almost synchronous nature are noted at observatories located at significantly different distances from the earthquake source.

Analysis of PKIIKP waves reflected off the inner surface of the solid core boundary and recorded close to the antipode indicates that the shear wave velocity at its top can be 10-60% below the value of 3.5 km/s envisaged by standard models of the Earth.

The results of spectral analysis of coordinates obtained by continuous data acquisition using a stationary GPS receiver at the Mikhnevo Geophysical Observatory, Institute of Geosphere Dynamics, Russian Academy of Sciences, are presented. A detailed analysis of the digital data series recorded over a long period of time (observations have been carried out starting from June 2014) shows that the spectrum of coordinate data variations incorporates a considerable amount of quasi-harmonic components, including fluctuations with periods similar to those of waves of tides.

The key prospective research directions and tasks within the new, currently actively developing scientific direction "Near-surface geophysics" are formulated and discussed. A combined approach is suggested for studying the interactions between the geospheres at the Earth's crust-atmosphere boundary-the region of the most intense mass- and energy exchange between the internal and external geospheres-and for exploring the interactions and transformations of the geophysical fields in the near-surface zone of the Earth, including its biosphere. A number of new results yielded by studying the processes of the interaction between the geospheres and physical fields of the Earth are presented. The importance of establishing the geophysical conditions of the human environment and the characteristics of manmade activity is highlighted.

On August 7, 2016, an earthquake with magnitude 4.8 occurred in the vicinity of the city of Mariupol close to the southern boundary of the East European Platform (EEP). The earthquake was accompanied by aftershocks with magnitudes ranging from 2.2 to 3.9 that lasted for five days. This region experiences external influence from the neotectonically active Alpine zone, which is expressed in intraplate deformations, horizontal and vertical movements of the Earth's surface, and seismicity. The sources of the earthquake and its aftershocks are located within the block bounded by the neotectonically active Maloyanisol, Kalmius, and Primorsky faults. In the axial part of the block, a seismogenic structure is traced by the submeridional Kalchik lineament zone identified by the combined analysis of geological and geophysical data and visual interpretation of the satellite image. This neotectonically active zone accommodates the epicenters of the main event and most of the aftershocks.

A new phenomenological model describing the propagation of acoustic disturbances in the stratospheric waveguide is proposed based on instrumental observations of infrasound signals from high-power explosive sources in the atmosphere. A generalized relationship between the energy of the acoustic source in the atmosphere and the characteristic frequency in the spectrum of the acoustic signal is obtained. The developed model is verified against the description of natural and manmade acoustic sources with the known energy. It is shown that the proposed model agrees with the observations and the data obtained in the other works.

This paper presents a model and a computational algorithm for recovering the X-ray component of the solar spectrum based on GOES XL (0.1-0.8 nm), XS (0.05-0.4 nm or 0.05-0.3 nm), and SDO QD (0.1-7 nm) data. The model relies on the emission spectrum of optically thin plasmas in the Mewe approximation, which is the temperature spectrum. An assumption is made about the possibility of representing the total spectrum as a superposition of Mewe spectra situated in the absorbing solar atmosphere to an optical depth equal to 1 for the energy corresponding to its temperature parameter. Thus, this model is a version of the multi-temperature approximation. Spectrum parameters are determined from support functions, approximation expressions for which are given in Appendix.

This paper presents a new development of small-diameter, high-spatial-resolution, semipassive bimorph deformable mirrors to be used in different imaging systems. To manufacture the small control elements, laser engraving technology is used. An ultrasonic welding technique to connect the wires to the electrodes (actuators) is applied for this kind of mirror. The initial flatness of the mirror surface equals 0.33 mu m (P-V) due to the use of substrate polishing technology after gluing the glass substrate to a piezo disk. We present the main parameters of these wavefront correctors, such as the response functions of different electrodes, temporal behavior, and the ability to compensate for high-order aberrations.

Self-reference hyperspectral holographic microscopy with an extended, spatially incoherent, polychromatic source is suggested and experimentally verified. The reference field is the zero-order Fourier component of the object filtered out by a ring-shaped mask placed in the Fourier plane of the optical system. A set of spectrally resolved complex amplitudes of the object is obtained on the basis of a standard microscope equipped with a Michelson interferometer. Experiments on registration of hyperspectral holograms confirming the validity of the proposed theoretical model are carried out.

The new method is proposed for interpreting data of acoustic emission during initiation and growth of dynamic breakaways. The method is based on the analysis of wave form of the emitted acoustic pulses. Clustering of the pulses by the wave form criterion shows that in the localization zone of strains different-scale processes described with various scaling relations take place. All classes of acoustic pulses obey the power-series amplitude-frequency distribution. The sharp-arrival acoustic pulses posses unaltered scaling relations in the period of nucleation and growth of dynamic breakaways whereas the smooth-arrival pulses demonstrate the nonlinear change in the scaling relations. At the final stage of the dynamic breakaway formation, the proportion and amplitude of acoustic pulses with smooth arrival increase.

The subject of research is dynamic slips on large faults initiated by man-made impacts. In addition to recognized types of man-made impacts such as fluid injection or seismic vibrations, the possible trigger effect of rock extraction and displacement during mining operations is considered. It is shown that dynamic sliding can be initiated only on faults in which three geomechanical conditions for the occurrence of instability are fulfilled: closeness of the value of Coulomb stresses in the fault plane to the local ultimate tensile strength; the condition of weakening of frictional contact with an increasing sliding velocity and relative movement of fault sides; and the implementation of a certain ratio between the stiffness of the enclosing massif and the rate of reduction of resistance to friction. Features of formation of a dynamic slip on a fault are considered in the series of laboratory and numerical experiments. It is shown that the movement always begins in the segment with the property of velocity weakening, regardless of the location of such a segment relative to the load application. According to the calculations, the excavation of rock in a large mining quarry leads to a change of about 1 MPa in the Coulomb stresses in the fault plane in areas that significantly exceed the size of the nucleation zone of earthquakes with M <= 6. This may turn out to be sufficient to initiate seismogenic slips on stressed faults.

The results of determining the parameters of seismic anisotropy of the upper mantle of the central part of the East-European craton are given. According to the tectonic concepts actively developing in recent decades, the East-European craton consists of megablocks (microplates) of different age: there are three main megablocks - Fennoscandia, Volga-Uralia and Sarmatia. The area of their triple junction is the subject of this article. The SKS/SKKS anisotropy method was applied. Its essence is to use SKS phases in order to obtain delay times for the arrival of two quasi-shear waves that are formed during the trace of a shear wave through an anisotropic medium and gets through it with different velocities. The result is to simulate the azimuth of the maximum velocity axis along which "fast" quasi-shear wave trace and to get the delay time between "fast" and "slow" waves. The technique does not allow to obtain accurate estimates of the depth of the anisotropic layer, however, taking into account the long periods of the SKS wave and the pronounced anisotropic properties of olivine, as the main material composing the upper mantle, it is assumed that these effects are related to the mantle processes. Authors used the data from "Obninsk" (OBN) and "Mikhnevo" (MHV) stations that are located in the zone of the triple junction of blocks. For Obninsk station - 1266 events were used, for Mikhnevo station - 472. For each station, we obtained estimates of the azimuth of the maximum speed axis and the delay time of arrival of quasi-shear waves. As a result of the study, the mantle anisotropy of the region is assessed as weak, which is an expected result for tectonically stable platform regions (delay time 0.4 s for the OBN station and 0.2 s for the MHV station). The direction of the maximum speed axis is strictly sub-latitude (90° for the OBN and 100° for MHV station), which is in accordance with the known the East-European lithospheric plate motion. For the OBN station, two groups of events were identified, with significantly different results, structured by azimuth. For events mainly with western azimuths of arrival of seismic waves, the solution is 90° and 0.4 s, while processing events from the eastern direction of arrival, along with a coordinated solution, a second pronounced local extremum is detected, corresponding to angles and delay time about 0.5-1.0 s. According to the results of MHV data processing, a second local extremum was also found, corresponding to similar angles of about 160°, however, with a shorter delay time (about 0.1-0.2 s). It can be assumed that the presence of two extrema is associated with the anisotropic parameters of two different megablocks, near the junction boundary of which are located the OBN and MHV stations.

The article describes the results of laboratory experiments conducted on a unique setup, which allows to model not only the process of hydraulic fracturing, but also to vary the external conditions. The advantages of the setup include the ability to model such tasks: Reorientation of a hydraulic fracture due to the stress state changes caused by the development of the field; the formation of unstable fractures in the injection wells; verification of hydraulic fracturing simulators used in oil producing companies. The setup allows to study large samples (0.43 m in diameter, 0.07 m in height). It is possible to place in the sample not only a model well with fracturing, but also adjacent wells. Thus, we can model part of the development system and its effect on hydraulic fracture propagation. Also, a non-uniform three-dimensional stress-strain state which largely determines the geometry of the fracture can be created with the setup. The experiments were aimed at the study of the problems described above. It was found that the pore pressure distribution created by the development of neighboring wells can actually influence the fracture trajectory. Also, the influence of existing fractures on the propagation of a new fracture was established. In addition, in the experiment it was possible to obtain a refracture. The presented experimental results allow a better understanding of the formation of real hydraulic fracturing, which should be taken into account in the numerical simulation. © 2019, Neftyanoe Khozyaistvo. All rights reserved.

Anomalies of magnetic field of the Earth during high-magnitude earthquake have many times been addressed in the scientific literature. The earlier research of magnetic anomalies mostly used data of magnetic recording at points nearby epicenters of earthquakes. Recently, researchers lay emphasis on the 2011 Tohoku earthquake of moment magnitude Mw 9.0 occurred on the east coast of Honshu (Japan, epicenter at 38.32 degrees North latitude and 142.37 degrees East longitude). This study focuses on geomagnetic perturbations far away from the epicenter of the Great East-Japan Earthquake and uses observatory data from international network Intermagnet and Geophysical Observatory Mikhnevo. Processing and analysis of the instrumental observation data shows that ini tiation of earthquakes is accompanied by variations in the magnetic field. These anomalies are distinct and recorded at great distances from the epicenter. Records of anomalous magnetic signals can be used in prediction algorithms of earthquakes and rock bursts. On the other hand, perturbations during storms confine practical importance of predictive monitoring as magnetospheric and ionospheric disturbances considerably exceed lithospheric disturbances.

Formulas of safe ranges and relative elastic strains during large-scale blasting in surface or underground mines are presented. A safe range means stability of exposed rock surface in surface or underground mines under seismic effect of large-scale blasts. Based on the relative strain formula, controlled and uncontrolled parameters of drilling and blasting as well as physicotechnical properties of rocks are analyzed. The influence of controlled blast parameters on relative strains of rocks is assessed. Some methods of depression of large-scale blast action on the stability of exposed rock surfaces are described. The research findings can be used in industrial testing, for retention of exposed rock surfaces (benches and pit walls, unsupported side walls of rooms and pillars, etc.) during large-scale blasting in surface and underground mines. In the Oskol ore region of the Kursk Magnetic Anomaly, an underground multipurpose test ground is arranged for studying seismic effect of large-scale blasts in complex-structure ferruginous quartzite bodies in Lebedinsky and Stoilensky open pit mines and in Gibkin Mine.

To expand the range of instrumentation for nonlinear geotomography using pendulum waves, recording of complex deformation and wave processes, as well as analysis of the related seismic emission processes induced by surface and underground mining, earthquakes and powerful explosions, this article describes the modern and promising measuring equipment designed by the Institute of Mining, Siberian Branch, Russian Academy of Sciences. Specifications of the equipment provide recording of the dynamic and kinematic characteristics of pendulum waves in high-stress geomedia with hierarchical block structure. The formalized connection between such structure and seismic emission processes was described earlier (Part II of the article). This part of the article presents two basic measuring and computing systems for monitoring absolute displacements and strains in real geomedia in a dynamic mode in underground and surface mines under extreme climate of Siberia. Efficiency of the measurement systems in recording of low-velocity (less than 100 m/s) pendulum waves is illustrated by the field records of blasting at copper–nickel mines in the Norilsk Region (instrumentation system MOED-p) and in open pit mines at the kimberlite pipes in Yakutia (multi-functional deformation–wave measuring and computing system Karier). The comparative analysis of these records and the wave packets of higher gas-dynamic activity induced in Kuzbass mines by earthquakes according to the readings of automated gas control systems shows the deterministic connection of earthquakes and low-velocity pendulum waves (less than 5 m/s).

The attenuation coefficients of longitudinal and shear waves propagating in the Earth's upper crust below the central region of the East European Platform have been determined using seismic observations along a profile from the Novogurovskii limestone quarry to the Mikhnevo small-aperture seismic array. Assuming that dissipative properties of the Earth's crust are invariable, we drew a contour map characterizing the propagation of seismic energy generated by open pit mine blasting in the central part of the East European Platform; the map reflects both historical and recent earthquakes as well. The distribution of seismic impacts of industrial explosions is compared with the distribution of zones of tectonic dislocations revealed by lineament analysis. The map also contains estimates of the intensity of open pit blasting in 2013-2017.

In this paper, we developed algorithms for multichannel processing of seismic array records that allow detecting signals of weak seismic events observed against the background of natural seismic noise. The algorithm for detecting signals of weak seismic events is based on the coherence assessment of longitudinal waves (P-waves) recorded by a small aperture array. The advantage of this algorithm over the known single-channel short/long term averaging (STA/LTA) detector is the ability to detect time intervals of P-waves at a signal-to-noise ratio (SNR) less than unity. Based on the time intervals of the array records with the registered coherence measure values that exceed a certain threshold, the apparent slowness vector is estimated by using the phase bimforming algorithm that is robust to noise (Zhang et al., 2008; Kushnir and Varypaev, 2017). The developed algorithms of multichannel processing were tested using real seismic records of a small aperture array installed in the Kursk Magnetic Anomaly area near the mine workings for iron ore extraction. Signals of both strong (underground industrial explosions) and weak seismic events were detected for 20 h of seismic recording. In some cases, seismic events were shown to have a complex source mechanism. Using the Capon filter (Capon, 1969), for weak seismic events, P-waves with a duration not exceeding 0.2 s and a temporal shape similar to the known function of a Ricker pulse (Bording, 1996) are found to have resemblance.

The waveform cross correlation technique is used to detect signals from aftershocks of the ML = 6.1, August 14, 2016, Sakhalin earthquake using regional seismic network data. Regular P- and S-wave phase arrivals are associated with seismic sources; the resulting cross correlation bulletin is compared with a standard seismic bulletin for the same aftershock sequence. An advantage of the cross correlation bulletin is that it has more detected seismic events tied to three or more stations and a lower catalog completeness threshold; even the epicenters of the weakest aftershocks are located with greater accuracy. The exact aftershock locations tend to cluster along a narrow zone related to the Central Sakhalin Fault.

The results of experimental and theoretical studies of the applicability of strong pulsed magnetic fields to destruct ferruginous quartzite are presented. A “magnetokinetic” model of ferruginous quartzite destruction, based on the interaction of magnetite grains with quartz matrix at the passage of a high-gradient electromagnetic pulse through rock, is proposed. It is shown that the high-gradient pulsed magnetic field can be used to destruct quartz-containing rocks in a massif during both drilling and blasting and when solving geoenvironmental problems in mining crystalline rocks, complex-structure massifs of ferruginous quartzites by the example of deposits of the Kursk magnetic anomaly (KMA) and others.

This paper shows the results of the refined locations for underground Peaceful Nuclear Explosions (PNEs). Peaceful nuclear explosions (PNEs) were made for industrial applications in the Soviet Union. This study is based on a comparison of PNEs' parameters. These explosions were recorded by seismographic stations in Kazakhstan from 1966 to 1988. The monitoring/verification community generally utilizes PNE locations from Sultanov et al. (1999). In reality, there are errors and some PNEs are poorly located. Our locations were determined using an integrated approach encompassing published open literature sources and archive seismogram analysis from Borovoye Geophysical Observatory. Treated PNEs seismograms have been available to researchers since 2001. They became available after the cooperation between Russian and U.S. organizations. The first one was the Institute of Geosphere Dynamics of the Russian Academy of Sciences (IDG RAS), the organization that operated the Observatory in the Soviet era. The second one was the National Nuclear Center of the Republic of Kazakhstan (NNC since 1992). The third one, from the U.S. side, was the LamontDoherty Earth Observatory of Columbia University (LDEO). We present two digital seismograms of old-style seismograms from a digitized archive in ASCII format. We provide travel times for P-waves, some seismograms, and additional source parameters. Dataset License: license CC BY-NC.

In the given work the new velocity model of the central part of the East European craton is presented. To achieve this goal six broadband seismic stations were installed along the profile about 500 km long. To recall the velocity structure, the receiver function technique has been used. For the inversion we used Levenberg - Marquardt algorithm for both P-to-S and S-to-P converted waves along with the travel times discrepancy of the transition zone 410-660 km. Preliminary processing of the velocity sections made it possible to investigate the inner velocity structure along a sublatitudinal profile from the marginal zone of the Sarmatia microcontinent through the multidirectional collision zones, to the marginal zone of the Volga-Uralia microcontinent. The structure of the collision zones, which was investigated at the “Aleksandrovka”, “Mikhnevo”, “Obninsk” and “Voskresensk” observation points, may be associated with the Proterozoic tectonic processing and upward movements of the mantle plumes. The marginal zone of the microcontinent Volga-Uralia belong to the region of the partially reworked Archean crust and were studied at the observation point “Shatura”. The deep structure of the Tokmovskiy ovoid of the Volga-Uralia microcontinent was investigated in the “Monakovo” registration point. In the velocity sections, the complex transition crust-upper mantle zone is clearly distinguished, which is a combination of the boundaries of Moho, corresponding to the various tectono-magmatic stages of the region. Revealed increased (relative to the reference model IASP91) velocities in the upper mantle are traced at all stations. A layer of lower velocities is observed in the depth range of 100–150 km.

The purpose of the present study is to examine the geomagnetic anomalies possibly linked with seismic activity. We analyzed the geomagnetic data recorded at the Mikhnevo Geophysical Observatory (54.959ºN, 37.766ºE) and INTERMAGNET Magnetic Observatories in order to discover anomalous geomagnetic variations associated with the high-magnitude earthquakes. The magnetic field variations were analyzed during seismic events that occurred in different regions with a magnitude greater than ~ 5. It was established that at the final stage of the preparation of the focus and with the main shock, magnetic field perturbations are recorded. At the same time, geomagnetic variations are manifested in two forms: Short-period, occurring within 5–15 min after the main shock and long-period, the beginning of which is recorded either immediately after the short-period, or 5 0 min before the main shock. For shallow focus earthquakes we observed both short-period (period of ~ 0.5 − 0.8 min) and long-period (period of ~ 5–20 min) geomagnetic disturbances. The maximum geomagnetic anomaly amplitude is 1.5 – 2 nT for short-period variations and 2 4 nT for long-period variations. For deep focus earthquakes we observed only long-period geomagnetic disturbances. Observations of the local variations in the geomagnetic field have afforded us some evidence that the observed geomagnetic anomalies are linked with the high-magnitude seismic events.

Study of the hydrogeological response to remote earthquakes is a separate scientific direction at the boundary of hydrogeology and geophysics. It’s necessary for understanding hydrogeomechanical processes occurring in fluid-saturated reservoirs. Spectral analysis is a convenient tool for estimation the relation between underground water level variations and ground displacement during passage of seismic waves from remote earthquakes. Water level variations can be classified as step-like, co-seismic and post-seismic changes. Different types of water level response manifest themselves in different ways in the high-and low-frequency ranges. This paper reviews water level responses to remote earthquakes (epicentral distances of more than 1800 km), that were recorded at Mikhnevo Geophysical Observatory under the platform conditions. Hydrogeological responses in the high-frequency range to seismic impact were recorded predominantly. Water level response in the low-frequency range was detected for a few events. Of greatest interest are hydrogeological responses to Wenchuan 05.05.2008 M8.0, Tohoku 11.03.2011 M9.1, Chile 02.27.2010 M8.8, and 09.16.2015 M8.3 earthquakes, which do not fit into the general pattern. For them lower values of the peak ground velocity in the low-frequency range correspond to higher values of the water level amplitudes. Such a discrepancy between the intensity of the water level changes and the ground velocity in the low-frequency range can be used for typifying of hydrogeological responses and may indicate a local change in the microstructure of the fluid-saturated reservoir.

The objective of this research is to analyze the multifractal behavior of geomagnetic field corresponding to the well-known 27-day variation (solar rotation period) and its harmonics and the 1-day (solar diurnal) periodicities. We discuss the multifractal behavior of geomagnetic variations recorded at the middle latitude stations, using wavelet transform modulus maxima (WTMM). The WTMM is capable of partitioning the time and scale domain of a signal into fractal dimension regions, and the method is sometimes referred to as a "mathematical microscope" due to its ability to inspect the multi-scale dimensional characteristics of a signal and possibly inform about the sources of these characteristics. WTMM provides an understanding of the multifractal scaling behavior of a signal using the multifractal singularity spectra and the generalized Hurst exponents as diagnostic tools. In this research it is established that the 1-day period exhibits monofractal behavior regardless of the solar activity. Results indicate that except for the 1-day period, the geomagnetic variations at all other periods shows a higher degree of multifractality during solar maximum compared to solar minimum

The ML 6.1 earthquake that occurred on June 18, 2013 in Kuzbass is the strongest seismic event related to mining operations in this region. Opinions about its genesis differ. On the one hand, its hypocenter and most aftershocks occurred directly underneath the Bachat open-pit mine, which suggests that this seismic event was due to anthropogenic impacts. On the other hand, the earthquake focus was located at a depth of several kilometers, which, according to some authors, argues against the anthropogenic factor – the technogenic change in the parameters of the stress field was insignificant against the lithostatic pressure and, especially, the rock strength (e.g. [Lovchikov, 2016]). Our study aims to discover and assess an impact of the mining operations in the near-surface areas of the crust, investigate whether the Bachat earthquake was caused by the mining operations, and clarify which processes in particular were the most probable triggers of dynamic movement in the Bachat earthquake source. The probable geometrical parameters of the fault plane were estimated from the structural and tectonic conditions of the study area and the published locations of the aftershocks [Emanov et al., 2017]. It is established that seimic events of magnitudes similar to that of the Bachat earthquake cannot be caused by the overall anthropogenic load on the area, and it is unlikely that such a strong earthquake may occur due to the direct effects of seismic vibrations resulting from mass explosions during the mining operations. Our analytical models and numerical simulations, as well as the analysis of seismological observation data show that the most probable factor that initiated dynamic movements in the earthquake source was the extraction of the huge rock volume and its transportation from the Bachat open-pit mine. It should be noted that the size of the zone, wherein the geomechanical initiation criteria are met, is considerably larger than the critical size of a nucleation zone for a M 6 earthquake. However, open-pit mining operations can hardly affect the localization of strong earthquake sources. Mining operations can only trigger a seismic event that has been already prepared by the natural evolution of the crust.

The airburst events at Chelyabinsk and Tunguska in Russia are the best-documented asteroid impacts of recent times. Models that assess the potential danger from such events rely on an accurate picture of their aftermath. Here, we re-examine the most critical eyewitness accounts of the Tunguska airburst, namely those that describe injuries and casualties, and those that paint a picture of what events were responsible. Not all relevant information has survived in the written record and there are contradictions that create some ambiguity. We find that inside and near the tree-fall area were at least 30 people. Many lost consciousness and at least 3 passed away (immediately or later) as a direct consequence of the Tunguska event. The airburst created a butterfly-shaped pattern of glass damage extending 4–5 times wider than that seen at Chelyabinsk. At these larger distances, any injuries from falls, shattering glass cuts, or from UV radiation exposure were not reported.

Plumes produced by the impacts of asteroids and comets consist of rock vapor and heated air. They emit visible light, ultraviolet, and infrared radiation, which can greatly affect the environment. We have carried out numerical simulations of the impacts of stony and cometary bodies with a diameter of 0.3, 1, and 3 km, which enter the atmosphere at various angles, using a hydrodynamic model supplemented by radiation transfer. We assumed that the cosmic object has no strength, and deforms, fragments, and vaporizes in the atmosphere. After the impact on the ground, the formation of craters and plumes was simulated, taking the internal friction of destroyed rocks and the trail formed in the atmosphere into account. The equation of radiative transfer, added to the equations of gas dynamics, was used in the approximation of radiative heat conduction or, if the Rosseland optical depth of a radiating volume of gas and vapor was less than unity, in the volume-emission approximation. We used temperature and density distributions obtained in these simulations to calculate radiation fluxes on the Earth's surface by integrating the equation of radiative transfer along rays passing through a luminous region. We used tables of the equation of state of dunite and quartz (for stony impactors and a target) and air, as well as tables of absorption coefficients of air, vapor of ordinary chondrite, and vapor of cometary material. We have calculated the radiation impulse on the ground and the impact radiation efficiency (a ratio of thermal radiation energy incident on the ground to the kinetic energy of a body), which ranges from ~0.5% to ~9%, depending on the impactor size and the angle of entry into the atmosphere. Direct thermal radiation from fireballs and impact plumes, poses a great danger to people, animals, plants, and economic objects. After the impacts of asteroids at a speed of 20 km s−1 at an angle of 45°, a fire can occur at a distance of 250 km if the asteroid has a diameter of 0.3 km, and at a distance of 2000 km if the diameter is 3 km.

The results of numerical modeling of meteoroids' interaction with Earth's atmosphere are presented. We model the entry in two dimensions and then interpolate the results into a 3-D model to calculate interaction of shock waves with the surface. Maximum shock pressures, wind speeds, and areas subjected to substantial overpressure are calculated for oblique impacts of asteroids and comets. We show that vertical impacts produce a smaller damage zone on the surface than oblique ones. Damage caused by shock waves covers an order of magnitude larger area than any other hazardous effects. The function of energy release in the atmosphere, which is traditionally used in meteoritics, has a limited application if cosmic bodies are larger than tens of meters in diameter: at each time moment energy is smoothed along a substantial length of the trajectory; both emitted radiation (routinely used for calibration of semi-analytical models) and shock wave amplitude are complex functions of temperature–density distributions in atmosphere.

The location of earthquake epicenters in the central and northern parts of the East European Platform in 2009-2016 has been analyzed. The earthquake epicenters have been recorded by seismic stations of the Geophysical Survey of the Russian Academy of Sciences and using the Mikhnevo Small-Aperture Array of the Institute of Geosphere Dynamics, Russian Academy of Sciences. The results obtained are indirectly indicative of the seismic activity of the regional Riphean structures complicating the foundation surface and of their possible activation at present. The available data on the historical earthquakes also confirm their confinement to paleorifts. It seems appropriate to take into account the position of ancient aulacogens in assessing the seismic hazard of the East European Platform.

The subject of research is dynamic slips on large faults initiated by man-made impacts. In addition to recognized types of man-made impacts such as fluid injection or seismic vibrations, the possible trigger effect of rock extraction and displacement during mining operations is considered. It is shown that dynamic sliding can be initiated only on faults in which three geomechanical conditions for the occurrence of instability are fulfilled: closeness of the value of Coulomb stresses in the fault plane to the local ultimate tensile strength; the condition of weakening of frictional contact with an increasing sliding velocity and relative movement of fault sides; and the implementation of a certain ratio between the stiffness of the enclosing massif and the rate of reduction of resistance to friction. Features of formation of a dynamic slip on a fault are considered in the series of laboratory and numerical experiments. It is shown that the movement always begins in the segment with the property of velocity weakening, regardless of the location of such a segment relative to the load application. According to the calculations, the excavation of rock in a large mining quarry leads to a change of about 1 MPa in the Coulomb stresses in the fault plane in areas that significantly exceed the size of the nucleation zone of earthquakes with M <= 6. This may turn out to be sufficient to initiate seismogenic slips on stressed faults.

The measurement data on seismic load parameters induced by massive blasting carried out in surface and underground mines are presented. The maximum amplitude of seismic vibrations at the probable depth of potential sources of high-magnitude stimulated-tectonic earthquakes is calculated. These estimates and their comparison with the precision deformography observations show that residual displacements along faults at seismic depths under the impact of massive blasts in surface mines are not more than dens-hundreds microns. The seismic data demonstrate insufficiency of these impacts for initiation of high-magnitude earthquakes

The new method is proposed for interpreting data of acoustic emission during initiation and growth of dynamic breakaways. The method is based on the analysis of wave form of the emitted acoustic pulses. Clustering of the pulses by the wave form criterion shows that in the localization zone of strains different-scale processes described with various scaling relations take place. All classes of acoustic pulses obey the power-series amplitude-frequency distribution. The sharp-arrival acoustic pulses posses unaltered scaling relations in the period of nucleation and growth of dynamic breakaways whereas the smooth-arrival pulses demonstrate the nonlinear change in the scaling relations. At the final stage of the dynamic breakaway formation, the proportion and amplitude of acoustic pulses with smooth arrival increase.

Рассматривается применение методов и средств адаптивной оптики в задаче уничтожения космического мусора излучением мощного лазера наземного базирования. Атмосферная турбулентность и аэрозольные частицы, присутствующие в атмосфере Земли, ухудшают качество излучения, достигающего космического мусора. Адаптивная оптическая система, интегрированная с мощным лазером, вносит предискажения в волновой фронт лазера, способствуя концентрации большей мощности на фрагментах космического мусора. В данной статье акцент делается на обеспечение частотных характеристик адаптивной оптической системы.

Оцениваются количество, масса и динамика популяции мелкого космического мусора в низкоорбитальной области, а также последствия (с точки зрения прогрессирующего продолжения засорения космоса) реализации планов развёртывания здесь многоаппаратных коммуникационных космических систем. Последнее делает исследование этой области особенно актуальным. Рассматриваются различные аспекты последствий техногенного засорения околоземного космоса, особенности опасности со стороны мелкого космического мусора для космической деятельности и экологии Земли и околоземного пространства в сравнении с опасностью со стороны крупного мусора. Отмечается существенный недостаток полных и надёжных сведений о мелком космическом мусоре из-за дефицита средств, способных его наблюдать.

Для решения различных инженерных задач часто требуется регистрация сигналов в диапазоне 0.1-2000 Гц. Нижняя граница этого диапазона выходит за пределы рабочей полосы геофонов. В данной работе рассмотрено расширение частотных характеристик геофона двумя способами: путем перемножения передаточных функций и путем введения отрицательного сопротивления. Оценены пределы применимости этих методов. Верхний предел скорости, регистрируемой геофоном, определяется зазором, в котором катушка смещается относительно рамки датчика. Нижний предел зависит от общего инструментального шума измерительного канала, основной вклад в который вносят броуновский шум механической колебательной системы и шум измерительной схемы. Прототип устройства был построен на основе перемножения передаточных функций. С помощью лабораторных измерений на вибрационном столе и записей микросейсмического шума было показано, что модифицированный геофон работает как датчик скорости с собственной частотой 2 Гц. Это значение зависит от микросейсмических условий места размещения измерительной системы. При регистрации сейсмичности с помощью модифицированного геофона удалось зарегистрировать массовые взрывы в камерах шахты и карьерные взрывы в диапазоне частот до 2 Гц. Таким образом, проведенные исследования позволяют сделать вывод, что модифицированный геофон можно использовать для мониторинга локальной и региональной сейсмичности в качестве аналога короткопериодных сейсмометров.

Надежный прогноз распространения трещин в ходе гидравлического разрыва пласта (ГРП) в нетрадиционных коллекторах является сложной задачей, которая требует изучения механических параметров, микроструктуры, упругих и прочностных характеристик горных пород. Цель данной работы заключается в исследовании механических параметров коллекторов в микромасштабе и оценке условий, которые необходимо создать в нетрадиционных коллекторах для получения разветвленной сети трещин. Создание такой сети трещин позволяет повысить эффективность воздействия на пласт и обеспечить добычу из изолированных ранее пор. Для достижения цели предложен метод, включающий подготовку набора данных, содержащих петрофизические и геомеханические характеристики и сведения о минеральном составе, подготовку и инициализацию двумерных и трехмерных микромасштабных цифровых моделей горных пород, численное моделирование их напряженно-деформированного состояния и распространения в них трещин. В статье проводятся результаты экспериментальных исследований по определению механических параметров образцов горных пород, компьютерной томографии (3D КТ) до и после образования трещин, сканирования электронным микроскопом (2D QEMSCAN) и определения минерального состава горных пород. Выполнены мультимодальная сегментация и обработка данных 2D QEMSCAN и 3D micro-CT для построения трехмерных цифровых моделей горных пород. Затем на трехмерной сегментированной цифровой модели породы построена расчетная сетка, которая была загружена в механический симулятор, где матрице породы были присвоены определенные ранее механические свойства. В результате численного моделирования определено напряженно-деформированное состояние горных пород для различных условий нагружения и выбраны условия, при которых происходит наибольшее трещинообразование. Приведен пример использования предложенного метода для исследования наиболее перспективного российского нетрадиционного газового коллектора с размером пор до десятков нанометров.

В отличие от влияния крупного космического мусора влияние мелкого на космическую деятельность и экологию Земли и околоземного пространства часто недооценивают. В статье показано, что это несправедливо. По данным из различных источников оцениваются количество, масса и динамика популяции мелкого космического мусора в низкоорбитальной области и его опасность для космической деятельности, а также последствия (с точки зрения прогрессирующего засорения космоса) реализации планов развертывания в низкоорбитальной области многоаппаратных коммуникационных космических систем. Последнее придает исследованию этой области особенную актуальность. Рассматриваются различные аспекты последствий техногенного засорения околоземного космоса, особенности опасности со стороны мелкого космического мусора для космической деятельности и экологии Земли и околоземного пространства в сравнении с опасностью со стороны крупного мусора. Отмечается существенный недостаток полных и надежных сведений о мелком космическом мусоре из-за дефицита средств, способных его наблюдать.

The study of the impact of ionospheric disturbances on the conditions of functioning of satellite communication and navigation systems and the development of methods to reduce this effect requires the development of methods for evaluating the parameters of ionospheric disturbances and their spatial and temporal distribution. Studies show that electron concentration disturbances, which can have a significant impact on the functioning of transionospheric radio channels, can occur both in the upper and lower ionosphere. At the same time, the methods of studying the dynamics of ionospheric disturbances in the lower ionosphere are not enough developed, and the interrelation of the lower and upper perturbations of the ionosphere is insufficiently studied. The aim of the work is an experimental study of disturbances of the upper and lower ionosphere in order to clarify the mechanisms of their relationship and study the spatiotemporal distribution of mid-latitude disturbances. The results obtained show that the contribution of the electron density disturbances in the D region to the total electron content of the ionosphere can be significant and considerably depends on the type of heliogeophysical processes.

Meteoroids are most easily studied using the atmosphere as a detector. Under the right conditions, the passage of the meteoroid through the atmosphere may result in a meteorite falling to Earth or even the formation of an impact crater, but in most cases only the luminosity and ionization are available for analysis. Therefore, meteoroid properties (physical, chemical and all other possible properties) need to be determined through observations. The most obvious way to evaluate meteoroid properties is to apply a model to fit the observational data. Due to the variety of physical conditions that occur during the entry of meteoroids into the atmosphere, modelling efforts require the use of a wide range of different models- from sputtering of the surface under direct impacts of particles up to high-fidelity gasdynamical modelling. When starting to analyze observational data or to describe any physical phenomenon connected with meteors and bolides, one needs to understand clearly in what conditions this phenomenon is occurring and what physical processes need to be taken into account. This chapter reviews current entry models and discusses their boundaries and limitations.

We analyze the geomagnetic effect caused by the strong earthquakes using the data from the Geophysical Observatory "Mikhnevo" (MHV) of Institute of Geosphere Dynamics of Russian Academy of Sciences (IDG RAS) and from a number of observatories of the international INTERMAGNET network. It is shown that seismic events are accompanied by characteristic variations in the Earth's magnetic field. These induced geomagnetic variations contain a clearly pronounced short-period component with a period of similar to 0.5-0.8 min which is recorded during shallow earthquakes and a long-period component (similar to 5-20 min) observed in the most cases. The maximum amplitudes of the induced geomagnetic variations are similar to 1.5-5 and similar to 2-20 nT for the short-period and long-period components, respectively. It is noted that the induced geomagnetic perturbations recorded by the observatories at significantly different distances from the source of the earthquake feature almost simultaneous and morphologically similar behavior.

Presented are the results of laboratory experiments on investigating manifestations of acoustic emission (AE) of a gouge-filled fault during stick-slip. The laboratory experiments were held at the slider-model setup, when a granite block slides along a rough granite base under normal and shear loads. In the course of experiments we altered the structure of the two-component filler of the fault and focused on variations of the AE parameters. The kinematic parameters of fault slip events in all the realizations remained approximately the same. The effect of gouge structure on the statistics of AE has been revealed. An alteration of proportion of quartz sand / glass beads in the filler of the fault was accompanied by an alteration of the b-value of frequency-energy distribution from 0.53 to 0.85, and the p-value of Omori law from 1.00 to 2.06. Also, it has been demonstrated that the nucleation of a slip event is accompanied by an alteration of the mechanism of AE generation – at the initial stage the ‘tensile crack’ signals prevailed, while at the final stage – the ‘shear crack’ signals did. The alteration of AE genesis manifested vividly in a corresponding alteration of the emitted waveforms for all the realizations.

Several variants of rate-state equations were considered in application to description of laboratory data on block sliding under normal and shear stresses. Both acoustic emission and stick-slip motion of the block were registered and considered as an analog of ordinary and slow earthquakes. Various types of fluids were added to the filler between the moving and stationary blocks. Obtained results on the block sliding were compared with numerical simulations which were conducted using several variants of the rate-state equations, and the best matching model was chosen for further study. With the help of that model, the seismic activity induced by fluid injection during Basel project was simulated. It was shown, that some long-term aftereffects of the fluid injection can be explained by specific value of the interblock stiffness related to the surround rock stiffness.

An important new paper by Kurosawa and Genda (2017, https://doi.org/10.1002/2017GL076285) reports a previously overlooked source of heating in low velocity meteorite impacts. Plastic deformation of the pressure-strengthened rocks behind the shock front dissipates energy, which appears as heat in addition to that generated across the shock wave itself. This heat source has surprisingly escaped explicit attention for decades: First, because it is minimized in the geometry typically chosen for laboratory experiments; and second because it is most important in rocks, and less so for the metals usually used in experiments. Nevertheless, modern numerical computer codes that include strength do compute this heating correctly. This raises the philosophical question of whether we can claim to understand some process just because our computer codes compute the results correctly

The research of Earth's physical fields and their variations is particularly important to establish causes and mechanisms of changes in the environment and in the climate. The results of the analysis of instrumental observation concerning the variations in electric and magnetic fields, as well as acoustic vibrations in the near-surface Earth zone are considered in relation to the variations of meteorological parameters. We used the results of synchronous observations concerning physical fields carried out in the period of 2011-2014 in conductions of Geophysical observatory "Mikhnevo" of Institute of Geosphere Dynamics of Russian Academy of Science (IDG RAS) (Russia, Moscow region, settlement Mikhnevo; 54.959 degrees N, 37.766 degrees E). Synchronism of the variations of mentioned geophysical fields and change in atmospheric parameters has been determined, and for the first time not only synchronous, but advanced manifestations of geomagnetic field perturbations are shown, we introduce a new parameter - "reverse" magnetic tipper, variations of which due to atmospheric disturbances are more strongly marked in comparison with the variations of magnetic tipper.

In this paper we present the results of the laboratory experiment aimed at the research of the hydraulic fracture propagation rate. The laboratory experiment was carried out according to similarity criteria. The fracture growth rate was determined by one direct method and two indirect methods. The direct method was based on registering the formation of the fracture by conductive strips. The first indirect method was based on the variations of the pressure in the well. The second one was based on a numerical solution of the problem of hydraulic fracture propagation.

We consider the main factors that affect underground water flow including aquifer supply, collector state, and distant earthquakes seismic waves’ passage. In geodynamically stable conditions underground inflow change can significantly distort hydrogeological response to Earth tides, which leads to the incorrect estimation of phase shift between tidal harmonics of ground displacement and water level variations in a wellbore. Besides an original approach to phase shift estimation that allows us to get one value per day for the semidiurnal M2 wave, we offer the empirical method of excluding periods of time that are strongly affected by high inflow. In spite of rather strong ground motion during earthquake waves’ passage, we did not observe corresponding phase shift change against the background on significant recurrent variations due to fluctuating inflow influence. Though inflow variations do not look like the only important parameter that must be taken into consideration while performing phase shift analysis, permeability estimation is not adequate without correction based on background alternations of aquifer parameters due to natural and anthropogenic reasons.

The article is devoted to the problem of estimating the coordinates of micro-seismic sources (localizing the sources) using multichannel data recorded by a surface seismic array. A new statistical algorithm is proposed for the source localization, which is mainly based on the phases of the Discrete Finite Fourier Transforms of the array sensor seismograms. This algorithm was constructed using the Maximum Likelihood concept under the following constraints: (a) noise components of the array seismograms are statistically independent stationary Gaussian processes with different power spectral densities; (b) the signal-to-noise ratios in the array seismograms are small, but the duration of signals generated by a micro-seismic source in the sensors is quite large; (c) the time function of a micro-seismic source can be approximated by a stationary Gaussian random process. The asymptotic probability density function was obtained in the paper for the phase differences of two Gaussian stationary random time series. This function provided a theoretical basis for constructing the new statistical phase algorithm. The algorithm requires evaluation of the coherence functions for all pairs of the sensor seismograms. For this reason, it inquires more calculations for the source localization than the known phase algorithms. But Monte Carlo simulation has shown that the new phase algorithm provides a more accurate estimation of micro-seismic source coordinates compared to the most popular phase algorithm.

The space rocket launch malfunctions frequency has been analyzed depending on the level and the phase of solar activity cycle and the season of year. Comparative analysis of the temporal variations of the relative number of failed launches in Russian Federation and the United states has been conducted. It was stated that those variations were anti-persistent. It was shown that for the phase of rise of solar activity the relative amount of failed launches both in Russian Federation and the United states exceeds the similar values for that of its decline. However, an explicit dependence between solar activity and the amount of failed launches is not observed.

Permeability is one of the fundamental properties of porous media and is required for large-scale Darcian fluid flow and mass transport models. Whilst permeability can be measured directly at a range of scales, there are increasing opportunities to evaluate permeability from pore-scale fluid flow simulations. We introduce the free software Finite-Difference Method Stokes Solver (FDMSS) that solves Stokes equation using a finite-difference method (FDM) directly on voxelized 3D pore geometries (i.e. without meshing). Based on explicit convergence studies, validation on sphere packings with analytically known permeabilities, and comparison against lattice-Boltzmann and other published FDM studies, we conclude that FDMSS provides a computationally efficient and accurate basis for single-phase pore-scale flow simulations. By implementing an efficient parallelization and code optimization scheme, permeability inferences can now be made from 3D images of up to 109 voxels using modern desktop computers. Case studies demonstrate the broad applicability of the FDMSS software for both natural and artificial porous media.

We carried out numerical modeling of impacts of asteroids and icy bodies with a diameter from 30 m to 100 m and calculated radiation fluxes on the ground, luminous efficiencies and areas of potential fire. The integral luminous efficiency of impactors with a diameter of 30 m entering the atmosphere at acute angles can reach 20 and 40% for stony and icy bodies respectively, and the impacts of 100-m asteroids can initiate forest fires in areas with dimensions of 100 km.

Soil structure defines major physical properties and biophysical functions of soils. Imaging soil structure using different 2/3D techniques is a routine methodology used by soil scientists. Still, for structured soils their spatial variability and hierarchical structure imposes a significant challenge for all imaging methods in terms of field-of-view and resolution trade-off. While creating a truly multiscale 3D digital model of soil is without question of utmost importance, there is currently no single imaging method that could potentially encompass all necessary relevant soil scales within a single image. In this paper, we tested for the first time an image fusion technique to produce a multiscale soil image based on separate images obtained with different spatial resolutions. The method is based on universal soil structure descriptors, i.e. spatial correlation functions, which were shown to be very useful in soil applications. Using a relatively simple 2D test case based on X-ray tomography (XCT) images at three different scales, we show the applicability of image fusion for soil images and solve a long standing problem of imaging resolution. In total we fused seven images into a single image: one 114 μm resolution macroscale XCT image (porosity <0.01), four 15 μm resolution microscale XCT images (with porosities 0.039–0.049), and two 3.3 μm resolution microscale XCT images (with porosities of 0.24 and 0.76). The resulting single, 15 μm resolution image represented 6 × 6 cm2 of soil structure. Its porosity increased from <0.01 to 0.073 due to representation of all pore sizes visible on the images prior to fusion. Current drawbacks of the approach are discussed and an outline is provided of its future usage to address important soil structure issues.

Impact melt flows are observed within the continuous and discontinuous ejecta blanket of the 9 km lunar crater Pierazzo, from the crater rim to more than 40 km away from the center of the crater. Our mapping, fractal analysis, and thermal modeling suggest that melt can be emplaced ballistically and, upon landing, can become separated from solid ejecta to form the observed flow features. Our analysis is based on the identification of established melt morphology for these in-ejecta flows and supported by fractal analysis and thermal modeling. We computed the fractal dimension for the flow boundaries and found values of D = 1.05–1.17. These are consistent with terrestrial basaltic lava flows (D = 1.06–1.2) and established lunar impact melt flows (D = 1.06–1.18), but inconsistent with lunar dry granular flows (D = 1.31–1.34). Melt flows within discontinuous ejecta deposits are noted within just 1.5% of the mapping area, suggesting that the surface expression of impact melt in the extended ejecta around craters of this size is rare, most likely due to the efficient mixing of melts with solid ejecta and local target rocks. However, if the ejected fragments (both, molten and solid) are large enough, segregation of melt and its consequent flow is possible. As most of the flows mapped in this work occur on crater-facing slopes, the development of defined melt flows within ejecta deposits might be facilitated by high crater-facing topography restricting the flow of ejecta soon after it makes ground contact, limiting the quenching of molten ejecta through turbulent mixing with solid debris. Our study confirms the idea that impact melt can travel far beyond the continuous ejecta blanket, adding to the lunar regolith over an extensive area.

The circumsolar disc was the birthplace of both planetesimals and giant planets, yet the details of their formation histories are as elusive as they are important to understand the origins of the Solar System. For decades the limited thickness of Vesta's basaltic crust, revealed by the link between the asteroid and the howardite-eucrite-diogenite family of meteorites, and its survival to collisional erosion offered an important constraint for the study of these processes. Some results of the Dawn mission, however, cast doubts on our understanding of Vesta's interior composition and of the characteristics of its basaltic crust, weakening this classical constraint. In this work we investigate the late accretion and erosion experienced by Vesta's crust after its differentiation and recorded in the composition of eucrites and diogenites and show that it offers an astrochemical window into the earliest evolution of the Solar System. In our proof-of-concept case study focusing on the late accretion and erosion of Vesta's crust during the growth and migration of Jupiter, the water enrichment of eucrites appears to be a sensitive function of Jupiter's migration while the enrichment in highly-siderophile elements of diogenites appears to be particularly sensitive to the size-frequency distribution of the planetesimals. The picture depicted by the enrichments created by late accretion in eucrites and diogenites is not qualitatively affected by the uncertainty on the primordial mass of Vesta. Crustal erosion, instead, is more significantly affected by said uncertainty and Vesta's crust survival appears to be mainly useful to study violent collisional scenarios where highly energetic impacts can strip significant amounts of vestan material while limitedly contributing to Vesta's late accretion. While our proof-of-concept case study is based on a simplified physical model and explores only a limited set of scenarios, our results suggest that the astrochemical record of the late accretion and erosion of Vesta's crust provided by eucrites and diogenites can be used as a tool to investigate any process or scenario associated to the evolution of primordial Vesta and of the early Solar System.

We use Kaguya MI images acquired at wavelengths 415, 750, and 950 nm to map TiO2 and FeO content and the parameter of optical maturity OMAT in lunar regions Lubiniezky E and Taurus-Littrow with a spatial resolution of 20 m using the Lucey method [Lucey et al., JGR 2000, 105. 20,297]. We show that some ejecta from large craters, such as Tycho and Copernicus may cause lunar surface erosion, transportation of the eroded material and its sedimentation. The traces of the erosion resemble wind tails observed on Earth, Mars, and Venus, although the Moon has no atmosphere. The highland material of the local topographic prominences could be mobilized by Tycho's granolometrically fine ejecta and caused by its transportation along the ejecta way to adjacent mare areas and subsequent deposition. The tails of mobilized material reveal lower abundances of Ti and Fe than the surrounding mare surface. We have concluded that high-Ti streaks also seen in the Lubiniezky E site, which show unusual combinations of the TiO2 and FeO content on the correlation diagram, could be the result of erosion by Tycho's ejecta too. In these locations, Tycho's material did not form a consolidated deposit, but resulted in erosion of the mare surface material that became intermixed, consequently, diluting the ejecta. The Taurus-Littrow did provide evidence of the mechanical effect of Tycho's ejecta on the local landforms (landslide, secondary craters) and do not show the compositional signature of Tycho's ejecta probably due to intermixing with local materials and dilution.

The ∼20-m sized asteroid that entered the Earth's atmosphere at 19 km/s over the Chelyabinsk Region of Russia on February 15, 2013, broke and deposited ∼500 kt of kinetic energy at 45–25 km altitude, causing an airburst strong enough to create widespread glass damage. The shockwave hit a densely populated area. More than a thousand people asked for medical assistance at hospitals. In this paper, we analyze the available information about how many and what type of injuries were sustained. We combine previously collected data from government reports and from phone and internet surveys shortly after the event with newly collected data from local hospitals. As expected, the percentage of injuries was highest near the asteroid trajectory, but surprisingly the type of injury (cuts or bruises) do not show dependence on the distance from the asteroid trajectory. Results are compared to asteroid impact risk assessment models. The results provide insight for first responders in future asteroid impacts and help to rеfine these models.

This paper presents an analysis of the development of the current seismic state of the Kuznetsk coal basin, which is characterized by an increase in technogenic seismicity of different types under the influence of prolonged intensive mining operations. The development of technogenesis led to a significant increase in technogenic seismicity in the Kuznetsk Basin in the 1970-1980s, when the number of technogenic earthquakes began to exceed the number of natural earthquakes. Among the various types of induced seismicity, special attention is paid to strong technogenic tectonic earthquakes with a regional magnitude M-b > 3 and, accordingly, a seismic energy release of more than 10(9) J, i.e., earthquakes of energy class K > 9. These small-focus earthquakes are often accompanied by destruction of underground mines, collapse of quarries and pits, damage to surface facilities and equipment, and other adverse effects. In this paper, such earthquakes are defined as technogenic tectonic to emphasize their dual origin: technogenic impacts and the subsequent relaxation of tectonic stresses. It is also noted that the Earth's interior in Kuzbass initially had its own natural seismicity and a developed system of tectonic faults. Natural seismotectonic activity combined with constantly increasing scales of mining and explosive consumption has led to an increase in the number of technogenic seismic events and their intensity. A striking example of such an event was the 18 June, 2013 Bachat earthquake with a regional magnitude M-b = 5.8 and a seismic intensity of 7 in the epicentral zone. It was the world's largest man-made earthquake induced by the mining of solid minerals. We consider the possible causes of this catastrophic earthquake and discuss the conditions favoring the formation of foci of such technogenic tectonic earthquakes resulting from changes in the geodynamic and hydrogeological conditions in the Earth's crust under man-caused impacts. These induced changes in natural processes are accompanied by a change in the stress-strain state, resulting in the concentration of tectonic stresses at heterogeneities and in fault zones, which become sources of induced technogenic seismicity. The paper discusses the current period of the occurrence and increase in such anthropogenic seismicity in the Kuzbass region with increasing scales of coal mining and blasting. Over the last 20 years, the consumption of explosives at Kuzbass enterprises increased from 100-200 to 500-600 thousand tons per year, and, accordingly, the amounts of broken and transported rock increased from several million tons per year to a billion tons per year, which disturbed the dynamic equilibrium in the Earthis crust and changed the existing field of tectonic stresses. Moreover, the continuously increasing consumption of explosives has also increased the technogenic impact on the crust structures. The location of the epicenters of large-scale blasts inducing seismic events with regional magnitudes M-b = 3.0-4.5 has made it possible to identify regions with the greatest technogenic impact in Kuzbass. Using the data of the ISC seismological catalog, we separated seismic events with the above magnitudes into day and night ones. Since blasting work is forbidden at night, night seismic events are referred to as technogenic tectonic earthquakes (night event criterion). The maximum magnitude of seismic events induced by blasting operations in the Kuznetsk Basin was estimated at M-b<4.4. The annual number of technogenic tectonic earthquakes with 3.04.5 was determined based on the night event criterion. The regions of their occurrence were identified from the location of the epicenters of technogenic tectonic earthquakes. (C) 2018, V.S. Sobolev IGM, Siberian Branch of the RAS.

The short-term forecast of earthquakes associated with fault rupture is a challenge in seismology and rock mechanics. The evolution of mechanical characteristics of a local fault segment may be encoded in the ambient noise, thus, converting the ambient noise to an efficient source of information about the fault stress-strain conditions. In laboratory experiments we investigate micro-vibrations of a block-fault system induced by weak external disturbances with the purpose of getting reliable evidence of how the system transits to the metastable state. We show that precursory changes of spectral characteristics of micro-vibrations are observed for the complete spectrum of failure modes. In the course of experiments we systematically change the properties of interface to perform the transition from stick-slip to steady sliding and observe the characteristics of micro-vibrations of the laboratory block-fault system. Detected were systematical alterations of the system natural frequency and those alterations were determined by the evolution of fault stiffness. The detected regularities suggest that the final stage of seismic event preparation can be revealed in analyzing the spectral characteristics of ambient noise. The detection of natural oscillations of a block-fault system can be a new useful tool to monitor active faults in real time.

In the mining process, fracture zones are subject to periodic explosions of considerable amplitude and duration that can lead to adverse consequences. For this reason, it is necessary to assess the possibility of a major seismic event even in tectonically quiet areas. This paper investigates the reaction of the fault zone that crosses the Korobkovo mineral deposit (Kursk Magnetic Anomaly, Russia) to periodic explosions during the annual mining process. Parametrization of mass explosions made it possible to identify regularities in the seismic activity of fault zones. The obtained results allow us to speak about the relatively stable state of the rock massif during the observation period.

Fault stiffness is an integral parameter sensitive to the change in the stress-strain state of the fault zones. In this paper we present a new method for stiffness estimation based on an analysis of the dynamic parameters of the microseismic ambient noise. Data processing is based on cross-correlation of seismic noise components and cross-spectral analysis in a sliding window. The deformation characteristics were studied at small aperture (less than 100 m) in the high frequency range (hundreds of Hz) at the section of the fault zone of the Korobkovskoye ore deposit. The analysis carried out made it possible to determine the propagation velocity and length of the surface waves under study, and estimate the stiffness of the fault from the obtained data.

A shear stiffness of a fault is significantly reduced when the local fault area (the earthquake preparation zone) changes to a metastable state. The transition to a metastable state is clearly manifested in laboratory experiments as a decrease of the frequency of natural oscillations, which can be found in the seismic noise spectrum. To study this effect in nature we chose the Chilean subduction zone. Our research shows that the effect of frequency decrease is detected before the megathrust earthquakes. For weaker earthquakes this effect is not stable and depends on many external factors. The obtained results form the basis of a new method for estimation the stress-strain state of the fault zones and the short-term earthquake prediction method.

Precision monitoring of the groundwater level has been carried out at the territory of the Mikhnevo geophysical observatory since 2008. Observations are conducted in two wells, which expose confined and unconfined aquifers. The paper considers the reaction of a fractured-pore reservoir to seismic waves from distant earthquakes. A comparative analysis of hydrogeological effects associated with the passage of seismic waves from distant earthquakes is performed in the high- and low-frequency ranges.

The paper presents the first results of a complex study of rock samples collected along a cross-section of a local discontinuity of the Primorsky fault of the Baikal rift zone. The study includes petrographic and mineralogical analyses and laboratory friction testing. The main objective of the study is to determine the correlation between the structural properties of rock samples at the micro- and mesolevels and their friction properties during shear deformation. Petrographic analysis of rock samples showed that the most intensive deformations are localized in a very narrow area, in which signs of dynamic impacts on minerals during tectonic movements are observed. In turn, the analysis of frictional properties of rock samples on the slider-model setup showed that their friction behavior significantly depends on the degree of dynamo-metamorphic rocks.

The results of small-scale (1m scale) field experiments involving a slider-model set up are presented. The experiments investigate the seismo-acoustic portrait of the process of preparation of dynamic events of different types. Regularities of radiation of elastic vibrations in the frequency band of 10 Hz to 80 kHz are studied. It is shown that radiation of elastic vibrations at frequencies less than 1 kHz takes place only at the moment of a large dynamic event, whereas high-frequency (>10 kHz) acoustic pulses are radiated during the entire seismic cycle. The analysis of alteration of seismo-acoustic pulse radiation in time in different frequency bands gives the new information about regularities of preparation of fault slip event at different scale levels.

The work is devoted to the study of rock fracture toughness importance for correct hydraulic fracturing simulations. The parameter characterizes the rock's ability to resist the fracture process. For numerical simulations of the fracture based on the postulates of the failure mechanics, the fracture toughness is one of the determining parameters along with the elastic properties of the rock and the injection conditions. The aim of the paper is to determine how much the fracture toughness affects the fracture length in the numerical model describing the laboratory experiments. The used laboratory setup made it possible to create conditions that determine the actual fracture process. The strength parameters of the model material were measured. In particular the fracture toughness was measured using indentation methods. Numerical model calibrated by the laboratory experiment was used to solve the postulated problem.

We consider the methods for modelling doughnut and super-Gaussian intensity distributions in the far field by means of deformable bimorph mirrors. A method for the rapid formation of a specified intensity distribution using a Shack - Hartmann sensor is proposed, and the results of the modelling of doughnut and super- Gaussian intensity distributions are presented.

Wavelet analysis is becoming more popular in geophysics. It is used for numerous researches, including tropical convection, the El Nino-Southern Oscillation, atmospheric cold fronts, temperature variations, the dispersion of ocean waves, and coherent structures in turbulent flows, number of sunspots etc. In this paper we research how informative is the application of wavelet analysis to the analysis of geomagnetic field variations at the mid-latitude observatory "Mikhnevo" of Institute of Geosphere Dynamics of Russian Academy of Science. We review continuous wavelet transform by focusing attention on such aspects as choice of mother wavelet, choice of scales, cone of influence, visualization of results, reconstruction of time series from wavelet transform and its application to estimate the Holder exponents and singularity spectra. In our work we use Morlet wavelet with frequency parameter of 6. In so doing, the reconstruction of the time series from the wavelet transform has a mean square error of 3.4%. The application of wavelet analysis made it possible to distinguish pronounced periodicities of the geomagnetic field with periods of 27, 13.5, 9, 6 days. In solar quiet-day variations is dominated by the 24- 12-, 8-, and 6-hour period components. An analysis of the modulus of the wavelet transform coefficients qualitatively indicates a scaling (close to the monofractal) character of the variations of the geomagnetic field in the diurnal range. Moreover, the intensity of periodic variations of geomagnetic variation isn't constant in time. The application of the method of wavelet transform modulus maxima confirmed the monofractal character of the diurnal variation for any solar activity. In contrast to the 1-day variation, the 27-day variation and its harmonics show a higher degree of multifractality during a maximum of solar activity in comparison with the minimum of solar activity.

Stochastic reconstructions based on universal correlation functions allow obtaining spatial structures based on limited input data or to fuse multiscale images from different sources. Current application of such techniques is severely hampered by the computational cost of the annealing optimization procedure. In this study we propose a novel hierarchical annealing method based on rescaled correlation functions, which improves both accuracy and computational efficiency of reconstructions while not suffering from disadvantages of existing speeding-up techniques. A significant order of magnitude gains in computational efficiency now allows us to add more correlation functions into consideration and, thus, to further improve the accuracy of the method. In addition, the method provides a robust multiscale framework to solve the universal upscaling or downscaling problem. The novel algorithm is extensively tested on binary (two-phase) microstructures of different genesis. In spite of significant improvements already in place, the current implementation of the hierarchical annealing method leaves significant room for additional accuracy and computational performance tweaks. As described here, (multiscale) stochastic reconstructions will find numerous applications in material and Earth sciences. Moreover, the proposed hierarchical approach can be readily applied to a wide spectrum of constrained optimization problems

Semipassive bimorph flexible mirrors is one of the most widely used devices for correction of the given laser beam intensity. However, the key disadvantage of these kind of mirrors is their low spatial resolution of the corrected phase. In this work, we present two approaches for increasing spatial resolution of the deformable mirrors - one to use a multilayer bimorph mirrors and another to put higher density of control electrodes and use ultrasonic welding to make the wire connection to these electrodes

Conventional high-power lasers suffer from the wavefront aberrations, that significantly decrease the radiation power during the employment of the laser complex. For compensation of the wavefront distortions and improving the quality metrics of the radiation adaptive optics approaches are used. The 121-elements and the 19-elements stacked-actuator deformable mirrors for these kind of applications were developed.

Efficiency of the laser beam focusing through the scattering medium with known concentration values was numerically investigated. We used the response functions of 3 kinds of bimorph deformable mirrors - with 14, 32 and 48 electrodes. The algorithm for numerical correction were programmed. The obtained results shown that 14 electrodes (2 rings) are not enough to compensate for the distortions, produced by the scattering medium with the given concentration values.

The ability to focus laser beam β = 0.65 nm), propagated through the scattering medium, was investigated both numerically and experimentally. Numerical estimations were performed with the Monte Carlo simulation and Shack-Hartmann technique. Experimental setup with the bimorph mirror as a laser beam corrector and two kinds of sensors as feedback devices - Shack-Hartmann sensor and far-field focal spot analyzer - was designed. Three kinds of correction algorithms were tested and compared to each other.

Images from Mars Global Surveyor and later images from Mars Reconnaissance Orbiter reveal that roughly half of the meteoroids striking Mars (at meter to few decameter crater diameters) fragment in the Martian atmosphere, producing small clusters of primary impact craters. Statistics of these “primary clusters” yield valuable information about important Martian phenomena and properties of interplanetary bodies, including meteoroid behavior in the Martian atmosphere, bulk strengths of bodies striking Mars, and the fraction of Martian “field secondary” craters, a datum that would improve crater count chronometry. Many Martian impactors fragment at altitudes significantly higher than 18 km above the mean surface of Mars, and we find that most bodies striking Mars and Earth have low bulk strengths, consistent with crumbly or highly fractured objects. Applying statistics of primary clusters at various elevations and independent diameter bins, we describe a technique to estimate the percentage of semirandomly scattered “field secondary” craters. Our provisional estimate of this percentage, in the diameter range ~250 m down to ~22 m, is ~40% to ~80% of the total impacts, with the higher percentages at smaller diameters. Our data argue against earlier suggestions of overwhelming dominance by either primaries or secondaries in this diameter range.

In this paper we consider two approaches widely used in testing of spherical optical surfaces: Fizeau interferometer and Shack-Hartmann wavefront sensor. Fizeau interferometer that is widely used in optical testing can be transformed to a device using Shack-Hartmann wavefront sensor, the alternative technique to check spherical optical components. We call this device Hartmannometer, and compare its features to those of Fizeau interferometer.

We investigated the ability to focus laser beam (λ = 0.65 nm), propagated through the scattering suspension of polystyrene microspheres in distilled water, by means of two bimorph mirrors. Shack-Hartmann sensor was used to measure the local slopes of the Poynting vector, and the CCD camera was used to measure the intensity of the focal spot in the far-field. Correction efficiency of the two bimorph deformable mirrors-with 14 and 31 control channels-were compared. Numerical and experimental investigation of the focusing improvement of the laser beam propagated through the scattering medium was performed.

The transformation of an intensity distribution from Gaussian to a flattop, doughnut, etc. still is a very interesting and important task. And the necessary result could be obtained with the use of adaptive optics that changes the phase of the beam and modifies the shape of the focal spot in the far-field zone. In this paper, we present the flattop and doughnut beam formation result with the use of a bimorph and stacked-actuator deformable mirrors as well as LC phase modulator. The experimental results are also given.

Formation and correction of the given laser beam intensity and phase is an important practical and scientific problem. Semipassive bimorph flexible mirror is one of the most widely used devices for this purpose. But the key disadvantage of these kind of mirrors is their low spatial resolution of the corrected phase. Mainly this problem occurs when one deals with the small aperture wavefront correctors. In this work we present two approaches to overcome this problem-one to use a multilayer bimorph (multimorph) mirrors and another to put higher density of control electrodes and use a special technique (ultrasonic welding) to make the wire connection to these electrodes. Here we also present a numerical model to simulate bimorph correctors, based on a variation approach of the finite elements method.

The process of remapping the intensity profile of a laser beam is presented. Bimorph deformable mirror was used to change the beam phase; the control signals for the mirror were calculated in accordance with both phase analysis and far-field intensity distribution measurements.

The correction of the laser beam aberrations and the formation of the laser beam intensity is very important scientific task. This problem widely is being decided at this moment. The employment of the bimorph deformable mirrors for this kind of applications is very promising. But this type of the wavefront correctors has one reasonable shortcoming - low spatial resolution of the control electrodes, it doesn't allow to compensate for the high-order wavefront aberrations. This kind of aberrations is valuable for imaging applications, mainly if needs to reconstruct specific details. Therefore, we have to use the wavefront correctors with high spatial resolution of the electrodes. In this work we present two types of the bimorph deformable mirrors for solving this problem - multilayer bimorph (multimorph) mirrors and bimorph mirrors with high density of the control electrodes. To place high number electrodes on the piezodisk the laser engraving technology was used, and ultrasonic welding technology used to make the wire connection to these electrodes. We developed the powerful numerical model to simulate bimorph mirrors.

The latest results on intensity distribution transformation from Gaussian to a flattop and doughnut are presented in the paper. The wavefront was modified with bimorph deformable mirror to reach the desired intensity distribution in the farfield. LC phase modulator was also considered as an alternative device for laser beam shaping. The theoretical calculations and experimental results of the efficiency of different types of wavefront correctors are given.

During propagation of the high-power laser radiation through atmosphere the quality of the beam is significantly reduced due to atmosphere turbulence. For compensation of the wavefront distortions and improving quality of radiation, as a rule, adaptive optics approaches are used. The design and main characteristics of 121-element water-cooled stacked-actuator deformable mirror for this kind of applications is discussed in this paper.

Fast adaptive optical system can be used, for example, for correction of laser beam passed through a strong turbulent atmosphere. The frequency that such a system should operate with to achieve an acceptable level of wavefront correction is about 1 - 1.5 kHz. There are two most popular methods to develop this system: by using a standard PC computer and by using FPGA. This paper presents the advantages and disadvantages of each of these approaches. The results obtained with the use of these systems are presented. Recommendation for achieving higher performance are given.

Laser beam focusing (λ = 0.65 μm) through the scattering suspension of polystyrene microspheres in distilled water was investigated. Shack-Hartmann sensor was used to measure the local slopes of the Poynting vector, the CCD camera was used to measure the far-field focal spot's intensity. Numerical and experimental investigations of focusing efficiency of the two bimorph deformable mirrors - with 14 and 48 control channels - were performed.

We present the full-scale observational data of the near-ground electric field potential gradient in the megacity area and outside of its influence zone. The megapolis influence is manifested in an increase of signal amplitudes which is associated with the aerosol particles concentration difference. The obtained data analysis allows the technogenic aerosol megacity pollution level estimation. It is proposed to use the ratio of the averaged electric field potential gradient amplitudes at measurement sites as an integral pollution level indicator. Analytical expressions reflecting the integral pollution level indicator and the near-ground layer aerosol particle concentration relation are obtained.

We present experimental results of the study of acoustic gravity waves and electric field generation during auroras. Vertical component of electric field in the atmosphere surface layer and atmosphere pressure were recorded during the field study. Analysis of the obtained data shows that synchronous variations of the pressure and electric field strength appear with the development of auroras. It is seen that the amplitude of electric field perturbations is approximately proportional to the amplitude of variation in the pressure.

Analysis of microbaric variations and variations of the electric field during atmosphere strong disturbances were carried out on the base of the data of instrumental registrations obtained in the geophysical observatory Mikhnevo of the Institute of Geospheres Dynamics of the Russian Academy of Sciences (IGD RAS). It is shown the hurricanes and storms are accompanied by high-amplitude variations of acoustic and electrical fields. Amplitudes of variations of these fields increase in a several hours before front arrival. This fact in the aggregate with meteorological parameters could be considered as a predicted indication of approaching hurricane or storms. It is determined that thundery front arrival is forestalled by long period electric field variations, internal gravity waves and increased acoustic impedance. Regularities, which were determined resulting from investigations, could be raise of forecast reliability and efficiency.

Given are results of analysis of data obtained by instrumental observations of infrasound vibrations performed in the area of Leninsky Avenue, Moscow. It was found that most intensive sources of infrasound are traffic lights and crossroads. Article illustrates difference in amplitude and spectral characteristics of infrasound depending on traffic flow regime. It contains date evidencing relation of infrasound noise with avenue load.

It describes new approach to assessment of energy sources of infrasound perturbations by spectrum of fluctuations in atmospheric pressure given stratigraphy of the atmosphere. It offers phenomenological model of spread of infrasound in standard atmosphere based on data of instrumental observations made during studying infrasound signals from powerful explosive atmospheric sources. There has been developed technique for assessment of energy which uses integral dependence of energy on power spectrum. Obtained results are consistent with known researches data.

Solar flare on September 6, 2017 was one of the strongest in recent years. The powerful X-ray and ultraviolet radiation of the flash caused significant effects in the upper and lower ionosphere, in the geomagnetic field and surface electric field. The interrelation and spatio-temporal distribution of geophysical disturbances induced up by the flare and their influence on the accuracy of positioning of global navigation satellite systems are shown.

The report analyzes the optical data received by the MSX satellite during Fluxus and North Star active rocket experiments, conducted in 1997 and 1999 on the injection of high-speed plasma jets into the ionosphere. It has been demonstrated that 1 to1.5 seconds after injection, the irradiation of the background medium increases. The brightness of the luminescence is associated with the bursts of the flow of precipitated electrons, stimulated by injection of a plasma jet.

The effect of infrasonic pulsed radiation from the Chelyabinsk bolide on the perturbations of the electron concentration in the D region of the Earth's ionosphere is considered. According to the electromagnetic measurements in the geophysical observatory Mikhnevo of the Institute of Geospheres Dynamics of Russian Academy of Science (IDG RAS), an estimate of the displacement of the reflection point of the SDV signals is obtained. Influence of infrasound radiation on the propagation of VLF signals on the Novosibirsk-Mikhnevo path is considered. The amplitude of the displacement of particles of the environment from infrasonic radiation is estimated. There is a good agreement between theoretical and experimental estimates.

The progress in the physics and chemistry of the lower ionosphere depends on the verification of the numerical models on the experimental data. We establish the framework, that the lower ionosphere model can be considered as a valid one, only if the prediction for the VLF-LF radiowave propagation coincides with evidence both in amplitude and phase temporal dynamics. The extremely strong X-flares 06 and 10 September 2017 were chosen as a testbed for the empirical and theoretical models of the midlatitude lower ionosphere. Both models used GOES-15 X-ray flux measurements. Empirical model captures only the time moment of disturbance. Theoretical model captures the main feature in VLF response. We summarize the observed problems in simulation and prospective solutions as well.

The empirical models of the lower ionosphere are used for fast prediction of VLF-LF propagation properties, for the initialization in the inverse problem solvers and as a climatological testbed for new numerical models. We used two widely used empirical models and verify them on the experimental VLF data from Mikhnevo geophysical observatory for 2014 year. Numerical results were obtained by parabolic equation method. The presented results prove the severe limitations of the current empirical models. The main bottlenecks are formulated.

We discuss the role and the usage of the ionosphere models in the improvement of UHF-SHF radar operation. The up-to-date empirical ionosphere models (International Reference Ionosphere (IRI), Fully Analytical Ionosphere Model (FAIM), Ne-Quick2) have too crude spatial and temporal resolution. The aforementioned models cannot describe the localized irregularities (like traveling ionospheric disturbances or waves) which, in turn, are regularly observed at the midlatitude high frequency chirp ionosonde. In the presence of such irregularities the additional range error in UHF range can exceed 1-2 km. The poorly known quasi-random nature of such irregularities leads us to the unique solution, namely, the rejecting of the laminar layered ionosphere in favor of the random electron density field. Such new probabilistic ionosphere model must be elaborated and verified on the experimental data.

The principles of the probabilistic-statistical modeling of the D-region of the ionosphere are described. The work is devoted to the calculation of electron concentration using deterministic-probabilistic modeling. In this work the electron concentration is calculated using the five-components system of the ionization-recombination cycle equations. Probability density functions (PDFs) of the input parameters of the model are used to solve the system. It was shown that theoretical PDFs of the Ne are in good agreement with two experimental databases of electron concentration. Results of the deterministic-probabilistic model are compared with the experimental VLF signals obtained in geophysical observatory Mikhnevo from the three transmitters in different heliogeophysical conditions.

We present the results of the analysis for the GOES-15 and SDO satellites data under the extra strong solar X-class flares X9.3 September 06 2017 and X8.2 September 10 2017. It is shown that X9.3 flare was accompanied by the significant increasing of the UV flux and by the growth of the extremely hard X-ray part of the spectrum. The evidence from ionosondes, GPS receiver and Schumann resonance monitoring has shown different response to these neighbor flares. The flare classification based on the peak flux value is not sufficient for the geophysical applications. The interpretation of the ionosphere response requires the full spectrum analysis.

In the study of the ionosphere total electron content (TEC), defined from the data of global navigation satellite systems, are widely used. It is assumed that the main contribution to the value of TEC is made by the F region. At the same time, the results of many studies show that during the X-ray flares the ionization of the D region can increase substantially, reaching values of 10 6 cm -3 . In this paper, we analyze the changes in the parameters of the D region during an X-class flare on September 6, 2017. It is shown that a correct interpretation of the variations of TEC with powerful X-ray flares requires taking into account of the contribution to its ionization value of the lower ionosphere.

The paper presents the results of an analysis of the frequency variations of the first mode of the of Schumann resonator in the geophysical observatory Mikhnevo of the Institute of Geospheres Dynamics of Russian Academy of Science (IDG RAS) during solar X-ray flares of the M and X classes in 2011 - 2017. It is shown that the frequency variation depends not only on the flash class, but also on the magnetic field component and local time. It is suggested that this is due to the geometry of the path from the African Thunderstorm Activity Center.

The results of the analysis of the navigation task solution in the conditions of registration of the signals of the global navigation satellite systems GPS and GLONASS in the Mikhnevo GFO (the geophysical observatory) are presented. It is shown that in the classical algorithm, the choice of satellites from the observed constellation should be made not according to the criterion of elevation, but by the number of conditionality of the navigation task matrix. The use of adaptive iterative algorithms almost completely compensates geophysical perturbations while maintaining the twofrequency regime.

This paper describes the results of experimental study influences of urban planning and green spaces on the acoustic transport noises. The contribution of green spaces to the acoustic noise attenuation is shown.

The paper presents the results of experimental studies of the effect of acoustic noise of the sound and infrasonic frequency bands on the auditory, visual, motor, tactile responses of a person, as well as on the time of making decisions. A method for estimating the time of human reactions was proposed, which was implemented by the authors as a software application for mobile devices. The obtained results unequivocally show an increase in the reaction time of all types under the influence of sound and infrasound noise even of a small level.

We study the surface electric field and the vertical atmosphere current at "Mikhnevo" geophysical observatory by means of a sensor cluster. The electric current sensor allows to disambiguate the displacement and conductive currents and to study their variations in sense of geophysical conditions. Data obtained under fair weather conditions and under significant perturbations are presented.

We present the results of a statistical analysis of geomagnetic activity measured at the Mikhnevo Geophysical Observatory of the Institute of Geosphere Dynamics of the Russian Academy of Sciences (54.960° N; 37.774° E) located in Moscow region (central part of the Eastern European Platform) and its relation to the solar activity. We use the station geomagnetic K-index as a characteristic of the geomagnetic activity. We apply the results of instrumental observations of the geomagnetic field carried out at the Mikhnevo Geophysical Observatory from 2009 to 2015 to calculate the K-index using the method of adaptive smoothing. The geophysical situation of the Moscow region is characterized by a significant number of days with a disturbed state of the geomagnetic field (in the period analyzed here, magnetic storms were recorded in 181 cases and a disturbed geomagnetic situation was identified in 333 cases). At the same time, there is a tendency for an increase in geomagnetic activity with time: from 2009 to 2015, the number of days with disturbed geomagnetic conditions increased almost eight times. The recurrence of geomagnetic disturbances is characterized by clearly pronounced periodicity with characteristic periods of about 2 weeks, 27 and 60 days, half a year, and 1 year. The total duration of geomagnetic disturbances, which is characterized by K ≥ 4, varies significantly with time. The evaluation of the correlation between the total monthly number of geomagnetic disturbances characterized by a value of K ≥ 3 and the parameter determining the intensity of solar radio emissions (flux density) at a frequency of 2800 MHz (with a wavelength of 10.7 cm) (F 10.7) provide evidence about the significant correlation between the number of geomagnetic disturbances and solar activity.

Analysis of the results of instrumental observations of the electric field and micro-variations in the atmospheric pressure in the surface atmosphere during strong thunderstorms in Moscow in the period 2014−2016 is carried out. It is shown that the arrival of a thunderstorm front has been preceded by long-period (~10 min) variations in the electric field strength, internal gravity waves, and increased magnitudes of impedance acoustic correlation. After the arrival of a cold atmospheric front, as well as in the periods of thunderstorm events, high-frequency (~1 min) variations in the electric field and increased turbidity of the atmosphere are observed. Wind motions in the atmosphere are almost absent in the atmosphere, but internal gravity waves are observed at the final stage of the phenomena. The period of variations in the electric field increases up to ~15 min.

Temporal variations in the relative number of failed rocket launches in Russia (Soviet Union) and the United States have been compared to reveal that these variations are antipersistent. The accident rates of rocket and space equipment launches have been analyzed as a function of the level and phase of solar activity cycle. The relative number of failed launches in Russia (Soviet Union) and the United States for the growth phase of solar activity has been shown to exceed the number for the phase of solar activity decline, although no clear correlation between solar activity and the number of failed launches has been detected.

In this paper, unusual optical phenomena observed in our country and abroad upon launches of Russian rockets are discussed and interpreted: they are regarded as the aftereffects of sunlight scattering by gas-dust clouds created by rocket fuel combustion products in different modes of engine operation. The results of instrumental observations of the clouds can be used to study physical processes in the upper atmosphere.

The review and new measurements are presented for depth/diameter ratio and slope angle evolution during small (D < 1 km) lunar impact craters aging (degradation). Comparative analysis of available data on the areal cratering density and on the crater degradation state for selected craters, dated with returned Apollo samples, in the first approximation confirms Neukum's chronological model. The uncertainty of crater retention age due to crater degradational widening is estimated. The collected and analyzed data are discussed to be used in the future updating of mechanical models for lunar crater aging.

Numerical simulation of atmospheric disturbances during the first hours after the Chelyabinsk and Tunguska space body impacts has been carried out. The results of detailed calculations, including the stages of destruction, evaporation and deceleration of the cosmic body, the generation of atmospheric disturbances and their propagation over distances of thousands of kilometers, have been compared with the results of spherical explosions with energy equal to the kinetic energy of meteoroids. It has been shown that in the case of the Chelyabinsk meteorite, an explosive analogy provides acceptable dimensions of the perturbed region and the perturbation amplitude. With a more powerful Tunguska fall, the resulting atmospheric flow is very different from the explosive one; an atmospheric plume emerges that releases matter from the meteoric trace to an altitude of the order of a thousand kilometers.

Numerical simulation methods are used to investigate the thermal evolution of ejecta from a meteorite crater in the interaction with the perturbed atmosphere in the first few minutes after the impact. The study considers the role of air radiation, collisions of air molecules with the body’s surface, and the heat transfer into the interior in the heat exchange of the ejecta and reveals the possibility of additional heating (compared with that at the time of the impact), which affects the geochemical and paleomagnetic properties of the ejecta.

Numerical simulation of the destruction, evaporation, deceleration, and emission of the Chelyabinsk superbolide has been carried out. The model assumes that the main energy is radiated in the stage when the asteroid is already completely destroyed and does not have solidity (quasi-liquid approximation). The radiation transfer during the motion is taken into account in the approximation of radiative heat conductivity and volumetric emission. The distributions of temperatures and densities are obtained at the moments when the bolide is at different altitudes. The intensity of radiation at the Earth’s surface is calculated at certain times by solving the radiative transfer equation along the rays passing through the luminous region using the air and LL-chondrite vapor absorption coefficients. The features of superbolide radiation, the contribution of air and vapor to radiation, the size of the luminous region, and the radiation spectrum have been considered. The calculated efficiency of radiation—17% of the kinetic energy of a cosmic body—agrees with the results of observations. It is shown that due to anisotropy of the superbolide radiation, the determination of luminous efficiency from measurements can depend on the observation point. For estimations, the pointsource approximation can be used, but in general, the source luminous efficiency is unknown, and its location is determined with some error; therefore, numerical simulation is required to reliably estimate the consequences of space body falls.

The numerical analysis of the propagation of shock waves initiated by either a space body striking the Earth’s surface, or underground explosions, allows us to compare the energies required to attain the same amplitudes of shock waves at impacts and explosions. Proceeding from this and based on the data of seismic efficiency of underground explosions, the authors have estimated the fraction of the kinetic energy of a space body transformed into the energy of seismic disturbances when the body strikes the Earth. This fraction is about 10–3, which is an order of magnitude more than the most common estimates. Space bodies decelerating and collapsing in the atmosphere also generate seismic waves in the ground due to the impact of the air-shock wave on the Earth’s surface. In this case, the seismic efficiency is considerably lower, according to the calculations, it is about 10–5.

Quick assessment of hazardous effects from impacts of large celestial bodies is achieved through the development of a new consequence calculator. A distinctive feature of this calculator is a new block, the Hazardous-Orbit Constructor, which simulates the conditions of entry of a celestial body into the Earth’s atmosphere and determines the orbital parameters of the body based on given atmospheric entry conditions. This block is used to simulate the atmospheric entry conditions of known asteroids and meteoroids and to determine the orbital parameters of known bolides leading to meteorite fall events. For the case of asteroid 2008 TC3 and the Přibram meteorite, it is shown that within the potential impact area of the celestial body, the atmospheric entry angle may vary considerably.

This paper summarizes the observations of microseismic emissions by these authors in several areas of the Russian part of the Fennoscandian Shield to assess the potential of microseismicity to determine the present-day activity of local features in the upper part of the geologic medium. We give amplitude-frequency characteristics and the space-time distribution of naturally occurring microseismic events that are hypothesized to be of endogenous origin. We discuss the relationships these characteristics have to the regional geodynamic setting, average dimensions, and petrographic composition of active rock blocks.

This paper reports the development of a new-generation short-period borehole electrodynamic seismometer designed for research, with special emphasis on seismology and volcanology (Sobisevich et al., 2008) and for important applications (Bashilov, 2001), e.g., developing special monitoring and security systems, as well as the search for and monitoring of hydrocarbon exploration.

This paper is concerned with the design of a portable seismic bottom station (PSBS) based on a molecular electron seismometer for research in seismology and volcanology (Sobisevich et al., 2008) and for dealing with a number of important applied problems (Bashilov, 2001) in the design of special monitoring systems, alarm systems, as well as the exploration and development of hydrocarbon deposits in shelf areas and transitional zones. The station is a further development of a portable bottom module, PBM (Bashilov et al., 2013) whose testing results are also presented in this article. The design has been modified and supplemented in response to the remarks made during testing on Lake Seliger (Bashilov et al., 2017).

The results of analysis of more than 1300 new PKiKP/PcP amplitude ratios measured in Southeast Asia and South America at the epicentral distances of 3.2°–35.2° are presented. The density jump in the Eastern Hemisphere of the Earth’s inner core (IC) is 0.3 g/cm3, and it is 0.9 g/cm3 in the Western one. Taking the large discrepancy in the obtained estimates into consideration, maintenance of such large lateral variations in the mosaic properties of the IC reflecting surface requires considerable variations in the thermodynamic parameters (mostly temperature) of the inner–outer core transition. However, if the observed asymmetry in the density jump distribution is of a global character, the data presented support the translation model of the IC dynamics. This model implies IC crystallization in the Western Hemisphere and melting in the Eastern one, not vice versa, as suggested by another geodynamic model based on thermochemical convection in the outer core and the thermal balance of the core–mantle system.

Based on complex analysis of the results of instrumental observations during strong atmospheric disturbances, it is shown that hurricanes and squalls are accompanied not only by high wind velocities, but also by high-amplitude microbaric variations, variations in amplitudes of the microseismic background, and the vertical component of the electric field. It is established that 1–4 hours before the onset, squalls and hurricanes are characterized by increased amplitudes of microbaric variations in the range of periods of 2–6 min, as well as by low-frequency variations in the electric field and variations in the microseismic background, which together with the meteorological parameters can be considered as a complex prognostic criterion of an impending hurricane (squall).

This paper reports data on the structure of the central zone of the seismogenic fault in the originally deep segments of the fault zone. The isotopic analyses have made it possible to estimate the absolute age of the ancient coseismic faults at 673 ± 5 Ma, which is indicative of seismic activation of deep faults in the studied segment of the marginal suture of the Siberian Craton in the Neoproterozoic.

The results of instrumental observations have shown that the spectra of geomagnetic variations exhibit a quasi-harmonic component, the frequency of which is close to the basic spheroidal mode of the Earth 0S2. In periods 15 days long after three large earthquakes and in the absence of strong magnetic disturbances, the fine structure of this mode in geomagnetic variations is identified in the form of singlets. The frequencies of these singlets are similar to the theoretical values calculated using an ideal elastic isotropic model of the Earth of spherical symmetric form without its rotation.

The article reports the results obtained in the trial of elements of the monitoring system for potentially hazardous areas at Korobkovo deposit of the Kursk Magnetic Anomaly. The system is based on the seismic and deformation measurements aimed to estimate and control shear stiffness of potentially hazardous faults. The fault shear stiffness is estimated through the analysis of parameters of seismic waves in the vicinity of a fault. The sources of seismic signals in the trial were explosions carried out at the neighbor surface and underground mines.

The actual lithostatic stresses are calculated with regard to physical characteristics and structural features of rock mass. The results are compared with the in-situ observations. It is shown that vertical stresses naturally grow with depth though their values are very different along horizontal cross sections due to the complex structure of rock mass. On the average, the vertical stresses are close in values to the lithostatic stresses. The horizontal stresses measured by the borehole slotter method are many times higher than their calculated values, which is governed by the nonunform properties of rocks or is reflective of tectonic compression.

In terms of the complex-structure ferruginous quartzite ore body mining in the Kursk Magnetic Anomaly, the authors validate the requirement to account for anisotropy of rocks with a view to improving performance of preparatory and blasting operations, stabilizing grain size composition, reducing production of oversizes, saving energy input of milling, enhancing useful component extraction into concentrate and decreasing losses with regard to the sound subsoil management conditions. The effect of the first to third scale anisotropy on the quality of blasting fragmentation of ferruginous quartzite is analyzed. The theoretical formulas to calculate radius of controlled fragmentation zone as function of geological and geophysical characteristics of rock mass are presented, and the practical results of blasting at open pit mines in the Kursk Magnetic Anomaly area are described.

An experimental study of small-scale mineral particles in the atmosphere over Kyrgyzstan is carried out. It is shown that the substance of the studied particles corresponds to quartz-enriched minerals, feldspars, layered silicates, minerals containing lime carbonate, etc. Overall, there is a definite correspondence between the mineral particle compositions in the atmosphere of Kyrgyzstan and in the other regions of Central Asia. The constructed size-distribution functions of the particles agree with the results of studying the dust aerosol properties in the deserts of Central Asia obtained in the southwestern part of Tajikistan in 1989.

The results of processing and analyzing the instrumental observations of the Earth’s magnetic field at the Geophysical Observatory Mikhnevo of the Institute of Geosphere Dynamics of the Russian Academy of Sciences (IGD RAS) for 2010–2015 are presented. Quasi-harmonic components with the periods close to the lunar–solar tidal waves are revealed in the spectra of geomagnetic variations over a period of 0.4 to 30 days. The elliptical S1 tidal wave which is detected in the geomagnetic variations has modulations with periods of 1/3, 1/2, and 1 year. The spectra of the geomagnetic variations contain peaks corresponding to the free oscillations of the Earth. The analysis of the time series of the magnetic field for the period of the strong earthquakes in the absence of geomagnetic disturbances revealed the fine structure of the Earth’s fundamental spheroidal mode 0S2, which splits into five singlets. The established features of the spectrum of geomagnetic variations are helping the development of the new method for studying the deep structure of the Earth and the properties of the inner geospheres for estimating the viscosity of the Earth’s outer core and dynamics of the current systems in the outer (liquid) core, as well as for exploring, with the use of empirical data, the general regularities governing the regimes of energy exchange processes in the geospheres.

The results of studying the deep structure of the Earth’s crust and upper mantle in the central part of the Russian platform from receiver functions are presented. The records of teleseismic waves by the Monakovo small-aperture seismic array in the region of the northwestern slope of the Tokmovskii Arch of the Volga–Kama anteclise are used. The modification of the P-receiver function method (Vinnik, 1977) suggested in (Sanina et al., 2014) for analyzing the receiver functions in the regions with a complexly structured upper part of the section and the presence of a thick sedimentary cover is applied. The method is based on separating the high- and low-frequency components of the seismic record and successive reconstruction of the V-s velocity section in the upper part of the crust, which is performed first and, next, the entire deep section of the crust and the mantle down to a depth of ~300 km. The positions of the seismic conversion boundaries in the crust and upper mantle beneath the Monakovo array are determined. The upper mantle velocity section constructed based on the observations at the Mikhnevo array (Sanina et al., 2014) is compared with the world data on the ancient Precambrian platform.

The results of laboratory experiments aimed at studying the pattern of the transition process of a model fault into a metastable state are presented. The experiments are conducted on a slider model installed onto a long granite base wherein vibrations are excited. The idea of the experiments is that the mechanical properties of the fault change under the transition into the metastable state. These changes can be detected by the detailed examination of the parameters of microseismic noise. The conducted experiments show that, despite the low Q-factor of the block–fault mechanical system, the spectrum of the recorded oscillations definitely contains the harmonic components corresponding to the eigenmodes of this system. In the model with the interblock contact filled with quartz sand, the fundamental mode of the free oscillations alters most noticeably in the frequency band 1000–1200 Hz, where the clear effect of the spectral peak’s migration towards lower frequencies is observed as the contact approaches the moment of dynamic failure, and the approximately initial value is recovered after the sliding stops. The revealed effect gives hope that the changes in the stress–strain state of the fault zone at the final stage of earthquake preparation can be detected by analyzing the parameters of low-frequency seismic noise. The segment of the record during and after the passage of surface waves from remote earthquakes is perhaps amongst the most favorable for determining the characteristic values of the region under study. These oscillations with a period of a few dozen seconds have significant amplitudes and durations, which promotes the excitation of the resonant vibrations of the blocks.

Several variants of rate-state equations were considered in application to description of laboratory data on block sliding under normal and shear stresses. Both acoustic emission and stick-slip motion of the block were registered and considered as an analog of ordinary and slow earthquakes. Various types of fluids were added to the filler between the moving and stationary blocks. Obtained results on the block sliding were compared with numerical simulations which were conducted using several variants of the rate-state equations, and the best matching model was chosen for further study. With the help of that model, the seismic activity induced by fluid injection during Basel project was simulated. It was shown, that some long-term aftereffects of the fluid injection can be explained by specific value of the interblock stiffness related to the surround rock stiffness.

In the framework of the theory of interaction between nonlinear geomechanical and physicochemical processes in coal seams under mining and based on the piston mechanism of gas dynamic processes, it has experimentally been proved that nonlinear quasi-metric elastic pendulum waves from natural and induced earthquakes have influence on gas-dynamics in mines in Kuzbass. The objects selected to identify the interrelationship were the large earthquakes occurred in Kuzbass on November 9, 2016 (magnitudes 2.7 and 3.7) and the records of the quake-induced gas dynamic activity in the Alarda and Osinniki mines.

The influence of underground mine workings arranged nearby faults on the initiation of large seismic event is considered. Numerical modeling proves that amount of underground mine workings affects actual stiffness of rocks and initiates dynamic movements accompanied by intensive seismic radiation. As rock mass quality worsens, the effective shear modulus drops. The calculations show that the effective shear modulus lowers by 20% for the stopes on the same level, decreases 1.5 times in case of the stopes arranged on two levels and nearly halves for three levels. Such reduction in the actual shear stiffness of rock mass may be critical in terms of initiation of dynamic shift along a fault.

The influence of surface mining on the initiation of large seismic event is considered. The conditions of shearing-type dynamic events are described. A surface mine with the similar parameters as the Bachatsky open pit mine in Kuzbass is adduced as an example for quantifying the mining-induced change in the stress state in the plane of a future rupture as a result of an induced tectonic earthquake nearby a fault plane is quantified. The calculations are performed for different geometrical parameters of the fault zone: the changes are more observable in the zones of gently dipping thrust faulting and less appreciable in the area of steep normal faulting and strike-slip. In case of large surface mines, the zone of positive change in the Coulomb stresses higher than several tenths mega pascals has a considerable dimension and an area markedly larger than the area of nucleation zone of earthquakes of the magnitude M ≤ 6. In such conditions, even a small variability at the level of first percentage points of the natural stresses can be sufficient for the initiation of seismicity-generating shearing along the high-stress faults. It is found that, as against underground mining, the surface mining activities have no influence on localization of large earthquake sources but can draw the event nearer.

Investigated are the regularities of fault slip under weak impulsive disturbances in laboratory experiments. The fault was simulated by an interface between two granite blocks loaded with normal and shear stresses, and the impulsive disturbances were excited by impacts of steel balls. We found that the passage of an elastic wave does not produce any residual displacement in the absence of shear load. But the process of inelastic fault deformation manifests quite vividly even under a slight constant shear stress. The sign of residual deformation does not depend on the direction of pulse propagation, but it does coincide with the direction of the applied shear load. Depending on the stress–strain state of the fault and the parameters of the impact, there are two scenarios of fault evolution: (1) production of residual deformations with decaying amplitudes under repeated cycles or (2) initiation of slow deformation process and accumulation of displacements up to the occurrence of slip instability. In the case of a continuously increased shear load, the effects of weak periodic impacts essentially depend on the initial slip behavior. The weakest effect is observed in the case of high-amplitude stick-slip. In contrast, in the case of slow, irregular quasi-dynamic slip, tapping leads to an almost complete transformation of the potential energy of deformation into aseismic creep. Thus, a short dynamic disturbance propagating within a stressed blocky medium can trigger a slow deformation process whose contribution to the cumulative deformation may be quite appreciable. Because postdynamic movements can contribute substantially, a delay in the manifestation of dynamic events with respect to the moment of the initial disturbance may be observed. In turn, periodic dynamic disturbances of the stress–strain state can essentially change the mode of background seismicity and the proportion of radiation efficiency of events.

Earth's atmosphere offers little protection against comet impacts, because many comets are bigger than 1 km. Fewer comets hit Earth than asteroids of the same size, except perhaps for sizes larger than 10 km. Comets release copious amounts of solid debris called meteoroids, and these meteoroids disperse to form meteoroid streams, some of which cause meteor showers on Earth. Recent meteor shower observations reveal the presence of potentially dangerous parent comets and trace their dynamical evolution. In addition, some showers leave a signature of "cosmic dust" in our atmosphere.

We present the experimental evidence for European VLF network data on the response of the lower ionosphere and frequency-dependent VLF data under the consequent X-class solar flares 06 September and 10 September 2017. The stations under analysis include European AWESOM monitors, which are distributed over all Europe. Data from geophysical observatory 'Mikhnevo' (MKH) of the Institute of Geosphere Dynamics (54.57N, 37.46E) covers frequency range from 1Hz to 100 kHz, thus allowing the monitoring of all VLF/LF transmitters as well as Schumann resonance. The monitoring is evaluated both in magnetic field channel by METRONIX MFS07 magnetometer (3 components) and in electric field channel by RhodeSchwarz ESCI receiver (vertical electric field).

This paper reviews the methods of correcting the frequency response of short-period seismometers and geophones, i.e., the multiplication of the transfer sensor functions by the transfer function of the second-order correction filter and the provision of a considerable attenuation in the oscillating system (h = 5-10) followed by correcting the frequency response with the first-order filter. The correction device circuit developed by the authors for expanding the frequency range of the GS-20DX geophone has been described. The proposed method has been proved to be effective according to the laboratory tests of the geophone with the frequency response correction according to this circuit.

The study of the stress-strain state of a medium in seismically quiet areas is difficult because of the absence of strong events. Under such circumstances, each earthquake, even relatively weak, is of high importance. In this case, all possible information on tectonic stresses and their dynamics, e.g., information on time, location, and magnitude of aftershocks, should be obtained from available seismic data. The earthquake near the town of Mariupol which occurred on August 7, 2016, had a body wave magnitude of 4.5-4.9 from the data of the different seismological centers. We detected 12 aftershocks that occurred within 5 days after the main shock using two seismic arrays (AKASG and BRTR) and one three-component station (KBZ) of the International Monitoring System, as well as two array stations of the Institute of Geosphere Dynamics, Russian Academy of Sciences. For six aftershocks, signals were found at three or more stations. The other aftershocks were detected from the data at two out of three nearest stations. Signal detection and association with aftershocks of the main shock, as well as estimation of magnitude and relative location of the found aftershocks, were carried out using the method of waveform cross-correlation (WFCC). The signals from the main shock that acted as the only master event (ME) for the WFCC method were used as waveform templates. To increase the signal-to-noise ratio and to determine the exact onset time of regular seismic waves from aftershocks, we used waveform templates of different length, from 10 to 180 s depending on the wave type and distance to the station, as well as band filtering in narrow frequency bands. The highest sensitivity of the detector and accuracy of the P-wave onset time estimates were reached when a waveform template included all regular waves from P to L (g) . Association of signals with aftershocks was based on back projection of signal arrival times to origin times using the travel time from a master event to the station, which was measured with a very low error, being equal to almost half of the digitization step length. To develop a seismic event hypothesis, the origin times at two or more stations should be spaced within a 2-s interval.

A large number of events with sources in the immediate vicinity of an array are usually detected during seismological observations with seismic arrays. These events should be detected and correctly interpreted during processing of seismic array records in order to avoid clogging up the event catalog. This problem can be solved by classifying records of local events by genetic features and creating a databank with the most representative samples. The present paper considers local events recorded using a unique scientific setup, the Mikhnevo small aperture seismic array. Epicenters of local seismic events are located less than 5 km from the center of the array. Seismic responses of acoustic shock waves are also examined. Seismic events caused by anthropogenic sources are identified and classified using cluster, cross-correlation, and wavelet analysis. Events accompanied only by the arrival of surface waves, as well as events represented by body, surface, and acoustic waves, are identified. Shock wave events are classified as a separate category. A small group of supposedly natural weak events is also found. As a result, a databank of waveforms of local seismic events for the Mikhnevo seismic array is established. In the future, this will make it possible to automate their identification when investigating the seismicity of the East European Platform.

A family of seismometers has been developed with capacitive transducers that convert the relative displacement between the inertial mass and the base of the instrument into an electric signal. These high-sensitivity seismometers have a unified electronic circuit; they can be rather easily manufactured, installed, and calibrated, which makes mass production of these instruments look promising. To assess the possibility of using these seismometers as substitutes for imported counterparts, a comparative analysis was carried out to study the performance of a portable short-period SM-3E broadband digital seismometer and imported seismometers of the same type. Seismic recordings of these instruments were statistically analyzed in the time and frequency domains.

The paper addresses experiments to assess whether seismic systems can be used for autonomous border surveillance on land and sea. Seismic systems as an integral part of border surveillance systems, especially maritime ones, should comply with strict performance requirements. The first-priority problem was to prepare appropriate domestic equipment and an experimental technique for seismic surveying on land and sea. When this problem was formulated, there was no suitable domestic broadband equipment. Fundamentally new technical solutions were employed to create prototypes of seismic modules of the SM-5, SM-6, and SM-3M types. On their basis, one- and three-component short-period and broadband of seismic sensor prototypes were developed, including the SM-5M, SM-6, TS-5, TS-6MSh, etc., which were used to create a prototype for a digital deep seafloor seismic station (TsDSS-M). Also, for transition zones, a seafloor seismic station was developed and tested, which is based on molecular electronic sensors that have achieved significant progress recently. The paper describes the prototypes of the TsDSS-M digital seafloor seismic station and MDM bottom seismic module for transition zones, both based on electrodynamic and molecular electronic sensors. The prototypes were tested on Lake Seliger. Shallow-water tests demonstrated the reliability and high performance of the prototypes; the desired characteristics proved to be appropriate. Importantly, TS-5 seismic modules are now manufactured at an industrial scale; this has solved the problem of import substitution in this area.

In this paper, we compare the fracture opening pressure in the laboratory experiment and in the theory. The opening pressure knowledge is necessary not only for hydraulic fracturing, but also to estimate the stability of the wellbore. In addition, this value determines the possible formation of small fractures in the rock, where the pore pressure exceeds the fracture opening pressure. Also, the knowledge of this value is necessary for calculating the maximum horizontal stress, the finding of which is a nontrivial task. Our study showed that the experimental value of the fracture opening pressure differs from the theoretical one by several times.

The lithospheric mantle of the central part of the East European Craton has not been studied in detail. The main goal of the research is to develop a model of the deep structure of this region. Recently new vertical velocity sections were constructed to a depth of 300 km, obtained by the receiver function method, along the sublatitudinal profile Obninsk-Nizhny Novgorod. The position of the main boundary of the crustmantle is reconsidered from the velocity sections. Velocity differentiation is found within the upper mantle, which is associated with a change in geophysical and geochemical properties. Suggested model is aimed at analyzing the relationship between the structure of the lithospheric mantle and the structures of the earth's crust, which must be carried out at different hierarchical levels. Structurally, the region in question is represented by Archean microcontinents-the Volga-Ural and Sarmatia and the connecting zone of the Proterozoic folding. Under the earth's crust, the stable areas of the sub-continental lithospheric mantle-the domains up to 100 km in size, which are characterized by definite geological, geochemical and geophysical properties-stand out in the upper mantle. Under Archean microcontinents forming East European Craton, agglomeration of domains forming pristine archean is traced. The position of the lower boundary of the domains is determined by the age of their formation. Under Archean microcontinents-Volga-Ural, Sarmatia, the bottom of the sole is presumably traced at depths of up to 400 km, under Proterozoic folding-up to 250 km. In some areas, melting of the lower part of the domains and along its boundaries is possible, controlled in some cases by the presence of large fault zones.

The central part of the East European craton (EEC) is the site of extensive mining activity. The small aperture array “Mikhnevo” (MHVAR) monitors the weak seismic events in the distance range about 500 km. The most of them are identified as industrial explosions using the S/P amplitude ratio, day-time distribution criteria, spectral content, recurrence and clustering of events. The detailed analysis of waveform variations allows monitoring of the change in the position of the explosion as well as the subtle changes in the technology of the blasting. Basing on array data and regular seismic measurements in the vicinity of quarries we estimate the effective attenuation for P waves. Experimental calibration curves for industrial explosions show strong variations with azimuth. The observed ground velocity is equivalent to the intensity I=1.5-2 near the quarries with the energy of explosions of the order 5·108 J/year, and to the intensity of I=3, if the energy is of the order 5·1010 J/year. Presumable maximum impact of the industrial explosions is estimated in case of simultaneous activity on all the sites. The central part of the EEC is vulnerable to seismic effects from minor quarry blasts similar to the area near big mining sites.

The development of methods for automatic preprocessing of observational data of small-aperture seismic arrays that precede the detection and identification of seismic events by the method of waveform cross-correlation is considered. Preprocessing is based on adaptive channel selection. The methods developed by us provide for the calculation of the quality metrics of the seismic channel by means of spectral and amplitude analysis of records. The selection of channels is based on the correspondence of the quality of records to predetermined criteria. As a result of the selection, a list of records admitted to the correlation processing is formed. This list can contain fewer channels than there is in the initial records of the small-aperture seismic group. The final result of the selection of channels is to increase the average for the group of coefficients of cross-correlation of the samples with the investigated records in comparison with the situation when all available records are “allowed” to processing. As a result of applying the described methods to the records of the small aperture array “Mikhnevo” (MHVAR) of the Institute of Geosphere Dynamics of the Russian Academy of Sciences, an increase in the average value of the cross-correlation coefficients reached 14%.

The geodynamic situation in the region of the “Rostov NPP”(next NPP) location is considered in terms of assessing the neotectonic activity of the territory and its relationship to seismicity. The authors used their own and published data, as well as the results of field seismic observations conducted by the small aperture array of the Institute of Geosphere Dynamics Russian Academy of Sciences in 2016. The estimation of vertical Pliocene-Quaternary deformations by a method of stratigraphic and geomorphic reference surfaces is used. The absence of newly formed PlioceneQuaternary faults disturbances was noted, but the importance of the reactivation of ancient structures, including those controlling the position of the Karpinsky Ridge, was also noted.

Electromagnetic (EM) induction technique is one of the most important geophysical techniques in understanding the subsurface structure. The theory of magnetotelluric (MT) method, the main branch of the EM technique, was introduced during 50’s by Tickonov and Cagniard with the natural variation of electromagnetic fields, as its source. We will present the results of a study focused on the processing and modeling of magnetotelluric (MT) data in watered area located in the Moscow Region (Geophysical observatory "Mikhnevo" of Institute of Geosphere Dynamics of Russian Academy of Science). Issues related to the robust processing, and modeling of the data will be addressed. Moreover, we investigate relationship between seasonal changes in regime of groundwater level in conditions of the observatory "Mikhnevo" and variations of calculated magnetic tipper. We compare values of magnetic tipper, which is calculated on basis of numerical model of the magnetic tipper response associated with the change in the weight of the water-saturated layer, and magnetic tipper calculated from the components of the magnetic field on the Earth's surface.

The physical effects that may prove useful for developing a new approach to short‐term earthquake prediction have been studied in laboratory conditions. In seismology and earthquake foci mechanics, one of the major challenges is searching for indicators of an upcoming seismic event and attempting to reliably record such indicators by available instruments. In this regard, the best result of the laboratory studies of dynamic slip along faults would be the identification of specific macroscopic parameters controlling the deformation process, which are measurable in field. Dynamic stiffness of a fault zone seems to be an appropriate parameter. The recent laboratory experiments have shown that the value of this parameter predetermines the slip mode along the fault (unstable slip, creep, tremor, etc.), and a radical decrease in shear stiffness takes place as the fault zone reaches the metastable state. The effect discovered in the laboratory conditions gives grounds to suggest that changes in the stress‐strain state of the fault zone at the final stage of earthquake preparation are detectable from the parameters of microseismic noise in the low-frequency range. Apparently, the noise records during and after the arrival of surface waves from distant earthquakes can provide the best opportunity for determining the parameters characterizing the study area. The wave oscillations with a period of a few dozen seconds have significant amplitudes and duration, which contributes to the excitation of resonance oscillations of the blocks. There are problems requiring additional laboratory experiments: estimating the size of a fault, which predetermines regularities in decreasing of the own frequency of the block‐fault system; determining the ratio of the mechanical parameters of the fault in the nucleation zone and on the periphery of the future rupture, etc. Having analyzed the results of experimental studies carried out by other researchers, we conclude that laboratory experiments under normal conditions and low pressures can successfully address a number of fundamental issues on the way to creating a new approach to short‐term earthquake prediction. Increasing pressure and temperature to values characteristic of seismogenic depths does not lead to the occurrence of any fundamentally new features in the behavior of the block‐fault system at the stage when dynamic slip is being prepared. During slip, friction reduces due to melting, physical and chemical transformations at the micro‐ and nanoscales and other processes on the slipping surface, but these effects play no role at the stage when dynamic rock failure and the onset of slip are being prepared.

In the part 2 of the study [Ruzhich, Kocharyan, 2017], we aimed at identifying the elements of paleoearthquake sources in the crust, which formed at the hypocentral depths in the exhumed Primorsky segment of the ancient collisional suture. The study area covered the southeastern margin of the Siberian craton (Pribaikalie, East Siberia). Slickensides, pseudo‐tachyllite (basaltic glass) and other petrological evidence of intensive tectonic movements were sampled. The structure of the deep segments of the collisional suture were reconstructed from on the data on coseismic ruptures and faults, and the PT parameters were estimated. In the past decades, similar research problems were actively investigated (e.g. [Sibson, 1973; Byerlee, 1978; Morrow et al., 1992; Hodges, 2004; Kirkpatrick et al., 2012]). In Russia, the interest in studying geological and geophysical features of the deeply denuded areas in ancient faults is still limited [Sherman, 1977; Ruzhich, 1989, 1992, 1997; Savel'eva et al., 2003; Ruzhich et al., 2015; Kocharyan, 2016]. The deeply denuded Primorsky segment of the collisional suture of the Siberian Craton underwent the geological evolution of a billion years. In the analysis, we used additional geological data from the petrology studies of the Main Sayan fault zone and other exhumed fault segments, including the seismogenerating faults in the Mongolia-Baikal region [Zamaraev, Ruzhich, 1978; Zamaraev et al., 1979; Ruzhich et al., 2009]. From the PT conditions for the occurrence of the slickensides, pseudo‐tachylyte, and the Primorsky segment structure, the 40Ar/39Ar method estimated the age of the slickensides containing tourmaline at 673±4.8 Ma, which may correspond to the Neoproterozoic stage of the breakdown of the megacontinent Rodinia. Another dating, 415.4±4.1 Ma, obtained for the muscovite sample from a decompressional rupture, refers to the Early Paleozoic stage in the development of the collisional suture, when accretion of the Siberian Craton and the Olkhon terrain took place [Donskaya et al., 2003; Fedorovsky et al., 2010]. Based on these ages and other available petrological data, the depths of the heterochronous systems of coseismic ruptures were estimated: 18 km in the Neoproterozoic, and 12 km in the Middle Paleozoic stage of the seismotec-tonic evolution of the crust in Pribaikalie. The deep paleoseismological settings need to be further investigated in order to more thoroughly clarify the physical and chemical conditions that contributed to the occurrence of the ancient and recent sources of strong earthquakes in the deep segments of faults in the crust. Such information is a prerequisite for further progress towards resolving the problems of securing seismic safety in various regions.

Поствзрывные деформации дневной поверхности выделены на ряде участков площадки Балапан Семипалатинского испытательного полигона по результатам полевых работ – геоморфологического обследования и геодезического нивелирования по профилям. Поверхностная техногенная зональность является косвенным отражением изменения состояния геологической среды. Массовая скорость движения пород выбрана в качестве основного критерия для сравнения изменений относительных отметок дневной поверхности в результате произведенных взрывов и при землетрясениях. Полученные значения смещения и массовой скорости движения пород при взрывах сопоставлены с опубликованными данными по землетрясениям.

The work is devoted to the development of a fundamentally new way of modeling the ionospheric D-region - deterministic-probabilistic. The results of N e calculations using this technique are analyzed. Research of this kind is of fundamental importance, related to the rejection of a purely deterministic description of a continuously changing environment such as the ionosphere. In this work, the electron density is calculated using a five-component system of ionization-recombination cycle equations. Probability density functions (PDFs) of input parameters of the model are used to solve the system. The most important sources of the D-region ionization are taken into account to calculate PDFs of the ionization rate. The necessary number of iterations is determined by the convergence of PDFs of the electron density from 50 km to 85 km at midlatitudes under different heliogeophysical conditions. Theoretical N e PDFs have been shown to be in good agreement with two experimental databases on electron density, especially at large D-region heights. The next important stage of modeling is the thorough verification of N e PDFs from experimental radiophysical data on VLF-LF propagation.

Разработаны алгоритмы многоканальной обработки записей сейсмических групп, позволяющие детектировать сигналы слабых сейсмических событий, наблюдаемых на фоне естественных сейсмических помех. В основе алгоритма детектирования сигналов слабых сейсмических событий лежит оценка меры когерентности продольных волн (P-волн), регистрируемых малоапертурными группами. Преимущество такого алгоритма перед известным одноканальным детектором STA/LTA заключается в возможности обнаруживать временные интервалы P-волн с отношением сигнал/помеха (SNR), меньшим единицы. По временным интервалам записей группы, где фиксируются превышающие определённый порог значения меры когерентности, оценивается вектор кажущейся медленности с помощью робастного к помехам фазового алгоритма бимформинга [Zhang et al., 2008; Kushnir, Varypaev, 2017]. Разработанная методика многоканальной обработки была апробирована на реальных сейсмических записях малоапертурной группы, установленной в районе Курской магнитной аномалии, непосредственно вблизи горных выработок по добыче железной руды. В течение 20 ч сейсмических записей были обнаружены сигналы как сильных (подземные промышленные взрывы), так и слабых сейсмических событий. В некоторых случаях удалось показать, что сейсмические события имеют сложный механизм очага. С помощью фильтра Кейпона [Capon, 1969] установлена схожесть (с точностью до знака вступления) P-волн слабых сейсмических событий, длительность которых не превышает 0.2 с, а временная форма подобна известной функции импульса Рикера [Bording, 1996].

На основе экспериментальных данных сейсмических наблюдений на профиле от Новогуровского известнякового карьера до малоапертурной сейсмической группы “Михнево” получены оценки коэффициентов затухания продольных и поперечных волн в верхней части коры центрального региона Восточно-Европейской платформы. В предположении об однородности диссипативных свойств земной коры построена карта изолиний распространения сейсмической энергии от карьерных взрывов в центральной части Восточно-Европейской платформы, содержащая сведения об исторических и современных землетрясениях. Проведено сопоставление пространственного распределения сейсмического воздействия промышленных взрывов с элементами зон тектонических нарушений по данным линеаментного анализа. Карта сопровождается оценкой интенсивности взрывных работ по данным за 2013-2017 гг.

The article is devoted to mathematical and physical modeling of the process of hydraulic fracture initiation and propagation in the material with known physical-mechanical properties. Fracture toughness was the main focus of the research as it is a parameter characterizing the rock's ability to resist fracturing process. This parameter alongside with rock elastic properties and pumping conditions is one of the governing parameters while considering the fracture propagation in terms of mechanics of brittle fracture. The study is aimed at understanding the impact of fracture toughness on geometric properties of a fracture by means of numerical modeling of laboratory experiments of hydraulic fracture propagation in a model material. The strength properties including fracture toughness of the used model material have been studied using the indentation methods. The difference between experimentally observed and numerically calculated (keeping in mind the estimated strength properties) fracture geometry is studied in the paper and the possible reasons for this difference are discussed.

The increasing near-Earth space (NES) exploration with its technogeneous contamination, and the resulting growth of space objects breakups risk for space flights makes more urgent the problem of estimating this danger, an adequate and accurate estimate being very important. In practice, given the complexity of obtaining the accurate estimates of this characteristic because of the large uncertainty in the initial data, it is a common practice simplifying the calculations, neglecting a set of factors, included some essential ones. In this work, some challenging aspects in evaluating and using the estimates of potential danger of space objects breakups and possible ways of improving these estimates are discussed.

We model ground effects produced by airbursts for a wide range of impact scenarios and suggest simple interpolations which may be used to predict impact hazard.

We model the Twannberg meteorite fall and compare the strewn field shape, total mass on the surface and the largest mass with available data. The most probable pre-atmospheric radius should be 1-2 m, although a larger body cannot be excluded.

We revisit the release of climatically-active gases by the Chicxulub impact using an advanced hydrocode and new data on the angle and direction of impact, and target rocks.

We calculated the dynamic flows in the upper atmosphere up to a few hours after the impact in case of small bodies (Chelyabinsk) and larger events (Tunguska).

Numerical simulations of impacts and calculations of radiation fluxes on the ground have been performed. Fractions of impactor kinetic energy emitted as thermal radiation, areas of potential fire ignition and melting of rocks are determined.

The Australasian tektite strewn field is exceptional, not only as the largest and most recent, but also as the only strewn field without an identified source impact crater. Therefore, scenarios without the formation of an impact crater, such as a low altitude cometary airburst, have proven hard to discard. Here, new geochemical evidence is presented for mixing of projectile and target material, which implies the formation of an Australasian tektite-related impact crater. First, ninety-two Australasian tektites were grouped according to their Cr, Co and Ni concentrations. Based on this data, Australasian tektites with the highest Ni contents (>200 μg/g) occur more than 1500 km south-southeast (SSE) of the northern Indochina region, with the highest concentration of Ni-rich tektites in South Vietnam, the islands of Borneo, Belitung, and Java, and reports in literature for Ni-rich tektites in central Australia. The tektites with the highest Cr and Ni abundances often also show highly siderophile element (HSE) enrichments of up to 4 ng/g Ir. The most Ni-rich samples exhibit broadly chondrite-relative HSE proportions. However, a chondritic impactor contribution appears to be inconsistent with the observed Ni/Cr, Ni/Co, and Cr/Co ratios. A previously suggested significant terrestrial mantle contribution can also not explain the siderophile element enrichments in combination with relatively low FeOtot (<7 wt.%) and MgO (<4 wt.%) contents. Elemental fractionation during impact cratering or tektite formation by an impactor with a chondritic signature may explain these observations. Alternatively, a projectile component from a primitive achondrite may be advocated, with contribution from a mafic to ultramafic extraterrestrial lithology with a relatively unfractionated HSE signature and Ni/Cr ratio distinctly higher than those of Earth's mantle. Element distribution maps obtained from individual Australasian tektites document complex mingling processes of chemically distinct melt batches, each exhibiting variable contributions from distinct endmember compositions. These texturally recorded mingling processes are consistent with high-resolution numerical models of impact cratering processes that resolve the growth of Kelvin-Helmholtz instabilities at the projectile/target interface during impact, when both materials co-occur at high pressure. These numerical models indicate that Ni-rich tektite populations across the central part of the Australasian tektite strewn field could represent projectile-enriched material preferentially ejected downrange. Continued tracing of this Ni-rich component across the strewn field may help to constrain the location of the yet to be identified source crater of the Australasian (micro)tektites.

The extraordinary Chelyabinsk airburst of 15 February 2013 is considered in the frame of quasi-liquid model (QL model), in which the entering body is treated as a strengthless quasi-liquid object, and its deformation and the flow are described by the hydrodynamic equations. Despite the QL model was originally proposed to model the impacts of the cosmic objects, which size is larger than a few tens of meters, the model predicts overpressure and radiation distributions on the ground in reasonable agreement with observational data for Chelyabinsk event. This model can be used for assessment of impact hazards for the whole range of dangerous cosmic objects. The influence of entry angle on surface effects is considered.

We present the results of numerical simulation for impacts of relatively small asteroids and ice bodies of 30-100 m in size, decelerated in the atmosphere and exploding before they reach the surface, but still producing seismic effects due to the impact wave reaching the surface. The calculated magnitudes fall within the range of 4 to 6, and average seismic efficiency of these events is 2.5 × 10-5. The results obtained allow the seismic hazard from impacts of cosmic bodies to be estimated.

The Morasko strewn field located near Poznań, Poland comprises seven impact craters with diameters ranging from 20 to 90 m, all of which were formed in glacial sediments around 5000 yr ago. Numerous iron meteorites have been recovered in the area and their distribution suggests a projectile with the trajectory from NE to SW. Similar impact events producing crater strewn fields on average happen every 500 yr and pose a serious risk for modern civilization, which is why it is of utmost importance to study terrestrial strewn fields in detail. In this work, we investigate the Morasko meteoroid passage through the atmosphere, the distribution of its fragments on the ground, and the process of forming individual craters by means of numerical modeling. By combining atmospheric entry modeling, Pi-group scaling of transient crater size and hydrocode simulations of impact processes, we constructed a comprehensive model of the Morasko strewn field formation. We determined the preatmospheric parameters of the Morasko meteoroid. The entry mass is between 600 and 1100 tons, the velocity range is between 16 and 18 km s-1, and the trajectory angle is 30-40°. Such entry velocities and trajectory angles do not deviate from typical values for near-Earth asteroids, although the initial mass we determined can be considered as small. Our studies on velocities and masses of crater-forming fragments showed that the biggest Morasko crater was formed by a projectile about 1.5 m in diameter with the impact velocity 10 km s-1. Environmental consequences of the Morasko impact event are very localized.

Data on observations of acoustic gravity waves and variations in the electric field strength in the surface layer of the atmosphere are presented. Analysis of the obtained data shows that synchronous variations in the pressure and electric field strength appear with the passage of a weather front, solar terminator, and in some other cases. It is seen that the amplitude of electric field perturbations is approximately proportional to the amplitude of variation in the pressure. A possible mechanism of generating electric field perturbations during the passage of microbaroms has been considered.

This paper presents the results from the simulation of a phreatomagmatic eruption, in which the formation of the eruptive column is controlled by interaction between magma and water or ice. The process leads to intensive fragmentation of the magma and to mixing of ash and steam with ambient air. Such processes were typical of the initial phase in the April 2010 eruption of Eyjafjallajökull Volcano. It is hypothesized that phreatic explosions produce a dynamic pulsating system that consists of buoyant volumes of the mixture (thermals) that are forming at the base of the eruptive column. A 3-D simulation was used to assess two possible regimes in the evolution of the eruptive column: (1) continuous transport of the mixture into the eruptive column through its base for the case in which the thermals are generated at a high rate and (2) periodic flotation of the thermals whose diameters are comparable with that of the base of the eruptive column. It is shown that one can find a suitable selection of the initial concentrations of ash, steam, and air to achieve a satisfactory agreement between theory and actually observed heights of the gas–ash “clouds” that were formed during the Eyjafjallajökull eruption. The data for our calculations were taken from publications. We also investigated how wind and the changes in the initial parameters affect the process.

Soon after the discovery of asteroid 99942 Apophis, it was classified as a potentially hazardous object with a high probability of an impact on the Earth in 2029. Although subsequent observations have substantially reduced the probability of a collision, it has not been ruled out; moreover, similar-sized asteroids in orbits intersecting the Earth's orbit may well be discovered in the near future. We conduct a numerical simulation of an atmospheric passage and an impact on the Earth's surface of a stony cosmic body with a diameter of 300 m and kinetic energy of about 1000 Mt, which roughly corresponds to the parameters of the asteroid Apophis, at atmospheric entry angles of 90° (vertical stroke), 45°, and 30°. The simulation is performed by solving three-dimensional equations of hydrodynamics and radiative transfer equations in the approximations of radiative heat conduction and volume emission. The following hazards are considered: an air shock wave, ejecta from the crater, thermal radiation, and ionospheric disturbances. Our calculations of the overpressure and wind speed on the Earth's surface show that the zone of destruction of the weakest structures can be as large as 700-1000 km in diameter; a decrease in the flight path angle to the surface leads to a marked increase in the area affected by the shock wave. The ionospheric disturbances are global in nature and continue for hours: at distances of several thousand kilometers at altitudes of more than 100 km, air density disturbances are tens of percent and the vertical and horizontal velocity components reach hundreds of meters per second. The impact of radiation on objects on the Earth's surface is estimated by solving the equation of radiative transfer along rays passing through a luminous area. In clear weather, the size of the zone where thermal heating may ignite wood can be as large as 200 km, and the zone of individual fire outbreaks associated with the ignition of flammable materials can be twice as large. In the 100-km central area, which is characterized by very strong thermal damage, there is ignition of structures, roofs, clothes, etc. The human hazardous area increases with the decrease in the trajectory angle, and people may experience thermal effects at distances of up to 250-400 km from the crater.

After the catastrophic disruption of the Chelyabinsk meteoroid, small fragments formed funnels in the snow layer covering the ground. We constrain the pre-impact characteristics of the fragments by simulating their atmospheric descent with the atmospheric entry model. Fragments resulting from catastrophic breakup may lose about 90% of their initial mass due to ablation and reach the snow vertically with a free-fall velocity in the range of 30-90 m s-1. The fall time of the fragments is much longer than their cooling time, and, as a consequence, fragments have the same temperature as the lower atmosphere, i.e., of about -20 °C. Then, we use the shock physics code iSALE to model the penetration of fragments into fluffy snow, the formation of a funnel and a zone of denser snow lining its walls. We examine the influence of several material parameters of snow and present our best-fit model by comparing funnel depth and funnel wall characteristics with observations. In addition, we suggest a viscous flow approximation to estimate funnel depth dependence on the meteorite mass. We discuss temperature gradient metamorphism as a possible mechanism which allows to fill the funnels with denser snow and to form the observed "snow carrots." This natural experiment also helps us to calibrate the iSALE code for simulating impacts into highly porous matter in the solar system including tracks in the aerogel catchers of the Stardust mission and possible impact craters on the 67P/Churyumov-Gerasimenko comet observed recently by the Rosetta mission.

Analyzes of numerical simulation results permit to suggest simplified approximations, which allow to estimate radiative fluxes on the Earth's surface based on impactor properties.

Described are results of laboratory experiments which revealed regularities of gradual transition from stick-slip mode to aseismic creep. The behaviour of model gouge-filled fault was investigated with experimental setup of the spring-bock model. It was experimentally proven that small variations of a percentage of materials with velocity strengthening and velocity weakening properties in the fault principal slip zone may result in significant variation of the portion of seismic energy radiated during a fault slip event. The tests simulated different modes of interblock sliding whose characteristic values of scaled kinetic energy varied by several orders of magnitude, while differences in contact strength and shear stress drop remained relatively small. The obtained results led to the conclusion that the earthquake radiation efficiency and the fault slip mode are governed by the ratio of two parameters—maximum fault slip-weakening rate and shear stiffness of the enclosing massif. The ratio can be essentially changed by small variations of the material composition of the fault principal slip zone.

На основе анализа и обобщения результатов инструментальных наблюдений за магнитным полем на Геофизической обсерватории «Михнево» Института динамики геосфер Российской академии наук в период 2009-2015 гг. установлено, что геофизическая обстановка Московского региона характеризуется значительным количеством дней с возмущенным состоянием геомагнитного поля. Установлена тенденция к увеличению геомагнитной активности со временем: за период с 2009 по 2015 гг. количество дней с возмущенной геомагнитной обстановкой увеличилось практически в 8 раз. Повторяемость геомагнитных возмущений характеризуется четко выраженными периодичностями с характерными периодами около 14, 27, 60, 182 и 365 сут.

Приведен анализ результатов инструментальных наблюдений за электрическим полем и микропульсациями атмосферного давления в приземной атмосфере в период сильных гроз в г. Москве за период 2014-2016 гг. Показано, что приход грозового фронта предварялся длиннопериодными (период ~10 мин) вариациями напряженности электрического поля, внутренними гравитационными волнами, а также повышенными значениями импедансного акустического соотношения. После прихода холодного атмосферного фронта, а также в период грозовых явлений наблюдаются более высокочастотные вариации электрического поля (период ~1 мин) и повышенная турбулизация атмосферы. На заключительной стадии явления практически отсутствуют ветровые движения в атмосфере, наблюдаются внутренние гравитационные волны, период вариаций электрического поля увеличивается до ~15 мин.

На основе результатов инструментальных наблюдений за геомагнитными вариациями, вызванными распространением сейсмических волн через разломную зону, получены зависимости между амплитудами наведенного сейсмомагнитного эффекта и сейсмического сигнала в зависимости от расстояния до серединной линии разлома r. Впервые показано, что амплитуда сейсмомагнитного эффекта максимальна в зоне влияния разлома. Предложена феноменологическая модель генерации магнитных сигналов при распространении сейсмических волн через раздробленную горную породу в зоне тектонического разлома. Предполагается, что геомагнитные вариации возникают при изменении электрической проводимости фрагментированных горных пород в результате деформировании контактов отдельностей. Рассчитанные по модели амплитуды геомагнитных вариаций согласуются с данными инструментальных наблюдений.

Приведены и обсуждаются результаты инструментальных наблюдений за геомагнитными вариациями на среднеширотной обсерватории «Михнево» Института динамики геосфер РАН (54.9595° N; 37.7664° Е). Определены основные периодичности локальных фоновых вариаций магнитного поля Земли в приземной атмосфере. Наряду с вариациями ~27 суток, зарегистрированы также периодичности с периодами ~ 6 - 9; 12 - 14; 60 суток и полугодовая периодичность. Показано, что периодичности фоновых геомагнитных вариаций имеют спорадический и скейлинговый характер. Обнаружен эффект чередования периодов увеличения и деградации интенсивности геомагнитных вариаций.

Рассматривается влияние гравитационного взаимодействия в системе Земля-Луна-Солнце на формирование временных вариаций геофизических полей и некоторых природных процессов. По результатам анализа результатов инструментальных наблюдений выделены основные периодичности и цикличности временных вариаций объемной активности подпочвенного радона, периоды которых совпадают с периодами изменений вертикальной компоненты приливной силы. Демонстрируется амплитудная модуляция сейсмического фона лунно-солнечным приливом. Показано, что интенсивность релаксационных процессов в земной коре характеризуется околосуточной периодичностью, а в спектре вариаций уровня подземных вод хорошо выделяются приливные волны. На основе данных, полученных при регистрации наклонов земной поверхности, анализируется роль приливной деформации в формировании блоковых движений в земной коре. Предложен новый подход к регистрации приливных волн в атмосфере на основе анализа микропульсаций атмосферного давления с помощью адаптивных режекторных фильтров.

Представлены результаты обработки и анализа геомагнитных вариаций, выполнены оценки их спектров и впервые выделены волны лунно-солнечных приливов на огибающих геомагнитных вариаций околосуточного диапазона, а также с периодами 13.66 и 27.55 сут. Установленные особенности спектра геомагнитных вариаций открывают новые возможности для оценки вязкости внешнего ядра Земли, описания геомагнитного динамо, разработки новых моделей движения внутреннего ядра Земли и динамики токовых систем во внешнем (жидком) ядре, а также установления общих закономерностей, определяющих режимы энергообменных процессов в геосферах.

В работе представлены результаты анализа пространственно-временных рядов объемной активности радона 222Rn (ОА), в том числе синхронных временных рядов на разных глубинах, в районах измерений с тектоническими структурами разного ранга. Установлено, что средние значения и вариации ОА 222Rn определяются расположением источников радона и серединных участков тектонических структур и монотонно увеличиваются с глубиной. Установлено, что временные вариации на разных глубинах синхронны, что говорит о значительном вкладе в процесс переноса фильтрации и нелинейной диффузии. Предложена модель выноса на поверхность радона 222Rn, в которой коэффициент диффузии радона зависит от глубины, а скорость фильтрации постоянна.

Приведены и анализируются результаты синхронных инструментальных наблюдений за вариациями геомагнитного поля на поверхности земной коры и сейсмического фона, выполненных на Геофизической обсерватории «Михнево» ИДГ РАН в период 2008–2015 гг. Показано, что геомагнитные импульсы (SI-сигналы) и внезапные начала магнитных бурь (SSC-сигналы) могут вызывать повышенные вариации сейсмического фона в диапазоне частот 0.01–0.1 Гц. Установлена зависимость между амплитудами геомагнитных вариаций импульсного типа и вызванных вариаций фоновых сейсмических колебаний.

Анализируются результаты инструментальных наблюдений, выполненных на геофизической обсерватории «Михнево» и в Центре геофизического мониторинга г. Москвы ИДГ РАН в период 2008–2015 гг., с целью исследования влияния лунно-солнечного прилива на вариации атмосферного давления. Вариации атмосферного давления регистрировались в частотном диапазоне 104–102 Гц. Оценка спектральных характеристик вариаций атмосферного давления проводилась на основе метода параметрической авторегрессии. С целью повышения уровня дискриминации близких по периодам приливных волн в атмосфере применялся метод выделения гармонических составляющих с помощью узкополосных адаптивных режекторных фильтров. В результате обработки данных на спектрах вариаций атмосферного давления выделены основные приливные волны с околосуточными и полусуточными периодами. Получено, что суточные и полусуточные гармоники вариаций атмосферного давления сопровождаются боковыми равноудаленными спектральными линиями, что является прямым указанием на модуляцию указанных спектральных составляющих. Периоды модуляции соответствующих приливных волн составляют около 13.6; 27.5 сут, а также 1/3, 1/2 и 1 г. Глубина модуляции приливной волны S1 годовой гармоникой составляет около 0.9, а полугодовой – ~0.2. Для приливных волн S2, K2, R2, T2 и λ2 соответствующие величины модуляции оцениваются величинами ~ 0.5 и 0.15.

Астероид 99 942 Апофис в течение короткого времени после его обнаружения был классифицирован как очень опасный объект, вероятность столкновения которого с Землей в 2029 г. очень высока. И хотя последующие наблюдения значительно уменьшили оценку вероятности столкновения, оно не исключено, кроме того, астероиды аналогичного размера на орбитах, пересекающихся с орбитой Земли, вполне могут быть обнаружены в ближайшем будущем. Мы провели численное моделирование полета через атмосферу и удара о поверхность Земли каменного космического тела диаметром 300 м c кинетической энергией порядка 1000 Мт, что примерно соответствует параметрам астероида Апофис, для углов входа в атмосферу 90° (вертикальный удар), 45° и 30°. Моделирование проводилось путем решения трехмерных уравнений гидродинамики и уравнений переноса излучения в приближениях лучистой теплопроводности и объемного высвечивания. В качестве опасных факторов рассматривались воздушная ударная волна, выбросы из кратера, тепловое излучение и ионосферные возмущения. Расчеты избыточного давления и скорости ветра на поверхности Земли показали, что размер (диаметр) зоны разрушений наиболее слабых конструкций может достигать 700–1000 км, причем уменьшение угла наклона траектории к поверхности приводит к заметному увеличению площади, поражаемой ударной волной. Возмущения ионосферы имеют глобальный характер и длятся часами: на расстояниях в несколько тысяч километров на высотах более 100 км возмущения плотности воздуха составляют десятки процентов, а вертикальные и горизонтальные компоненты скорости достигают сотен метров в секунду. Воздействие излучения на объекты, расположенные на поверхности Земли, оценивалось путем

Приводятся данные наблюдений акустико-гравитационных волн и вариаций напряженности электрического поля в приземном слое атмосферы. Анализ полученных данных показал, что при прохождении атмосферного фронта, солнечного терминатора и в ряде других случаев возникают синхронные вариации давления и напряженности электрического поля. Наблюдается приблизительная пропорциональность амплитуды возмущений электрического поля и амплитуды изменения давления. Рассмотрен возможный механизм генерации возмущений электрического поля при прохождении микробаром.

Дается критический анализ различных методов восстановления озонового слоя Земли: выбросы газов класса алканов, разрушение фреонов лазерным ИК-излучением и с помощью СВЧ – разряда, воздействие лазерным УФ-излучением и электрическим разрядом в атмосфере, использование излучения солнца и лазерного ИК-излучения, использование источников гамма-излучения, создание на больших высотах искусственного образования, экранизирующего диссоциирующее озон солнечное излучение. Отмечены наиболее оптимальные методы с точки зрения их эффективности, экономических затрат и экологических последствий. К ним относится использование источников гамма-излучения, электрического разряда в атмосфере и СВЧ-пробоя.

Представлены результаты численного моделирования падений относительно небольших астероидов и ледяных тел размером 30–100 м, которые тормозятся в атмосфере, не достигая поверхности Земли, но создают сейсмический эффект за счет воздействия ударной волны на поверхность. Вычисленные магнитуды лежат в диапазоне от 4 до 6, а средняя сейсмическая эффективность таких событий составляет 2.5.10-5. Полученные результаты позволяют оценивать сейсмическую опасность, исходящую от ударов космических тел.

Обобщение результатов обследований гипоцентральных зон сильнейших техногенных землетрясений показало, что накопленная в массиве горных пород деформация реализуется в виде подвижек по уже существующим разломам. Согласно результатам проведенных экспериментов, переход участка разлома в метастабильное состояние сопровождается снижением его динамической сдвиговой жесткости. Процесс изменения механических свойств контакта начинается задолго до того, как регистрируется макроскопическое перемещение берегов разлома. Этот эффект может быть обнаружен инструментально и использован в качестве основы развиваемого нового подхода к мониторингу техногенно-тектонических землетрясений.

Приведены первые результаты апробации элементов системы мониторинга потенциально опасных участков Коробковского месторождения КМА. В основу системы положены сейсмические и деформационные измерения, направленные на оценку и контроль сдвиговой жесткости потенциально опасных разломов. Методом оценки жесткости разлома является анализ параметров сейсмических волн в его окрестности. Для диагностики выбранных разломов, в качестве источников сейсмических сигналов использовались взрывы на ближайших карьерах или взрывы в камерах шахты.

Существование различных типов скольжения разломов часто связывают с концепцией существования прочных (asperity) и слабых участков. Более подходящим представляется предположение о наличии участков с отличающимися фрикционными свойствами. При этом разные фрикционные свойства заключаются в различии не столько коэффициента трения (разной фрикционной прочности), сколько закономерностей переходного процесса от трения покоя к трению скольжения. Именно как участки с разной скоростью снижения сопротивления сдвигу в процессе скольжения следует, по нашему мнению, понимать «жесткие» и «мягкие» включения. Изменения вещественного состава геоматериала в зоне скольжения разлома, порового давления, литостатических напряжений, температуры приводят к тому, что участки крупных разломов обладают разной жесткостью и на них реализуются различные режимы скольжения. Кроме того, деформации, происходящие на одном из сегментов гетерогенной разломной зоны, неизбежно сказываются на режиме скольжения соседних участков, а иногда и разлома в целом.

В статье на основе многоблочной модели rate-state с двухпараметрическим законом трения рассматривается развитие техногенных сейсмических процессов в результате закачки жидкости в недра. Решается задача об изменении порового давления в зоне разлома и изменении состояния скольжения по разлому. Определено влияние переменных, входящих в закон трения rate-state, на режим скольжения. Показано, что, при изменении параметров модели можно получить как случай быстрого роста сейсмической активности после начала закачки, так и ситуацию, когда основные сейсмические события происходят уже после окончания роста порового давления. Полученные результаты использованы для моделирования сейсмичности в районе Базельского геотермального проекта.

Универсальный предвестник катастроф (замедление скорости восстановления состояния системы после воздействия при приближении состояния системы к порогу неустойчивости) предваряет катастрофические изменения состояния различных систем. Критическое замедление сопровождается увеличением «памяти» (что отражается в автокорреляции) и дисперсии в стохастически индуцированных колебаниях состояний системы. При приближении к порогу неустойчивости уменьшается частота и увеличивается амплитуда волновых движений, вызванных внешним воздействием. Последнее обстоятельство приводит к тому, что эти волновые движения могут являться триггером ката-строфического события.

В работе представлены результаты лабораторных экспериментов по гидроразрыву пласта (ГРП) и измерению порового давления в образце в процессе экспериментов. Построены математические модели фильтрации жидкости в среде, модели уточнены по экспериментальным данным. По результатам интерпретации экспериментальных данных с помощью построенных моделей были сделаны выводы о влиянии трещины гидроразрыва на проницаемость образца.

Обсуждаются новые материалы, собранные при геологическом изучении условий образования сейсмодислокаций сильных землетрясений, возникших на земной поверхности, а также в эксгумированных сегментах зон разломов Монголо-Байкальского региона Центральной Азии. Изложены авторские представления о РТ-условиях, оптимальных для зарождения очагов сильных землетрясений в сейсмофокальном горизонте земной коры и о способствующих этому факторах. Показано, что именно мультидисциплинарное изучение эндогенных условий зарождения очагов сильных землетрясений позволяет разрабатывать более эффективные подходы к обеспечению сейсмобезопасности населения за счет снижения инженерно-сейсмического риска.

На примере геодинамических и сейсмических условий района Ростовской АЭС рассмотрено моделирование прогнозных пределов и прогнозных графиков повторяемости для разных условий деформирования с учетом структуры и скорости деформации геодинамических зон. Достоверность результатов моделирования контролируется наблюденными графиками повторяемости магнитуд рассматриваемого района и районов проявления катастрофических землетрясений. Результаты моделирования рекомендуется рассматривать при разработке превентивных мер по снижению последствий катастрофических землетрясений.

На основе комплексного анализа геолого-геофизических условий и сейсмогеологических данных определены основные сейсмогенерирующие структуры – Малоянисольский, Кальмиуский и Приморский разломы, ограничивающие блок, в пределах которого сосредоточены очаги землетрясения 07.08.2016 г. и 12 афтершоков, установленных методом кросс-корреляции волновых волн по ближайшим сейсмическим группам. Эпицентры основного толчка и большинства афтершоков приурочены к субмеридиональной Кальчикской линеаментной зоне, выделенной в осевой части сейсмоблока.

В работе рассмотрена геодинамическая обстановка региона расположения Ростовской АЭС с позиций оценки неотектонической активности территории и её связи с сейсмичностью. Использованы собственные и литературные данные, а также результаты полевых сейсмических наблюдений, проводимых малоапертурной группой ИДГ РАН в 2016 году. Использована оценка вертикальных плиоцен-четвертичных деформаций методом стратиграфических и геоморфологических реперных поверхностей; отмечено отсутствие новообразованных плиоцен-четвертичных нарушений и важное значение реактивации древних структур, в том числе контролирующих положение Кряжа Карпинского.

В работе представлены первые результаты исследований образцов пород, отобранных из зоны влияния разрывного нарушения, направленных на определение корреляционных связей между структурными свойствами образцов пород на микро- и мезоуровне и их механическими свойствами при сдвиговом деформировании. Участок работ расположен в зоне влияния Приморского разлома Байкальской рифтовой зоны, на левом борту долины реки Бугульдейка в месте впадения в озеро Байкал. Предварительный анализ микроструктуры шлифов отобранных образцов показал, что интенсивные сдвиговые деформации локализуются в узкой зоне, в которой отчетливо прослеживаются признаки динамического воздействия на минералы в процессе тектонического проскальзывания. В результате лабораторных исследований механических свойств на установке «слайдер»-модели установлено, что реализация определенного режима (стабильное и/или прерывистое) скольжения определяется не столько прочностью породы, сколько преобразованием её структуры на мезоуровне при контактном метаморфизме.

Приведены результаты сейсмического и деформационного мониторинга регионального разлома, проводимого на глубине 300 м от свободной поверхности в подземных выработках шахты, добывающей железную руду. В качестве источников для сейсмопросвечивания разлома используются массовые взрывы на шахте. Показано, что в области малых деформаций 10-8 – 10-7 нормальная жесткость нарушения сплошности проявляет нелинейность – с увеличением амплитуды воздействия на порядок, нормальная жесткость разлома снижается более, чем на порядок.

Обобщен опыт определения энергии источников инфразвуковых возмущений в атмосфере по спектру волновых форм в диапазоне частот 0,003÷0,3 Гц. Показано, что спектры сигналов от источников различной мощности отличаются значением преимущественной частоты. Представлена феноменологическая модель распространения акустических волн в атмосфере со стандартной стратификацией скорости звука, позволяющая оценивать зависимость характерной частоты от энергии источника. Выполненные с помощью модели расчеты характерной частоты сигнала при распространения инфразвуковых колебаний от мощных источников в стандартном стратосферном волноводе хорошо согласуется с результатами наблюдений.

В работе рассмотрено влияние полного солнечного затмения 20 марта 2015 года на ионосферу по данным измерения в Геофизической обсерватории «Михнево» параметров сигналов СДВ радиостанций на трассах, проходящих через зону затмения. Для контроля изменений в верхней ионосфере использовались данные по вариациям полного электронного содержания ионосферы по данным двухчастотного навигационного приемника.

Рассматриваются новые методы уточнения детерминированно-вероятностной модели ионосферы на примере D-области. Сравниваются плотности вероятности входных параметров, рассчитанные в 2014 и 2017 гг. Обсуждаются плюсы и минусы усовершенствованной модели, и предложены новые способы повышения ее точности.

Проведённый анализ наземных, морских и спутниковых измерений потоков метана в Арктике показал, что увеличение эмиссии метана из таких резервуаров захороненного метана, как метановые газогидраты, зоны вечной мерзлоты, северных болот может заметно превысить мощность антропогенных источников. При этом вклад парникового эффекта от работы положительных обратных связей может оказаться сравнимым или даже превысить антропогенный вклад в арктической зоне. Модельные расчеты показали, что изменения концентраций метана, воды, гидроксила и озона в условиях повышения эмиссии метана приводят к возникновению положительной обратной связи с потеплением в районе выбросов. Включение при повышении температуры, механизмов по высвобождению метана из естественных резервуаров приводит к еще большему накоплению метана в атмосфере и большему потеплению. При этом увеличение эмиссии антропогенных источников нужно рассматриваться, как своеобразный спусковой крючок, который запускает значительно более мощные процессы.

Приводятся данные натурных измерений акустико-гравитационных волн в системе о. Байкал–Тункинская долина. Анализ проведенных измерений показал, что сочетание сложного рельефа долины и температурного градиента между водной поверхностью и землей является причиной развития бризово-долинной циркуляции. Рассмотрен механизм генерации акустико-гравитационных волн. Определены условия возникновения генерации, обусловленные движением воздушных масс от о. Байкал в сторону долины.

Взаимодействие метеорных тел с атмосферой приводит к генерации как оптического (метеоры), так и акустического (импульсы давления) излучения. Большинство метеорных частиц не достигают земной поверхности, и их свойства (масса, размер и т.д.) оцениваются по данным наблюдений с использованием целого ряда предположений и моделей взаимодействия с большой неопределенностью. Одновременные комбинированные наблюдения метеоров позволят сопоставить оценки параметров метеороидов, полученные по разным наблюдательным данным, уточнить модели взаимодействия частиц с атмосферой. В статье рассказывается о результатах комбинированных (оптических и акустических) метеорных наблюдений, организованных Институтом астрономии РАН (ИНАСАН) и Институтом динамики геосфер РАН (ИДГ РАН).

В статье приведены результаты оценки скачка плотности на границе внутреннего ядра Земли различными методами по двум группам измерений на эпицентральных расстояниях от 11 до 24 градусов. Сравнение полученных оценок скачка плотности с модельными кривыми показывает, что расширение набора данных за счёт использования амплитуды шума на интервале ожидаемого вступления PKiKP, даёт заметное снижение результирующих оценок. Показано, что оценки, полученные методом максимального правдоподобия, дают величину скачка плотности в диапазоне 0.3–0.6 г/см3. В то время как оценка только по средним значениям обнаруженных волновых форм PKiKP и РсР даёт значения порядка 0.6–0.9 г/см3.

Наилучшим результатом моделирования процесса скольжения по разлому является установление таких макроскопических параметров, контролирующих деформационный процесс, которые могут быть измерены в натурных условиях. Представляется, что наилучшим кандидатом на эту роль является динамическая жесткость разломной зоны. Эксперименты последних лет показывают, что величина этого параметра радикально снижается в процессе перехода разломной зоны в метастабильное состояние, определяет тип скольжения по разлому и может быть оценена активными и пассивными сейсмическими методами. При этом критерием подобия при лабораторном и численном моделировании является сохранение величины отношения жесткости нарушения сплошности к жесткости вмещающего массива.

Классическая задача об образовании кратера на поверхности полупространства анализируется методами численного моделирования для случая «реальных» уравнений состояния (УС) Тиллотсона и ANEOS. Выбрана простейшая модель прочности – сухое трение, ограниченное переходом от хрупкого к пластическому пределу прочности с уменьшением прочности при повышенных температурах. Показано, что такая модель прочности разрушает традиционный подход к построению законов подобия, требуя построения более сложной зависимости от скорости удара.

Работа посвящена количественной оценке амплитуды вертикальных неотектонических деформаций стратиграфическим методом в пределах западного склона Воронежской антеклизы Восточно-Европейской платформы (ВЕП) с учётом колебаний уровня мирового океана, калиброванных на реперах ВЕП. На примере западного склона Воронежской антеклизы показано, что абсолютные неотектонические деформации различных кайнозойских реперных уровней не превышают по амплитуде первые десятки метров и связаны с инверсионными восходящими движениями на северном борту Днепровской впадины. В то же время верхнемеловые пострифтовые опускания, оцененные по туронскому реперу в южной части исследуемого района, остаются некомпенсированными. В целом, рассматриваемый регион можно охарактеризовать как неотектонически стабильный.

В работе проведен анализ записей микросейсмического шума в диапазоне высоких частот на территории Восточно-Европейской платформы, которая характеризуется мощными отложениями рыхлых осадочных пород, а также высоким уровнем антропогенных помех. С помощью кросс-корреляции сейсмических шумов показано, что для группы «Михнево» характерно присутствие как объемных, так и поверхностных волн. Для группы «Ростов» основной вклад в микросейсмический шум вносят поверхностные источники, обусловленные влиянием вблизи расположенного водохранилища.

Приведены основные результаты сейсмического мониторинга площадки Ростовской АЭС, проведенного малоапертурной группой ИДГ РАН в 2016 году. Описаны условия размещения, характеристика аппаратуры и конфигурация группы. Чувствительность группы в конкретных условиях установки обеспечивала регистрацию сейсмических событий с магнитудой 3 на расстояниях до 300 км; с магнитудой 1 на расстоянии 60 км от центрального датчика группы. Показано, что детальный анализ слабой сейсмичности с помощью малоапертурной группы возможен, но требует длительных наблюдений.

В статье рассматриваются скачкообразные изменения уровня безнапорного водоносного горизонта, приуроченного к карбонатному коллектору трещинно-порового типа, которые не связаны с техногенными помехами и градиентом атмосферного давления. Выделенные подъемы и снижения уровня с амплитудами до 28 мм приурочены преимущественно к границам зон интенсивной трещиноватости водовмещающих пород и подтверждают наличие магистральных микротрещин. Полученные данные использованы для анализа анизотропии фильтрационной свойств флюидонасыщенного коллектора.

В процессе добычи углеводородов в прискважинном пространстве пласта возникают различного рода напряжения и деформации, которые оказывают значительное влияние на его фильтрационные свойства. Цель исследования состояла в изучении зависимости фильтрационных свойств низкопроницаемой пористой породы от приложенного внешнего давления. Была проведена серия опытов по измерению проницаемости модельных образцов керна при различных давлениях обжатия, результаты эксперимента сопоставлены с существующими моделями стресс-зависимой проницаемости. Показано что на основании сопоставления модели с данными опыта можно судить о структуре порового пространства и характере проницаемости.

Экспериментальной моделью сланцевого пласта выбран углеводородный материал – полиметилметакрилат (оргстекло). В экспериментальной модели разрыв сланцевого пласта имитировался щелью, организованной в оргстекле. Щель продувалась потоком газа. Скорость потока измерялась опытным путем. Зафиксированы значения скоростей потока, испарение и унос массы материала с поверхности щели.

Приведены результаты анализа совместных вариаций электрического поля и метеопараметров атмосферы при прохождении холодных атмосферных фронтов по данным Геофизической обсерватории (ГФО) «Михнево» и Центра геофизического мониторинга г. Москвы ИДГ РАН за период наблюдений с 2010 по 2016 гг. Получена эмпирическая зависимость между амплитудой вариаций напряженности электрического поля, изменением и скоростью изменения температуры в результате прохождения атмосферного фронта в отсутствие сильной облачности и грозовых явлений. Разработана эмпирическая модель влияния холодных атмосферных фронтов на вариации электрического поля. Модель предполагает изменение пространственного распределения электрических зарядов в приземном слое атмосферы в результате интенсификации движения воздушных масс в переходной зоне атмосферного фронта.

Выполнен комплексный анализ микробарических пульсаций, вариаций электрического поля и микросейсмического фона в условиях г. Москвы в период сильных возмущений атмосферы. Показано, что ураганы и шквалы сопровождаются не только высокими скоростями ветра, но также высокоамплитудными микробарическими вариациями, вариациями амплитуд микросейсмического фона и вертикальной компоненты электрического поля. Установлено, что рассматриваемые сильные возмущения атмосферы за 1–4 часа предваряются повышенными амплитудами микробарических вариаций в диапазоне частот Брента-Вяйсаля, а также низкочастотными вариациями электрического поля и вариациями микросейсмического фона в диапазоне частот 0.008–20 Гц, что в совокупности с метеорологическими параметрами можно рассматривать в качестве комплексного прогностического признака приближающегося урагана (шквала). Такой подход может повысить надежность и оперативность прогноза.

Приведены оценки количества тепла Земли, выделяемого в период ее роста (первые 100 млн лет существования) при радиоактивном распаде короткоживущих 26Al, 60Fe и долгоживущих 238U, 235U, 232Th, 40K. Оценки проведены для двух наиболее правдоподобных групп моделей состава Земли: геохимической (за основу взят состав углистых хондритов) и космохимической (основа – состав энстатитовых хондритов).

Представлены результаты численного моделирования начальной стадии разлета плазменной струи с параметрами, аналогичными активным экспериментам КУМУЛЮС и ФЛАКСУС. Рабочее вещество плазмы и кинематические характеристики плазменной струи определяются конструкцией и параметрами генератора ВГПС-1 ИДГ РАН. Параметры среды соответствуют земной атмосфере на высотах 80 и 140 км. Впервые выполнена оценка влияния процессов переноса излучения на параметры расширяющегося плазменного образования на стадии инжекции. Показано, что перенос излучения значительно изменяет характеристики воздушной плазмы и его необходимо учитывать при интерпретации экспериментальных данных.

На основе данных из современных литературных источников и собственных квантовомеханических расчетов составлен банк данных по спектроскопическим характеристикам компонент алюминиевой плазмы в широком диапазоне величин газодинамических параметров. Рассчитаны таблицы коэффициентов поглощения, групповые и полные росселандовы и планковские пробеги излучения в диапазоне плотностей от 10-5 до 100 кг/м3 и температур от 0.3 до 50 кК. Составленные таблицы радиационных свойств алюминиевой плазмы использовались при численном моделировании активных геофизических экспериментов с выбросом горячей алюминиевой струи в ионосфере.

В работе предложена и обосновывается гипотеза, объясняющая сильное различие в степени ионизации высокоскоростной плазменной струи при инжекции в разреженную ионосферу и в искусственное воздушное облако в эксперименте «Северная звезда». Подчеркивается роль малых примесей (молекул и кластеров воды, продуктов их диссоциации) и ультрафиолетового излучения плазменной струи в предварительной ионизации фона. Основным механизмом поддержания высокой степени ионизации струи может оказаться обмен зарядом между нейтральным алюминием струи и заряженными частицами фона. Высокая скорость струи обеспечивает близость сечения обмена зарядом к максимуму сечения нерезонансной перезарядки.

В статье предложен метод верификации прогностических моделей нижней ионосферы по данным регистрации собственных частот Шумановских резонансов и их сопоставлению с расчетными данными. Расчеты собственных частот выполняются в трехмерной геометрии с неоднородным заполнением волновода земля-ионосфера слабоионизованной столкновительной плазмой. Представлены результаты для двух различных моделей нижней ионосферы для спокойных геофизических условий.

В работе представлены результаты мониторинга собственных частот Шумановского резонатора в ГФО «Михнево» во время солнечных рентгеновских вспышек Х-класса в сентябре 2017 года. Две вспышки (Х8.3 и Х9.4) имели близкую продолжительность, различаясь по энергии в 2 раза. Сдвиг собственных частот резонатора был зарегистрирован только в одном случае. Полученные результаты и их сравнение с теоретическими моделями показали необходимость учета в прогностических моделях не только балла (мощности) вспышки, но и ее интегральной энергетики.

В статье представлены результаты анализа алгоритмов решения навигационной задачи в условиях регистрации сигналов глобальных навигационных спутниковых систем GPS и ГЛОНАСС в ГФО «Михнево». Показано, что в классическом алгоритме выбор спутников из наблюдаемого созвездия должен вестись не по критерию высоты над горизонтом, а по числу обусловленности матрицы навигационной задачи. Применение адаптивных итерационных алгоритмов позволяет практически полностью компенсировать геофизические возмущения при сохранении двухчастотного режима. Предложена модификация штатного алгоритма позиционирования в ГНСС.

В работе анализируются разбросы (ошибки) в оценке на основе экспериментальных данных по трём частотам показателей степени флуктуационного спектра. Расхождения в оценках по парам частот объясняются различными путями прохождения ионосферы сигналами на разных частотах. Временные зависимости этих разбросов отражают пространственно-временные неоднородности флуктуаций, не описываемые степенными спектрами турбулентности. Проведённый фрактальный анализ данных ошибок позволяет выявить характерные масштабы и ориентацию тех структур ,которые формируют ионосферный спектр флуктуаций, генерирующих ошибки GPS связи.

В статье представлены результаты численного моделирования максимально применимых частот КВ диапазона в условиях изменения геомагнитного поля. Возмущения ионосферы, вызванные изменением геомагнитного поля, сказываются на распространении КВ радиоволн в Восточно-Сибирском секторе РФ. Наиболее критичными результатами являются: изменение интервалов доступности для работы в моде 1F2 и изменение частотных диапазонов для мод слоя Е, во многом определяющих помеховую обстановку в КВ диапазоне. Эффект хорошо наблюдается при сильно возмущённых условиях (Kp=7) и остаётся заметен даже при Kp=4 на длинных трассах, проходящих через Арктическую область.

Проведено экспериментальное исследование возможности фокусировки лазерного излучения с длиной волны 0.65 мкм сквозь рассеивающую суспензию полистироловых микросфер диаметром 1 мкм, взвешенных в дистиллированной воде, с использованием биморфного адаптивного зеркала. Для измерения локальных наклонов вектора Пойнтинга рассеянного излучения применялся датчик Шака-Гартмана, интенсивность и размер фокального пятна в дальней зоне регистрировались с использованием ПЗС-камеры. Выполнен сравнительный анализ эффективности фокусировки рассеянного лазерного пучка с использованием 3 методик: минимизации смещений фокальных пятен на датчике Шака-Гартмана, оптимизации фокуса алгоритмом «восхождения на холм» с использованием датчика Шака-Гартмана и оптимизации фокуса алгоритмом «восхождения на холм» по интенсивности фокального пятна в дальней зоне.

Путем сопоставления данных измерения полного электронного содержания ионосферы с фазовыми и амплитудными измерениями сигналов СДВ-ДВ-радиостанций на глобальных и региональных трассах исследуются особенности структуры и динамики ионосферной плазмы. Проведена реконструкция структуры ионосферы над территорией Европы. По результатам реконструкции выполнены исследования пространственно-временной динамики перемещающихся ионосферных возмущений для условий мощной геомагнитной бури 17 марта 2015 г. Анализ изменения фаз СДВ-радиосигналов совместно с данными измерения ПЭС является не только дополнительным инструментом для изучения динамики ионосферных возмущений, но и позволяет судить о возмущениях электронной плотности в различных слоях ионосферы.

Путем сопоставления данных измерения полного электронного содержания ионосферы с фазовыми и амплитудными измерениями сигналов СДВ-ДВ-радиостанций на глобальных и региональных трассах исследуются особенности структуры и динамики ионосферной плазмы. Проведена реконструкция структуры ионосферы над территорией Европы. По результатам реконструкции выполнены исследования пространственно-временной динамики перемещающихся ионосферных возмущений для условий мощной геомагнитной бури 17 марта 2015 г. Анализ изменения фаз СДВ-радиосигналов совместно с данными измерения ПЭС является не только дополнительным инструментом для изучения динамики ионосферных возмущений, но и позволяет судить о возмущениях электронной плотности в различных слоях ионосферы.

По современным представлениям на точность позиционирования ГНСС наибольшее влияние оказывают ионосферные неоднородности с характерными размерами от 100 м БШФФ-2017. Секция D. Физика атмосферы 93 до нескольких километров. Разработанная нами методика, использующая пространственно-разнесенные приемники ГНСС на трех базах от 250 м до 80 км, позволяет исследовать пространственно-временное распределение локальных ионосферных неоднородностей в среднеширотной ионосфере. Представлены результаты для бури в ионосфере 17 марта 2015 г.

Described are results of laboratory experiments which revealed regularities of gradual transition from stick-slip mode to aseismic creep. The behaviour of model gouge-filled fault was investigated with experimental setup of the spring-bock model. It was experimentally proven that small variations of a percentage of materials with velocity strengthening and velocity weakening properties in the fault principal slip zone may result in significant variation of the portion of seismic energy radiated during a fault slip event. The tests simulated different modes of interblock sliding whose characteristic values of scaled kinetic energy varied by several orders of magnitude, while differences in contact strength and shear stress drop remained relatively small. The obtained results led to the conclusion that the earthquake radiation efficiency and the fault slip mode are governed by the ratio of two parameters—maximum fault slip-weakening rate and shear stiffness of the enclosing massif. The ratio can be essentially changed by small variations of the material composition of the fault principal slip zone.

В статье приведены первые результаты экспериментов, направленных на исследование влияния инжекции флюида на режим деформирования межблокового контакта. Судя по полученным результатам, инжекция флюида может как снизить долю энергии деформирования, идущей на излучение сейсмической волны, так и увеличить ее. Наиболее эффективным является инжекция в контактную зону дилатантной жидкости, вязкость которой увеличивается с ростом скорости деформирования. При этом, в лабораторном эксперименте динамические срывы были подавлены не сразу после инжекции, а спустя один цикл деформирования. Полученные результаты, прежде всего, демонстрируют перспективность проведения дальнейших исследований в этом направлении.

В статье представлены результаты лабораторных экспериментов, в которых исследовались различные режимы деформирования модельного разлома. В ходе экспериментов были смоделированы как эпизоды скольжения с большой скоростью, соответствующие в натуре обычным землетрясениям, так и медленное скольжение – аналог низкочастотных землетрясений и событий медленного скольжения. Детально исследован процесс подготовки деформационных событий различного типа и выявлены характерные стадии данного процесса. Показано, что изменение кинематических параметров разлома описывается законом эволюции, единым для всех режимов скольжения. Полученные результаты подтверждают ранее высказанный тезис о единой природе деформационных событий различного типа от асейсмического крипа до обычных землетрясений. Анализ полученных результатов позволяет сделать вывод, что макроскопическим параметром, контролирующим деформационный процесс, является сдвиговая жесткость разлома. Для оценки величины и закономерностей изменения сдвиговой жесткости in situ могут быть использованы сейсмические методы.

Сейсмическая станция “Михнево” была сооружена в соответствии с Распоряжением Совета Министров СССР № 1134 РС от 06.02.1954 к югу от Москвы и приступила к работе в 1954 г. в целях контроля за проведением ядерных испытаний США и Англии. В течение десятилетий эта станция играла ведущую роль как экспериментальная база для отработки новых технических средств и методов контроля за ядерными испытаниями и была оснащена самым современным сейсмологическим оборудованием. В настоящее время, перенеся центр тяжести из военно-прикладной области в область фундаментальных геофизических исследований, она сохраняет лидирующую позицию в области сейсмологических наблюдений благодаря разработкам высококачественной отечественной цифровой аппаратуры и созданию единственной в центральной части Европейской территории России современной малоапертурной сейсмической группы, способной регистрировать слабые сейсмические события МL ≥ 1.5 – на расстоянии до 100 км.

Ударные волны и удар о Землю осколков Челябинского метеорита, упавшего 15 февраля 2013 г., возбудили различные типы волн в атмосфере и Земле. Используя времена вступления и азимуты прихода сейсмических и инфразвуковых волн, зарегистрированных станциями Международной системы мониторинга, мы установили три различных источника сейсмических и инфразвуковых волн.

Сейсмической группой ИДГ РАН “Михнево”, сейсмической сетью Геофизической службы РАН и минигруппой “Малин” (Украина) в районе Днепровско-Донецкого авлакогена, в пределах которого в промышленных масштабах проводятся промысловые и горно-взрывные работы с 2007 по 2015 гг., зарегистрирован ряд сейсмических событий. Особое внимание уделено анализу природы трех землетрясений, произошедших в 2015 г.

Modern noninvasive methods for probing the three-dimensional structure of materials, such as X-ray tomography, make it possible not only to obtain precise data on the structure of a sample but also to use them for assessing effective properties of the material by numerical methods. We have studied the pore structure of three samples of permeable porous ceramics by X-ray microtomography and numerically determined the permeability by solving the Stokes equation in the three-dimensional geometry of the pore structure. The data thus obtained are in excellent agreement with results of laboratory measurements. Morphological analysis of the pore structure (pore size distribution) allowed us to explain the results obtained for three samples of ceramics produced from granules of various sizes and shapes.

Field staining experiments in five different plots at two sites in Japan (Okaya in Nagano Prefecture and Konohara in Mie Prefecture) were undertaken to improve understanding of subsurface stormflow runoff within organic layers of natural forested hillslopes. This type of shallow lateral subsurface flow, specifically referred to as biomat flow, was observed only at the Okaya site based on staining experiments conducted under controlled water application rates. When the same irrigation rate (50–100 mm h−1) was applied to the Konohara site, overland flow without a significant shallow subsurface component was the dominant flow mechanism. Even in gently sloping (15–20°) forest soils at the Okaya site, biomat flow was responsible for lateral dye transport over much longer distances than subsurface flow in the matrix of mineral soil layers. Based on analysis of staining pattern images observed in the Okaya site, we conclude that (i) the organic biomat layer could be divided into two sub-layers of different structure, (ii) biomat flow transported the dye tracer longer distances than subsurface flow in the matrix and (iii) the biomat layer topography affected biomat flow by generating preferential flowpaths and subsequent percolation into the deeper soil. Based on field experimental results and pore-scale consideration of water infiltration into pores of soils with varying wettability properties, we hypothesized and developed a conceptual model for two key biomat flow mechanisms. The first mechanism considers lateral subsurface flow because of a permeability contrast between the much more porous and hence permeable biomat layer and the underlying mineral soil. The second mechanism involves a hydrophobic soil layer between the biomat and the underlying mineral soil. Flow across the hydrophobic layer is believed to occur when a threshold pore pressure is exceeded, i.e. as a result of a perched water table within the biomat layer. Lower pore pressures are needed to initiate flow when preferential flow paths exist, which are less hydrophobic than the surrounding organic layers. Numerical models of catchment hydrology should include lateral biomat flow when such layers are present in hillslope soils, in addition to typical subsurface flow within the soil matrix.

We reconstructed pore structures of three porous solids that differ from each other in morphology and topology of pore space. To achieve this, we used a stochastic method based on simulated annealing and X-ray computed microtomography. Simulated annealing was constrained by the following microstructural descriptors sampled along the principal and diagonal directions: the two-point probability function for the void phase and the lineal-path functions for both void and solid phases. The stochastic method also assumed the isotropic pore structures in accordance with a recent paper (Čapek et al. in Transp Porous Media 88(1): 87–106 (2011)). With the exception of the solid with the widest pores, we made tomographic volume images in high and low resolution, which enabled us to study the effect of resolution on microstructural descriptors and effective transport properties. A comparison of the two-point probability function and the lineal-path function sampled in the principal directions revealed that the pore structures derived from the tomographic volume images were slightly anisotropic, in opposition to the assumption of the stochastic method. Besides the anisotropy, other microstructural descriptors including the pore-size function and the total fraction of percolating cells indicated that the morphological and topological characteristics of the pore structures depended on the reconstruction method and its parameters. Particularly, the pore structures reproduced using the stochastic method contained wider pores than those obtained using X-ray tomography. Deviations between the pore structures derived from low- and high-resolution tomographic volume images were also observed and imputed to partial volume artefacts. Then, viscous flow of incompressible liquid, ordinary diffusion, Knudsen flow and self-diffusion of water in the reconstructed pore spaces were simulated. As counterparts, experimental data were measured by means of permeation and Wicke–Kallenbach cells and pulsed field gradient NMR. Deviations between the simulated quantities on the one hand and experimental data on the other hand were generally acceptable, which corroborated the pore-space models. As expected, the predictions based on the tomographic models of pore space were more successful than those derived from the stochastic models. The stationary effective transport properties, i.e. the effective permeability, the effective pore size and the geometric factor, were sensitive to a bias in long-range pore connectivity. Furthermore, the time-dependent effective diffusivity was found to be especially sensitive to relatively small morphological deviations between the real and reconstructed pore structures. It is concluded that the combined predictions of the effective permeability, the effective pore size, the geometric factor and time-dependent effective self-diffusivity of water are needed for the reliable evaluation of pore-space reconstruction.

In 2012, remote measurements of electromagnetic signals in the ELF/VLF band were taken at different points in Russia during experiments on artificial ionospheric modification with the powerful HF wave at the EISCAT heating facility (Tromsø, Norway). The use of the new, highly sensitive magnetometric equipment allowed signals with an amplitude of a few femtoteslas to be recorded at a distance of up to 2000 km from the source. Analysis of the measurement results discovered substantial differences in the amplitude-phase characteristics of the signals, which were caused by a change in helio-geophysical conditions in the region of heating and along the signal passage route, and features of signal propagation, which are related to their mode of guided propagation, the directivity of the source, and angles of reception.

В 2012 г. при проведении экспериментов по искусственной модификации ионосферы мощной КВ волной на нагревном стенде EISCAT-Heating (Тромсе, Норвегия) были проведены дистанционные измерения электромагнитных сигналов КНЧ/ОНЧ диапазона в различных точках России. Использование новой высокочувствительной магнитометрической аппаратуры позволило зарегистрировать сигналы амплитудой в единицы фемтотесла на расстояниях до 2000 км от источника. Анализ результатов измерений выявил значительные различия амплитудно-фазовых характеристик сигналов, обусловленные изменением гелиогеофизических условий в районе нагрева и на трассе распространения сигнала, и особенности распространения сигналов, связанные с их модовым волноводным распространением, направленностью источника, углами приема.

A phenomenological model of generation of magnetic signals under the deformation of a shattered rock in the body of a fault zone resulting from seismic pulse action is proposed. It is assumed that the geomagnetic variations appear at a change in the conductivity of the fragmented rocks at the boundaries of the joints. It is shown that the amplitudes of geomagnetic variations calculated based on the model are consistent with the data of the instrumental observations.

Предложена феноменологическая модель генерации магнитных сигналов при деформировании дробленой горной породы в теле разломной зоны в результате воздействия сейсмическим импульсом. Предполагается, что геомагнитные вариации возникают при изменении электрической проводимости фрагментированных горных пород на контактах отдельностей. Показано, что рассчитанные по модели амплитуды геомагнитных вариаций соответствуют данным инструментальных наблюдений

The article reports the lab experimentation on seismic/acoustic emission during different-type inter-block movements of rock mass. The fact that co-seismic displacement under induced earthquakes occurs along the existing interfaces is the basis for relatively simple tests on a slip-model plant. Using different materials as fracture fillers allowed modeling entire range of probable deformation modes. The deformation modes are conditionally grouped as creep or steady-state slip, unsteady-state slip and regular discontinuous slip or stick-slip. The authors show that statistics of acoustic emission during slip is described using the Gutenberg–Richter law. The strongest “representative” events under shearing occur quasiregularly, with probability much higher than follows from G–R law. The functional relation is found between the acoustic emission energy and the shear velocity.

Представлены результаты лабораторных экспериментов, в которых исследован сейсмоакустический эффект, наблюдаемый при различных режимах смещения по границам между блоками горной породы. Тот факт, что косейсмические перемещения при техногенных землетрясениях происходят по существующим границам раздела, служит основанием относительно простой постановки экспериментов на установке “слайдер”–модели. Использование различных материалов в качестве заполнителя трещины позволило смоделировать весь спектр возможных деформационных режимов. Последние, с известной долей условности, можно разделить на три группы. Первая — крип, или стабильное скольжение; вторая — нестабильное скольжение; третья — регулярное прерывистое скольжение, или стик–слип. Показано, что статистика акустических событий, излучаемых в процессе скольжения, описывается распределением Гутенберга—Рихтера. При этом наиболее крупные “характеристические” события при сдвиге происходят квазирегулярно с вероятностью значительно выше, чем следует из закона повторяемости. Установлена функциональная связь между потоком излученной энергии акустической эмиссии (АЭ) и скоростью деформации нарушения сплошности.

Представлены результаты натурных экспериментов, в которых исследовались различные режимы гравитационного соскальзывания блока по естественной поверхности разлома. Использование в качестве заполнителя межблокового контакта различных материалов позволило реализовать весь спектр деформационных событий. Последние можно условно разделить на три группы: ускоренный крип, медленные подвижки, динамический срыв. В экспериментах показано, что тип деформационных событий, которые могут быть реализованы, определяется как структурными параметрами межблокового контакта, так и вещественным составом его заполнителя. Разработаны основы новой геомеханической модели возникновения динамических событий разного типа. В основе модели лежит представление о том, что в процессе сдвигового деформирования субнормально к берегам трещины образуются «контактные пятна» - кластеры силовых мезоструктур, эволюция которых определяет режим деформирования. Пространственная конфигурация «контактных пятен» сохраняется на протяжении всего цикла «нагружение - срыв» и перестраивается в результате динамического события. Разрушенные силовые мезоструктуры способны замещаться аналогичными образованиями под влиянием сил межгранулярного взаимодействия, когда внешнее воздействие будет полностью скомпенсировано. До тех пор пока «контактные пятна» разрушены не полностью, динамика деформационного процесса определяется их реологией. При деформировании трещины, заполненной неоднородным материалом, миграция «контактных пятен» приводит не только к изменению параметров деформирования, но и к трансформации самого режима вследствие изменения реологии локальных участков межблокового контакта. С использованием фрактального анализа установлено, что для зарождения динамических срывов необходимо формирование пространственно-структурированных «контактных пятен», характеризующихся малой фрактальной размерностью; а события медленного скольжения могут существовать лишь в определенной параметрической области, названной нами «купол медленных событий». Установлено, что вероятность формирования медленных подвижек выше на участках разломов, характеризующихся максимальными значениями фрактальной размерности: в окончаниях разломов, в зонах их ветвления и взаимного пересечения.

Статья является первой частью экспериментальной работы, в которой изучались законо-мерности формирования различных режимов деформирования нарушений сплошности горных пород в лабораторных и полевых условиях. В лабораторных экспериментах изучены условия возникновения различных режимов скольжения для нескольких типов нару-шений - контактов прочных поверхностей, трещин, заполненных кварцевым песком, тальком и глиной. Используемый набор материалов и характеристики экспериментальной установки позволили реализовать в опытах широкий спектр режимов сдвигового деформирования - от динамических срывов с максимальной скоростью в десятки мм/с, до стабильного скольжения со скоростью 1 мкм/с. Радикальное изменение поведения трещины с глиносодержащим заполнителем происходит при ее обводнении. Длительность подвижки значительно возрастает тем в большей степени, чем выше содержание глины. Движение блока имеет длительную фазу (~100 с) плавного увеличения скорости смещения и фазу торможения примерно той же длительности. При этом скорость смещения снижается до нескольких десятков мкм/с. Как до начала перемещения блока, так на всех фазах его движения вплоть до полной остановки процесс происходит без излучения акустической эмиссии в пределах чувствительности аппаратуры. Показано, что медленные движения обладают всеми фазами, характерными для прерывистого скольжения, - разгоном, длительным скольжением, торможением, остановкой и фазой состояния покоя. Проведенные лабораторные эксперименты подтверждают ранее высказанный тезис о том, что все типы деформационных процессов в земной коре формируют единый ряд явлений.

Вариации прочности породы и различия в напряженном состоянии массива не могут объ-яснить наблюдаемой разницы в эффективности излучения сейсмических волн отдельными событиями, расположенными в пределах одного горнодобывающего предприятия. Выполненные лабораторные и численные эксперименты показали, что при несущественных изменениях предельной прочности трещины различие в сдвиговой жесткости приводит к радикальному изменению КПД сейсмического события. Полученные в лабораторном эксперименте соотношения между ключевыми параметрами необходимо учитывать при построении геомеханических моделей натурных объектов

В статье представлены результаты лабораторных экспериментов, в которых обнаружен новый эффект радикального изменения режима сдвигового деформирования трещины при переходе определенного предела вязкости тонких пленок флюида, смачивающего поверхности частиц материала- заполнителя.

The first part of this work is dedicated to the response of different-age structures to lunisolar tides, which can be considered as a sounding signal for monitoring the state of fluid-saturated reservoirs. The complex approach to processing the data obtained at the testing sites of the Institute of Geosphere Dynamics of the Russian Academy of Sciences, Institute of Geophysics of the National Academy of Sciences of Ukraine, and KIEV station of the IRIS seismic network is applied for recognizing the tides against the hydrogeological, barometric, and seismic series. The comparative analysis of the experimental and theoretical values of the diurnal and semidiurnal tidal components in the time series of ground displacements is carried out. The tidal variations in the groundwater level are compared with the tidal components revealed in the ground displacement of the different-age structure of the Moscow Basin and Ukrainian Shield, which are parts of the East European artesian region. The differences in the tidal responses of the groundwater level and ground displacement probably suggest that the state of the massif is affected by certain additional factors associated, e.g., with the passage of earthquake-induced seismic waves and the changes in the hydrogeodynamic environment.

В первой части данной работы исследован отклик разновозрастных структур на лунно-солнечные приливы, которые могут рассматриваться в качестве зондирующего сигнала для мониторинга состояния флюидонасыщенных коллекторов. Для выделения приливов из гидрогеологических, барометрических и сейсмических рядов применен комплексный подход к обработке данных, полученных на полигонах Института динамики геосфер РАН, Института геофизики НАН Украины и станции KIEV сейсмической сети IRIS. Выполнен сравнительный анализ экспериментальных и теоретических значений суточных и полусуточных приливных компонент в смещении грунта. Вариации приливов в уровне подземных вод сопоставлены с приливными компонентами, прослеженными в смещении грунта разновозрастных структур Московского и Украинского массивов, входящих в состав Восточно-Европейской артезианской области. Различие в откликах на приливы в уровне подземных вод и смещении грунта, вероятно, свидетельствует о влиянии дополнительных факторов на состояние массива, связанных, в частности, с прохождением сейсмических волн от землетрясений и изменением гидрогеодинамической обстановки

The authors analyze mine logs of seismic events in Poland, Finland, Canada, Russia and South Africa. For the analyzed events, induced seismic energy varies by 2-3 orders of magnitude at the same value of seismic moment. The upper and lower limits of the range correspond to “hard” and “tender” sources, respectively. The most probable cause of the wide scatter of the reduced energy values seems to be fluctuating properties of discontinuities due to change in material composition of fracture filler and in water content of rocks.

Проанализированы каталоги сейсмических событий рудников Польши, Финляндии, Канады, России и Южной Африки при ведении горных работ. Оказалось, что для рассмотренных событий приведенная сейсмическая энергия может изменяться на 2 - 3 порядка при одном и том же значении сейсмического момента. Верхняя граница диапазона соответствует “жестким”, а нижняя - “мягким” очагам. Наиболее вероятной причиной столь большого разброса значений приведенной энергии представляется вариация свойств нарушений сплошности, связанная с изменением вещественного состава материала-заполнителя трещин и обводненности массива.

The possibility of using the ASKRO spectrometric channel for monitoring the volumetric activity of the products of decay of radon 214Pb and 214Bi in the atmospheric boundary layer during precipitation is examined. The sensitivity of the spectrometer with respect to 214Pb and 214Bi in a measurement geometry determined using as the standard 1 mg 226Ra was equal to 0.015 ± 0.005 and 0.018 ± 0.006 m3/(Bq•sec), respectively, for confidence probability P = 0.95. According to the spectrometric measurements the total washout coefficient for 214Pb and 214Bi from clouds was equal to (1.1–5)•105. The role of radon and its decay products in the formation of rain drops is found to be very small.

Рассмотрена возможность использования спектрометрического канала АСКРО для мониторинга в приземном слое атмосферы при выпадении осадков объемной активности продуктов распада радона 214Pb и 214Bi. Чувствительность спектрометра по 214Pb и 214Bi в геометрии измерения, определенная с использованием эталона 1 мг 226Ra, составила 0,015 ± 0,005 и 0,018 ± 0,006 м 3/(Бк-с) соответственно для доверительной вероятности Р ═ 0,95. Суммарный коэффициент вымывания 214Pb и 214Bi из облака по результатам спектрометрических измерений составил (1,1-5)10 5. Роль радона и продуктов его распада в образовании капель дождя оценивается как незначительная

We demonstrate that several techniques based on waveform cross-correlation are able to significantly reduce the detection threshold of seismic sources worldwide and to improve the reliability of arrivals by a more accurate estimation of their defining parameters. A master event and the events it can find using waveform cross-correlation at array stations of the International Monitoring System (IMS) have to be close. For the purposes of the International Data Centre (IDC), one can use the spatial closeness of the master and slave events in order to construct a new automatic processing pipeline: all qualified arrivals detected using cross-correlation are associated with events matching the current IDC event definition criteria (EDC) in a local association procedure. Considering the repeating character of global seismicity, more than 90 % of events in the reviewed event bulletin (REB) can be built in this automatic processing. Due to the reduced detection threshold, waveform cross-correlation may increase the number of valid REB events by a factor of 1.5–2.0. Therefore, the new pipeline may produce a more comprehensive bulletin than the current pipeline—the goal of seismic monitoring. The analysts’ experience with the cross correlation event list (XSEL) shows that the workload of interactive processing might be reduced by a factor of two or even more. Since cross-correlation produces a comprehensive list of detections for a given master event, no additional arrivals from primary stations are expected to be associated with the XSEL events. The number of false alarms, relative to the number of events rejected from the standard event list 3 (SEL3) in the current interactive processing—can also be reduced by the use of several powerful filters. The principal filter is the difference between the arrival times of the master and newly built events at three or more primary stations, which should lie in a narrow range of a few seconds. In this study, one event at a distance of about 2,000 km from the main shock was formed by three stations, with the stations and both events on the same great circle. Such spurious events are rejected by checking consistency between detections at stations at different back azimuths from the source region. Two additional effective pre-filters are f–k analysis and F prob based on correlation traces instead of original waveforms. Overall, waveform cross-correlation is able to improve the REB completeness, to reduce the workload related to IDC interactive analysis, and to provide a precise tool for quality check for both arrivals and events. Some major improvements in automatic and interactive processing achieved by cross-correlation are illustrated using an aftershock sequence from a large continental earthquake. Exploring this sequence, we describe schematically the next steps for the development of a pro-cessing pipeline parallel to the existing IDC one in order to improve the quality of the REB to-gether with the reduction of the magnitude threshold.

This work presents new experimental data on differential amplitudes and travel times tBC_tDF of the PKPDF and PKPBC seismic waves in the Earth’s core beneath Southeastern Asia. In the equatorial paths, this area has a higher (by approximately 0.3%) velocity of propagation of seismic waves than in the standard model ak135. The features of the travel time residuals in the polar path indicate the presence of a local block of 250 Å~ 250 Å~ 200 km in size, for which the velocity value depends on the direction of propagation of the P _wave and is higher by 1.4% than in the model ak135. Attenuation of seismic waves in this block also depends on the direc-tion: it is two times higher for the polar direction than for the equatorial direction. These two factors indicate that this structure is characterized by features transverse isotropy, and anisotropy in the eastern hemisphere has a domain character.

В работе представлены новые экспериментальные данные о дифференциальных амплитудах и временах пробега tBC-tDF сейсмических волн PKPDF и PKРВС в земном ядре под Юго-Восточной Азией. Показано, что рассматриваемая область на экваториальных трассах имеет более высокую, примерно на 0.3%, скорость распространения сейсмических волн, чем в стандартной модели ak135. Особенности невязок времен пробега на полярных трассах указывают на существование локального объема 250 х 250 х 200 км, в котором величина скорости зависит от направления распространения продольной волны и на 1.4% больше, чем в модели ak135. Затухание сейсмических волн в этом объеме также зависит от направления прихода: для полярного направления затухание в два раза выше, чем для экваториального. Эти два фактора позволяют сделать вывод, что обнаруженная структура имеет особенности, присущие поперечно-изотропным средам, и анизотропия в восточном полушарии носит блоковый (доменный) характер.

Кросс-корреляция волновых форм является эффективным инструментом обнаружения и оценки характеристик сейсмических сигналов. Для целей Договора о всеобъемлющем запрещении ядерных испытаний использование кросс- корреляции может привести к глобальному снижению порога обнаружения на 0.3–0.4 единицы магнитуды. Успех метода в значительной степени зависит от наличия мастер- событий. В части I этой статьи показано, что в сейсмически активных регионах лучшие мастер- события (гранд- мастера), размноженные по узлам регулярной сетки, позволяют повысить эффективность обнаружения сейсмических сигналов и их источников. В сейсмически пассивных районах возможны два подхода к созданию глобальной сетки мастер- событий для сейсмических станций Международной системы мониторинга: размножение сигналов от гранд- мастеров и создание синтетических шаблонных сейсмограмм. Эффективность синтетических шаблонов зависит от точности предсказания формы и амплитуды сигналов, которая контролируются глубиной очага, механизмом и функцией источника, а также распределением скорости и затухания вдоль пути распространения. Мы тестируем синтетические сейсмограммы, полученные для трех механизмов источника: взрыв, надвиг, а также CMT- решение Гарварда для одно-го из афтершоков землетрясения вблизи Суматры 11 апреля 2012 г., и для двух моделей скорости: ak135 и CRUST2.0. Шестнадцать синтетических мастер- событий были распределены по сетке 1х1, которая покрывала зону афтершоков. Было построено пять кросс-корреляционных стандартных списков событий (XSEL). Вступления и события в этих бюллетенях сравнивались с теми, что получены с использованием реальных и гранд-мастер событий, а также с событиями в официальном бюллетене Международного центра данных (Reviewed Event Bulletin). Бюллетени XSEL на основе синтетических шаблонов, рассчитанных с использованием скоростной модели ak135 и функций источника взрыва и надвига с изотропной диаграммой направленности, похожи на бюллетени, построенные реальными и гранд- мастерами. Основным результатом исследования является количественное доказательство возможности охватить все асейсмичные области синтетическими мастер- событиями без потери в эффективности сейсмического мониторинга на основе кросс- корреляции.

Предлагается использовать метод кросс- корреляции волновых форм в целях сейсмического мониторинга Договора о всеобъемлющем запрещении ядерных испытаний ( ДВЗЯИ), доказав возможность построения глобальной сетки мастер- событий с шаблонными сигналами на станциях Международной системы мониторинга ( МСМ). В пределах сейсмически актив ных регионов очевиден выбор наиболее качественных и представительных записей от землетрясений в качестве шаблонов мастер- событий, что позволяет снизить амплитудный порог обнаружения в Международном центре данных ( МЦД) в 2–3 раза. Такое снижение порогового значения практически удваивает количество обнаруживаемых событий, что имеет решающее значение для сейсмического мониторинга в рамках ДВЗЯИ. Однако охват земного шара реальными мастер- событиями ограничен теми областями, где имеется природная сейсмичность. В данной работе, состоящей из двух частей, мы исследуем возможность заполнения глобальной сетки реальными и синтетическими мастер- событиями. В первой части мы оцениваем эффективность работы кросс-корреляции при использовании регулярной сетки, заполненной “ гранд- мастер” ( ГМ) событиями, шаблонные волновые формы которых являются точными копиями сигналов от мастер- событий высокого качества. Во второй части мы создаем и тестируем синтетические шаблоны сигналов для сейсмически малоактивных областей. Эффективность обоих подходов подвергается количественной проверке на последовательности афтершоков землетрясения на Суматре, произошедшего 11 апреля 2012 г. Ранее нами был создан бюллетень событий, использующих кросс- корреляцию с шестнадцатью реальными мастер- событиями, который является естественной точкой отсчета для оценки эффективности копирования сигналов от мастер- событий и синтетических шаблонных волновых форм. В части I нами установлено, что точные копии ГМ демонстрируют порог обнаружения на уровне реальных мастер-событий, то есть снижают порог обнаружения в 2–3 раза по сравнению с нынешней системой обработки в МЦД. Использование в МСМ сейсмических групп позволяет повысить разрешающую способность системы сейсмического мониторинга с помощью кросс-корреляции.

The Mikhnevo small-aperture array (SAA) was designed as an instrument for various regional seismic studies, including the compilation of a detailed catalogue of industrial blasts in the East European craton. This array includes 12 observation points arranged in three circles and equipped with SM3-KV shortperiod seismometers. The Institute of Geospheres Dynamics launched the array in 2004, and since that time it has been detecting up to 1000 industrial blasts per year. The Mikhnevo SAA uses beam formation for array processing. The stacking of indi-vidual waveforms reduced to a reference point allows the suppression of microseismic noise and improving the signal-to-noise ratio (SNR) relative to a three-component station. An improved SNR for a given signal is equivalent to a reduced detection threshold: much weaker signals can be detected with the use of a beam-formation technique. In turn, much more signals from small industrial explosions are detected. Weak signals are difficult to identify because of the higher uncertainty in the estimates of such characteristics as azimuth, slowness, and amplitude. Having a ten-year catalog of industrial blasts and the archive of raw digital records for this period, we apply a waveform cross-correlation (matched filter) technique, which has an extremely high relative location accuracy and thus identification capability. We have created a set of master events with relevant waveform templates for automatic data processing and creation of an accurate catalogue of industrial blasts.

A small-aperture seismic array consisting of seven three-component seismometers carried out continuous measurements of regional seismicity in a selected area of the Nizhni Novgorod nu-clear power plant during four months of 2013. Automatic signal detection using beamforming was applied separately for each motion component. Two horizontal components were trans-formed into radial and transverse components for the given values of the velocity and azimuth of the plane wave front. We have investigated the dependence of the coherence of microseismic noise on frequency, azimuth, and slowness, as well as determining the level of cross-correlation between signals on separate channels in order to estimate expected improvement in the signal-to-noise ratio, which is crucial for signal detection. Most signals detected by the seismic array from regional sources are associated with quarry blasts. Using repetitive explosions at seven quarries, we have quantitatively estimated and compared the increase in detection efficiency of regional seismic phases using a three-component small aperture seismic array and a subarray of vertical sensors. Horizontal sensors showed a higher efficiency in the detection of transverse waves, while the subarray of vertical sensors missed S-waves from certain events. For one of the nearby quarries, the vertical subarray missed up to 25% of events (5 of 20). The results of the investigation point to the need for the use of three-component seismic arrays for the study of regional seismicity.

Малоапертурная сейсмическая группа (МСГ), состоящая из семи трехкомпонентных сейсмометров, в течение четырех месяцев 2013 г. осуществляла режимные наблюдения региональной сейсмичности в районе выбранной площадки Нижегородской атомной станции. Автоматическое обнаружение сигнала с помощью метода регулируемого направленного приема применялось для каждой компоненты движения отдельно, причем две горизонтальные компоненты преобразовывались в радиальную и трансверсальную компоненты для заданных значений скорости и азимута фронта плоской волны. Для оценки ожидаемого увеличения отношения сигнал/шум, что имеет определяющее значение для обнаружения сигнала, мы исследовали зависимость когерентности микросейсмического шума от частоты, азимута и медленности, а также определили уровень взаимной корреляции сигналов на отдельных каналах. Основной поток сигналов, зарегистрированных сейсмической группой от региональных источников, связан с карьерными взрывами. Используя повторяющиеся взрывы на семи карьерах, мы количественно оценили рост эффективности обнаружения региональных сейсмических фаз с помощью трехкомпонентной МСГ по сравнению с подгруппой вертикальных датчиков. Горизонтальные датчики показали более высокую эффективность в обнаружении поперечных волн, в то время как подгруппа вертикальных датчиков пропускала S-волны от некоторых событий. Для одного из ближних карьеров вертикальная подгруппа пропускала до 25 % событий (5 из 20). Результаты работы указывают на необходимость использования трехкомпонентных сейсмических групп для исследования региональной сейсмичности.

Приведены результаты исследований, характеризующих роль и радиационные проявления мелкомасштабного аэрозоля над регионом Центральной Азии.

Предложена численная модель влияния уровня подземных вод на геомагнитные вариации на поверхности земной коры при наличии вертикальной неоднородности в виде разломной зоны. Предполагается, что эффект связан с изменением электродинамических характеристик приповерхностного слоя грунта в результате сезонных вариаций мощности безнапорного водоносного горизонта. В результате численного 3D-моделирования процесса показано, что при определенном выборе параметров задачи изменение уровня подземных вод в безнапорном горизонте вызывает синхронные вариации магнитного типпера с амплитудой, соответствующей значениям, полученным в результате инструментальных наблюдений.

Recent spacecraft missions detected presence of hydroxyl or water over large areas on the lunar surface. Several craters near the lunar poles have increased concentrations of hydrogen suggest-ing impact delivery of water. Using a numerical model, we have carried out computer simula-tions of the impacts of asteroids and comets in order to estimate the fate of water that can be contained in the projectiles. We find that at impact velocities below ~10 km/s a significant fraction of a stony projectile remains in the crater and is heated to temperatures below 1000 K. At these velocities hydrated minerals contained in carbonaceous projectiles decompose only partly. We conclude that the impacts of water-bearing carbonaceous asteroids could produce deposits of free and chemically bound water inside some lunar craters. The relative number of these craters may reach several percent. In contrast to asteroids, water from cometary impacts, even at low velocities, is vaporized, and vapor plume expands and disperses over the lunar surface.

It is difficult to find a Vesta model of iron core, pyroxene and olivine-rich mantle, and HED crust that can match the joint constraints of (a) Vesta’s density and core size as reported by the Dawn spacecraft team; (b) the chemical trends of the HED meteorites, including the depletion of sodium, the FeO abundance, and the trace element enrichments; and (c) the absence of exposed mantle material on Vesta’s surface, among Vestoid asteroids, or in our collection of basaltic meteorites. These conclusions are based entirely on mass-balance and density arguments, independent of any particular formation scenario for the HED meteorites themselves. We suggest that Vesta either formed from source material with non-chondritic composition or underwent after its formation a radical physical alteration, possibly caused by collisional processes, that affected its global composition and interior structure.

In recent decades, several missions have detected signs of water and other volatiles in cold, per-manently shadowed craters near the lunar poles. Observations suggest that some of these vola-tiles could have been delivered by comet impacts and therefore, understanding the impact delivery mechanism becomes key to explaining the origin and distribution of lunar water. During impact, the constituent ices of a comet nucleus vaporize; a significant part of this vapor remains gravitationally bound to the Moon, transforming the tenuous, collisionless lunar exosphere into a collisionally thick, transient atmosphere. Here, we use numerical simulations to investigate the physical processes governing volatile transport in the transient atmosphere generated after a comet impact, with a focus on how these processes influence the accumulation of water in polar cold traps. It is observed that the transient atmosphere maintains a certain characteristic structure for at least several Earth days after impact, during which time volatile transport occurs primarily through low-altitude winds that sweep over the lunar day-side. Meanwhile, reconvergence of vapor antipodal to the point of impact results in preferential redistribution of water in the vicinity of the antipode. Due to the quantity of vapor that remains gravitationally bound, the atmosphere is sufficiently dense that lower layers are shielded from photodestruction, prolonging the lifetime of water molecules and allowing greater amounts of water to reach cold traps. Short-term ice deposition patterns are markedly non-uniform and the variations that arise in simulated volatile abundance between different cold traps could potentially explain variations that have been observed through remote sensing.

A relic impact structure was recognized within the strewn field of the Agoudal iron meteorite. The heavily eroded structure has preserved shatter cones in a limestone basement, and remnants of autochthonous and allochthonous breccias. Fragments of iron incorporated into the allochthonous breccia have a chemical composition (Ni = 5.16 wt%, Ir = 0.019 ppm) similar to that of the Agoudal meteorite, supporting a syngenetic origin of the strewn field and the impact structure. The total recovered mass of Agoudal meteorite fragments is estimated at approximately 500 kg. The estimated size of the SE–NW-oriented strewn field is 6 × 2 km. Model calculations with minimal preatmospheric size show that a similar meteorite strewn field plus one small crater with observed shock effects could be formed by fragmentation of a meteoroid approximately 1.4 m in diameter with an impact angle of approximately 60° from the horizontal. However, the most probable is an impact of a larger, 3–4 m diameter meteoroid, resulting a strewn field with approximately 10 craters, 10–30 m in diameter each, plus numerous meteorite fragments. The calculated scattering area of meteorite shrapnel ejected from these impact craters could completely cover the observed strewn field of the Agoudal meteorite.

A large extraterrestrial body hit the Yucat.n Peninsula at the end of the Cretaceous period. Models suggest that a substantial amount of thermal radiation was delivered to the Earth’s surface by the impact, leading to the suggestion that it was capable of igniting extensive wildfires and contributed to the end-Cretaceous extinctions. We have reproduced in the laboratory the most intense impact-induced heat fluxes estimated to have reached different points on the Earth’s surface using a fire propagation apparatus and investigated the ignition potential of forest fuels. The experiments indicate that dry litter can ignite, but live fuels typically do not, suggesting that any ignition caused by impact-induced thermal radiation would have been strongly regional dependent. The intense, but short-lived, pulse downrange and at proximal and intermediate distances from the impact is insufficient to ignite live fuel. However, the less intense but longer-lasting thermal pulse at distal locations may have ignited areas of live fuels. Because plants and ecosystems are generally resistant to single localized fire events, we conclude that any fires ignited by impact-induced thermal radiation cannot be directly responsible for plant extinctions, implying that heat stress is only part of the end-Cretaceous story.

Свойства сейсмических волн, зондирующих внутреннее ядро, показывают, что оно является анизотропным: волны, распространяющиеся параллельно оси вращения Земли имеют более высокую скорость распространения и большее затухание, чем на трассах, параллельных экваториальной плоскости. В настоящей работе исследуется анизотропия в затухании сейсмических волн PKPDF в диапазоне частот 0.2-1.2 Гц в локальной области внутреннего ядра под Юго-Восточной Азией на глубинах до 350 км от границы с внешним ядром для сейсмических лучей разной ориентации. На экваториальных трассах зависимость дифференциальных амплитуд PKPBC и PKPDF от частоты почти линейная, в то время как на полярных наблюдается нелинейная зависимость от частоты, что указывает на анизотропию поглощения и различную текстуру среды.

Проведена модернизация таблиц радиационных свойств воздушной плазмы. На основе данных из современных литературных источников и собственных квантовомеханических расчетов составлен банк данных по спектроскопическим характеристикам компонент плазмы воздуха в широком диапазоне величин газодинамических параметров. В расчетах вероятностей радиационных переходов применялись методы самосогласованного поля Хартри-Фока, метод случайных фаз с обменом и др. Учтен ряд электронно-колебательных полос молекулярного азота и окиси азота, дающих значительный вклад в мощность излучения в ультрафиолетовой и инфракрасной областях спектра. Ранее в известных таблицах радиационных свойств воздуха [Авилова, Биберман и др., 1970; Каменщиков, Пластинин, 1971] эти полосы не учитывались.

В работе выполнен анализ данных по потокам жесткого рентгеновского и гамма излучения Солнца измеренных на спутниках GOES и RHESSI, а также данных о распространении радиоволн в СДВ и КВ диапазонов. Проведен их сравнительный анализ и сделано заключение о сильном влиянии жесткой части солнечного спектра, относящейся к области энергий квантов более 10кэВ, на формирование ионосферы Земли.

На основе картирования стратиграфическими и геоморфологическими методами трансгрес-сивной реперной поверхности понтического времени и соответствующей денудационной поверхности (~5 млн лет назад) определены абсолютные (с учётом изменения уровня моря), постпонтические или неотектонические деформации. Построена соответствующая карта абсолютных вертикальных деформаций, описаны отдельные геологические структуры и особенности их развития, дана геодинамическая интерпретация развития морфоструктур.

Исследования и диагностика процессов, происходящих в полярной ионосфере Земли, становятся всё более актуальными, так как влияние этих процессов на изменения параметров космической погоды в околоземном пространстве отражается на качестве и надёжности функционирования технологических систем. Использование платформ микроспутников, оснащённых служебными системами нового поколения, для установки соответствующей диагностической аппаратуры и проведения измерений этих параметров является реальной альтернативой дорогостоящим космическим проектам на крупных космических аппаратах.

Современные неинвазивные методы исследования трехмерной структуры материалов, такие как рентгеновская томография, позволяют не только получить точные данные о строении образца, но и использовать их для определения эффективных свойств материала численными методами. Исследовали структуру трех образцов пористой проницаемой керамики с помощью микротомографии, а затем численно определи проницаемость с помощью решения уравнения Стокса в трехмерной геометрии порового пространства. Полученные значения находятся в отличном соответствии с лабораторными измерениями. Морфологическое исследование порового пространства (распределение пор по размерам) позволило объяснить полученные результаты для трех образцов керамики, изготовленных из гранул различного размера и формы.

Для исследования динамики возникших в результате мощной геомагнитной бури 17 марта 2015 года ионосферных неоднородностей на средних широтах были использованы данные регистрации полного электронного содержания ионосферы и фазы радиосигналов ОНЧ диапазона от радиостанций, расположенных в различных районах Земли. Анализ изменения фаз СДВ радиосигналов совместно с данными измерения ПЭС является не только дополнительным инструментом для изучения динамики ионосферных возмущений, но и позволяет судить о возмущениях электронной плотности в различных слоях ионосферы.

В работе приводятся результаты экспериментов по фильтрации воды, осложненной частицами перлита, через трещинно-поровое пространство в плоско-радиальной постановке задачи. Отмечены как типичные закономерности, связанные с декольматацией пласта, так и неожиданное снижение проницаемости под действием ударов. В работе делается вывод о том, что в первое время после изменения состояния коллектора он находится в существенно нестабильном состоянии и может нетипично реагировать на внешнее воздействие.

С развитием методов исследования трехмерной структуры пористых и композитных материалов (микротомография, конфокальная микроскопия, FIB-SEM) и расширением базы вычислительных ресурсов появилась возможность моделировать различные процессы непосредственно в трехмерной геометрии образцов таких материалов (pore-scale modeling) для получения их эффективных свойств или более детального понимания исследуемых процессов, например, фильтрации. В настоящей работе мы решаем уравнение Стокса конечно-разностным методом с помощью схем второго и четвертого порядка точности в трехмерной области, геометрия которой повторяет микроструктуру исследуемого образца породы. Полученные для образца песчаника численные значения проницаемости находятся в соответствии с лабораторными измерениями.

Представлены результаты длительных (до года) натурных экспериментов, посвященных изменению состава, строения, физических и физико-механических свойств вулканогенных пород (андезитов и базальтов) под воздействием гидротермальных процессов (термальных растворов различного состава, температуры, рН) на территории Нижне- Кошелевского термального поля (Ю. Камчатка).

Обсуждается возможность использования эмпирического закона трения «Rate and State» для воспроизведения в численных расчетах режимов скольжения различных типов – «нормальных» и «медленных землетрясений», «эпизодов медленного скольжения». Показано, что канонический закон «Rate and State» позволяет добиться хорошего согласия с экспериментальными данными в случае динамических срывов в режиме прерывистого скольжениия, однако с его помощью не удается воспроизвести кинематические характеристики движения при переходных режимах скольжения. Для численного моделирования «медленных» движений предложено дополнить «Rate and State»-модель вязким членом. При этом динамическая вязкость зависит как от свойств собственно контакта, так и от условий нагружения. Показано, что модифицированная таким образом «Rate and State»-модель позволяет моделировать широкий спектр режимов сдвигового деформирования, в том числе и «медленные» движения.

По результатам сейсмологического мониторинга выполнен тематический анализ обоснования сейсмической безопасности атомных электрических станций и хранилищ отработанного ядерного топлива. Показана неэффективность режимных сейсмологических наблюдений с использованием автономных сейсмических станций, расположенных на удалении более 10 - 15 км друг от друга, что связано со слабой сейсмической активностью районов расположения атомных электрических станций и хранилищ отработанного ядерного топлива и с высоким уровнем помех в пунктах наблюдения. Такие условия диктуют необходимость использования при сейсмологическом мониторинге высокочувствительных систем наблюдения, позволяющих регистрировать очень слабые землетрясения с магнитудами вплоть до отрицательных. На основе анализа результатов наблюдения слабых событий существует возможность вероятностных оценок сейсмичности и обоснования современной геодинамической активности с учетом структурной приуроченности очагов землетрясений.

В статье рассмотрены результаты регистрации шахтной сейсмичности в районе Воркутинского каменноугольного месторождения. Сдвиговая модель очага сейсмического события в виде мгновенно вскрывающейся круговой трещины применялась для оценки моментных магнитуд зарегистрированных геодинамических событий, которые варьируются от 0,48 до 2,04. Сопоставление статических и динамических параметров очага позволило получить линейную корреляционную зависимость между моментной магнитудой и энергетическим классом событий. Оценка приведенной сейсмической энергии показала аномально сильную зависимость от масштаба события.

Используя разработанный нами оптический метод, который основан на поглощении твердым веществом (частицами суспензии) излучения от внешнего источника, экспериментально определяется профиль концентрации осаждаемых частиц вдоль потока суспензии, фильтрующейся через протяженный "прозрачный" фильтр. Расход суспензии измеряется с течением времени при постоянной разности давлений на входе и выходе из фильтра. С помощью методов механики сплошной среды, строится уравнение неразрывности выделенного движущегося объема суспензии, изменение массы частиц в котором пропорционально концентрации суспензии в единице объема фильтра с изменяющейся пористостью. По измеренной концентрации осажденных частиц вдоль фильтра находится коэффициент пропорциональности для предложенной зависимости интенсивности осаждения частиц от концентрации суспензии

В серии лабораторных экспериментов в постановке «слайдер»-модели исследовалась возможность изменения режима деформирования модельной трещины, заполненной многокомпонентным гранулированным материалом. Показано, что основным параметром, определяющим закономерности процесса разупрочнения контакта, является структура заполнителя трещины. Обнаружен критический переход от динамики «медленных» событий к «быстрым». Данный переход происходит при определенном изменении структуры заполнителя и сопровождается изменением закономерностей излучения накопленной упругой энергии.

Одной из перспективных технологий разработки кероген содержащих пород Баженовской свиты является термогазовый метод воздействия на пласт. Предполагается, что в процессе подобного воздействия может формироваться область пиролиза керогена, продвигающаяся в направлении фильтрационного потока. При пиролизе будет происходить увеличение пористости. В качестве аналога такого процесса, с гидродинамической точки зрения, может рассматриваться плавление части вещества, формирующего матрицу проницаемых пород, при разогреве фильтрационным потоком, имеющим высокую температуру. В статье представлено экспериментальное исследование динамики продвижения фронта плавления части вещества скелета при фильтрации через него разогретой вязкой жидкости. Описан процесс формирования и продвижения фронта плавления в виде проплавленных каналов. Описано явление формирования оторочки из расплавленного вещества на фронте плавления.

На основе анализа данных наземных, морских и спутниковых измерений были выявлены особенности генерации метана в атмосфере в различных регионах Арктики, обладающих различным потенциалом метаногенеза. Установлено, что мощность источников метана не включённых в официальные таблицы IPCC составляет более 250 Тг/год. Сезонные изменения потоков метана в Арктической зоне объясняют наличие устойчивого осенне-зимнего максимума концентрации метана. Сделан вывод о том, что источниками, поддерживающими значительную эмиссию метана в СП в осенне-зимний период являются водно-болотные угодья, озёра и эмиссия метана в континентальной и морской частях Арктики, обусловленная таянием многолетнемерзлых грунтов.

Обсуждаются необычные оптические явления, наблюдавшиеся в нашей стране и за рубе- жом при запусках некоторых отечественных ракет-носителей. Дается интерпретация этих данных с единых методологических и теоретических позиций.

Сделан обзор текущего состояния засоренности околоземного космоса вследствие космической деятельности человека и его перспективы на основе последних иссле- дований отечественных и зарубежных ученых и на примере реальных многолетних наблюдений. Рассмотрены некоторые специальные последствия прогрессирующего процесса техногенного засорения космоса (в том числе имеющие оборонные аспекты).

Формулируются актуальные задачи и направления научных исследований, а также технико-технологических разработок по физике и геомеханике формирования и развития очаговых зон разрушения горных пород в природных и горно-технических системах. Отмечается, что сформулированные направления исследований и разработок могут составить основу для международного мегапроекта по наукам о Земле междисциплинарного характера на тему «Разработка и создание многослойной геоинформационно-мониторинговой системы геомеханико-геодинамической и экологической безопасности в мире».

На поверхности многих исследованных астероидов обнаружены линейные структуры (борозды). Многие исследователи интерпретируют эти борозды как след катившихся по поверхности валунов. Данная гипотеза существенно зависит от колебаний поверхности астероида при образовании ударных кратеров. В предлагаемой работе приводятся результаты численного моделирования удара на астероиде диаметром 22 км (модельный «Фобос»). Показано, что интенсивность колебаний свободной поверхности зависит от предполагаемой структуры Фобоса. Во многих случаях гипотеза о катящихся камнях представляется неправомерной

В настоящей работе проведено исследование причин некорректного определения местоположения глобальной навигационной спутниковой системой GPS. На основе данных геофизической обсерватории (ГФО) «Михнево» за ноябрь 2014–март 2015 гг. был проведён анализ ошибок определения координат при их статистическом накоплении. Обнаружено, что распределение ошибок не подчиняется нормальному закону, а существующие алгоритмы ионосферной коррекции не в состоянии компенсировать влияние атмосферных планетарных волн, что приводит к периодическому ухудшению точности систем GPS.

Существенным фактором, затрудняющим работу горнорудных карьеров, является пыль в периоды массовых выбросов, сопровождающих взрывную отбойку рудной массы. Приводятся результаты численного моделирования процесса проветривания карьера в естественных условиях и при искусственной вентиляции с помощью струи, сформированной нагревом ограниченной области воздуха у дна карьера. Анализируются распределения концентрации пыли внутри карьеров с пологими и крутыми бортами, а также в прилегающей к карьеру атмосфере. Получены оценки времени проветривания карьера.

В работе рассчитаны линейные тренды неравномерных и равномерных временных рядов времен пробега Р волн для станций Тромсе, Кево, Апатиты и Нурмиярми. Полученный результат хорошо согласуется с прежними результатами о высоком отрицательном линейном тренде в сейсмоактивных районах и почти нулевом тренде на платформенных территориях.

Обсуждаются результаты численного моделирования аэродинамического режима воздушных потоков в приповерхностной зоне атмосферы Земли при наличии орографической неоднородности. Показано, что при определенных условиях в воздушном потоке формируются вихревые структуры, характер которых варьируется со временем. Приведены пространственные распределения как самих вихревых структур, так и концентрации возмущенных пылевых потоков. Результаты работы могут служить основой для оценки аэроэлектрических, электродного и других геофизических эффектов в приповерхностной атмосфере, а также при описании газодинамических процессов, сопровождающих вентиляцию карьеров при добыче полезных ископаемых открытым способом, в частности, с использованием взрывной технологии.

Рассмотрена возможность нахождения распределения радиоактивных элементов, определяющих радиогенное тепло Земли, по данным регистрации геонейтрино. Представлены последние данные по геонейтрино, полученные детекторами KamLAND и Borexino. Высказано предположение, что некоторое различие в данных радиогенного тепла, полученных этими детекторами, связано с наличием неоднородности распределения радиоактивных элементов в мантии. Приведены проекты детекторов, способных регистрировать геонейтрино, которые могут быть реализованы в ближайшие годы.

В ГФО «Михнево» опробована и внедрена методика определения положения молниевых разрядов с использованием регистраторов КНЧ/ОНЧ излучения, размещенных в пространственно разнесенных измерительных пунктах. Это позволило повысить точность лоцирования молний по сравнению с методом моноимпульсной пеленгации. Внедрение нового метода открывает возможность исследования корреляции электромагнитного излучения молний с вариациями сейсмических и акустических полей.

В работе приведены результаты исследования возмущений приземного электрического поля и изменения условий распространения волн СДВ диапазона во время рентгеновских вспышек на Солнце по данным аппаратуры, установленной в геофизической обсерватории ИДГ РАН «Михнево».

В статье рассматривается проблема подпитки околоземного долунного роя веществом, выброшенным при столкновениях допланетных тел с растущей планетой в процессе ее аккумуляции. Оценен поток эжекты с растущей Земли на гелиоцентрические орбиты в зависимости от времени и массы планеты в рамках ко-аккреционной модели формирования системы Земля–Луна.

В статье приведены результаты натурных экспериментов, направленных на установление возможной причины изменения режима деформирования нарушения сплошности. Показано, что доминирующий режим определяется внутренними характеристиками «контактных пятен» – участков разлома, в котором происходит наиболее интенсивное силовое взаимодействие. При деформировании трещины, заполненной неоднородным материалом, миграция «контактных пятен» может привести к трансформации деформационного режима вследствие изменения реологии локальных участков межблокового контакта.

Рассмотрены методы и программные средства для создания информационно-аналитической системы мониторинга опасных космических объектов. Представлены структура системы и описание ее функциональных компонентов, позволяющих обеспечить оперативную оценку астероиднокометной опасности и прогноз последствий столкновения опасных небесных тел с Землей. Приведены результаты работы системы в части моделирования движения космических объектов.

Буровзрывные работы (БВР) до сих пор остаются одной из важных технологий проходки перегонных и станционных тоннелей Московского метрополитена. Нередко БВР ведутся в нескольких или десятках метров от действующих перегонных тоннелей и технологических выработок. В этих случаях следует считаться с тем, что у БВР есть негативная сторона - сейсмическое действие на горный массив, действующие тоннели, охраняемые сооружения метрополитена и застройку, и инфраструктуру города. Высокая интенсивность сейсмического действия может стать препятствием к проведению БВР. Альтернативой БВР может служить проходка выработок по схожей с БВР технологией, но с заменой штатного ВВ на деструктор, у которого тротиловый эквивалент около 0,002

Ранее в журнале «Метро и тоннели» была описана система электронного инициирования зарядов при БВР, проанализированы достоинства этой системы по сравнению с пиротехническими средствами инициирования. В данной работе приведены результаты натурных исследований сейсмического действия БВР при проходке горных выработок метрополитена с электрической и электронной системой инициирования. В работе показаны недостатки технологии короткозамедленного взрывания с применением электродетонаторов. Продемонстрировано преимущество электронной системы инициирования I-KON, которая позволила реализовать пошпуровое взрывание с минимально возможным сейсмическим воздействием.

В работе приведены результаты натурных исследований сейсмического действия БВР по проходке горных выработок на строительстве Московского Метрополитена. Регистрация сейсмовзрывных волн проводилась, как в горных выработках, так и на дневной поверхности. Получены параметры сейсмовзрывных волн, степень затухания волны и коэффициент сейсмичности для ближней зоны, в которой максимальные ускорения в сейcмовзрывной волне достигали 20g, максимальные скорости - 0,2 м/с. В работе показаны недостатки технологии КЗВ с применением электродетонаторов. Продемонстрировано преимущество использования электронной системы инициирования I-KON, которая позволила реализовать пошпуровое взрывание с минимально возможным сейсмическим воздействием.

В статье кратко обсуждается проблема идентификации различных режимов деформирования разломов – есть ли это разные физические процессы или представители единого ряда событий.

На основе анализа оптических и электромагнитных экспериментальных данных ионосферного эксперимента «North Star» выявлены характерные признаки регистрации ионных волновых структур на ионах NO. Данные структуры регистрируются измерительными блоками после прохождения области плазменного облака в возмущённой оптической вспышкой фоновой плазме. Предложено теоретическое обоснование механизма возбуждения данных структур, которые идентифицируются как нелинейные ионно-циклотронные градиентно-дрейфовые волны.

Для решения множества фундаментальных и прикладных задач самых различных научных дисциплин и производственных направлений необходимо проектировать материалы с заданными структурными характеристиками и физико-химическими свойствами. Одним из методов количественного описания микроструктуры пористых материалов и сред являются корреляционные функции, с помощью алгоритма оптимизации «отжигом» на их основе можно проводить сборки/реконструкции структур. В настоящей работе мы производим создание 60 образцов гипотетических материалов различной структуры по аналитически заданным корреляционным функциям с тремя изменяемыми параметрами. В дальнейшем для каждого образца рассчитывается эффективная проницаемость на основе численного решения уравнения Стокса в его трехмерной геометрии. На основе анализа полученных результатов наглядно показано, что можно сконструировать пористый материал с желаемыми физическими (проницаемость) и структурными (линейные размеры порового пространства) свойствами.

Проведено моделирование параметров ударных волн в фотосфере с энергией характерной для солнечных вспышек. Получены температуры, значительно превышающие характерные для солнечного ядра. Предположено, что в этих условиях в ударных волнах мог происходить синтез тяжелых элементов, уносимых солнечным ветром при солнечных вспышках. Это могло влиять наряду с аккрецией на условия образования планетарных солнечных систем. Первые результаты были получены для взрывов с постоянной мощностью без учета радиационно-газодинамических процессов и гравитации. В дальнейших исследованиях учтены радиационно-газодинамические процессы при различных условиях выделения энергии взрывов и гравитацию при определении начальных размеров Солнца для оптимального выноса массы солнечным ветром. Предложенный механизм образования планетарных систем, учитывающий как аккрецию, так и принос солнечным ветром тяжелых продуктов нуклеосинтеза в ударных волнах в фотосфере может быть общим для Вселенной.

We derived model functions for the crater production size-frequency distribution and chronology of the asteroids 951 Gaspra, 243 Ida, 21 Lutetia and 4 Vesta, based on a lunar-like crater production function and a lunar-like chronology with a smooth exponential decay in impact rate for the first ~1 Ga of Solar System history. For Gaspra, Ida and Lutetia we find surface ages roughly in agreement with published data. Using the same approach for Vesta leads to results with high correlation to Ar–Ar reset ages of HED meteorites, for which a strong dynamical and spectroscopic connection to Vesta has been found. In contrast to recently published young formation ages of the Rheasilvia and Veneneia basins of about 1 and 2 Ga, respectively, we find for Rheasilvia a formation age of 3.5±0.1 Ga and for the Veneneia formation a lower limit of 3.7±0.1 Ga. For comparison we also give surface model ages for a preliminary version of a chronology (pers. comm. D.P. O׳Brien) based on the Late Heavy Bombardment theory. Error bars presented in our work stem only from statistical analysis of measured crater distributions and do not include the uncertainty of the used chronology model.

We derived crater production functions and chronology functions of Phobos for two scenarios, which likely represent the end-members of its dynamical evolution. Case A assumes that Phobos has been in its current orbit about Mars since its formation. Case B assumes a recent capture of Phobos and the impact history of an average Main Belt Asteroid. We determined the age of an average surface to the west of the Stickney crater and of the interior of the Stickney crater. The results indicate (i) the formation or major collision of Phobos about 4.3 Ga (Case A) or 3.5 Ga (Case B) ago, (ii) the Stickney crater is about 4.2 Ga (Case A) or 2.6 Ga (Case B) old and (iii) grooves probably formed between 3.1 and 3.8 Ga (Case A) or 44 and 340 Ma (Case B). Thus, Stickney seems to be older than the investigated grooves on Phobos.

We use the shape and gravity field of Vesta determined from observations of the Dawn spacecraft to place constraints on the asteroid’s interior structure. We compute a three-layer interior structure model by minimizing the power of the residual gravity anomaly. The densities of the mantle and crust are based on constraints derived from the Howardite–Eucrite–Diogenite (HED) meteorites. Vesta’s present-day shape is not in hydrostatic equilibrium. The Rheasilvia and Veneneia impact basins have a large effect on Vesta’s shape and are the main source of deviation from hydrostatic shape. Constraining a pre-giant-impact rotation rate and orientation of the spin axis from an ellipsoidal fit to the parts of Vesta unaffected by the giant impacts, and using the theory of figure, we can constrain the shape of the core. Our solution for Vesta’s crust–mantle interface reveals a belt of thick crust around Rheasilvia and Veneneia. The thinnest crust is in the floor of the two basins and in the Vestalia Terra region. Our solution does not reveal an uplift of the crust–mantle boundary to the surface in the largest basins. This, together with the lack of olivine detected by the Visible and Infrared Spectrometer (VIR) data in Rheasilvia and Veneneia, indicates that Vesta’s presumed olivine mantle was either not brought to the surface by these large impacts or was covered by ejecta from subsequent impacts.

The propagation of impact-induced shock wave inside a planetary embryo is investigated using the Hugoniot equations and a new scaling law, governing the particle velocity variations along a shock ray inside a spherical body. The scaling law is adopted to determine the impact heating of a growing embryo in its early stage when it is an undifferentiated and uniform body. The new scaling law, similar to other existing scaling laws, is not suitable for a large differentiated embryo consisting of a silicate mantle overlying an iron core. An algorithm is developed in this study on the basis of the ray theory in a spherically symmetric body which relates the shock parameters at the top of the core to those at the base of the mantle, thus enabling the adoption of scaling laws to estimate the impact heating of both the mantle and the core. The algorithm is applied to two embryo models: a simple two-layered model with a uniform mantle overlying a uniform core, and a model where the pre-shock density and acoustic velocity of the embryo are radially dependent. The former illustrates details of the particle velocity, shock pressure, and temperature increase behind the shock front in a 2D axisymmetric geometry. The latter provides a means to compare the results with those obtained by a hydrocode simulation. The agreement between the results of the two techniques in revealing the effects of the core–mantle boundary on the shock wave transmission across the boundary is encouraging.

We present the results of laboratory experiments on studying the formation of different slip modes on the interfaces in a rock massif such as aseismic creep, stick-slip, and periodic slow-slip events. It is shown that the way of releasing the accumulated elastic energy is determined by the mesoscale structure of the gouge rather than by its macroscopic strength characteristics. The evolution of the stress chains which are formed and broken during the displacement on the fracture, as well as the length and number of these chains, completely determines the regularities of the deformation. The role of these load-bearing elements in nature can be played, e.g., by the “contact spots,” which determine the regularities of stress concentration near the interblock boundary. We consider the effects of low-amplitude vibrations on stressed fractures. It is shown that, depending on the mode of deformation, the vibration impact can either reduce or boost the amplitude of separate events and the fraction of energy that is released dynamically. In the conclusion of the paper, we discuss the possibility of using the shear strength of the fault zone as a geomechanical parameter controlling the mode of deformation.

В статье приведены результаты лабораторных экспериментов, направленных на исследование закономерностей формирования различных режимов скольжения по границам раздела массива горных пород –асейсмического крипа, стик-слипа, периодических подвижек с малой скоростью. Показано, что способ реализации накопленной упругой энергии определяется не столько прочностными макрохарактеристиками заполнителя, сколько его структурой на мезоуровне. Эволюция силовых цепочек, которые образуются и разрушаются в процессе сдвига по трещине, их протяженность и количество полностью определяют закономерности деформирования. В природе роль таких несущих элементов могут выполнять, например, “контактные пятна”, определяющие закономерности концентрации напряжений в окрестности границы между блоками. Рассматривается эффект воздействия низкоамплитудных колебаний на напряженные нарушения сплошности. Показано, что в зависимости от режима деформирования, вибрационное воздействие может как уменьшить, так и увеличить амплитуду отдельных событий и долю энергии, реализуемой динамически. В заключительной части статьи обсуждается возможность использования сдвиговой жесткости разломной зоны в качестве геомеханического параметра, контролирующего деформационный режим.

Results of measurements and processing of sizes, energy, and power of radiation of a cloud formed after an explosion of 50/50 TNT/RDX and TNT cast charges with masses ranging from 0.01 kg to 1000 tons on the ground surface and at different heights in air are presented; the measurements and data processing are performed within wide temporal (up to 10 s/kg1/3) and spectral (up to 28 µm) intervals. The results are compared with available published data. These explosives have the maximum radiative characteristics owing to the high content of carbon in explosion products. Under conditions of explosions in air, the measured emitted energy approaches 50% of the explosion energy. In the case of ground explosions, the radiation is anisotropic because of screening by ejected soil, and the ratio of energies emitted upward and along the ground surface can exceed the order of magnitude.

Представлены результаты измерения и обработки размеров, энергии и мощности излучения взрывного облака в широких временных (до 10 с/кг1 /3) и спектральных (до 28 мкм) интервалах при взрывах литых зарядов ТГ 50/50 и тротила массой от 0.01 кг до 1000 т на земле и в воздухе на разных высотах. Приведено их сравнение с литературными данными. Эти взрывчатые вещества имеют максимальные радиационные характеристики вследствие высокого содержания углерода в продуктах. В условиях взрывов в воздухе измеренная излученная энергия приближалась к 50 % от энергии взрыва. При наземных взрывах излучение было анизотропно из-за экранировки выброшенным грунтом, а отношение энергий, излученных вверх и вдоль поверхности земли, могло превышать порядок величины.

The results of experimental investigations and thermodynamic calculations of the detonation of explosive proppant, an RDX-containing water-saturating sand, are reported. The material studied is of interest for use as an explosive additive to propping material injected into hydraulic fractures of oil-bearing beds. The tests were conducted in duralumin casings with cylindrical or planar inner channels. The dependences of the detonation velocity on the RDX content in the mixture in the range of 14 to 74 wt %, RDX and sand particle size, and initial temperature are examined. The critical detonation diameter of the charge decreases with increasing content RDX in the mixture, being only several millimeters at RDX contents of 30 wt % and above. Polydisperse RDX provides a high detonability of such mixtures; use of narrow particle size RDX fractions, especially coarse (0.4–0.7 mm), significantly increases the critical detonation diameter. As the initial temperature of the mixture is increased from 20 to 90°C, the critical detonation width decreases severalfold. The detonation of mixtures in a convergent planar channel occurs at a constant rate, which differs little from the detonation velocity measured in a cylindrical channel. Reaching the place where the opening of the channel is less than the critical width, detonation fails abruptly. Thermodynamic calculations of the detonation characteristics of the explosive proppant are performed using the BKWS equation of state under the assumption that the sand component behaves as an inert additive, being in mechanical equilibrium with the detonation products of the RDX-water mixture. A satisfactory agreement with the experimental data on the detonation velocity and its dependence on the RDX content is demonstrated. This makes it possible to conclude that RDX mixed with water-saturated sand detonates within a narrow reaction zone without significant convective heat transfer to the inert additive.

Проведены экспериментальные исследования и термодинамические расчеты детонации взрывного проппанта – гексогенсодержащего водонасыщенного песка. Исследуемый материал представляет интерес для использования в качестве взрывчатой добавки к расклинивающему наполнителю, который закачивается в трещины гидравлического разрыва нефтеносных пластов. Опыты проводились в дюралюминиевых оболочках с цилиндрическим и плоским каналами. Изучена зависимость скорости детонации от содержания гексогена в смеси в диапазоне от 14 до 74 вес. %, размеров частиц гексогена, песка и начальной температуры. Критический диаметр заряда, способного детонировать, снижается при увеличении содержания гексогена в смеси, составляя всего несколько миллиметров при содержании гексогена от 30 вес. % и выше. Полидисперсный гексоген обеспечивает высокую детонационную способность смесей; фракции частиц гексогена в узком диапазоне размеров, в особенности крупный гексоген с частицами размером 0.4–0.7 мм, заметно повышают критический диаметр детонации. При повышении начальной температуры смеси от +20°C до +90°C критическая толщина детонации снижается в несколько раз. Детонация исследуемых смесей в сужающемся плоском канале протекает с постоянной скоростью, которая мало отличается от скорости детонации, измеренной в цилиндрическом канале. Достигнув участка, где раскрытие канала оказывается меньше критического, детонация резко обрывается. Термодинамические расчеты детонации взрывного проппанта проведены с использованием уравнения состояния BKWS в предположении, что песок является инертной добавкой, которая находится в механическом равновесии с продуктами детонации смеси гексоген + вода. Получено удовлетворительное согласие с экспериментом по скорости детонации и ее зависимости от содержания гексогена. Это позволяет заключить, что гексоген в смеси с водонаполненным песком детонирует в пределах узкой зоны реакции, без существенных потерь тепла на нагрев инертной добавки путем конвекции

In the case of fracturing of rocks in subcritical stress state, the stress release due to fracturing could be accompanied by stress increase near the fracture tips, so the rock deformation near the tips could also generate elastic waves (so called "stopping-phase"). Results of experimental modeling of elastic wave generations by fatigue tensile fractures are considered. The model sample consisted of elastic layer made of rubber and fragile layer made of paraffin, the layers were bounded. The elastic layer was stretched and fixed, so the fragile layer was under static tension and started fracturing by tensile fractures. First fractures appeared in visually intact material, later fractures were preceded by a cloud of small "micro" fractures. The fracturing generated elastic waves, which had two components: one corresponded to fracturing of the fragile layer and had characteristic frequency 5-10 kHz; another one had frequency 100-300 Hz, opposite onset and corresponded to tension of elastic layer. It was concluded that tensile fractures in stressed rocks could be considered as a kind of a double-source of elastic waves: one source is the fracture itself, another source is an area of deformations due to stress increase in the vicinity of the fracture tips.

The article reviews research and development results in the sphere of designing unique apparatuses and equipment for modeling and in situ recording of nonlinear elastic waves and associated electro-magnetic emission in block-hierarchical rock masses in the condition of high stresses. The joint experimental outcomes and theoretical research findings gained by leading institutions of the Russian Academy of Sciences and its branches within recent decades, in the framework of integration interdisciplinary projects offer the methodology and instrumentation support for new promising systems of integrated geomechanical and geophysical monitoring of mining-induced earthquakes and rockbursts in Russian mines that may act as unique natural “laboratories” for both academic and applied research in geosciences

Обсуждаются прикладные аспекты современных представлений о блочно-иерархическом строении массивов горных пород, феноменологических основ теории волн маятникового типа применительно к формированию и реализации очаговых зон катастрофических событий в природных и горно-технических геосистемах. Устанавливается формализованная связь между концентрационным критерием прочности твердых тел по С. Н. Журкову, экспериментальным критерием “схлопывания” подземных выработок и канонической структурой спектрального состава волн маятникового типа по В. Н. Опарину, а также факту дальнодействия мощных взрывных воздействий в геосредах по М. А. Садовскому - В. В. Адушкину. Обосновывается необходимость энергетического подхода к описанию процесса трансформации упругой энергии очаговых зон катастрофических событий в кинетическую энергию движения составляющих их структурных элементов. Вводится новое понятие о “сейсмоэмиссионных событиях интерференционного типа”.

We present a new method for estimation of seismic coda shape. It falls into the same class of methods as non-parametric shape reconstruction with the use of neural network techniques where data are split into a training and validation data sets. We particularly pursue the well-known problem of image reconstruction formulated in this case as shape isolation in the presence of a broadly defined noise. This combined approach is enabled by the intrinsic feature of seismogram which can be divided objectively into a pre-signal seismic noise with lack of the target shape, and the remainder that contains scattered waveforms compounding the coda shape. In short, we separately apply shape restoration procedure to pre-signal seismic noise and the event record, which provides successful delineation of the coda shape in the form of a smooth almost non-oscillating function of time. The new algorithm uses a recently developed generalization of classical computational-geometry tool of α-shape. The generalization essentially yields robust shape estimation by ignoring locally a number of points treated as extreme values, noise or non-relevant data. Our algorithm is conceptually simple and enables the desired or pre-determined level of shape detail, constrainable by an arbitrary data fit criteria. The proposed tool for coda shape delineation provides an alternative to moving averaging and/or other smoothing techniques frequently used for this purpose. The new algorithm is illustrated with an application to the problem of estimating the coda duration after a local event. The obtained relation coefficient between coda duration and epicentral distance is consistent with the earlier findings in the region of interest.

Приведены результаты совместного анализа локальных длиннопериодных (с периодом более 1 сут) геомагнитных вариаций и уровня подземных вод безнапорного водосодержащего горизонта в центральной части Восточно-Европейской платформы на среднеширотной геофизической обсерватории "Михнево" ИДГ РАН (54,960N; 37,7740E) за период 2010-2011 гг. Наряду с известными вариациями с периодом около 27 суток и двумя гармониками указанной периодичности в ~6-8 и ~12-14 сут. установлены периодичности локальных вариаций магнитного поля Земли с периодом около 1 года. С другой стороны установлено, что основная по величине амплитуды вариация уровня подземных вод верхнего безнапорного горизонта характеризуется годовой периодичностью, определяемой притоком талой воды и ее инфильтрацией в весенне-летний период. В результате сравнения сезонных вариаций гидрогеологического режима и годовой цикличности геомагнитных вариаций показана значимая корреляция между сезонными вариациями одного из основных параметров магнитного поля - магнитного типпера, и изменением уровня подземных вод в безнапорном горизонте

The instrumental observations of geomagnetic variations in the middle latitudes are analyzed. The main periodicities are revealed in the background local variations of the magnetic field of the Earth. Besides the 27–29-day variations, which are associated with the rotation of the Sun around its axis, also the harmonic components with periods of ∼1, 6–8, 13–14, 57–60 days, and about a year are identified. It is shown that the periodicities in the background variations are both regular and sporadic. The peculiarities in the time behavior of some spectral components of geomagnetic variations are established.

Приведены результаты анализа данных инструментальных наблюдений за геомагнитными вариациями в условиях среднеширотной обстановки. Определены основные периодичности локальных фоновых вариаций магнитного поля Земли. Наряду с вариациями 27-29 сут., вызываемые периодичностью обращения Солнца вокруг своей оси, зарегистрированы также периодичности с периодами ~ 1; 6-8; 13-14; 57-60 сут и около года. Показано, что периодичности фоновых вариаций имеют регулярный и спорадический характер. Установлены особенности изменения во времени отдельных спектральных составляющих геомагнитных вариаций.

The combined approach is used for studying recent tectonic activity in the central part of the East European Craton (EEC).This approach incorporates the methods of automated lineament analysis and satellite geodesy with the conventional geological mapping analysis. The space tectonic map (space image based) is reconstructed, and morphostructures that are active at the recent and present tectonic stage are delineated by processing the Landsat image mosaic. The direction and rate of horizontal displacement of crustal blocks, which is caused by deep geodynamical processes, are determined using the GPS data. The study is preliminary since only few GPS stations within the EEC have sufficiently long time series of observations.

При изучении неотектонической активности центральной части Восточно-Европейской платформы (ВЕП) применен комплексный подход, включающий методы автоматизированного линеаментного анализа и космической геодезии с использованием результатов традиционного геологического картирования. В результате обработки мозаики космоснимков LANSAT построена космотектоническая схема и выделены морфоструктуры, активные на современном и неотектоническом этапе. Данные GPS-наблюдений использованы для определения направления и скорости горизонтального смещения блоков, обусловленного глубинными геодинамическими процессами. Исследования носят предварительный характер из-за недостаточного количества GPS-станций в пределах ВЕП, имеющих продолжительный временной ряд наблюдений.

The present communication provides the first data on the velocity section of the lithosphere down to 250–300 km depth using the receiver function method in the area of Mikhnevo Geophysical Observatory, Institute of Geosphere Dynamics, Russian Academy of Sciences (IGD RAS).

Приведены первые результаты определения скоростного разреза литосферы 250-300 км.

Одна из задач, решаемых малоапертурной сейсмической антенной (МСА) “Михнево”, –создание каталога промышленных взрывов в пределах Восточно-Европейской платформы.Начиная с момента установки антенны в 2004 г., с ее помощью ежегодно обнаруживаетсядо 1000 взрывов разной мощности. Метод формирования лучей, основанный на суммировании приведенных к центральной станции записей индивидуальных каналов сейсмической антенны, значительно повышает отношение сигнал/шум по сравнению с трехкомпонентной станцией и снижает амплитудный порог обнаружения. Это позволяет выделять очень слабые сигналы и значительно увеличивает число обнаруживаемых карьерных взрывов. Для сигналов с малым отношением сигнал/шум даже разрешающей способности антенны недостаточно для однозначной идентификации источника. Метод согласованного фильтра с шаблонными волновыми формами, тщательно выбранными из десятилетнего архива цифровых записей МСА “Михнево”, позволяет создать кросскорреляционные алгоритмы, обладающие исключительно высокой точностью относительной локации и идентификации карьеров. Это делает возможным создание эффективной системы автоматической обработки данных и выпуска точного каталога промышленных взрывов.

The results of numerical simulations of the Eltanin impact are combined with the available geological data in order to reconstruct the impact dynamics and to get some constraints on the impact parameters. Numerical simulations show that the Eltanin projectile size should be less than 2 km for a 45° oblique impact and less than 1.5 km for a vertical impact. On the other hand, we demonstrate that the projectile diameter cannot be considerably smaller than 1 km; otherwise, the impact-induced water flow cannot transport eroded sediments across large distances. The maximum displacement approximately equals the water crater radius and rapidly decreases with increasing distances. Numerical simulations also show that ejecta deposits strongly depend on impact angle and projectile size and, therefore, cannot be used for reliable estimates of the initial projectile mass. The initial amplitudes of tsunami-like waves are estimated. The presence of clay-rich sediments, typical for the abyssal basins in cores PS2709 and PS2708 on the Freeden Seamounts (Bellingshausen Sea, Southern Ocean) combined with numerical data allow us to suggest a probable point of impact to the east of the seamounts. The results do not exclude the possibility that a crater in the ocean bottom may exist, but such a structure has not been found yet.

Previous investigations of impact-induced atmospheric erosion considered mainly crater-forming impacts. Simple estimates show that in dense primary planetary atmospheres, considerable erosion could be induced by aerial bursts resulting from impacts of 1-10 km sized projectiles. Numerical simulations of cometary and asteroidal impacts (striking unmodified and crater-forming, impacting as fragmented meteorites, or causing aerial bursts) into dense (200 bar) atmospheres of different temperatures have been performed to obtain the amount of atmospheric erosion. The results have been approximated by simple analytical formulae.

The asteroid (4) Vesta, parent body of the Howardite-Eucrite-Diogenite meteorites, is one of the first bodies that formed, mostly from volatile-depleted material, in the Solar System. The Dawn mission recently provided evidence that hydrated material was delivered to Vesta, possibly in a continuous way, over the last 4 Ga, while the study of the eucritic meteorites revealed a few samples that crystallized in presence of water and volatile elements. The formation of Jupiter and probably its migration occurred in the period when eucrites crystallized, and triggered a phase of bombardment that caused icy planetesimals to cross the asteroid belt. In this work, we study the flux of icy planetesimals on Vesta during the Jovian Early Bombardment and, using hydrodynamic simulations, the outcome of their collisions with the asteroid. We explore how the migration of the giant planet would affect the delivery of water and volatile materials to the asteroid and we discuss our results in the context of the geophysical and collisional evolution of Vesta. In particular, we argue that the observational data are best reproduced if the bulk of the impactors was represented by 1-2 km wide planetesimals and if Jupiter underwent a limited (a fraction of au) displacement.

Background: Cavitation is a rather common and important effect in the processes of destruction of nano- and microscale particles in natural and technological processes. A possible cavitation disintegration of polymineral nano- and microparticles, which are placed into a liquid, as a result of the interaction of the particles with collapsed cavitation bubbles is considered. The emphasis is put on the cavitation processes on the interface between liquid and fine solid particles, which is suitable for the description of the real situations. Results: The results are illustrated for the minerals that are most abundant in gold ore. The bubbles are generated by shock loading of the liquid heated to the boiling temperature. Possibilities of cavitation separation of nano- and microscale monomineral fractions from polymineral nano- and microparticles and of the use of cavitation for beneficiation are demonstrated. Conclusion: The cavitation disintegration mechanism is important because the availability of high-grade deposits in the process of mining and production of noble metals is decreasing. This demands for an enhancement of the efficiency in developing low-grade deposits and in reprocessing ore dumps and tailings, which contain a certain amount of noble metals in the form of finely disseminated fractions. The cavitation processes occuring on the interface between liquid and fine solid particles are occasionally more effective than the bulk cavitation processes that were considered earlier.

The existing view of the photoemission properties of lunar regolith does not provide the unambiguous treatment of the parameters and distributions of photoelectrons over the illuminated part of the Moon. This is indicated by the present calculations of the density, temperature, and distribution function of photoelectrons. It has been demonstrated that the quantum yield of lunar regolith is the main parameter determining the generation of photoelectrons near the surface of the Moon. At present, this parameter is determined with significant uncertainty. The measurement of the quantum yield of regolith directly on the surface of the Moon has been proposed as a variant of the solution of the indicated problem. Such measurements can be performed in the framework of future lunar missions.

Существующие представления о фотоэмиссионных свойствах лунного реголита не дают однозначной трактовки относительно параметров и распределений фотоэлектронов над освещенной частью Луны. На это указывают проведенные в данной работе вычисления концентрации, температуры и функции распределения фотоэлектронов. Продемонстрировано, что основным параметром, влияющим на генерацию фотоэлектронов у поверхности Луны, является квантовый выход лунного реголита. На сегодняшний день имеется весьма существенная неоднозначность в определении его величины. В качестве варианта решения указанной проблемы предлагается проведение экспериментов по измерению квантового выхода реголита непосредственно на поверхности Луны. Последнее может быть осуществлено в рамках будущих лунных миссий.

The orbit of the Chelyabinsk object is calculated, applying the least-squares method directly to astrometric positions. The dynamical evolution of this object in the past is studied by integrating equations of motion for particles with orbits from the confidence region. It is found that the majority of the Chelyabinsk clones reach the near-Sun state. 67 percent of these objects have collisions with the Sun for 15 Myr in our numerical simulations. The distribution of minimum solar distances shows that the most probable time for the encounters of the Chelyabinsk object with the Sun lies in the interval from -0.8 Myr to -2 Myr. This is consistent with the estimate of a cosmic ray exposure age of 1.2 Myr (Popova et al 2013). A parent body of the Chelyabinsk object should experience strong tidal and thermal effects at this time. The possible association of the Chelyabinsk object with 86039 (1999 NC43) and 2008 DJ is discussed.

Two criteria for the applicability of a gas-dynamic approximation of continuous medium to describing the dispersion of combustion products of rocket propellants at high altitudes are formulated. Related numerical estimates are given for different launch vehicles and one upper stage with fairly extended boost phases. The use of a continuous medium approximation is shown to have a clear altitude restriction.

Сформулированы два критерия применимости газодинамического приближения сплошной среды к описанию разлета продуктов сгорания ракетных топлив на больших высотах. Приведены численные оценки по ним для различных ракет-носителей и одного разгонного блока, имеющих достаточно протяженные активные участки полета. Показано, что использование приближения сплошной среды имеет четкое ограничение по высоте.

It is demonstrated that it is required to create probabilistic statistical models of the ionosphere for calculating radio propagation in a wide frequency range. This, in fact, presents a new type of ionospheric modeling. These models are classified into pure statistical and deterministic-stochastic. We describe the key principles of building such models, present some examples of their construction, and discuss some difficulties arising from them.

Обоснована необходимость разработки вероятностно-статистических моделей ионосферы для расчета распространения радиоволн широкого диапазона частот, относящихся, по сути, к новому типу ионосферного моделирования. Рассмотрены основные принципы построения таких моделей, которые разделяются на чисто статистические и детерминировано-вероятностные. Приведены примеры разработки моделей и отмечены некоторые трудности при их создании.

We introduce order-k α-hulls and α-shapes - generalizations of α-hulls and α-shapes. Being also a generalization of k-hull (known in statistics as ''k-depth contour''), order-k α-hull provides a link between shape reconstruction and statistical depth. As a generalization of α-hull, order-k α-hull gives a robust shape estimation by ignoring locally up to k outliers in a point set. Order-k α-shape produces an ''inner'' shape of the set, with the amount of ''digging'' into the points controlled by k. As a generalization of k-hull, order-k α-hull is capable of determining ''deep'' points amidst samples from a multimodal distribution: it correctly identifies points which lie outside clusters of samples. The order-k α-hulls and α-shapes are related to order-k Voronoi diagrams in the same way in which α-hulls and α-shapes are related to Voronoi diagrams. This implies that order-k α-hull and α-shape can be readily built from order-k Voronoi diagram, and that the number of different order-k α-shapes for all possible values of α is proportional to the complexity of order-k Voronoi diagram.

The Mikhnevo small-aperture array (SAA) was designed as an instrument for various regional seismic studies, including the compilation of a detailed catalogue of industrial blasts in the East European craton. This array includes 12 observation points arranged in three circles and equipped with SM3-KV shortperiod seismometers. The Institute of Geospheres Dynamics launched the array in 2004, and since that time it has been detecting up to 1000 industrial blasts per year. The Mikhnevo SAA uses beam formation for array processing. The stacking of individual waveforms reduced to a reference point allows the suppression of microseismic noise and improving the signal-to-noise ratio (SNR) relative to a three-component station. An improved SNR for a given signal is equivalent to a reduced detection threshold: much weaker signals can be detected with the use of a beam-formation technique. In turn, much more signals from small industrial explosions are detected. Weak signals are difficult to identify because of the higher uncertainty in the estimates of such characteristics as azimuth, slowness, and amplitude. Having a ten-year catalog of industrial blasts and the archive of raw digital records for this period, we apply a waveform cross-correlation (matched filter) technique, which has an extremely high relative location accuracy and thus identification capability. We have created a set of master events with relevant waveform templates for automatic data processing and creation of an accurate catalogue of industrial blasts.

Представлены современные данные по глобальному тепловому потоку из недр и внутренним источникам энергии Земли. На основании последних опубликованных данных по регистрации геонейтрино детекторами KamLAND и BOREXINO сделан вывод о нереалистичности моделей состава BSE (Bulk Silicate Earth) с содержанием радиогенных элементов, производящим наибольшее количество тепла. Отмечена возможность существования в земных недрах гипотетического геореактора.

В статье рассматривается проблема однородности состава вещества, из которого формируются планетезимали, объединяющиеся в планету. Расширяется понятие зоны питания растущей планеты – учитываются ненулевой эксцентриситет орбиты планеты и влияние крупных тел на скорость ее роста. Рассматриваются различные механизмы перемешивания вещества в зоне питания планеты и их роль в формировании системы Земля–Луна.

В работе представлены результаты расчетов числа вторичных электронов, молекулярных, а также атомарных ионов азота и кислорода, создаваемых электронным ударом при воздействии на атмосферу электронов с энергиями 20 эВ–1 кэВ в диапазоне высот от 80 до 300 км. Приводятся сведения о спектрах вторичных электронов. Полученные значения числа вторичных электронов и ионов могут использоваться в расчетах ионизационной кинетики и радиофизических характеристик ионизуемых областей атмосферы.

Вхождение в атмосферу Челябинского болида произошло 15 февраля 2013 года в 3 часа 20 минут GMT. Сейсмические колебания, вызванные ударной волной от этого события, были записаны 6 сейсмическими станциями в районе п. Коркино, находящемся на эпицентральном расстоянии Δ = 10 км от координат точки максимальной яркости. В работе проведено определение амплитуды сейсмических колебаний. Амплитуда соответствует избыточному давлению для этой области. Измеренные времена вступления волны по сейсмограммам согласуются с теоретически рассчитанными временами. Выполнено вычисление азимута на источник и угла падения с использованием трехкомпонентного датчика. Рассчитанные координаты акустического источника на основе азимута и угла падения подтверждают тезис, что первый звук приходит из ближайшей точки траектории.

В статье обсуждаются результаты регистрации возмущений в ионосфере Земли, наблюдавшихся после падения Челябинского метеорита 15 февраля 2013 года. Представлены результаты трехмерных газодинамических расчетов, позволяющие объяснить механизм формирования этих возмущений.

В статье рассмотрены результаты натурных исследований длительностью до двух лет, проведенных в массивах гидротермальных глинистых грунтов на Нижне- и Верхне-Кошелевском термальных полях Южной Камчатки для изучения влияния гидротермальных процессов на изменения состава, строения и свойств вулканогенных пород без активного воздействия термальных вод. Показано, что в андезитах и базальтах, помещенных в массив гидротермальных глинистых грунтов, выщелачивание и растворение исходных минералов преобладают над образованием новых, в результате чего пористость пород увеличивается. Так, у самых устойчивых из исследованных пород - андезитов - произошло увеличение пористости с 10 до 13% за 2 года.

Приведены результаты экспериментов по проведению пассивного микросейсмического мониторинга для выявления изменений нефтегазовых коллекторов в процессе разработки месторождений.

Рассматривается движение по разлому с трением, описываемым двухпараме- трическим законом rate-and-state. предполагается, что техногенное воздействие приводит к уменьшению эффективной прочности разлома (например, за счет уве-личения порового давления при закачке жидкости). показано качественное из-менение характера прерывистого скольжения при изменении критической вели-чины сдвигового напряжения. анализ решений системы уравнений проводится с использованием метода грассбергера-проккаччиа. получено, что при измене-нии критических напряжений от 5 до 30 мпа корреляционная размерность рас-тет линейно; при более высоких значениях критических напряжений наблюдается тенденция к насыщению зависимости корреляционной размерности от критиче-ских напряжений.

На радиолокационных изображениях (РЛИ), полученных со спутников Radarsat-1 и Radarsat-2 в апреле - июне 2012 г. на поверхности Каспийского моря в районе п-ова Мангышлак и его подводного продолжения, разделяющего котловины Северного и Среднего Каспия, было обнаружено большое количество мелких нефтяных пятен. Область появления этих пятен приурочена в основном к молодой Скифско-Туранской плите, а также к соседним участкам Прикаспийской впадины древней Восточно-Европейской платформы. Подавляющее число пятен нефти появилось в период 25 мая - 1 июня 2012 г. Установлено, что периодичность срабатывания грифонов в виде «бегущих волн» может отражать импульсы повышенной геодинамической активности недр тектонической впадины Каспийского моря, которые могли быть спровоцированы природно-техногенными факторами. Рассматриваются геолого-геофизические предпосылки и причины активизации грифонов. Активность грифонов свидетельствует о возможной нефтегазоносности локальных структур.

В предыдущих наших работах была дана оценка гравитационного эффекта смещения оси вращения Земли и показана принципиальная возможность регистрации этого эффекта современными инструментальными средствами. При этом было показано, что создание системы глобального мониторинга такого эффекта на фоне других помех приводит к проблеме адекватного описания гравитационного поля Земли, необходимость решения которой требует уточнения формулировки закона всемирного тяготения и пересмотра существующих методов расчета силы тяжести, что неизбежно влечет за собой корректировку представлений о характере современных геологических процессов и особенностях эволюции Земли. Решение этой задачи тесно связано с вопросами метрики пространства-времени и круговорота вещества и энергии Земли. В настоящей статье обсуждаются вопросы эволюции представлений о метрике пространства-времени в окрестности Земли и уточнения формулировки закона всемирного тяготения.

На радиолокационных изображениях, полученных со спутников Radarsat-1 и Radarsat-2 в апреле–июне 2012 г. на поверхности Каспийского моря в районе п-ова Мангышлак и его подводного продолжения, разделяющего котловины Северного и Среднего Каспия, было обнаружено большое количество мелких нефтяных пятен, идентифицированных как грифонные. Область появления этих пятен приурочена в основном к молодой Скифско-Туранской плите, а также к соседним участкам Прикаспийской впадины древней Восточно-Европейской платформы. Подавляющее число пятен нефти появилось в период 25 мая -1 июня 2012 г. Периодичность срабатывания грифонов в виде “бегущих волн” отражает импульсы повышенной геодинамической активности недр тектонической впадины Каспийского моря, которые могли быть спровоцированы природно-техногенными факторами. Рассматриваются геолого-геофизические предпосылки и причины активизации грифонов. Активность грифонов свидетельствует о возможной нефтегазоносности локальных структур.

Проведено исследование поведения металлов, диэлектриков, взрывчатых веществ и различных конструкций при ударе разогнанных взрывом порошков и швейных игл. Наблюдался эффект сверхглубокого проникания в стали и дюрале с длиной измеренных каналов до 100 диаметров частиц при скоростях удара порошков корунда и вольфрама до 2 км/с. Предложен струйный механизм сверхглубокого проникания порошков в металлы. Предполагается, что струя проникает в трещину при хрупком разрушении, когда пластическое течение не успевает развиваться из-за высокой скорости деформации. Показана возможность разрушения иглами разных конструкций, блоков плексигласа, против метеоритных экранов, контейнеров с упругими и взрывчатыми материалами с выделением энергии намного превышающей энергию игл. Полученные результаты и разработанные разгонные устройства применялись для моделирования удара метеоритов и космического мусора, входа метеоритов в атмосферу и стойкости противометеоритных экранов, в активных геофизических ракетных экспериментах.

Проведено исследование влияния солнечных вспышек и ветра на формирование газопылевого облака и планет. Предположено, что у поверхности Солнца возникали сильные ударные волны с энергией характерной для солнечных вспышек. В ударных волнах происходил ядерный синтез тяжелых элементов уносимых солнечным ветром. Анализ решения взрывных задач в фотосфере показал, что для получения массы планет как в настоящее время необходима примерно на три порядка большая масса вещества, уносимая солнечным ветром, чем теперь. Это возможно при меньшей массе солнца и второй космической скорости в период формирования планет, которые определены из сопоставления взрывных расчетов и зависимости 2 космической скорости от массы для Солнца и Юпитера.

Проведен анализ дифференциальных времен пробега и дифференциальных амплитуд сейсмических волн PKPDF и PKPBC, зондирующих внутреннее ядро под Юго-Восточной Азией. Показано, что область на экваториальных трассах (угол между направлением сейсмического луча в ядре и осью вращения Земли больше 350) имеет более высокую, примерно на 0.3%, скорость распространения сейсмических волн, чем в стандартной модели ak135. Особенности невязок времен пробега на полярных трассах ( <350) указывают на существование локального объема 250х250х200 км3, в котором величина скорости зависит от направления распространения продольной волны. Установлено, что затухание сейсмических волн в этом объеме также зависит от направления прихода волны – для полярного направления затухание в три раза выше, чем в экваториальном направлении.

Контроль уровня сейсмичности района размещения крупных инженерных объектов необходим даже на слабоактивных в сейсмическом отношении территориях. В условиях европейской части России эта задача должна решаться путем проведения комплексного геофизического мониторинга. В статье рассмотрены преимущества использования малоапертурных сейсмических групп для регистрации слабых сейсмических событий, описан опыт ИДГ РАН в работах по комплексному геофизическому мониторингу отдельных участков земной коры

Для мониторинга сейсмических явлений на участках размещения АС сети регулярных (региональных) сейсмических станций, как правило, недостаточно, поэтому для контроля стабильности сейсмического режима площадки размещения АС должна быть предусмотрена организация локальной системы высокочувствительных сейсмических наблюдений. В статье рассмотрены примеры локальных сейсмологических наблюдений в России на платформенных участках размещения АЭС в период инженерных изысканий для выбора площадки и разработки проекта.

Приведен анализ результатов инструментальных наблюдений за геофизическими полями в зонах влияния тектонических разломов. Показано, что разломные зоны характеризуются существенно более высокими по сравнению с серединными участками структурных блоков земной коры вариациями геофизических полей, интенсивным откликом на слабые внешние воздействия в виде твердого лунно-солнечного прилива и барических вариаций атмосферы, а также интенсивностью релаксационных процессов. Преимущественно в разломных зонах наблюдается трансформация энергии между геофизическими полями разной природы.

15 февраля 2013 г. крупный каменный метеорит вошел в атмосферу Земли и разрушился в несколько этапов над городом Челябинск. Основная масса мелких обломков выпала на поверхность с малой (терминальной) скоростью, однако зафиксировано падение, по крайне мере одного крупного (~600 кг) обломка, пробившего лед на озере Чебаркуль. Позднее этот обломок (или его часть) был извлечен со дна озера. В месте падения образовалась округлая полынья размером 6-8 м, частично покрытая плавающим льдом. В настоящей работе проводится предварительный анализ процесса образования этой полыньи с учетом минимальной (обнаруженной) массы обломка и его скорости, оцененной величиной, близкой к терминальной скорости падения данной массы в атмосфере.

Для оценки состояния урбанизированной территории обычно применяется комплексный подход, включающий классические методы - инженерно-геологические, геоморфологические и геофизические методы исследований. В данной работе впервые был проведен линеаментный анализ техногенно-измененной геологической среды под влиянием антропогенной деятельности. Интерактивное дешифрирование мозаики космоснимков Московского региона с использованием программного пакета LESSA позволяло провести экспресс-анализ техногенной нагрузки на ландшафт, охарактеризовать геодинамически активные зоны и природно-техногенную среду мегаполиса

На основе модели Барриджа-Кнопова и закона трения Дитриха-Руины предложена численная модель пригодная для описания процесса деформирования разломной зоны, отдельные участки которой обладают свойствами фрикционного разупрочнения. Тестовые расчеты показали, что возникшая на локальном участке динамическая неустойчивость при определенных условиях может охватывать обширные области. Скорость распространения деформационной волны определяется свойствами разломов более мелкого иерархического уровня.

Анализ большого объема данных широкого диапазона масштабов сейсмических событий продемонстрировал существование немонотонной зависимости величины кажущегося напряжения от масштаба, которая определяется различным генезисом землетрясений (техногенная сейсмичность, малые землетрясения и афтершоки, средние и крупнейшие землетрясения). Эта зависимость довольно слабая (усредненная поинтервально величина Es/M0 изменяется всего лишь в пределах одного порядка) по сравнению с разбросом значений Es/M0.

В работе проводится анализ сейсмических событий различного масштаба для апробации метода численной коррекции датчиков. Результаты регистрации промышленных взрывов подтвердили возможность использования геофонов типа GS-20DX при проведении сейсмических наблюдений в платформенных условиях в диапазоне частот 4-14 Гц. Ошибка определения магнитуд по записям короткопериодных сейсмометров с расширенными частотными характеристиками, используемых для мониторинга землетрясений, соответствует точности оценок магнитуд в каталогах.

В работе приведены результаты мониторинга сейсмовзрывных волн при массовых взрывах на разрезе Черногорский в Хакасии. Были зарегистрированы велосиграммы и акселерограммы на дневной поверхности и в горных выработках шахты Хакаская. Показано, что в горных выработках амплитуды сейсмовзрывных волн в 3 раза меньше, чем на дневной поверхности. По зарегистрированным акселерограммам предложено рассчитывать волны напряжений и деформаций. Их параметры определяют устойчивость горных выработок.

Представлены результаты измерений сейсмического действия массового взрыва при отработке слепого рудного тела. Определены максимальные скорости колебания почвы в районе взрыва и балльность.

В настоящей работе собран и проанализирован обширный ряд экспериментальных данных во всем диапазоне масштабов, который относится к сейсмотектонике и геомеханике, - от микрособытий с линейным размером очага порядка нескольких сантиметров до мегаземлетрясений. Рассмотрены закономерности изменения геометрических характеристик разноранговых разломов и трещин и их механических свойств, линейных размеров очага землетрясения, времени подготовки динамического события и сейсмической энергии. Усреднение по всему диапазону масштабов дает соотношения, близкие к закону геометрического подобия. Более детальное рассмотрение позволяет обнаружить, что существует несколько иерархических уровней, в которых изменение параметров событий с масштабом происходит по разным законам, зачастую сильно отклоняющимся от законов подобия. Показано, что линейные размеры L~500-1000 м являются некоторой переходной областью, которая оказывается границей между двумя диапазонами, в которых масштабные соотношения существенно разные. Следует отличать и шахтную сейсмичность, глубина очагов которой невелика. Установлено, что для землетрясений Байкальской рифтовой системы отмечается аномальная тенденция сильного возрастания приведенной энергии, рассчитанной по величине класса события, с увеличением масштаба. В интервале моментных магнитуд от 5 до 6.3 усредненное приведенное значение сейсмической энергии превышает среднемировую величину для этого диапазона, по крайней мере, в 25 раз. Необходимо разобраться, является ли этот эффект артефактом, связанным с некорректным расчетом величины сейсмической энергии, или имеет место не объясненный пока физический эффект.

В асейсмичных регионах, таких как Восточно-Европейская платформа,воздействие слабых сейсмических колебаний, в том числе и от техногенных источников, может оказаться важнейшим фактором, определяющим сейсмобезопасность инженерных сооружений и природных объектов. Это требует разработки новых методик геофизического и деформационного мониторинга, которые должны быть приспособлены к условиям конкретных охраняемых объектов

Продолжено исследование эффекта электрической поляризации, возникающей при ударном воздействии на образцы горных пород, проявляющих аномальный пьезоэлектрический эффект. Физическая модель поляризации построена на рассмотрении дислокационной динамики в области фронта волны сжатия, дающей основной вклад в величину эффекта. Определена величина модуля связи ударной поляризации и временной производной механического напряжения, которая равна 10-8 Кл/(м2∙МПа).

Показано, что в результате нагрева воздуха инфракрасным излучением горячей лавы, развивается газодинамическое течение, которое приводит к образованию слоя повышенной температуры на нижней границе тропопаузы. Рассмотрено воздействие на атмосферу лавовых полей с характерным размером 1–10 км. Чем больше размер, тем быстрее развивается теплый слой, способный поднять тропопаузу, что в последующем может изменить фотохимические процессы в нижней стратосфере.

Исследовано влияние ветра на формирование облака из смеси метана и воздуха при струйном истечении метана из мощного геологического источника. Показано, что ветер несколько видоизменяет механизм переноса метана из струи в облако по сравнению со случаем невозмущенной ветрами атмосферы и в значительной мере влияет на высоту всех облачных структур. Проведенные расчеты продемонстрировали, что с ростом размеров струи может образовываться протяженная в вертикальном направлении область с параметрами, достаточными для воспламенения.

С использованием полученных из наблюдений астрометрических положений [Popova et al., 2013] была определена орбита Челябинского объекта. На основании полученной орбиты исследовано движение объекта в прошлом и изучена возможность связи Челябинского объекта с астероидами 86039 (1999 NC43) и 2008 DJ.

Одним из наиболее длительных явлений после 10-секундного болида при пролете Челябинского метеорита (далее – ЧМ) был шлейф, оставленный метеороидом в атмосфере. Этот след напоминал гигантский инверсионный след самолета, был хорошо виден над Уралом в течение получаса, постепенно размывался ветрами и дрейфовал на юг и позднее – на восток. Именно его можно увидеть на большинстве фотографий события. В статье описывается численное моделирование шлейфа в течение первых 3 минут после пролета метеороида. Результаты сравниваются с наблюдениями. Анализируется возможность образования баллистического плюма при небольших ударах.

Сделаны теоретические оценки магнитуды сейсмического события, обусловленного падением Челябинского болида. Путем численого моделирования образования и распространения ударных волн, вызванных торможением космического тела и выделением энергии вдоль его траектории в атмосфере, рассчитаны давления на поверхности Земли. Определение магнитуды сейсмического источника проводится с помощью формул, основанных на решении задачи Лэмба для полупространства, на границе которого действует давление. Константы в формулах были ранее выбраны в соответствии с опубликованными данными по экспериментальным взрывам в воздухе. В предположении, что кинетическая энергия Челябинского космического тела при входе в атмосферу в тротиловом эквиваленте была равна 300 кт, вычисленная магнитуда сейсмического события равна 3,85. Для энергии тела 500 кт магнитуда оказалась равной 4,0. Эти величины согласуются с опубликованными результатами измерений магнитуды в пределах погрешностей измерений. Были также проведены вычисления магнитуд сферически-симметричных взрывов в воздухе с энергиями от 30 кт до 30 Мт на высотах от 5 до 45 км. Магнитуда Челябинского события соответствует сферически-симметричным взрывам с энергиями, равными кинетической энергии тела, на высоте около 35 км.

Вход космического объекта в атмосферу сопровождается ярким излучением, генерацией ударной волы, привнесением космического вещества на разные высоты в атмосфере и последующими химическими реакциями, и другими эффектами. Свечение Челябинского метеороида было видно на обширной территории, а жители Челябинской области наблюдали не только пролет болида, но и другие явления, вызванные входом метеороида в атмосферу (приход ударной волны, вызвавшей разрушения и травмы, тепловые, звуковые эффекты и т.д.). В данной работе представлены данные об этих эффектах Челябинского метеороида, полученные в результате опросов очевидцев.

Приведена методика расчета пространственных координат и результаты вычислений пеленгов и координат источника излучения звукового сигнала и их ошибок при взрыве челябинского метеорита по данным регистрации акустических сигналов в различных пунктах.

В статье рассмотрены вопросы оценки энергии Челябинского болида по длиннопериодным инфразвуковым колебаниям атмосферного давления. Предложена методика, в которой используется интегральная зависимость энергии от спектра мощности. Полученные результаты достаточно удовлетворительно совпадают с данными, полученными в других работах.

Рассматривается генерация и распространение ударной волны в атмосфере Земли после падения Челябинского космического тела, определяется максимальное избыточное давление в разных точках земной поверхности, оценивается размер зоны повреждений. Исследованы разные способы задания энерговыделения вдоль траектории метеороида и зависимость зоны повреждений от характера энерговыделения. Определены времена прихода звукового сигнала (воздушной волны) в разные точки земной поверхности, анализируется форма импульса давления.

Рассмотрены электромагнитные возмущения различной природы и масштабов, сопровождающие падения метеороидов. Предложен новый механизм генерации электромагнитного сигнала в диапазоне частот от Гц до килогерц при таких падениях. Проанализированы особенности падения Челябинского метеороида. Проведены оценки возмущений параметров ионосферной плазмы и характеристики электромагнитных сигналов, которые могут быть зарегистрированы на Земле. Предложена модель формирования электрофонных шумов в результате резонансного возбуждения циклотронных частот ионов приземной плазмы.

Челябинское событие (далее ЧС) описывается в контексте множественных столкновений Земли с космическими объектами разного размера на протяжении всей ее эволюции. Падения тел размером менее 10 м происходят довольно часто, метровых - в среднем около одного раза в неделю, но, как правило, эти падения происходят в местах, удаленных от жилых районов, и поэтому фиксируются только специалистами. Челябинский метеороид (далее ЧМ), хотя и имел довольно большой размер ~20 м, представлял собой типичный каменный астероид. Такие тела сталкиваются с Землей примерно один раз в 50-100 лет, но уникальность этого события связана главным образом с местом падения – в район с высокой плотностью населения и развитой промышленностью. В статье рассмотрены основные физические явления, происходящие при взаимодействии метеороидов размером в первые десятки метров с атмосферой – торможение, абляция, фрагментация, распространение ударной волны. Описаны современные способы регистрации и моделирования болидных явлений. В заключительной части формулируются актуальные задачи для дальнейших исследований.

Рассматривается взаимодействие Челябинского метеороида (ЧМ) с атмосферой, оценивается его кривая блеска и соответствующее энерговыделение. Предлагается модель фрагментации метеороида в атмосфере, дающая возможность воспроизвести наблюдательные данные (световую кривую, кривую торможения). Описывается поле рассеяния метеорита, оценивается выпавшая масса, сравниваются модельное и реальное расположение фрагментов.

Исследовано возможное влияние сильных ударных волн с термоядерным синтезом над поверхностью Солнца в фотосфере при солнечных вспышках и ветра на формирование газопылевого облака и планет земного типа.

Проведено исследование влияния солнечных вспышек и ветра на формирование газопылевого облака и планет. Предположено, что у поверхности Солнца возникали сильные ударные волны с энергией характерной для солнечных вспышек. В ударных волнах происходил ядерный синтез тяжелых элементов уносимых солнечным ветром. Анализ решения взрывных задач в фотосфере показал, что для получения массы планет как в настоящее время необходима примерно на три порядка большая масса вещества, уносимая солнечным ветром, чем теперь. Это возможно при меньшей массе солнца и второй космической скорости в период формирования планет, которые определены из сопоставления взрывных расчетов и зависимости 2 космической скорости от массы для Солнца и Юпитера.

A new method of estimating the global fluxes of methane into the Earth’s atmosphere is proposed. This method allows one to take into account the whole spectrum of methane sources irrespectively of their location and calculate seasonal variations in methane fluxes. The results of numerical calculations of the amount of methane emitted into the atmosphere on the basis of this method are supported by data obtained from field measurements. In the Northern Hemisphere (NH), during fall, maximum concentrations of CH4 are due to methane sources in the arctic region which have not been taken into account before. For the condition of balance between the emission and sink of methane to be fulfilled, the total capacity of its sources amounts to no less than ~530 Tg/year for the NH and ~470 Tg/year for the Southern Hemisphere (SH). The results of our calculations and an analysis of the behavior of the concentration and mass of methane in the Earth’s hemispheres show that the global flux of methane from the surfaces of the lithosphere and ocean into the atmosphere may amount to more than ~1000 Tg/year.

Предложен новый метод оценки глобальных потоков метана в атмосферу Земли, который учитывает весь спектр его источников независимо от места их расположения и позволяет рассчитывать сезонные изменения потоков метана. Численные расчеты количественных поступлений метана в атмосферу предлагаемым методом подтверждаются данными, полученными при проведении натурных наблюдений. Максимум концентрации СН4 в СП в осенний период связан с действием в арктическом регионе не учитываемых ранее источников метана. Для соблюдения условия баланса между поступлением метана в атмосферу и его стоком полная мощность источников в СП составляет не менее ~530 Тг/год, в ЮП ~470 Тг/год. Проведенные расчеты и анализ закономерностей поведения концентрации и массы метана в полусферах Земли показал, что глобальный поток метана с поверхности литосферы и океана в атмосферу может составлять более ~1000 Тг/год.

Calibrating and verifying 2-D and 3-D vadose zone flow and transport models requires detailed information on water and solute redistribution. Among the different water flow and mass transfer determination methods, staining tracers have the best spatial resolution allowing visualization and quantification of fluid flow including preferential flow paths. Staining techniques have been used successfully for several decades; however, the hydrological community is still searching for an “ideal” vadose zone tracer regarding flow path visualization. To date, most research using staining dyes is carried out with Brilliant Blue FCF. Fluorescent dyes such as Uranine, however, have significant advantages over nonfluorescents which makes them a promising alternative. This paper presents the first analysis of key properties any fluorescent substance must possess to qualify as a staining fluorescent tracer in vadose zone hydrological applications. First, we summarize the main physico-chemical properties of Uranine and evaluate its staining tracer potential with conventional suitability indicators and visibility testing in a soil profile. Based on numerical analysis using the theory of fluorescence, we show that a low molar absorption coefficient is a crucial parameter to quantify concentration accurately. In addition, excitation of a tracer on wavelengths different from the maximum excitation wavelength can extend the linear range of the concentration-fluorescence relationship significantly. Finally, we develop criteria for evaluating the suitability of any potential fluorescent soil staining compound for soil hydrological applications: 1) high quantum yield, 2) low molar absorption coefficient, 3) fluorescence independent of temperature, 4) low photodecomposition rates, and 5) fluorescence stable across a wide range of pH values.

Microseismicity variations in space and time due to pore pressure changes in an inhomogeneous permeable sample are considered. The analysis is based on laboratory experiments performed to study the relation between acoustic emission (which corresponds to microseismic events in real scale) and pore pressure changes due to water injection into, or release from, a porous sample under load. The study showed not only some characteristics of microseismicity variations during non-stationary fluid flow but also the possibility to solve the inverse problem of estimating local permeability from variations of microseismic activity in a particular volume of the porous medium.

Rheasilvia impact on asteroid 4 Vesta may have been sufficiently large to create disrupted terrains at the impact antipode. This paper investigates the amount of deformation expected at the Rheasilvia antipode using numerical models of sufficient resolution to directly observe terrain modification and material displacements following the arrival of impact stresses. We find that the magnitude and mode of deformation expected at the impact antipode is strongly dependent on both the sound speed and porosity of Vesta's mantle, as well as the strength of the Vestan core. In the case of low mantle porosities and high core strengths, we predict the existence of a topographic high (a peak) caused by the collection of spalled and uplifted material at the antipode. Observations by NASA's Dawn spacecraft cannot provide definite evidence that large amounts of deformation occurred at the Rheasilvia antipode, largely due to the presence of younger large impact craters in the region. However, a deficiency of small craters near the antipodal point suggests that some degree of deformation did occur.

We numerically modeled the formation of Rheasilvia crater, an enormous impact basin centered on asteroid 4 Vesta's south pole. Using a trial and error method, our models were adjusted to produce the best possible fit to Rheasilvia's size and shape, as observed during the Vesta orbital stage of the Dawn mission. The final model yields estimates of the shock wave decay, escaped material volume, depth of excavation, and other relevant characteristics, to the extent allowed by the two-dimensional (axially symmetric) approximation of the Simplified Arbitrary Lagrangian Eulerian hydrocode. Our model results permit interpretation of the Dawn data on Vesta's shape, topographic crater profiles, and the origin of the Vestoid asteroid family as escaped ejecta from the Rheasilvia crater.

The authors calculate possible errors in characterization of low-magnitude seismicity sources using the Brune model and methods of identification of seismic event energy class and local magnitude. The adequacy of the model has been proved by comparing its results with the recordings of seismic vibrations in the North Ural Bauxite Mine. The errors due to the drastic distortion of the emission spectrum become significant at the distance of 1000 m from the emission source and grow as the distance increases. Cases of great deviations from the similarity law are analyzed based on the actual seismic monitoring in the North Ural Bauxite Mine, in mines in Poland, Finland and Canada, as well as in water basins. It is shown that phenomena due to physical difference of various size fracturing dynamics do not radically change a seismic source capacity. Other causes, due to instrumentation shortcomings or incorrect data interpretation, may result in overestimated seismic energy and scaling-up of low-magnitude seismic events.

The paper reports on laboratory experiments with the aim of studying the effect of microstructural and macromechanical properties of a crack filled with discrete material on the formation of a sliding mode. It is shown that the spectrum of possible deformation events on the discontinuity is governed by both the macroscopic characteristics of the filler and its mesoscale structure. The evolution of force chains which are formed and collapsed in shear along the crack, their length and number fully control the type of deformation stable slip, stick-slip, and intermediate modes with low-velocity motion of the crack edges. The variation of Coulomb strength affects mainly the amplitude of stress jump in dynamic failure or sliding event with a low displacement velocity and little affects the deformation mode. Consideration is also given to the regularities by which the macroscopic characteristics of contact vary in shear.

В статье приводятся результаты лабораторных экспериментов, в которых изучалось влияние микроструктурных и макромеханических свойств трещины, заполненной дискретным материалом, на формирование режима скольжения. Показано, что спектр деформационных событий, которые могут произойти на нарушении сплошности, определяется как макрохарактеристиками материала-заполнителя, так и его структурой на мезоуровне. Эволюция силовых цепочек, которые образуются и разрушаются в процессе сдвига по трещине, их протяженность и количество полностью определяют тип деформирования — стабильное скольжение, прерывистое скольжение, промежуточные режимы, для которых характерны подвижки с малой скоростью относительного перемещения берегов. Вариация кулоновской прочности влияет, главным образом, на амплитуду скачка напряжений при динамическом срыве или акте проскальзывания с малой скоростью смещения и слабо сказывается на режиме деформирования. Исследованы закономерности изменения макрохарактеристик контакта в процессе сдвига.

В статье исследовано влияние сдвиговой жесткости разломной зоны на излучательную эффективность землетрясений. Показано, что этот параметр в значительной степени контролирует эффективность излучения сейсмического сигнала землетрясений, приуроченных к той или иной разломной зоне. Это означает, что режим скольжения фактически является свойством разлома в данный геологический момент эволюции. На разломах с аномально низкой сдвиговой жесткостью реализуются медленные события с отношением . При этом скорость распространения разрыва оказывается настолько низкой, что события выходят из категории сейсмогенных. Более медленное, по сравнению со случаем самоподобной среды, снижение эффективной жесткости разломных зон с масштабом приводит к тенденции постепенного возрастания с масштабом излучательной эффективности землетрясений средних магнитуд (Mw~ 3÷7), происходящих в близких тектонических условиях.

In this communication, we present the results of joint analysis of local long-period (with periods exceeding one day) geomagnetic variations and groundwater level in the water table aquifer in the cen tral East European Platform registered in the period of 2010—2011 at the mid-latitude Mikhnevo geophysical observatory (IDG RAN) located in the area with coordinates 54.96° N and 37.774° E. These observations revealed local variations in the Earth's magnetic field with periods of approximately one year, in addition to known variations with a periodicity of approximately 27 days and two harmonics with periods of -6—8 and -12—14 days. At the same time, it has been established that maximal-amplitude variations in the ground water level in the upper water table aquifer are characterized by a year-long periodicity determined by the influx of melting water and its infiltration during the spring summer season. The comparison between sea¬sonal variations in the hydrogeological regime and annual cyclicity of geomagnetic variations revealed a significant correlation between seasonal variations in the magnetic tipper, one ofthe main parameters ofthe magnetic field, and changes in the ground water level in the water table aquifer. The local geomagnetic variations were registered using a three-component fluxgate magnetometer LEMI-018 with an electronic block, which provides corresponding transformation of data from the flux¬gate sensor, their processing, and accumulation with a discreteness of 1 s. The digital rows formed with a dis¬creteness of 1 min served as initial data for the analysis of variations. The groundwater level in the Kashira water table aquifer located at a depth of 56.6 m was determined in the open borehole drilled up to 31.5 m at the Mikhnevo geophysical observatory. The measurements were conducted using a submersible LMR 3081 sonde that provides automatic registration ofthe water level with a discreteness of 1 s and an accuracy of at least 0.1 mm. The rows of average daily values of the absolute groundwater level ft were used for the analysis. .

The SSD-3 three-channel seismic recorder and the ADSS-3 three-component broadband standalone digital seismic station based on the SSD-3 together with SM-3E seismic sensors were developed. The main advantage of this equipment in comparison with foreign and domestic analogs is simplicity and convenience while maintaining high technical characteristics. The structure and operation of the seismic sensor and seismic recorder are considered, and their main technical characteristics are given. Laboratory, bench, and comparative tests of the seismic recorder and station demonstrated their working capacity and compliance with the development goal. Based on the test results, the ADSS-3 seismic station was commissioned as a three-component broadband observation point of the Mikhnevo small-aperture seismic array. The data obtained using the ADSS-3 made is possible to study the structure of the crust and upper mantle

Разработаны трёхканальный сейсмический регистратор ССД-3 и на его основе совместно с сейсмоприёмниками СМ-3Е – трёхкомпонентная широкополосная автономная цифровая сейсмическая станция АЦСС-3. Основное преимущество разработанной аппаратуры перед зарубежными и отечественными аналогами – простота и удобство в эксплуатации при сохранении высоких технических характеристик. Рассмотрено устройство и принцип работы сейсмоприёмника и регистратора, а также приведены их основные технические характеристики. Проведён комплекс лабораторных, стендовых и сравнительных испытаний созданных опытных образцов как регистратора, так и станции в целом, который показал их работоспособность и соответствие поставленной цели разработки. По результатам испытаний станция АЦСС-3 принята в эксплуатацию в качестве трёхкомпонентной широкополосной точки наблюдения малоапертурной сейсмической антенны «Михнево», где с её помощью методом функции приёмника проведено исследование структуры земной коры и верхней мантии данной территории.

To identify the modern geodynamic in the structures of the East European Craton (EEC) the complex approach is used. The results of visual and automated deciphering of LANDSAT satellite images are analyzed combined with the data of precision measurements for horizontal components of motion rates of GPS reference points. The approach used allowed us to consider the modern activity of geological structure and to distinguish the zones of higher geodynamic instability

In field experiments and numerical simulations the processes of damage zone development and dynamic pulse propagation for large explosions were studied. The effect of long discontinuities both on wave field parameters and form and dimensions of explosion damage zone was considered. Comparison of the results of numerical and field experiments showed that local changes in the wavefront geometry and in the characteristics of stress-strain state of rock can lead to considerable alterations of the size and shape of rock fractur¬ing zone. Rock damage zones can alternate with unbroken rock mass areas. So it is not always correct to use the peak ground velocity as the criterion of rock failure.

With the rapid progress of imaging methods it is now possible to obtain detailed rock structure information on different scales, ranging from nanometers to micrometers. Such knowledge facilitates use of pore-scale modeling approaches to predict numerous physical properties based on three dimensional structural data. Pore-scale modeling approaches can simulate different processes in the rock under natural conditions (pressure, temperature, etc.), which are more difficult to simulate in the laboratory. This is especially important for unconventional reservoir rocks such as the Bazhen formation siliceous rocks (black shales) used in this study. Based on X-ray microtomography and SEM imaging we develop a detailed categorization of different types of porosities (including micro, i.e. larger than µm size, and nano, i.e. sub-micron size, porosities) for samples of Bazhen siliceous rocks. Standard pore-scale modeling techniques do not account for different flow regimes within different pore sizes. Thus, we develop a pore-network model with different physics of gas flow for micro- and nanoporosity. High-resolution images are used for stochastic reconstructions of 3D structure and subsequently used for modeling of gas permeability. Resulting permeability values are in a good agreement with gas permeabilities measured for Bazhenov siliceous rocks. Finally, we present a framework to model gas permeability of unconventional reservoir rocks using multi-scale 3D structure information based on microCT scans and high resolution SEM/FIB-SEM imaging techniques.

Were evaluated basic parameters of local seismic disturbances caused by explosions at quarries and obtained estimates of peak ground velocity of explosive impact. We used data recorded at different distances from ripple-fired quarry explosions of different yield and different schemes of blasting. Spectral analysis of seismic signals caused by ripple-fired industrial explosions indicates the presence of abnormally high content of high-frequency components. It should be noted that this feature persists in the spectra of signals recorded at appreciable distances from quarries, which helps to identify the nature of explosive signals.

The study of block movements of the crust is of particular interest in terms of building local geodynamic models of the earth's crust. In this paper the methods of instrumental observations of the motions of the structural units. Method can determine the relative angular and linear displacement of the blocks and their slopes. Results are unique motion sensing units on the earth's surface and in underground workings. Analyzed the movement of blocks with strong dynamic effects in the form of seismic signals caused by powerful underground explosions. In this case the differential slip blocks well recorded. According to the results of numerous experiments found that the deformation of the medium block structure has a distinct heterogeneous nature: the deformation is localized in zones of weakening, which are represented by interblock gaps. As a result, the building blocks are able to move quasi-independent. Spatial movements of blocks are alternating character. With repeated exposure to the sign of deformation of interblock gaps may vary. In some cases, a reduction in the width specifically taken interblock gap, in other - its increase. Analysis of the results of light rangefinder observations, tipped the Earth's surface and the walls of underground openings allows not only to map the tectonic faults, but also determine the amount of active units.

The coefficient of normal rigidity of different-order fault zones was evaluated from seismic data. The crust tectonic faults were shown to be dynamic systems and nonstatic. Specifically, this is manifested in the variability of their rigidity with time. The value of the rigidity of fault zones varies in time with periods of 13–15 days, 27–32 days, and around 1 year. Here, the coefficient of normal rigidity of different-order fault zones can vary by 1.3 (semimonthly variations) 1.5 (monthly variations), and 2.5 times (annual variations), respectively. These variations are most likely governed by the rate and intensity of the transformation of matter of fault zones and, as a consequence, the variations in their mechanical properties under tidal conditions. Dynamic effects like seismoexplosive waves lead to a reduction in the rigidity of fault zones by 5–50% depending on the amplitude of the compression wave.

Определены значения коэффициента нормальной жесткости разломных зон разного ранга на основе сейсмических данных.

Приведены результаты совместного анализа локальных длиннопериодных (с периодом более 1 сут) геомагнитных вариаций и уровня подземных вод безнапорного водосодержащего горизонта в центральной части Восточно-Европейской платформы на среднеширотной геофизической обсерватории "Михнево" ИДГ РАН (54,960N; 37,7740E) за период 2010-2011 гг. Наряду с известными вариациями с периодом около 27 суток и двумя гармониками указанной периодичности в ~6-8 и ~12-14 сут установлены периодичности локальных вариаций магнитного поля Земли с периодом около 1 года. С другой стороны установлено, что основная по величине амплитуды вариация уровня подземных вод верхнего безнапорного горизонта характеризуется годовой периодичностью, определяемой притоком талой воды и ее инфильтрацией в весенне-летний период. В результате сравнения сезонных вариаций гидрогеологического режима и годовой цикличности геомагнитных вариаций показана значимая корреляция между сезонными вариациями одного из основных параметров магнитного поля - магнитного типпера, и изменением уровня подземных вод в безнапорном горизонте.

Представлен аналитический обзор научных исследований и технических разработок по созданию уникальных комплексов приборов и оборудования для моделирования и регистрации в натурных условиях нелинейных упругих волн и сопутствующих электромагнитно-эмиссионных процессов в напряженных массивах горных пород блочно-иерархического строения. Достигнутые за минувшее десятилетие результаты совместных экспериментальных и теоретических исследований ряда ведущих научных организаций РАН и ее региональных отделений, ведущих вузов страны в рамках выполнения междисциплинарных интеграционных проектов создают методологическую и приборно-измерительную базу для построения новых перспективных систем комплексного геомеханико-геофизического мониторинга техногенных землетрясений и горных ударов на рудниках и шахтах России — уникальных природных “лабораторий” для фундаментальных и прикладных исследований в области наук о Земле.

From the Apollo era of exploration, it was discovered that sunlight was scattered at the terminators giving rise to "horizon glow'' and "streamers'' above the lunar surface. Subsequent investigations have shown that the sunlight was most likely scattered by electrostatically charged dust grains originating from the surface. A renaissance is being observed currently in investigations of the Moon. The Luna-Glob and Luna-Resource missions (the latter jointly with India) are being prepared in Russia. Some of these missions will include investigations of lunar dust. Here we discuss the future experimental investigations of lunar dust within the missions of Luna-Glob and Luna-Resource. We consider the dusty plasma system over the lunar surface and determine the maximum height of dust rise. We describe mechanisms of formation of the dusty plasma system over the Moon and its main properties, determine distributions of electrons and dust over the lunar surface, and show a possibility of rising dust particles over the surface of the illuminated part of the Moon in the entire range of lunar latitudes. Finally, we discuss the effect of condensation of micrometeoriod substance during the expansion of the impact plume and show that this effect is important from the viewpoint of explanation of dust particle rise to high altitudes in addition to the dusty plasma effects.

A theoretical model that provides a self-consistent description of the concentrations of photoelectrons and dust particles located over the illuminated part of the lunar surface is presented. The model takes account of the observation point location and the effects of production of photoelectrons at the surfaces of the Moon and dust particles, the dynamics of dust particles in the electric and gravitational fields, and the charging of dust particles through their interaction with the solar radiation photons, the solar wind electrons and ions, photoelectrons, etc. An expression that describes the distribution of photoelectrons over the illuminated part of the lunar surface is obtained. The size and elevation distributions of the charged dust particles located over the illuminated part of the lunar surface are calculated for different angles between the local normal and the direction to the Sun. It is shown that no substantial restrictions are imposed on the choice of the landing site for future lunar spacecraft missions aimed at studying the near-surface dust on the Moon.

Представлена теоретическая модель для самосогласованного описания концентраций фотоэлектронов и пылевых частиц над поверхностью освещенной части Луны. Модель учитывает положение места наблюдения, а также эффекты образования фотоэлектронов на поверхности Луны и поверхностях пылевых частиц, динамики пылевых частиц в электрическом и гравитационном полях, зарядки пылевых частиц за счет их взаимодействия с фотонами солнечного излучения, электронами и ионами солнечного ветра, фотоэлектронами и т.д. Получено выражение, описывающее распределение фотоэлектронов над поверхностью освещенной части Луны. Выполнен расчет распределений по размерам и высотам подъема заряженных пылевых частиц над освещенными участками поверхности Луны для различных значений угла между местной нормалью и направлением на Солнце. Показано, что не существует существенных ограничений на место посадки аппаратов будущих лунных миссий, изучающих пыль в приповерхностном слое Луны.

A dusty plasma layer formed near the illuminated part of the surface of the Moon under the ac-tion of ultraviolet radiation, as well as fast and slow solar wind, has been numerically simulated. The numerical calculations including the photoemission properties of lunar regolith samples delivered to the Earth have been compared to estimates within known theoretical models. It has been shown that the flux of solar wind particles plays an important role in the formation of the surface photoelectron layer. The conditions of the charging and stable levitation of dust particles in the surface plasma layer of the Moon have been analyzed.

The use of spectrometric information from the ASKRO automated station to increase the reliability of identification of the low-activity technogenic radionuclides 131I, 137Cs, and 140La in the atmospheric boundary layer is examined. The Matros statistical algorithm for processing data with the spectrometer operating in the radiometric mode makes it possible to classify in 45 min the minimum activity 5–10 Bq/m3 with probability ~0.7; false detection comprises ≤0.01 over 100 h. The low identification reliability for lowactivity radionuclides, the relatively long time required for obtaining results, and the impossibility of processing the data obtained during periods of precipitation limit the use of the algorithm. It is shown that spectral processing by the method of the minimum makes it possible to identify in 15–30 min with probability ~1 the minimum activity of 137Cs and 140La – 11 and 6 Bq/m3, respectively – with false detection <10–4.

Рассмотрено использование спектрометрической информации для повышения достоверности идентификации техногенных \{131\}I, \{137\}Cs, \{140\}La низкой активности в приземном слое атмосферы с помощью спектрометра автоматизированного поста АСКРО. Cтатистический алгоритм обработки данных "Матрос" при работе спектрометра в радиометрическом режиме позволяет за 45 мин классифицировать с вероятностью ~0, 7 минимальную активность 5-10 Бк/м\{3\}, ложное обнаружение составляет меньше равно 0, 01 за 100 ч. Применение алгоритма ограничено малой достоверностью идентификации техногенного радионуклида низкой объемной активности, относительно большим временем получения результата, а также невозможностью обработки данных, полученных в условиях атмосферных выпадений. Показано, что спектральная обработка методом минимума позволяет за 15-30 мин идентифицировать с вероятностью ~1 минимальную объемную активность \{137\}Cs и \{140\}La 11 и 6 Бк/м\{3\} соответственно при ложном обнаружении меньше 10\{-4\}.

Basic reasons for different kinds of failures of record synchronization of the independent seismic stations, operating as elements both of domestic and foreign seismic arrays, are established. Proceeding from it, software and hardware are proposed for ensuring reliable and precise synchronization of stations. Their operation is based on periodic fine tuning of the station’s analog-to-digital converter (ADC) sampling cycle by an exact time signal obtained from the GPS receiver. This procedure is executed with minimum or even no additional load on the controller of the seismic recorder. Such an approach allows not only matching each ADC sample to astronomical time, but also to provide simultaneous ADC sampling of all stations in the seismic array with an accuracy of 10 μs, which is especially important for solving a number of geophysical problems. Experimental researches and trial operation of the created equipment are carried out. High reliability of the equipment and compliance of technical characteristics to the purposes of the development are confirmed.

The small-aperture seismic array (SSA) operating in the seismic observatory of the Institute of Geosphere Dynamics, Russian Academy of Sciences (IGD RAS) in Mikhnevo allows establish-ment of spatial and timing distribution of seismic events with a magnitude of M = 1.5 and higher. In the course of its exploitation, we revealed the disadvantages of the synchronization system of seismic stations, which led to mismatches of seismic records both with astronomic time and between the channels of different analog-to-digital converters (ADCs). The complex of hardware-software tools was worked out in order to enlarge the reliability of the system and to provide its correspondence to the requirements of the SSA modernization. By the signals of the GPS receiver, the minute marker driver generates the pulses whose rising edges precisely coincide with the beginning of every minute of astronomic time. In addition to the main functions, the RS-485/RS-232 transmitter-receiver transforms these pulses into a serial code and passes it to the remote seismic station via the digital communication line. A specially designed COM-port switch receives the data from seismic stations and directs them to the computer in a single stream. Each data fragment from different channels is recorded in the common file as it proceeds to the switch inputs, which completely excludes the time mismatch between the records.

We present the results of numerical modeling of the formation of the Ries crater utilizing the two hydrocodes SOVA and iSALE. These standard models allow us to reproduce crater shape, size, and morphology, and composition and extension of the continuous ejecta blanket. Some of these results cannot, however, be readily reconciled with observations: the impact plume above the crater consists mainly of molten and vaporized sedimentary rocks, containing very little material in comparison with the ejecta curtain; at the end of the modification stage, the crater floor is covered by a thick layer of impact melt with a total volume of 6–11 km3; the thickness of true fallback material from the plume inside the crater does not exceed a couple of meters; ejecta from all stratigraphic units of the target are transported ballistically; no separation of sedimentary and crystalline rocks—as observed between suevites and Bunte Breccia at Ries—is noted. We also present numerical results quantifying the existing geological hypotheses of Ries ejecta emplacement from an impact plume, by melt flow, or by a pyroclastic density current. The results show that none of these mechanisms is consistent with physical constraints and/or observations. Finally, we suggest a new hypothesis of suevite formation and emplacement by postimpact interaction of hot impact melt with water or volatile-rich sedimentary rocks

We report results of an interdisciplinary project devoted to the 26 km-diameter Ries crater and to the genesis of suevite. Recent laboratory analyses of “crater suevite” occurring within the central crater basin and of “outer suevite” on top of the continuous ejecta blanket, as well as data accumulated during the past 50 years, are interpreted within the boundary conditions imposed by a comprehensive new effort to model the crater formation and its ejecta deposits by computer code calculations (Artemieva et al. 2013). The properties of suevite are considered on all scales from megascopic to submicroscopic in the context of its geological setting. In a new approach, we reconstruct the minimum/maximum volumes of all allochthonous impact formations (108/116 km3), of suevite (14/22 km3), and the total volume of impact melt (4.9/8.0 km3) produced by the Ries impact event prior to erosion. These volumes are reasonably compatible with corresponding values obtained by numerical modeling. Taking all data on modal composition, texture, chemistry, and shock metamorphism of suevite, and the results of modeling into account, we arrive at a new empirical model implying five main consecutive phases of crater formation and ejecta emplacement. Numerical modeling indicates that only a very small fraction of suevite can be derived from the “primary ejecta plume,” which is possibly represented by the fine-grained basal layer of outer suevite. The main mass of suevite was deposited from a “secondary plume” induced by an explosive reaction (“fuel-coolant interaction”) of impact melt with water and volatile-rich sedimentary rocks within a clast-laden temporary melt pool. Both melt pool and plume appear to be heterogeneous in space and time. Outer suevite appears to be derived from an early formed, melt-rich and clast-poor plume region rich in strongly shocked components (melt ≫ clasts) and originating from an upper, more marginal zone of the melt pool. Crater suevite is obviously deposited from later formed, clast-rich and melt-poor plumes dominated by unshocked and weakly shocked clasts and derived from a deeper, central zone of the melt pool. Genetically, we distinguish between “primary suevite” which includes dike suevite, the lower sublayer of crater suevite, and possibly a basal layer of outer suevite, and “secondary suevite” represented by the massive upper sublayer of crater suevite and the main mass of outer suevite.

The asteroid impact near the Russian city of Chelyabinsk on 15 February 2013 was the largest airburst on Earth since the 1908 Tunguska event, causing a natural disaster in an area with a population exceeding one million. Because it occurred in an era with modern consumer electronics, field sensors, and laboratory techniques, unprecedented measurements were made of the impact event and the meteoroid that caused it. Here, we document the account of what happened, as understood now, using comprehensive data obtained from astronomy, planetary science, geophysics, meteorology, meteoritics, and cosmochemistry and from social science surveys. A good understanding of the Chelyabinsk incident provides an opportunity to calibrate the event, with implications for the study of near-Earth objects and developing hazard mitigation strategies for planetary protection

Various observational data including infrasound, seismic, optical (onboard) monitoring, ground video and photo records, and evidence from witnesses of the Chelyabinsk event on February 15, 2013, have been analyzed. The extensive material gathered has provided a base for investigations of the physical properties of the object, the results of which are discussed. A bolide light curve is constructed, which shows a multiplicity of flashes. Estimations of the energy of the meteoroid explosion, which took place in the atmosphere at an altitude of about 23 km, show evidence of the formation of a high-power shock wave equivalent to 300–500 kilotons of TNT. The object diameter corresponding to this energy falls within the range 16–19 m. The trajectory of the meteor is outlined. It is preliminarily concluded that the Chelyabinsk meteorite was a representative the Apollo asteroid family.

Проанализированы разнообразные наблюдательные данные, включающие инфразвуковые, сейсмические, оптические (спутниковые) регистрации, а также наземные видеорегистрации, фотографии и свидетельские показания очевидцев Челябинского события 15 февраля 2013 г. Большой наблюдательный материал является основой для проведенных к настоящему времени исследований физических свойств объекта, результаты которых обсуждаются в работе. Построена кривая блеска, которая показывает множественность вспышек болида. Получены оценки энергии взрыва метеороида при его разрушении в атмосфере на высоте ∼ 23 км с образованием мощной ударной волны (300–500 кт ТНТ). Показано, что диаметр объекта, соответствующий данному диапазону энергии, находится в пределах от 16 до 19 м. Приведены оценки траектории движения космического тела. Сделан предварительный вывод о принадлежности Челябинского метеорита к семейству астероидов Аполлона.

The present study focuses both on the influence of impact scale on ejecta expansion and on specific features of ejecta deposits around relatively small craters (i.e., those a few kilometers in width). The numerical model is based on the SOVA multimaterial multidimensional hydrocode, considering subaerial vertical impacts only, applying a 2-D version of the code to projectiles of 100, 300, and 1000 m diameter. Ejecta can roughly be divided into two catego-ries: “ballistic” ejecta and “convective” ejecta; the ballistic ejecta are the ejecta with which the air interacts only slightly, while the convective ejecta motion is entirely defined by the air flow. The degree of particle/air interaction can be defined by the time/length of particle travel before deceleration. Ejecta size-distributions for the impacts modeled can be described by the same power law, but the size of maximum fragment increases with scale. There is no qualitative difference between the 100 m diameter projectile case and the 300 m diameter projectile impact. In both cases, fine ejecta decelerate in the air at a small distance from launching point and then rise to the stratosphere by air flows induced by the impacts. In the 1000 m-scale impact, the mass of ejecta is so large that it moves the atmosphere itself to high altitudes. Thus, the atmosphere cannot decelerate even the fine ejecta and they consequently expand to the rarefied upper atmosphere. In the upper atmosphere, even fine ejecta move more or less ballistically and therefore may travel to high altitudes.

The results of calculations for the vertical fall of 10–300 m stony asteroids to the Earth are pre-sented. Bodies with dimensions of about 50 m are shown to be most efficient from the viewpoint of destruction. At the same time, they are the most dangerous yielding the largest product of the destroyed area and probability of fall.

The paper focuses on the increasing contribution of blasting operations to the energy balance of seismic processes. Although the progress in blasting technologies will not produce energy outputs that exceed the energy of natural earthquakes on a global scale, it is shown that in some cases, the regional contribution to seismic energy release by blasting operations is by a few orders of magnitude higher than the energy released by natural earthquakes. In particular, this is valid for the European part of Russia, which is characterized by reasonably weak natural seismic activity. In order to identify the sources of natural seismicity over the European territory of Russia, we present the classification of the industrial blasting operations. The spatial distribution of explosive activities is presented; the consumption of explosives is estimated; and the technology of short-delay mass explosions, which might be helpful for interpretation of seismic records, is described. Zoning the territory of the European part of Russia in terms of the release rate of seismic energy and the peak local magnitudes observed during blasting operations is carried out. It is shown that the hazard level associated with blasting activities does not exceed the corresponding parameters of seismic zoning. The results presented in this paper will probably be useful for solving an important question of seismological studies: is the recorded seismic event a blast or earthquake?

В работе обращено внимание на увеличивающийся вклад взрывных работ в энергетику сейсмических процессов. Показано, что если в глобальном масштабе развитие взрывных технологий не сможет превзойти энергетику природных землетрясений, то на региональном уровне в ряде случаев вклад в потоки сейсмической энергии от применяемых взрывных технологий на несколько порядков превосходит уровень энергии, высвобождаемый природными землетрясениями. Именно такая ситуация сложилась, в частности, на территории Европейской части России, характеризующейся относительно слабой сейсмичностью. В целях идентификации природных источников сейсмических событий на территории Европейской России проведена паспортизация взрывных работ промышленного назначения, а именно представлено размещение взрывных работ, приведены объемы потребления ВВ и координаты мест проведения взрывов, описана технология проведения массовых короткозамедленных взрывов, полезная для интерпретации сейсмических записей. Проведено районирование территории Европейской России по потокам сейсмической энергии и максимальным локальным магнитудам, возникающим при взрывных работах. Показано, что уровень сейсмической опасности от взрывных работ не превосходит показатели сейсмического районирования. Представленные в работе материалы могут оказаться полезными при решении важного для сейсмологических исследований вопроса: зарегистрированное сейсмическое событие – это взрыв или землетрясение?

Приведены результаты расчетов вертикального падения на Землю каменных астероидов размером от 10 до 300 метров. Показано, что наиболее эффективными с точки зрения разрушения являются тела размером около 50 метров. Они же являются наиболее опасными, дают максимальное произведение площади разрушенной области на вероятность падения.

A self-consistent model for the description of dusty plasma structures, such as noctilucent clouds (NLC) and polar mesosphere summer echoes (PMSE), which are frequently grouped together under the common term polar mesospheric clouds, is presented. The model takes into account the processes of condensation of water vapor, ionization, recombination, action of solar radiation, sedimentation, dust particle growth, dust particle charging, electric fields, etc. Using the model, we explain the basic data of observations on the behavior of charged component in polar summer mesosphere. Furthermore, we show the influence of initial distributions of fine particles as well as that of the processes of condensation and water molecule absorption by fine particles on the formation of NLC and PMSE. We also illustrate the possibility of the formation of layered structure and sharp boundaries of NLC.

The small aperture array MIKHNEVO (MHVAR) in the Moscow region controls the weak seismic activity in the distance range of about 500 km. More than six thousands of local events of different origin have been recorded during the past eight years. The most of them are identified as industrial explosions using the S/P amplitude ratio and day-time distribution criteria. Additional analysis of data is based on spectral content, recur¬rence and clustering of events. Several quarries with regularly repeated waveforms of explo¬sions are located at distances of 15 to 450 km from the array site. The magnitudes of events identified as quarry blasts lie within the range ML = 0.79-3.24. A database of waveforms for the known quarries has been collected. The detailed analysis of waveform variations allows monitoring of the change in the position of the explosion as well as the subtle changes in the technology of the blasting.

Рассмотрены условия возбуждения мелкомасштабных нелинейных ионно-циклотронных градиентно-дрейфовых диссипативных структур для ионосферной холодной плазмы. Для волнового электрического поля в этой структуре в электростатическом приближении получено решение в форме солитона с чирпом, являющегося решением уравнения Гинзбурга-Ландау. Вся диссипативная структура представляет собой солитон с чирпом, сопровождаемый движением связанного с ним зарядово-нейтрального сгустка плотности плазмы. Рассмотрены возможности возбуждения двух мод данного вида (высокочастотной и низкочастотной) в плазме, содержащей примеси из легких и тяжелых ионов. Обсуждаются электромагнитные поправки и возможный вклад, который движение данных структур вносит в процессы переноса в ионосфере.

Conditions for the excitation of small-scale nonlinear ion-cyclotron gradient-drift dissipative structures in cold ionospheric plasma are considered. The solution for the wave electric field in this structure in the form of a chirped soliton satisfying the equation of the Ginzburg—Landau type is derived in the elec¬trostatic approach. The dissipative structure as a whole represents the chirped soliton accompanied by the comoving quasineutral plasma hump. The possibility of the excitation of two modes of this type (the high-and low-frequency ones) in plasma containing light and heavy ion impurities is considered. The role of elec¬tromagnetic corrections and the possible contribution introduced by these structures to the transport pro¬cesses in the ionosphere are discussed.

Microseismicity variations in space and time due to pore pressure changes in an inhomogeneous permeable sample are considered. The analysis is based on laboratory experiments performed to study the relation between acoustic emission (which corresponds to microseismic events in real scale) and pore pressure changes due to water injection into, or release from, a porous sample under load. The study showed not only some characteristics of microseismicity variations during non-stationary fluid flow but also the possibility to solve the inverse problem of estimating local permeability from variations of microseismic activity in a particular volume of the porous medium.

В статье представлены результаты высокоточного мониторинга режима подземных вод, проводимого на территории геофизической обсерватории «Михнево» на протяжении последних 6 лет. Прослежены основные закономерности формирования полусуточных и суточных приливных компонент в уровне подземных вод и смещении грунта, определены амплитудный фактор и фазовый сдвиг для водовмещающего коллектора трещинно-порового типа. Результаты поэтапной обработки прецизионных гидрогеологических рядов свидетельствуют о зависимости фазового сдвига между приливами, выделенными в уровне подземных вод, и теоретически рассчитанным смещением грунта от значения гидростатического напора.

Приведено описание Центра геофизического мониторинга, организованного в ИДГ РАН. рассмотрены первые результаты регистрации сейсмических и акустических колебаний, а также электрического поля в атмосфере в условиях г. москвы. показано, что используемые каналы позволяют регистрировать как природные, так и техногенные возмущения наблюдаемых геофизических полей. приведены предварительные результаты анализа суточного хода сейсмического поля и вертикальной компоненты электрического поля в атмосфере, а также изменений сейсмического, электрического и акустического полей в период барических вариаций в атмосфере.

Рассмотрено синхротронное излучение релятивистских электронов в магнитном поле Земли. Показано, что спектр этого излучения для электронов с энергией до 8 МэВ, характерных для спектра электронов в эксперименте «Морская звезда», практически перекрывает весь радиочастотный диапазон от 1 кГц до 5 ГГц. В случае интенсивного источника такого типа в ионосфере, синхротронное излучение может представлять серьезную помеху современным средствам связи и навигации.

Проведён детальный анализ происхождения различных компонент магнитометрического сигнала, регистрируемого во время модулированного нагрева ионосферы стендом EISCAT. Спектральные характеристики амплитуд принимаемого в ГФО ИДГ РАН «Михнево» низкочастотного сигнала сопоставлены с этими данными. Сделан вывод о том, что модуляционный процесс связан не с током электроджета, а с ионосферными АГВ-магнитогидродинамическими возмущениями.

В работе рассматриваются фотодиссоционные процессы, входящие в системы уравнений химической кинетики заряженных и нейтральных компонент на высотах E и D-слоев ионосферы. В комплекс фотодиссоционных процессов включены реакции диссоциации молекул кислородной, водородной, азотной и углеродной групп с использованием уточненных значений сечений диссоциации и абсорбции, а также интервалов длин волн определения этих реакций. Разработан комплекс подпрограмм расчета скоростей ионообразования и коэффициентов скоростей реакций фотодиссоциации, предназначенный для использования в программах решения систем уравнений химической кинетики.

Обсуждается широкий круг вопросов, связанных с моделированием ионосферы, влияющей на распространение радиоволн практически всех диапазонов частот - СДВ, ДВ, СВ, КВ, ВЧ, СВЧ, используемых в гражданских и военных радиотехнических системах. Дается классификация моделей по разным признакам. Исходя из опыта решения прикладных задач, показывается, что для них наиболее оптимально описывать ионосферу, в том числе, и с физической точки зрения, эмпирическими статистическими моделями. Данное, по сути, новое направление моделирования в настоящее время и у нас и за рубежом развито слабо.

Разработаны методы моделирования действия молнии мощными электрическими разрядами и импульсами лазерной плазмы. Критерии моделирования получены из общих определяющих модельные и натурные процессы МГД уравнений. Приведены результаты измерений параметров электроразрядной и лазерной плазмы в модельных опытах. Проведено сравнение опытных данных с расчетами действия взрыва по разным методикам. Определены тротиловые эквиваленты разрядной и лазерной плазмы моделирующей грозовые явления, энергия, выделившаяся в молнии при обработке ее фотографий, параметры ударных волн при грозах. Исследовано влияние сильного ветра на грозы.

Исследовались вариации уровня воды во время восхода и захода солнца в скважине, расположенной на территории геофизической обсерватории ИДГ РАН «Михнево». Поскольку суточные вариации уровня воды зависят от множества причин и сильно отличаются в различные дни, то для выявления общего тренда данные очищались от влияния давления, приливной компоненты, низкопериодной составляющей и шума, после чего вычислялся средний уровень за месяц при синхронизации данных по моменту восхода, захода солнца или астрономического полдня. Были проанализированы три месяца: апрель 2009, июль 2011 и январь 2012 гг. Выявлены общие тенденции повышения среднего уровня воды в районе восхода, затем его снижения с достижением минимума в районе астрономического полдня, затем вновь повышения с последующим снижением среднего уровня воды в районе захода солнца.

В лабораторных экспериментах изучено влияние структуры материала-заполнителя на формирование различных режимов сдвигового деформирования нарушения сплошности и, в частности, на переход от режима стабильного скольжения к прерывистому (стик-слипу). Эволюция силовых цепочек, которые образуются и разрушаются в процессе сдвига по трещине, их протяженность и количество полностью определяют тип деформирования - стабильное скольжение, стик-слип или промежуточные режимы.

Доминирующий режим скольжения определяется, скорее характеристиками конкретного участка разлома, чем внешними вариациями напряженного состояния, которые, вероятно, играют роль триггера. Эффект внешнего воздействия на разломную зону в значительной степени определяется режимом ее деформирования. В случае квазистабильного скольжения с небольшим количеством низкоамплитудных подвижек, кумулятивный сейсмический момент, реализованный через динамические срывы, уменьшается многократно. При развитом стик-слипе, внешнее воздействие способно снизить амплитуды отдельных динамических событий, хотя кумулятивная величина излученной энергии остается неизменной. В условиях переходных режимов скольжения амплитуда динамических срывов может даже увеличиться при внешнем воздействии.

В статье представлены результаты высокоточного мониторинга режима подземных вод, проводимого на территории геофизической обсерватории «Михнево» на протяжении последних 6 лет. Прослежены основные закономерности формирования полусуточных и суточных приливных компонент в уровне подземных вод и смещении грунта, определены амплитудный фактор и фазовый сдвиг для водовмещающего коллектора трещинно-порового типа. Результаты поэтапной обработки прецизионных гидрогеологических рядов свидетельствуют о зависимости фазового сдвига между приливами, выделенными в уровне подземных вод, и теоретически рассчитанным смещением грунта от значения гидростатического напора.

В работе исследуется зависимость модифицированных с помощью метода коррекции частотных характеристик геофона GS20DX от параметров датчика и схемы коррекции. Результаты лабораторных экспериментов и численного моделирования позволяют говорить о том, что на АЧХ и ФЧХ значительное влияние оказывает величина затухания геофона. Результаты можно считать достоверными в том случае, когда коррекция выполняется при той величине затухания, которое имеется в геофоне.

В лабораторных экспериментах с помощью зондирующих импульсов проведены прямые измерения сдвиговой жесткости межблокового контакта на разных этапах его сдвигового деформирования. Проведено сопоставление результатов, полученных на разных стадиях прерывистого скольжения с ранее полученными экспериментальными данными.

Рассмотрено влияние параметров закона прерывистого скольжения («Rate and State») на характер изменения трения при изменении скорости движения и обусловленный этим процесс возникновения неустойчивости в «слайдер»–модели. При незначительном изменении фрикционного параметра (b-a) происходит резкий переход от прерывистого скольжения к стабильному. Показано, что наибольшее влияние на амплитуду скорости и периодичность динамических срывов играет именно фрикционный параметр, а влияние коэффициента трения μ0 не существенно

В работе приведены результаты численного эксперимента, направленного на анализ закономерностей формирования и эволюции поверхности скольжения в ходе косейсмической подвижки. Показано, что макроскопические межблоковые перемещения оказываются не распределенными по толщине материала, разрушенного в процессе сдвига, а локализуются вдоль тонких поверхностей скольжения, поперечный размер которых на порядки меньше, чем мощность участков дробления. Результаты расчетов качественно соответствуют данным геологических наблюдений последних лет

Проведен анализ распределения сейсмичности вдоль крупной разломной зоны Северной Калифорнии. Установлено, что линейная плотность распределения очагов сейсмических событий уменьшается с ростом сейсмогенной ширины разлома, и скорость уменьшения сейсмической активности определяется углом наклона графика повторяемости Гуттенберга-Рихтера. Показано, что наиболее активный современный деформационный процесс наблюдается в областях разлома с минимальной сейсмогенной шириной.

В статье рассмотрены возможные причины возникновения значительных отклонений от закона подобия при анализе данных сейсмических наблюдений. Показано, что эффекты, связанные с физическими различиями в динамике разрывов разного размера, обусловленные масштабной зависимостью физико-механических свойств горного массива и слагающих его геоматериалов, имеют ограниченный диапазон действия и в реальном диапазоне параметров не приводят к радикальному изменению эффективности сейсмического источника. Иные источники, связанные либо с недостатками измерительной аппаратуры, либо с некорректной интерпретацией результатов измерений, приводят подчас к наблюдаемому сильному росту приведенной сейсмической энергии с увеличением магнитуды слабых сейсмических событий.

Рассмотрены результаты совместной обработки гидрогеологических и сейсмических данных на полигонах ДГЭ “ Днепрогеофизика”, Института геофизики НАН Украины и Института динамики геосфер РАН, которые позволяют проследить приуроченность гидрогеологических откликов к типу сейсмических волн от землетрясений и выраженность постсейсмических эффектов в вариациях уровня подземных вод. В частности, за период наблюдений с 01.11.2010 по 31.05.2011 зарегистрирован значительный ко- и постсейсмический отклик на глобальное сейсмическое событие – катастрофическое землетрясение с магнитудой 8.9, произошедшее 11.03.2011 вблизи о. Хонсю (Япония).

Статья посвящена двум взаимосвязанным проблемами, имеющими научное и практическое значение: 1) надежности подземных хранилищ радиоактивных отходов (РАО) в соленосных толщах пород, 2) необходимости устранения опасных последствий промышленных подземных ядерных взрывов (ПЯВ). Своеобразие этих проблем раскрыто на примере подземного хранилища РАО Waste Isolation Pilot Plant (WIPP) и ПЯВ «Гном» (Нью–Мексико, США). В статье приведены сведения о географии и геологии края, проведен анализ геодинамических подвижек недр, режима подземных вод и активности карста в зоне ПЯВ "Гном"-WIPP, определены предпосылки и механизмы ожидаемого обводнения WIPP, предложены пути смягчения такой опасности.

Существуют два подхода в изучении геологического строения недр Северного и Среднего Каспия, которые различаются пониманием связи вод моря с подземной гидросферой. Сторонники первого подхода рассматривают Каспийское море как замкнутый бессточный водоем с непроницаемым дном, гидрология и гидрохимия которого определяются исключительно внешними факторами. Климат расценивается здесь как практически единственный регулятор сложного спектра характеристик морской среды, т.е. изменчивость концентраций химических элементов формируется за счет сезонной и межгодовой изменчивости, т.е. в такт с ритмами климата. Второй подход заключается в попытках выявить множество форм связи вод Каспия с подземной гидросферой и пустотным пространством его недр. Этот подход опирается на данные геофизики и бурения, которые раскрывают особенности структурной геологии и флюидодинамики недр Северного Каспия, а также соседних территорий, т.е. понимание геохимии вод и донных осадков Каспия не может быть достигнуто в отрыве от результатов изучения геологического строения и флюидодинамики его недр. Представлены первые экспериментальные данные, которые указывают на связь изменчивости характеристик водной среды Каспийского моря с флюидодинамикой его недр.

На основе сравнительного анализа двумерных (в шлифах) и трехмерных (Х-ray CT) изображений получены новые данные о строении порового пространства гор. EL дерново-подзолистой почвы. Трехмерные изображения почвенной массы и порового пространства построены с помощью компьютерной реконструкции на основе множества двумерных теневых рентгеновских проекций. Показано, что в гор. EL помимо горизонтальных трещиновидных пор, разделяющих пластинчатые агрегаты, имеется большое количество изолированных пузырьковых пор неизвестного генезиса. В почвообразующем покровном суглинке (гор. С) в отличие от подзолистого горизонта пузырьковые поры встречаются единично. Большинство пор с округлыми срезами представляют собой современные и реликтовые ходы корней. Полученные данные дополняют многочисленные сведения о строении подзолистых горизонтов дерново-подзолистых почв в целом и порового пространства этих горизонтов в частности. Благодаря проведенным исследованиям увеличен перечень генетических различий в строении педогенных и литогенных горизонтов дерново-подзолистых почв.

Представлены результаты экспериментальных исследований влияния состава растворов, темпе- ратуры и давления на изменения состава, строения и свойств вулканитов Кошелевского вулкана при гидротермальных процессах. С применением стандартных методик изучения физических и физико-механических свойств скальных грунтов, компьютерной рентгеновской микротомографии (μСТ) и pore-scale моделирования показано влияние первичных особенностей пород на изменение их фильтрационных, деформационных и прочностных характеристик.

Возникновение сейсмических событий при закачке жидкости в недра рассматривается в многочисленных работах и объясняется уменьшением эффективных напряжений при увеличении порового давления. Падение порового давления также может вызывать разрушение породы и сейсмические события, однако механика этих процессов отличается от случая роста порового давления. В настоящей работе описываются результаты серии лабораторных экспериментов, в которых пористые образцы насыщались жидкостью под высоким давлением, давление затем резко сбрасывалось. В экспериментах было найдено, что при сбросе давления жидкости в образце образуются микротрещины, о наличии которых можно судить по увеличению проницаемости материала после нескольких циклов закачки/сброса порового давления и по акустической эмиссии. Было показано, что уровень акустической эмиссии определяется градиентом порового давления, а не его величиной, как в случае закачки. Предлагается метод оценки изменения проницаемости образца, показана возможность оценки проницаемости по изменению акустической эмиссии и порового давления.

Методы диагностики локальных участков земной коры, использующие наблюдения за микросейсмическими фоновыми колебаниями, могут быть усовершенствованы на основе комплексного анализа геофизических полей в приповерхностной зоне. На примере анализа данных, полученных на территории Нижегородской области, показано, что учет вклада атмосферных возмущений в вариации сейсмического фона, в частности, использование одновременной регистрации напряженности электрического поля и сейсмоакустических колебаний при прохождении атмосферных грозовых фронтов позволяет выделить сейсмические сигналы, имеющие акустическую природу.

Рассмотрены результаты синхронной регистрации барических вариаций в приземном слое атмосферы и микросейсмических колебаний на геофизической обсерватории "Михнево" ИДГ РАН. Показано, что длиннопериодные барические возмущения, вызванные циклонической деятельностью в атмосфере, оказывают влияние на микросейсмический фон в диапазоне частот 0,01-1 Гц, связанные с прохождением атмосферных фронтов - на частотах 4-8 Гц. Получено, что барические возмущения атмосферных фронтов приводят к заметному повышению интенсивности релаксационных процессов в земной коре по сравнению с циклонами, барические возмущения от которых характеризуются существенно большей длительностью и мощностью.

Анализ состояния изученности природных процессов, явлений, факторов и методов прогноза катастрофических событий указывает на актуальность разработки единых нормативных критериев и требований к материалам обоснования безопасности ОИАЭ. На основе результатов инструментальных наблюдений за геофизическими полями на границе земная кора - атмосфера демонстрируется возможность использования пространственных и временных вариаций эманационного поля радона, электрического поля в приземном слое и спектральных характеристик микросейсмических колебаний для картирования разломных зон, их ранжирования по степени деформируемости, выявления участков, характеризующихся наличием подземных неоднородностей с контрастными свойствами. Для характеристики геодинамического режима земной коры предлагается привлекать данные, связанные с откликом среды на слабые внешние воздействия в виде твердого прилива, а также результаты анализа последствий катастрофических событий.

Приведены и обсуждаются результаты регистрации сейсмического эффекта карьерных массовых взрывов на предприятиях Курской магнитной аномалии. Получено существенное отличие в законах затухания сейсмического сигнала с расстоянием вдоль разных азимутов. В качестве основных факторов, определяющих амплитуду волны на удаленных расстояниях от источника, рассматриваются характеристики среды и глубина залегания границы Мохоровичича

Исследованы вариации невязок дифференциальных времен пробега (ДВП) волн PKP DF и PKP BC, зондирующих восточную часть земного ядра на полярных (угол между направлением сейсмического луча во внутреннем ядре и осью вращения Земли ξ<35°) и экваториальных трассах (ξ>35°), относительно ДВП в стандартной модели Земли ак135 на эпицентральных расстояниях 147-155°. Отклонение ДВП от стандартной модели ак135 на экваториальных трассах в среднем составляет 0,4 с для глубины погружения сейсмического луча во внутреннее ядро от 140 до 235 км, затем следует переходная зона толщиной около 40 км, в которой невязки ДВП уменьшаются до 0,2 с, оставаясь на этом уровне до глубины 350 км. Сравнение невязок на полярных и экваториальных трассах показывает, что на профиле к северу от Австралии по наблюдениям на временной сети наблюдений Lapnet невязки ДВП статистически неразличимы до глубины 190 км, то есть верхняя часть внутреннего ядра изотропна. В интервале от 190 до 300 км происходит относительно быстрый рост невязок, который можно рассматривать как переход от изотропии к анизотропии. На другом профиле по данным станции SYO верхняя часть внутреннего ядра в районе под Австралией до глубины порядка 220-240 км характеризуется изотропией. На большей глубине отмечаются признаки анизотропии. На южном профиле по данным станции SNAA каких-либо проявлений сейсмической анизотропии не установлено - невязки ДВП на экваториальных и полярных трассах неразличимы до глубины 350 км.

Приводятся результаты синхронных инструментальных наблюдений за геомагнитными вариациями, вызванными распространением сейсмических волн через тектонический разлом. Получены зависимости сейсмомагнитного эффекта от амплитуды сейсмического сигнала. Впервые показано, что амплитуда сейсмомагнитного эффекта максимальна в зоне влияния разлома и уменьшается экспоненциально с расстоянием до его серединной линии.

Приведены результаты анализа данных синхронных инструментальных наблюдений за фоновыми геомагнитными вариациями и сейсмическим фоном на среднеширотной геофизической обсерватории ИДГ РАН "Михнево", выполненными в период 2006-2011 гг. Определены основные периодичности и цикличности геомагнитных вариаций, показан их спорадический и самосогласованный характер. Установлена значимая корреляция между годовыми вариациями магнитного типпера и уровнем подземных вод.

В статье рассмотрен подход к определению влияния горного давления на разрушающее действие взрыва в твердой среде. Показано, что эффективность взрывного дробления горных пород зависит от соотношения между величиной действующих напряжений и прочностными характеристиками породы.

Большой опыт проведения геофизического мониторинга различных территорий показывает, что сейсмологические наблюдения необходимо дополнять наблюдениями за акустическими возмущениями. Использование микробарометров в составе сейсмической группы при геофизическом мониторинге в Нижегородской области в 2012 году показало, что возможно не только выделить низкоскоростные сейсмические сигналы (сигналы со скоростью распространения близкой к скорости звука), которые вызваны акустическими возмущениями, но и провести локацию этих сигналов в пространстве

Определены новые параметры гипоцентров землетрясений, произошедших в Северной Фенноскандии. Обрабатывались события, зарегистрированные сейсмическими станциями проекта POLENET/LAPNET в период с 2007 по 2009 года. Расчеты проводились параллельно по программе Hypoellipse и методом сеточного поиска. В результате землетрясения были разбиты на 4 группы: события с неустойчивой локацией, поверхностные землетрясения, глубинные землетрясения и возможные взрывы. Для землетрясений ошибка определения глубины менее 6,5 км, среднеквадратичная невязка менее 0,5 с. Глубокие события расположены в вытянутой с севера на юг области, которая относится к древней Ботниа-балтийской мегазоне.

Среди слабых сейсмических сигналов особое место занимают имеющие разный генезис импульсы длительностью от 1-2 до 8-10 с. Как правило, большинство исследований направлено на анализ природных сигналов, связанных с проявлением естественной активности отдельных блоков земной коры; при этом часто к природным ошибочно относят техногенные из-за сходства их параметров - длительности, частотного состава и т.п. Представлены результаты выделения среди всех импульсов, регистрируемых при наблюдениях на малоапертурной сейсмической антенне Михнево, техногенных сигналов от источников, расположенных на поверхности (передвигающиеся автомашины, работающие агрегаты и т.п.) и на глубине (бурение скважины до 46 м). Отдельно рассмотрены сигналы внешнего (экзогенного) происхождения, связанные с проходящим грозовым фронтом, которые также могут быть ошибочно отнесены к тектоническим

Проведены предварительные оценки характеристик электрической поляризации, возникающей при ударном воздействии на образцы горных пород, проявляющие аномальный пьезоэлектрический эффект. Физическая модель поляризации построена на основе механизма движущихся заряженных дислокаций. Конкретные расчёты проведены для образца из мрамора.

Рассмотрены электромагнитные возмущения различной природы и масштаба, сопровождающие падения метеороидов. Предложен новый механизм генерации электромагнитного сигнала в диапазоне частот от Гц до кГц при таких падениях. Проанализированы особенности падения Челябинского метеороида. Проведены оценки возмущений параметров ионосферной плазмы и характеристики электромагнитных сигналов, которые могут быть зарегистрированы на Земле или спутниками.

Приведены результаты регистрации инфразвука от Челябинского болида акустическими станциями, расположенными на территории России и Казахстана. Дана оценка энергии болида и определены координаты его разрушения в атмосфере по инфразвуковым данным. Энергия болида, оцененная по двум методикам, находится в диапазоне 415 ± 97 кТ и 445 ± 142 кТ, а местоположение его разрушения расположено между пунктами Коркино–Еманжелинск–Первомайский.

Ударная волна, возникшая при входе крупного метеороида 15 февраля 2013 года в Челябинской области, привела к возникновению значительной области повреждений. По официальным данным, пострадали 7320 зданий и 1613 человек обратились за медицинской помощью. Это первое событие, демонстрирующее к каким последствиям может привести вход даже не очень крупного (16-20 метров в диаметре) космического объекта. Другая особенность Челябинского события состоит в том, что имеется большое количество разнообразных данных, в том числе инструментальных, которые позволяют изучить это событие и его последствия более детально, чем это обычно удается. С 9 по 24 марта сотрудники ИДГ и ИНАСАН посетили район падения и собрали информацию об области разрушений. Анализ инфразвуковых данных, данных по излученной энергии и по разрушению остекления, позволил оценить энергию Челябинского болида в 300-600 кт ТНТ. Предложенная модель энерговыделения позволила описать область разрушений, вытянутую до 90 км в направлении, перпендикулярном траектории. Эта модель согласуется и с зарегистрированными временами прихода УВ в различные точки. Принципиальным в этой модели является протяженный характер энерговыделения, связанный как с пролетом, так и с разрушением метеороида, в основном на высотах 40-23 км.

В статье описаны физические процессы при входе космических тел в атмосферу Земли (торможение, абляция, фрагментация) и современнее численные методы их моделирования. Взаимодействие с атмосферой тела размером порядка 80 м приводит к эффектам, наблюдавшимся при падении Тунгусского космического тела – вывалу леса, образованию массивного мезосферного облака, состоящего из частицы космического вещества и льда. Челябинский метеороид был примерно в 4-5 раз меньше, но ударная волна, дошедшая до поверхности оказалась достаточно сильной, чтобы выбить стекла на площади порядка 2000 км2. По-видимому, тела размером порядка 10-100 м являются наиболее опасными для современного человечества: они многочисленны, но их трудно обнаружить; не достигая поверхности земли, они, тем не менее, могут нанести большой ущерб при попадании в густонаселенные районы.

Получены экспериментальные данные об изменении распределения насыщенности вытесняющей жидкости в поровом пространстве плоскопараллельного пористого массива, заполненном вытесняемой жидкостью большей вязкости. Исследована математическая модель развития неустойчивости двухфазного потока в виде пальцев (fingers) вытесняющей жидкости. Результаты моделирования сопоставлены с экспериментальными результатами.

Выполненный анализ результатов натурных наблюдений показывает, что даже при низкоамплитудных динамических воздействиях возможно формирование неупругих гидрогеологических эффектов. Проведенные лабораторные эксперименты позволили выявить некоторые механизмы, ответственные за неупругую реакцию скважины на динамическое воздействие. Показано, что существенное влияние на динамику уровня флюида оказывает эффект растяжения малопрочного слоя в сейсмической волне, а в ряде случаев и низкочастотные колебания, обусловленные перетеканием флюида из пласта в скважину и обратно.

Для регистрации радиальных перемещений стенок зарядных шпуров разработан датчик, чувствительный элемент которого выполнен в виде пластинки из оптически активного материала. Механическая деформация преобразуется в интерференционную картину поляризованных лучей.

Возникновение сейсмических событий при закачке жидкости в недра рассматривается в многочисленных работах и объясняется уменьшением эффективных напряжений при увеличении порового давления. Падение порового давления также может вызывать разрушение породы и сейсмические события, однако механика этих процессов отличается от случая роста порового давления. В настоящей работе описываются результаты серии лабораторных экспериментов, в которых пористые образцы насыщались жидкостью под высоким давлением, давление затем резко сбрасывалось. В экспериментах было найдено, что при сбросе давления жидкости в образце образуются микротрещины, о наличии которых можно судить по увеличению проницаемости материала после нескольких циклов закачки/сброса порового давления и по акустической эмиссии. Было показано, что уровень акустической эмиссии определяется градиентом порового давления, а не его величиной, как в случае закачки. Предлагается метод оценки изменения проницаемости образца, показана возможность оценки проницаемости по изменению акустической эмиссии и порового давления.

Исследовались вариации уровня воды во время восхода и захода солнца в скважине, расположенной на территории геофизической обсерватории ИДГ РАН «Михнево». Поскольку суточные вариации уровня воды зависят от множества причин и сильно отличаются в различные дни, то для выявления общего тренда данные очищались от влияния давления, приливной компоненты, низкопериодной составляющей и шума, после чего вычислялся средний уровень за месяц при синхронизации данных по моменту восхода, захода солнца или астрономического полдня. Были проанализированы три месяца: апрель 2009, июль 2011 и январь 2012 гг. Выявлены общие тенденции повышения среднего уровня воды в районе восхода, затем его снижения с достижением минимума в районе астрономического полдня, затем вновь повышения с последующим снижением среднего уровня воды в районе захода солнца.

Выполненный анализ результатов натурных наблюдений показывает, что даже при низкоамплитудных динамических воздействиях возможно формирование неупругих гидрогеологических эффектов. Проведенные лабораторные эксперименты позволили выявить некоторые механизмы, ответственные за неупругую реакцию скважины на динамическое воздействие. Показано, что существенное влияние на динамику уровня флюида оказывает эффект растяжения малопрочного слоя в сейсмической волне, а в ряде случаев и низкочастотные колебания, обусловленные перетеканием флюида из пласта в скважину и обратно.

В лабораторных экспериментах изучено влияние структуры материала-заполнителя на формирование различных режимов сдвигового деформирования нарушения сплошности и, в частности, на переход от режима стабильного скольжения к прерывистому (стик-слипу). Эволюция силовых цепочек, которые образуются и разрушаются в процессе сдвига по трещине, их протяженность и количество полностью определяют тип деформирования – стабильное скольжение, стик-слип или промежуточные режимы.

Доминирующий режим скольжения определяется, скорее характеристиками конкретного участка разлома, чем внешними вариациями напряженного состояния, которые, вероятно, играют роль триггера. Эффект внешнего воздействия на разломную зону в значительной степени определяется режимом ее деформирования. В случае квазистабильного скольжения с небольшим количеством низкоамплитудных подвижек, кумулятивный сейсмический момент, реализованный через динамические срывы, уменьшается многократно. При развитом стик-слипе, внешнее воздействие способно снизить амплитуды отдельных динамических событий, хотя кумулятивная величина излученной энергии остается неизменной. В условиях переходных режимов скольжения амплитуда динамических срывов может даже увеличиться при внешнем воздействии.

Выявлены основные причины разного рода сбоев синхронизации записей сейсмических станций, входящих в состав как отечественных, так и зарубежных сейсмических групп. Исходя из этого, предложены средства для обеспечения надежной и точной синхронизации станций. Их работа основывается на периодической подстройке цикла выборки АЦП регистратора станции сигналом точного времени, формируемым GPS-приемником. Такой подход позволяет не только установить соответствие каждого отсчета АЦП астрономическому времени, но и обеспечить одновременность выборок АЦП всех станций сейсмической группы с точностью до 10 мкс, что особенно важно для решения ряда геофизических задач. Проведены экспериментальные исследования и опытная эксплуатация разработанной аппаратуры.

На основе анализа дифференциальных невязок волн PKPDF и PKPBC на полярных трассах выделены 4 группы данных c существенно различающимися величинами невязок для сейсмических лучей, зондирующих внутреннее ядро по трем почти параллельным в широтном направлении профилях. На профиле к северу от Австралии, по наблюдениям на временной сети наблюдений Lapnet, область изотропии простирается до глубины 190-200 км. На среднем профиле по данным станции SYO верхняя часть внутреннего ядра в районе под Австралией до глубины порядка 220-240 км характеризуется изотропией. На большей глубине отмечаются признаки анизотропии, которая невелика и составляет не более 0,5%. На южном профиле по данным станции SNAA каких-либо проявлений сейсмической анизотропии не установлено: дифференциальные времена на экваториальных и полярных трассах статистически неразличимы во всем диапазоне исследованных глубин от 140 до 360 км.

Выполнены оценки линейного тренда времени пробега продольной волны (δtp) в интервале 1968-1989 гг. на трассах от площадки Балапан (Bal) Семипалатинского полигона до станций Каджи-Сай (KDS), Манас (MNS) и Арал (ARL). На трассах Bal – KDS (Δ = 7,93°) и Bal – ARL (Δ = 8,71°) оценки совпадают с ранее полученными результатами – уменьшение δtp в календарном времени на трассах Bal – Талгар (Δ = 6,78°), Bal – Пржевальск (Δ = 7,50°), Bal – Фрунзе (Δ = 7.70°), Bal – Нарын (Δ = 8,78°). Однако на трассе Bal – MNS (Δ = 8,68°) δtp в календарном времени увеличивается. Возможно, это обусловлено тем, что период времени наблюдений и количество экспериментальных данных на этой трассе минимальны по сравнению с другими трассами. Необходимы дальнейшие исследования вариаций времени пробега продольной сейсмической волны в среднеазиатском регионе.

По сейсмограммам станций Иультин, Сеймчан, Бодайбо и Закаменск исследован линейный тренд времени пробега продольной волны на трассе от Невадского полигона (NTS) в интервале 1963–1992 гг. Все трассы расположены в азимутальном створе 331.5° ± 4,5° от NTS, что может уменьшить влияние неоднородностей среды в области эпицентров испытаний. Оценки линейного тренда на всех трассах не противоречат ранее полученным результатам. Если оценивать тренд как равномерный по всей траектории сейсмического луча, то по результатам предыдущих исследований граница изменения полярности тренда времени пробега продольной волны от уменьшения к увеличению оценивается глубиной порядка 1100–1200 км.

По сейсмограммам станций Иультин, Сеймчан, Бодайбо и Закаменск исследован линейный тренд времени пробега продольной волны на трассе от Невадского полигона (NTS) в интервале 1963–1992 гг. Все трассы расположены в азимутальном створе 331.5° ± 4,5° от NTS, что может уменьшить влияние неоднородностей среды в области эпицентров испытаний. Оценки линейного тренда на всех трассах не противоречат ранее полученным результатам. Если оценивать тренд как равномерный по всей траектории сейсмического луча, то по результатам предыдущих исследований граница изменения полярности тренда времени пробега продольной волны от уменьшения к увеличению оценивается глубиной порядка 1100–1200 км.

Рассмотрены результаты синхронной регистрации барических вариаций в приземном слое атмосферы и микросейсмических колебаний на геофизической обсерватории "Михнево" ИДГ РАН. Показано, что длиннопериодные барические возмущения, вызванные циклонической деятельностью в атмосфере, оказывают влияние на длиннопериодную составляющую микросейсмического фона. Барические возмущения, связанные с прохождением атмосферных фронтов, вызывают вариации амплитуды микросейсмического фона в высокочастотной области спектра на частотах 4-8 Гц. Получено также, что барические возмущения атмосферных фронтов приводят к заметному повышению интенсивности релаксационных процессов в земной коре по сравнению с циклонами, барические возмущения от которых характеризуются существенно большей длительностью и мощностью.

Приведены и анализируются данные инструментальных наблюдений за вариациями геомагнитного поля и сейсмических колебаний на поверхности земной коры, выполненных на геофизической обсерватории «Михнево» ИДГ РАН. Приводится статистика магнитных бурь с внезапным началом (SSC-события) и внезапных геомагнитных импульсов (SI-события) за период 2008-2012 гг. Показано, что для геомагнитных вариаций типа SSC и SI наблюдаются повышенные амплитудные вариации сейсмического фона в частотном диапазоне 0,01-0,1 Гц. Установлена количественная зависимость между максимальной амплитудой вариации среднеквадратической скорости колебаний в сейсмическом фоне и амплитудой геомагнитных вариаций.

Приводятся результаты синхронных инструментальных наблюдений за геомагнитными вариациями, вызванными распространением сейсмических волн через тектонический разлом. Получены зависимости сейсмомагнитного эффекта от амплитуды сейсмического сигнала. Впервые показано, что амплитуда сейсмомагнитного эффекта максимальна в зоне влияния разлома и уменьшается экспоненциально с расстоянием до его серединной линии.

Короткая научно-популярная статья, описывающая падение Челябинского метеорита и научные статьи об этом явлении, опубликованные в том же выпуске журнала.

Научно-популярная статься о физических процессах, сопровождающих падение космических тел на землю. Сравнение Тунгусского события с падением Сихоте-Алиньского и Челябинского метеоритов.

A field study of the Chelyabinsk Airburst was conducted in the weeks following the event on February 15, 2013. To measure the impact energy, the extent of the glass damage was mapped by visiting over 50 villages in the area. To determine how that energy was deposited in the atmosphere, the most suitable dash-cam and video security camera footage was calibrated by taking star background images at the sites where video was taken. Shadow obstacles in videos taken at Chelyabinsk and Chebarkul were calibrated. To measure the nature of the damaging shockwave, arrival times were measured from the footage of 34 traffic cameras, data saved on a single timed server. To measure the impact of the shockwave, some 150 eyewitnesses were interviewed to ask about their personal experiences, smells, sense of heat, sunburn, etc. Meteorite find locations, shape, and size were documented by interviewing the finders and photographing the collections. Some of these meteorites were analyzed in a consortium study to determine what material properties contributed to the manner in which the meteoroid broke in the atmosphere. The results paint the first detailed picture of an asteroid impact airburst over a populated area. This information may help better prepare for future impact hazard mitigation scenarios.

The results of the registration seismic and air waves of Kambarata explosion at epicentral distances from 400 m to 50 km. From these data are determined attenuation seismic waves and built isoseists seismic intensity of the explosion at the industrial buildings and dwelling houses of the region. Engineering inspection of these facilities after the explosion showed that the explosion was provided by the seismic safety of protected structures. Study air waves showed that they formed exclusively lifting dome soil. Their amplitude was negligible and is not dangerous for the glazing houses in the region.

Our objective is to assess the performance of waveform cross-correlation technique, as applied to automatic processing of the aftershock sequence of the 2012 Sumatera (Mw=8.6) earthquake, relative to the Reviewed Event Bulletin (REB) issued by the International Data Centre. The REB includes ~1150 aftershocks between April 11 and May 23 with (IDC) body wave magnitudes from 3.05 to 6.19. The aftershocks cover a slightly unusual V-shaped area. The cross correlation technique allows a flexible approach to signal detection, phase association and event building. To automatically recover the sequence, we selected sixteen aftershocks with mb(IDC) between 4.5 and 5.0 from the IDC Standard Event List (SEL3) available on April 13. These events evenly but sparsely cover the whole area. After a superficial manual review these aftershocks were designated as master events. Waveform templates from only seven array stations with the largest SNR for the signals from the main shock were used to calculate cross-correlation coefficients. All detections obtained by cross-correlation were then used to build events according to the IDC definition, i.e. at least three primary stations with accurate arrival times, azimuth and slowness estimates. The qualified events populated the cross-correlation Standard Event List (XSEL). The XSEL was compared with two IDC products: the final automatic bulletin (SEL3) and the interactive bulletin (REB). There are some valid events missed in the REB but found in the XSEL. As a bootstrap exercise to confirm the significance of the XSEL findings, a large portion of the newly built events was reviewed interactively by experienced analysts. In order to investigate the influence of all defining parameters (cross correlation coefficient threshold and SNR, F-statistics and F-K analysis, azimuth and slowness estimates, relative magnitude, etc.) on the final XSEL we have constructed relevant frequency distributions for all detections and only for those which were associated with the XSEL events. These distributions are also station and master dependent. This allows the introduction of accurate threshold for all defining parameters.

We demonstrate that several techniques based on waveform cross correlation are able to significantly reduce the detection threshold of seismic sources worldwide and to improve the reliability of arrivals by a more accurate estimation of their defining parameters. A master event and the events it can find using waveform cross correlation at array stations of the International Monitoring System (IMS) have to be close. For the purposes of the International Data Centre (IDC), one can use the spatial closeness of the master and slave events in order to construct a new automatic processing pipeline: all qualified arrivals detected using cross correlation are associated with events matching the current IDC event definition criteria (EDC) in a local association procedure. Considering the repeating character of global seismicity, more than ninety per cent of events in the Reviewed Event Bulletin (REB) can be built in this automatic processing. Due to the reduced detection threshold, waveform cross correlation may increase the number of valid REB events by a factor of 1.5 to 2.0. Therefore, the new pipeline may produce a more comprehensive bulletin than the current pipeline – the goal of seismic monitoring. The analysts’ experience with the cross correlation event list (XSEL) shows that the workload of interactive processing might be reduced by a factor of 2 and even more. Since cross correlation produces a comprehensive list of detections for a given master event, no additional arrivals from primary stations are expected to be associated with the XSEL events. The number of false alarms, relative to the number of events rejected from the Standard Event List 3 in the current interactive processing, can also be reduced by the use of several powerful filters. The principal filter is the difference between the arrival times of the master and newly built events at three or more primary stations, which should lie in a narrow range of a few seconds. In this study, one event at a distance of about 2000 km from the main shock was formed by three stations, with the stations and both events on the same great circle. Such spurious events are rejected by checking consistency between detections at stations at different backazimuths from the source region. Two additional effective pre-filters are f-k analysis and Fprob based on correlation traces instead of original waveforms. Overall, waveform cross correlation is able to improve the REB completeness, to reduce the workload related to IDC interactive analysis, and to provide a precise tool for quality check for both arrivals and events. Some major improvements in automatic and interactive processing achieved by cross correlation are illustrated using an aftershock sequence from a large continental earthquake. Exploring this sequence, we describe schematically the next steps for the development of a processing pipeline parallel to the existing IDC one in order to improve the quality of the REB together with the reduction of the magnitude threshold.

Приведены результаты по мелкодисперсным частицам в природных и техногенных геосистемах. Рассмотрение ограничивается случаями твердой Земли, тропосферы и стратосферы. Даны определения основных мелкодисперсных объектов в геофизике (нанокристаллы, нано- и микромасштабные частицы, нанокластеры, нанопористые материалы, коллоидные частицы, аэрозоли и т.д.). Приведены особенности механических свойств нанообъектов и определены предельные размеры, при которых указанные особенности играют существенную роль. Описаны исследования мелкодисперсных частиц, образованных в экспериментах по разрушению горных пород. Проведено обсуждение роли мелкодисперсных частиц в Атмосферных Коричневых Облаках, а также влияния указанных облаков на климатические изменения. Рассмотрены следующие примеры участия мелкодисперсных частиц в межгеосферных взаимодействиях: космическая пыль; извержение вулкана Эйяфьядлайокюдл (Исландия); вихревой перенос мелкодисперсных частиц из тропосферы в стратосферу.

Рассмотрена плазменно-пылевая система в приповерхностном слое освещенной части Луны. Найдены максимальные высоты подъема пыли. Показано отсутствие мертвой зоны в области лунных широт около 800, в которой, как предполагалось [Stubbs et al. // Adv. Space Res. 2006. V. 37. P. 59], частицы пыли не могут подниматься над поверхностью Луны. Определены распределения пыли по размерам и высотам.

В статье рассматривается роль выбросов из ударных кратеров в эволюции Земли и планет Солнечной системы. Методами численного моделирования исследуются аккреция и эрозия планет, перераспределение планетного вещества в результате ударов крупных космических тел и вызываемые ими межгеосферные взаимодействия, несимметричность распределение выбросов вблизи кратерного вала и возможность небаллистического переноса выбросов. Проводится сравнение воздействия на геосферы ударных событий и вулканических извержений.

Разработана дипольная модель генерации электрических и магнитных импульсов в земной коре при электрической поляризации горных пород с низким водосодержанием в результате квазинезависимого поворота структурного блока при его релаксации в стесненных условиях. Электрические моменты диполей изменяются со временем в соответствии с амплитудой дифференциальных движений. Проведено численное 3D моделирование электродинамических процессов при различной ориентации блоков. Показано, что амплитуда электрического и магнитного импульсов, возникающих в окрестности активной грани деформирующегося блока, хорошо согласуется с результатами регистрации электрического поля в приповерхностном слое земной коры в зоне влияния тектонически активной Курайской структуры (Горный Алтай). Модель позволяет проводить сравнение разных участков земной коры по относительной величине параметров механического источника путем сравнения расчетных и экспериментальных данных.

Приводятся результаты численных экспериментов, выполненных с помощью упрощенной нестационарной модели турбулентного потока вязкого сжимаемого газа для двух классов течений, масштаб которых сравним с высотой тропосферы. В одном из них (на примере метана) исследована возможность достижения легкими газами тропопаузы при их интенсивном выделении из литосферы и определены необходимые для этого объемы. Во втором случае исследовано взаимодействие ветрового потока с орографическими неоднородностями и продемонстрировано развитие интенсивного вихревого процесса.

На основании статистического анализа банка данных Национального Бюро по безопасности на транспорте США показывается отсутствие влияния факторов космической погоды на авиационные происшествия. Рассмотрены типичные логические и методические ошибки, возникающие в такого рода исследованиях, и приводятся аргументы в пользу бесперспективности дальнейших исследований по данному вопросу.

Представлены статистические характеристики уровней радиосигналов среднеширотных радиостанций, работающих в СДВ–ДВ диапазонах, и зарегистрированных приемником, расположенным в геофизической обсерватории (ГФО) ИДГ РАН “Михнево” (54.94° с.ш.; 37.73° в.д.) в 2007–2010 гг. Указанные эксперименты позволили продемонстрировать, что в условиях глубокого солнечного минимума, т.е. отсутствия возмущающих факторов “сверху”, связанных с солнечной и геомагнитной активностью, наблюдаются интенсивные вариации уровней радиосигналов. Причина таких вариаций, на наш взгляд, связана с возмущениями “снизу”, определяемыми метеорологическими и волновыми процессами в средней и нижней атмосфере.

Формулируются основные направления и задачи исследований по проблеме межгеосферных взаимодействий на приповерхностных участках континентальной земной коры, представляющих наибольший интерес с точки зрения формирования условий жизнедеятельности человека. Установлены основные периодичности вариаций геофизических полей, определяющие природные ритмы окружающей среде. Рассматриваются взаимодействие и преобразование геофизических полей (электрическое поле в грунте и в приземном слое атмосферы, поля радоновых эманаций и микросейсмических колебаний). Отмечается важная роль тектонических нарушений и слабых возмущений твердой Земли в виде лунно-солнечного прилива и барических вариаций в атмосфере в формировании режимов геофизических полей на границе земная кора-атмосфера. Данные, полученные в результате синхронных инструментальных наблюдений, демонстрируют взаимовлияние и значимую корреляцию между амплитудными вариациями геофизических полей разной природы. Ключевые слова: геофизические поля, гравитационное взаимодействие, деформация, земная кора, тектонические разломы.

На основе результатов инструментальных наблюдений выполнен анализ временных вариаций геофизических полей на границе земная кора-атмосфера. Выделены основные периодичности и цикличности вариаций, совпадающие с соответствующими вариациями приливной силы в приземном слое атмосферы. На основании корреляционных соотношений делается заключение о том, что основным фактором, определяющим околосуточные и двухнедельные вариации электрического поля в грунте, эманационного поля радона, уровня подземных вод и поля микросейсмических колебаний является лунно-солнечный прилив. Анализируется также роль твердоприливной деформации в вариациях жесткости разломных зон и формировании блоковых движений в земной коре, в частности, прецессии структурных блоков. Причиной прецессионно-нутационного движения блоков является разновременная реакция блока и примыкающей к нему тектонической структуры, выполняющей роль межблокового промежутка, на продольную (вдоль разломной зоны) и поперечную (нормально к разлому) компоненты приливной деформации.

Приведены результаты систематических инструментальных наблюдений за вариациями геомагнитного поля в зонах влияния тектонических разломов при распространении сейсмических волн разной интенсивности. Показано, что сейсмические волны с амплитудой, превышающей 5-10 мкм/с, при распространении через разломную зону всегда вызывают вариации геомагнитного поля. При более слабых сейсмических возмущениях эффект имеет "мерцательный" характер, причем относительная частота возникновения эффекта падает с уменьшением амплитуды сейсмической волны. Впервые установлена количественная зависимость между максимальным значением полного вектора вариаций индукции геомагнитного поля в зоне разлома и амплитудой сейсмического возмущения.

Разработана новая численная модель генерации электрических импульсов в земной коре системой электрических диполей, равномерно распределенных по активной поверхности релаксирующего структурного блока при его стесненном повороте. Электрические моменты диполей изменяются со временем в соответствии с амплитудой дифференциальных движений. Показано, что амплитуды электрических импульсов и степень их затухания с расстоянием до источника соответствуют данным инструментальных наблюдений.

A mechanism for the production of crater rays is proposed that is based on the interaction of impact-induced shock waves with existing (old) craters. Numerical simulations are used to test this idea, and to study the influence of inherited craters’ size and location on the rays’ parameters. The results of the simulations show that crater rays (at least, some of them) could be produced through this mechanism.

We review dust and meteoroid fluxes and their dusty plasma effects in the interplanetary medium near Earth orbit and in the Earth’s ionosphere. Aside from in-situ measurements from sounding rockets and spacecraft, experimental data cover radar and optical observations of meteors. Dust plasma interactions in the interplanetary medium are observed by the detection of charged dust particles, by the detection of dust that is accelerated in thesolar wind and by the detection of ions and neutrals that are released from the dust. These interactions are not well understood and lack quantitative description. There is still a huge discrepancy in the estimates of meteoroid mass deposition into the atmosphere. The radar meteor observations are of particular interest for determining this number. Dust measurements from spacecraft require a better understanding of the dust impact ionization process, as well as of the dust charging processes. The latter are also important for further studying nanodust trajectories in the solar wind. Moreover understanding of the complex dependencies that cause the variation of nanodust fluxes is still a challenge.

We present a case modeling study of impact crater formation in H2O-bearing targets. The main goal of this work is to investigate the post-impact thermal state of the rock layers modified in the formation of hyper-velocity impact craters. We present model results for a target consisting of a mixture of H2O-ice and rock, assuming an ice/water content variable with depth. Our model results, combined with results from previous work using dry targets, indicate that for craters larger than about 30 km in diameter the onset of post-impact hydrothermal circulation is characterized by two stages: first, the formation of a mostly dry, hot central uplift followed by water beginning to flow in and circulate through the initially dry and hot uplifted crustal rocks. The post-impact thermal field in the periphery of the crater is dependent on crater size: in mid-size craters, 30-50 km in diameter, crater walls are not strongly heated in the impact event, and even though ice present in the rock may initially be heated enough to melt, overall temperatures in the rock remain below melting, undermining the development of a crater-wide hydrothermal circulation. In large craters (with diameters more than 100 km or so), the region underneath the crater floor and walls is heated well above the melting point of ice, thus facilitating the onset of an extended hydrothermal circulation. These results provide preliminary constraints in characterizing the many water-related features, both morphologic and spectroscopic, that high-resolution images of Mars are now detecting within many Martian craters.

We have assembled data on 13 cases of meteorite falls with accurate tracking data on atmospheric passage. In all cases, we estimate the bulk strength of the object corresponding to its earliest observed or inferred fragmentation in the high atmosphere, and can compare these values with measured strengths of meteorites in the taxonomic class for that fall. In all 13 cases, the strength corresponding to earliest observed or inferred fragmentation is much less than the compressive or tensile strength reported for that class of stony meteorites. Bulk strengths upon atmospheric entry of these bodies are shown to be very low, 0.1 to approximately 1 MPa on first breakup, and maximal strength on breakup as 1–10 MPa corresponding to weak and ‘‘crumbly’’ objects, whereas measured average tensile strength of the similar meteorite classes is about 30 MPa. We find a more random relation between bulk sample strength and sample mass than is suggested by a commonly used empirical power law.We estimate bulk strengths on entry being characteristically of the order of 10-1–10-2 times the tensile strengths of recovered samples. We conclude that pre-entry, meter-scale interplanetary meteoroids are typically highly fractured or in some cases rubbly in texture, presumably as a result of their parent bodies’ collisional history, and can break up under stresses of a few megapascals. The weakness of some carbonaceous objects may result from very porous primordial accretional structures, more than fractures. These conclusions have implications for future asteroid missions, sample extraction, and asteroid hazard mitigation.

Simple estimates suggest that ejecta blankets around larger craters should be more asymmetric than around smaller craters for the same oblique impact angle. Numerical simulations presented in the paper confirm that an increase in the scale of gravity-dominated craters (and in the size of the corresponding projectiles) increases the asymmetry of both impact craters and ejecta blankets around them.

Shock recovery experiments were performed with an explosive set-up in which three types of microorganisms embedded in various types of host rocks were exposed to strong shock waves with pressure pulse lengths of lower than 0.5 μs: spores of the bacterium Bacillus subtilis, Xanthoria elegans lichens, and cells of the cyanobacterium Chroococcidiopsis sp. 029. In these experiments, three fundamental parameters were systematically varied (1) shock pressures ranging from 5 to 50 GPa, (2) preshock ambient temperature of 293, 233 and 193 K, and (3) the type of host rock, including nonporous igneous rocks (gabbro and dunite as analogs for the Martian shergottites and chassignites, respectively), porous sandstone, rock salt (halite), and a clay-rich mineral mixture as porous analogs for dry and water-saturated Martian regolith. The results show that the three parameters have a strong influence on the survival rates of the microorganisms. The most favorable conditions for the impact ejection from Mars for microorganisms would be (1) low porosity host rocks, (2) pressures <10-20 GPa, and (3) low ambient temperature of target rocks during impact. All tested microorganisms were capable of surviving to a certain extent impact ejection in different geological materials under distinct conditions.

Despite its centennial exploration history, there are still unresolved questions about Meteor Crater, the first recognized impact crater on Earth. This theoretical study addresses some of these questions by comparing model results with field and laboratory studies of Meteor Crater. Our results indicate that Meteor Crater was formed by a high-velocity impact of a fragmented projectile, ruling out a highly dispersed swarm as well as a very low impact velocity. Projectile fragmentation caused many fragments to fall separately from the main body of the impactor, making up the bulk of the Canyon Diablo meteorites; most of these fragments were engulfed in the expansion plume as they approached the surface without suffering high shock compression, and were redistributed randomly around the crater. Thus, the distribution of Canyon Diablo meteorites is not representative of projectile trajectory, as is usual for impactor fragments in smaller strewn fields. At least 50% of the main impactor was ejected from the crater during crater excavation and was dispersed mostly downrange of the crater as molten particles (spheroids) and highly shocked solid fragments (shrapnel). When compared with the known distribution, model results suggest an impactor from the SW. Overall, every model case produced much higher amounts of pure projectile material than observed. The projectile-target mixing was not considered in the models; however, this process could be the main sink of projectile melt, as all analyzed melt particles have high concentrations of projectile material. The fate of the solid projectile fragments is still not completely resolved. Model results suggest that the depth of melting in the target can reach the Coconino sandstone formation. However, most of the ejected melt originates from 30-40 m depth and, thus, is limited to Moenkopi and upper Kaibab material. Some melt remains in the target; based on the estimated volume of the breccia lens at Meteor Crater, our models suggest at most a 2% content of melt in the breccia. Finally, a high water table at the time of impact could have aided strong dispersion of target and projectile melt.

Исследованы эффекты, связанные с нейтральной компонентой запылённой ионосферной плазмы, влияющие на зарядку пылевых частиц. Вычислены микроскопические токи ионов на пылевую частицу с учётом эффекта взаимодействия ионов с нейтральными компонентами ионосферной плазмы. Вычисления проведены как для случая отрицательных зарядов пылевых частиц, так и для случая положительных зарядов, реализуемого в присутствии достаточно интенсивного ультрафиолетового или рентгеновского излучения. Кроме того, для последнего случая проведено исследование нагрева электронов при фотоэффекте. Оказывается, что эффективность нагрева электронов зависит от концентрации нейтральной компоненты. Определены области высот ионосферы, на которых указанные эффекты оказывают заметное влияние на зарядку нано- и микромасштабных пылевых частиц различного происхождения. Показано, что рассматриваемые эффекты важны при описании серебристых облаков, полярных мезосферных радиоотражений, а также физических явлений, в которых участвуют частицы метеорного происхождения.

На основе анализа нелинейных эффектов при распространении сейсмических волн определена механическая жесткость тектонических разломов разного ранга. Объектами исследований являлись тектонические структуры центральной части Восточно-Европейской платформы (Московская синеклиза и Воронежский кристаллический массив), а также разломные зоны горных массивов Балапан и Дегелен (Дегеленский магматогенный узел Центральночингизской зоны) в Казахстане. Получена зависимость жесткости разломных зон от их протяженности. Анализ данных свидетельствует о хорошо выраженных временных вариациях жесткости тектонических структур с периодами 13-15 сут, 27-32 сут и около 1 года. При этом как нормальная kn, так и сдвиговая ks жесткость разломных зон разного ранга могут изменяться соответственно в 1,3 (двухнедельные вариации) 1,5 (месячные вариации) и 2,5 раза (годовые вариации).

В настоящей работе на основе данных деформографических и сейсмических наблюдений представлена, насколько нам известно, впервые, оценка возможного вклада колебаний, создаваемых промышленными взрывами, в развитие сейсмодеформационных процессов на Восточно-Европейской платформе (ВЕП) и ее обрамлениях.

Приведены результаты экспериментального исследования течений, возникающих во вращающейся вокруг наклонной оси сфере. Показано, что в жидкости возникают стабильные образования в виде цилиндрических поверхностей, угловая скорость которых отличается от скорости вращения сосуда. Получены количественные оценки рассогласованности движений жидкости и сосуда под влиянием неровностей на поверхности сосуда и малого возмущающего фактора в виде пузыря воздуха.

На основе совместного анализа временных трендов времен пробега сейсмических волн PKP(DF), PKP(BC) и PKP(AB) на 10 сейсмических станциях получена интервальная оценка скорости дифференциального вращения внутреннего ядра 0.3-0.7 градуса в год.

В работе приводятся результаты лабораторных экспериментов направленных на исследование особенностей деформирования тонких слоев геоматериалов в стесненных условиях. Результаты опытов интерпретированы с учетом современных данных о тонкой структуре сейсмогенных разломов. Исследованы закономерности влияния на напряженно-деформированное состояния таких параметров, как средний размер зерна заполнителя трещины, распределение частиц заполнителя по размерам, жесткость окружающего массива. Судя по полученным результатам, вклад в эффективную прочность дополнительных нормальных напряжений, обусловленных разуплотнением материала при динамическом распространении «разлома землетрясения», во многих случаях не является значительным.

В работе впервые экспериментально оценен характер изменения жесткости межблокового контакта на разных стадиях процесса прерывистого скольжения и рассмотрены некоторые возможные следствия наблюдаемого явления. Показано, что на заключительной стадии цикла, перед началом динамического срыва, сдвиговая жесткость контакта радикально снижается, что может быть обнаружено в природе сейсмическими методами. Этот эффект может оказаться основой для разработки новых активных и пассивных методов мониторинга сейсмоактивных регионов.

В работе анализируются данные наблюдений за изменением уровня воды в скважинах при воздействии сейсмических волн от удаленных землетрясений и взрывов. Показано, что в большинстве случаев величина постсейсмического изменения уровня пропорциональна корню квадратному из амплитуды волны деформаций. Средняя интенсивность остаточных изменений уровня составляет величину 1-5 см/микрострейн динамической деформации. Значительные отклонения от этого диапазона определяются особенностями строения пласта. В лабораторных экспериментах исследована возможность разрушения динамическими импульсами слабопроницаемых барьеров, формирующихся в трещинах массива при осаждении микрочастиц. Показано, что существенное увеличение трещинной проницаемости массива может происходить и в том диапазоне амплитуд колебаний, в котором разрушение породы или прорастание существующих трещин в результате прохождения сейсмической волны маловероятно. Установлена возможность постепенного накопления эффекта при длительном воздействии. Изменение количества открытых трещин и увеличение их эффективной проницаемости может привести к миграции флюидов, вариациям порового давления, а, следовательно, и всей гаммы механических характеристик локального участка массива.

Plasma processes in the Earth’s environments containing nano- and microscale grains are described. Possible observational manifestations of dusty ionospheric plasmas during high-speed meteor showers are discussed. A unified explanation of ionization properties of the polar mesosphere under summer conditions is given. Dusty plasma processes are also considered in application to active geophysical rocket experiments which involve release of some gaseous substance in near-Earth space, the origin of the primary Earth’s crust, hydrosphere and atmosphere, and global electromagnetic Schumann resonances.

Observations of fresh impact craters by the Opportunity rover and in high-resolution orbital images constrain the latest phase of granule ripple migration at Meridiani Planum to have occurred between similar to 50 ka and similar to 200 ka. Opportunity explored the fresh Resolution crater cluster and Concepcion crater that are superposed on and thus younger than the ripples. These fresh craters have small dark pebbles scattered across their surfaces, which are most likely fragments of the impactor, suggesting that the dark pebbles and cobbles observed by Opportunity at Meridiani Planum are a lag of impactor-derived material (either meteoritic or secondary impactors from elsewhere on Mars). Two larger, fresh-rayed craters in Meridiani Planum bracket ripple migration; secondaries from Ada crater are clearly superposed on and secondaries from an unnamed 0.84 km diameter crater have been modified and overprinted by the ripples. Three methods were used to estimate the age of these craters and thus when the latest phase of ripple migration occurred. The inactivity of the ripples over the past similar to 50 ka at Meridiani is also consistent with other evidence for the stability of the ripples, the lack of observed eolian bed forms in craters that formed in the past 20 years, and little evidence for much dune motion in the past 30 yr on Mars. Observations of crater morphology and their interaction with the ripples allow the development of a general time scale for craters in Meridiani Planum over the past million years.

Fully nonlinear electrostatic waves in a plasma containing electrons, positrons, and ions are investigated by solving the governing equations exactly. It is found that both smooth and spiky quasistationary waves exist, and large-amplitude waves necessarily have large-phase velocities, but small-amplitude waves can be both fast and slow.

Gusev Crater lies within the Aeolis Quadrangle of Mars at the boundary between the northern lowlands and southern highlands. The ancient valley Ma'adim Vallis dissects the highlands south of Gusev Crater and is thought to have fed the crater with sediments. High Resolution Stereo Camera data and Digital Elevation Models were used to construct a geologic-geomorphic map (173.5-178.5 degrees E, 10-18 degrees S) and cross-sections, complemented by data from Mars Orbiter Camera, Mars Orbiter Laser Altimeter and Thermal Emission Imaging System. Three geologic domains are recognised: the highlands in the south, Gusev Crater and lowlands in the north. Twelve units are mapped, with thicknesses ranging from hundred meters to several kilometres. Thicknesses of units, and their bedding attitude, are estimated combining the geologic map and topographic information. Relative ages are determined from crater counts, ranging from Early Noachian for highland units to Middle Amazonian for units in Gusev Crater and in lowlands. Episodes of intense geologic activity (deposition, volcanism, deformation) occur at around 4.0 Ga, 3.7 Ga, and 3.5 Ga. Comparing the geometry of the Gusev Crater with similar sized, filled and un-filled, Martian craters, suggests that the Columbia Hills are relics of the original central peak of Gusev Crater.

McEwen et al. (McEwen, A.S., Preblich, B.S., Turtle, E.P., Artemieva, N.A., Golombek, M.P., Hurst, M., Kirk, R.L., Burr, D.M., Christensen, P. [2005]. Icarus 176, 351-381) developed a useful test for the internal consistency of crater-count chronometry systems. They argued that certain multi-kilometer, fresh-looking martian craters with prominent rays should be the youngest or near-youngest craters in their size range. The "McEwen et al. test" is that the ages determined from crater densities of the smallest superimposed craters (typically diameter D similar to 5-20 m) should thus be comparable to the expected formation intervals of the host primary. McEwen et al. concluded from MOC data that crater chronometry failed this test by factors of 700-2000. We apply HiRISE and other imagery to eight different young craters in order to re-evaluate their arguments. We use existing crater chronology systems as well as the reported observed production rate of 16 m craters (Malin, MC., Edgett, K., Posiolova, L., McColley, S., Noe Dobrea, E. [2006]. Science 314, 1573-1557; Hartmann, W.K., Quantin, C., Mangold, N. [2007]. Icarus 186, 11-23; Kreslavsky [2007]. Seventh International Conference on Mars, 3325). Every case passes the McEwen et al. test. We conclude that the huge inconsistencies suggested by McEwen et al. are spurious. Many of these craters show evidence of impact into ice-rich material, and appear to have ice-flow features and sublimation pits on their floors. As production rate data improve, decameter-scale craters will provide a valuable way of dating these young martian geological formations and the processes that modify them. (C) 2010 Elsevier Inc. All rights reserved.

The 1.4-1.6 km thick Onaping Formation consists of a complex series of breccias and "melt bodies" lying above the Sudbury Igneous Complex (SIC) at the Sudbury impact structure. Based on the presence of shocked lithic clasts and various "glassy" phases, the Onaping has been described as a "suevitic" breccia, with an origin, at least in part, as fallback material. Recent mapping and a redefined stratigraphy have emphasized similarities and differences in its various vitric phases, both as clast types and discrete intrusive bodies. The nature of the Onaping and that of other "suevitic" breccias overlying impact melt sheets is reviewed. The relative thickness, internal stratigraphic and lithological character, and the relative chronology of depositional units indicate multiple processes were involved over some time in the formation of the Onaping. The Sudbury structure formed in a foreland basin and water played an essential role in the evolution of the Onaping, as indicated by a major hydrothermal system generated during its formation. Taken together, observations and interpretations of the Onaping suggest a working hypothesis for the origin of the Onaping that includes not only impact but also the interaction of sea water with the impact melt, resulting in repeated explosive interactions involving proto-SIC materials and mixing with pre-existing lithologies. This is complicated by additional brecciation events due to the intrusion of proto-SIC materials into the evolving and thickening Onaping. Fragmentation mechanisms changed as the system evolved and involved vesiculation in the formation of the upper two-thirds of the Onaping.

This paper is a current status report on a project focused on understanding the formation of large impact basins on terrestrial planetary bodies. A set of preliminary two-dimensional axisymmetric numerical models of collisions of asteroids with diameters from 150 to 800 km with the Moon, Mars, and Mercury illustrates the main mechanical effects of planetary-scale impacts. The target body is modeled on a regular grid with a spatial resolution of 5-10 km. Self-gravity is included in the hydrocode. The main consequence of such an impact is a deep melt pool at the center of the basin. Model results are tentatively compared with known impact basins such as South Pole-Aitken on the Moon and Hellas on Mars.

The properties of nano- and microparticles (60 nm 200 mu m) of the dust formed by mass blasting in the iron ore open pit of the Lebedinsky Mining and Concentrating Combine have been studied. Data on the morphology of particles, their magnetic properties, mineralogy, and dimensions have been obtained. Quartz, magnetite, and mica were identified among these particles. The dust mostly consisted of fragmented iron ore formation from the rock massif involved in the blasting.

Microseismic noise was studied in the frequency range 0.5-30 Hz in the conditions prevailing in the town of Vorkuta. A seismic noise model was developed consisting of power spectral densities of ground motion velocity separately for daytime and nighttime in different frequency ranges. The absolute noise level for frequencies of 1-5 Hz in Vorkuta varies between -140 and -150 dB in daytime and from -152 to -158 dB in nighttime, with the ranges for the 8-15 Hz noise being -140 to -155 dB in daytime and -155 to -165 dB in nighttime. Well-pronounced daily variations in noise amplitude were observed in the frequency ranges 1.5-3 Hz and 14-17 Hz. The noise amplitude varies by 7 dB over 24 hours, with the amplitude of horizontal component variation being 5 dB above that of the vertical component. The power spectral densities of ground motion velocity in the microseismic noise involve several spectral peaks, whose central frequencies did not vary by more than 0.15 Hz during the entire period of instrumental observation. The seismic background in the town of Vorkuta contains seismic events due to distant earthquakes and local industrial explosions.

The effect of accumulation of deformations on rock discontinuities due to low amplitude seismic vibrations has been investigated in laboratory and field experiments. A peculiar rheology of stressed faults and fractures leads to origination of relative residual displacements of discontinuity sides. A short-term disturbance in a stressed blocky medium can also trigger a slow slip, whose contribution to the integral amount of accumulated deformation may be appreciable.

Instrumental measurements of geophysical fields in several regions of the Earth's crust with a complex structure and tectonics are analyzed. The observed geophysical fields include the electric field in the boundary layer of the atmosphere and in the subsurface crust, the ground magnetic field, and the fields formed by microseismic vibrations and natural radon emanation. It is shown that the fault zones are characterized by noticeably higher (compared to the middle segments of crustal blocks) variations in the geophysical fields, a stronger response to the faint external impacts in the form of lunisolar tides, and baric variations in the atmosphere, as well as by higher intensity relaxation processes. Energy transformations between the geophysical fields of different origins are observed predominantly in the fault regions

Knowledge of the physical and chemical conditions on the primeval Earth is important for the study of the origin of the biosphere. This paper discusses the latest modification of the theory of the origin of the Earth and other planets. Possible consequences of the formation of the Sun in the area of the star formation closely surrounded by neighboring young stars are considered. The classical problem of the rate of accretion of Earth and other planets is generalized with new estimates allowing the correlation of the results from long-lived (U-Pb) and short-lived (Hf-W) space-chronometers. A model of the early evolution of the Earth, based on both dynamic estimates and the latest geochemical data (earliest Australian zircons, relict xenon pleiad) is discussed. The problems of the theory of early Earth's evolution, which so far cannot be adequately solved, are discussed.

It is shown that the inclusion of the effect of internal friction on the deformation of a damaged meteoroid leads to a marked (by 10-20 km) decrease in the height of the meteoroid deceleration and, hence, the height of the energy release. The possible decrease of the role of internal friction due to "acoustic fluidization" and the penetration of impact-compressed gas through the cracks in the interior of the damaged meteoroid are discussed.

We have analyzed the regularities in the spatiotemporal behavior of the methane concentration and mass, recorded in different regions of the globe. In the southern hemisphere (SH), the methane concentration does not depend on latitude. In the northern hemisphere (NH), the methane concentration increases towards the Arctic zone. The maximum CH4 concentration in the fall is due to the action of the additional methane sources in the NH Arctic region. The methane flux calculations showed that in the SH the methane flux into the Earth's atmosphere is barely season dependent. In the NH during the fall season, the methane flux considerably increases, and the difference between the maximum flux in August-September and the flux in December-January reaches three. The additional, still disregarded sources, sustaining high methane emission in the spring season at high SH latitudes are estimated to be as strong as 100-120 Tg per year. To equilibrate the methane supply to the atmosphere and methane sink in SH, additional, yet unidentified sources of over 300 Tg/yr are required. The global methane flux into the Earth's atmosphere should be no less than 1050-1100 Tg yearly.

Crater-ejecta correlation is an important element in the analysis of crater formation and its influence on the geological evolution. In this study, both the ejecta distribution and the internal crater development of the Jurassic/Cretaceous Mjølnir Crater (40 km in diameter; located in the Barents Sea) are investigated through numerical simulations. The simulations show a highly asymmetrical ejecta distribution and underscore the importance of a layer of surface water in ejecta distribution. As expected, the ejecta asymmetry increases as the angle of impact decreases. The simulation also displays an uneven aereal distribution of ejecta. The generation of the central high is a crucial part of crater formation. In this study, peak generation is shown to have a skewed development, from approximately 50 s to 90 s after impact, when the peak reaches its maximum height of 1 to 1.5 km. During this stage, the peak crest is moved about 5 km from an uprange to a downrange position, ending with a final central position which has a symmetrical appearance that contrasts with its asymmetrical development.

Проведено исследование свойств нано- и микромасштабных пылевых частиц, образующихся при массовых взрывах на железорудном карьере Лебединского горно-обогатительного комбината, в широком диапазоне размеров от 60 нм до 200 мкм. В ходе исследований получены данные о морфологии частиц, их магнитных свойствах, минералогическом и гранулометрическом составах. Обнаруженные минералы — кварц, магнетит и слюда. Основная часть пыли состоит из частиц разнообразной морфологии железистого кварцита, в массиве которого и производился взрыв.

Предложена модель генерации электрических и магнитных импульсов в земной коре при электрической поляризации горных пород с низким водосодержанием в результате квазинезависимого поворота структурного блока при его релаксации в стесненных условиях в качестве источника электрических и магнитных импульсов. В результате быстропротекающего стесненного поворота релаксирующего блока формируется дифференциальное смещение на контакте его активной грани с окружающими горными породами, что вызывает электрическую поляризацию вещества-заполнителя межблокового промежутка в результате преобразования его структуры и физико-механических свойств. Сформировавшаяся при этом система токов имеет импульсный характер и является источником электрических и магнитных импульсов, которые распространяются в пространстве. Приведены результаты численного 3D моделирования процесса генерации электрических и магнитных импульсов при дифференциальной подвижке активного структурного блока земной коры.

Показано, что учет влияния внутреннего трения на деформацию разрушенного метеороида приводит к заметному (на 10–20 км) уменьшению высоты его торможения и, соответственно, высоты, на которой выделяется энергия. Обсуждается возможное уменьшения роли внутреннего трения за счет“акустической флюидизации” и проникновения ударно_сжатого газа через трещины внутрь разрушенного метеороида.

Для задач всплытия высокотемпературного термика численно исследуются характерные особенности газодинамического потока при моделировании турбулентного перемешивания методом крупных вихрей. Продемонстрировано хорошее согласие динамики всплытия верхней кромки нагретого облака с экспериментальными и теоретическими данными при значении параметра метода (константы Смагоринского) порядка единицы, в то время как наиболее часто используются значения 0.1−0.2. Расчеты всплытия бесконечной системы регулярно расположенных у поверхности Земли термиков на достаточно подробных сетках позволили уточнить некоторые рассчитанные ранее характеристики подъема такой системы.

Проведён анализ закономерностей пространственно-временного поведения концентрации и массы метана, регистрируемого в различных регионах мира. В южном полушарии (ЮП) концентрация метана не зависит широты. В северном полушарии (СП) концентрация метана увеличивается с приближением к арктической зоне. Максимум концентрации СН4 в осенний период связан с действием в арктическом регионе СП дополнительных источников метана. Расчёты потока метана показали, что в ЮП поток метана в атмосферу Земли практически не зависит от сезона. В СП в осеннее время года наблюдается значительное увеличение потока метана и различие между максимальным потоком в августе-сентябре и потоком в декабре-январе достигает тройки. Дополнительная, ранее не учитываемая, мощность источников поддерживающих высокую эмиссию метана в осеннее время года на высоких широтах СП, оценивается в 100-120 Тг в год. Для соблюдения баланса между поступлением метана в атмосферу и его стоком в ЮП необходимы дополнительные, не учитываемые ранее источники мощностью более 300 Тг/год. Глобальный поток метана в атмосферу Земли должен составлять не менее 1050-1100 Тг в год.

Проведены исследования микросейсмического шума для условий г. Воркуты в диапазоне частот 0,5-30 Гц. Представлена модель сейсмического шума в виде спектральных плотностей мощности скорости колебаний отдельно для дневного и ночного периодов времени в разных диапазонах частот. Абсолютный уровень шума в г. Воркута в диапазоне частот 1-5 Гц изменяется от -140 до -150 дБ в дневное время и в диапазоне от -152 до -158 дБ в ночное; в диапазоне 8-15 Гц – от -140 до -155 дБ в дневное и от -155 до -165 дБ в ночное время. Наблюдаются выраженные суточные вариации амплитуды шума в диапазонах частот 1,5–3 Гц и 14–17 Гц. В течение суток амплитуда шума изменяется на 7 дБ, причем, амплитуда вариации горизонтальной составляющей на 5 дБ выше амплитуды вариации вертикальной компоненты. Спектральные плотности мощности скорости колебаний в микросейсмическом фоне характеризуются наличием ряда спектральных пиков, центральная частота которых за весь период инструментальных наблюдений изменяется не более, чем на 0,15 Гц. Сейсмический фон г. Воркуты характеризуется наличием сейсмических событий от удаленных землетрясений и местных промышленных взрывов.

Результаты обработки сейсмических данных и выявленные в процессе анализа закономерности расположения гипоцентров землетрясений сопоставляются в статье с данными изучения структуры разломов, модельных и численных экспериментов; приведено количественное исследование закономерностей локализации очагов внутри разломных зон. При помощи трехмерных построений продемонстрировано, что события локализуются в окрестности поверхности близкой к плоскости с почти постоянным углом падения. Причем основная масса событий оказывается сосредоточенной именно на этой условной плоскости. Судя по полученным результатам, область, в которой происходит активное деформирование при подготовке средних землетрясений представляет из себя совокупность локальных "полос", каждая из которых имеет характерный размер порядка 100 м, который, в свою очередь, сопоставим с техногенными возможностями воздействия на геосреду. Можно надеяться, что исследование не только пространственной, но и временной тонкой структуры сейсмичности в окрестности разломной зоны, позволит найти надежные ориентиры как места, так и времени осуществления подобных воздействий. Выявление характерных масштабов локализации сейсмичности может оказаться крайне важным в контексте задач о техногенном воздействии на разломную зону с целью частичного снятия напряжений.

Выполнены детальные экспериментальные исследования времен пробега сейсмических волн PKPdf и PKPbc зондирующих область земного ядра под Африкой. На основе установленных экспериментальных закономерностей предложена модель внешнего ядра с цилиндрической аномалией скорости продольных волн и определены количественно величина скоростной аномалии – 0.5-0.8% и радиус цилиндрической области -1375 км. Полученный результат существенным образом изменяет сложившиеся представления о величине анизотропии внутреннего ядра и видимо, связан с крупномасштабными движениями, предсказываемыми в ряде геодинамических моделей (в частности, моделях геодинамо).

Проведён анализ закономерностей пространственно-временного поведения концентрации и массы метана, регистрируемого в различных регионах мира. В южном полушарии (ЮП) концентрация метана не зависит широты. В северном полушарии (СП) концентрация метана увеличивается с приближением к арктической зоне. Максимум концентрации СН4 в осенний период связан с действием в арктическом регионе СП дополнительных источников метана. Расчёты потока метана показали, что в ЮП поток метана в атмосферу Земли практически не зависит от сезона. В СП в осеннее время года наблюдается значительное увеличение потока метана и различие между максимальным потоком в августе-сентябре и потоком в декабре-январе достигает тройки. Дополнительная, ранее не учитываемая, мощность источников поддерживающих высокую эмиссию метана в осеннее время года на высоких широтах СП, оценивается в 100-120 Тг в год. Для соблюдения баланса между поступлением метана в атмосферу и его стоком в ЮП необходимы дополнительные, не учитываемые ранее источники мощностью более 300 Тг/год. Глобальный поток метана в атмосферу Земли должен составлять не менее 1050-1100 Тг в год.

The primordial asteroid belt contained at least several hundred and possibly as many as 10,000 bodies with diameters of 1000 km or larger. Following the formation of Jupiter, nebular gas drag combined with passage of such bodies through Jovian resonances produced high eccentricities (e = 0.3-0.5). low inclinations (i < 0.5 degrees) and, therefore, high velocities (3-10 km/s) for "resonant" bodies relative to both nebular gas and non-resonant planetesimals. These high velocities would have produced shock waves in the nebular gas through two mechanisms. First, bow shocks would be produced by supersonic motion of resonant bodies relative to the nebula. Second, high-velocity collisions of resonant bodies with non-resonant bodies would have generated impact vapor plume shocks near the collision sites. Both types of shocks would be sufficient to melt chondrule precursors in the nebula, and both are consistent with isotopic evidence for a time delay of similar to 1-1.5 Myr between the formation of CAIs and most chondrules. Here, initial simulations are first reported of impact shock wave generation in the nebula and of the local nebular volumes that would be processed by these shocks as a function of impactor size and relative velocity. Second, the approximate maximum chondrule mass production is estimated for both bow shocks and impact-generated shocks assuming a simplified planetesimal population and a rate of inward migration into resonances consistent with previous simulations. Based on these initial first-order calculations, impact-generated shocks can explain only a small fraction of the minimum likely mass of chondrules in the primordial asteroid belt (similar to 10(24)-10(25) g). However, bow shocks are potentially a more efficient source of chondrule production and can explain up to 10-100 times the estimated minimum chondrule mass.

Formation of dusty plasmas in the Earth's ionosphere at 80-120 km altitudes during high-speed meteor showers and its detectable manifestations are discussed. Emphasis is given to ground-based observations such as detection of low-frequency (< 50 Hz) ionospheric radio noise, ground-based observations of infrasonic waves, and amplification of the intensity of green radiation at 557.7 nm from a layer at the 110-120 km altitude in the lower ionosphere. The physical processes responsible for these manifestations are considered.

The issue of crater retention age estimates on planetary surfaces is discussed with an attempt to quantify the effect of overlapping primary and secondary impact crater populations in restricted crater diameter ranges. The approach to this problem is illustrated with a simple model production function where the secondary crater input is artificially enhanced. Extrapolation of such a secondary crater model distribution to a global record results in extraordinarily high crater frequencies that do not exist on Mars, and implies the need of detailed studies of the size-frequency distribution for remote secondary craters, to date poorly known. A key case, the martian crater Zunil and its secondary crater held, illustrate that reasonable predictions for the secondary crater size-frequency distribution at small (<100 m) crater diameters affected the standard model crater retention age for the Cerberus plains less than the statistical uncertainty. These observations show that age determination based on appropriate crater counting statistics is valid in a wide primary crater diameter range.

The recent Carancas meteorite impact event caused a worldwide sensation. An H4-5 chondrite struck the Earth south of Lake Titicaca in Peru on September 15, 2007, and formed a crater 14.2 m across. It is the smallest, youngest, and one of two eye-witnessed impact crater events on Earth. The impact violated the hitherto existing view that stony meteorites below a size of 100 m undergo major disruption and deceleration during their passage through the atmosphere and are not capable of producing craters. Fragmentation occurs if the strength of the meteoroid is less than the aerodynamic stresses that occur in flight. The small fragments that result from a breakup rain down at terminal velocity and are not capable of producing impact craters. The Carancas cratering event, however, demonstrates that meter-sized stony meteoroids indeed can survive the atmospheric passage under specific circumstances. We present results of a detailed geologic survey of the crater and its ejecta. To constrain the possible range of impact parameters we carried out numerical models of crater formation with the iSALE hydrocode in two and three dimensions. Depending on the strength properties of the target, the impact energies range between approximately 100-1000 MJ (0.024-0.24 t TNT). By modeling the atmospheric traverse we demonstrate that low cosmic velocities (12-14 kms(-1)) and shallow entry angles (<20 degrees) are prerequisites to keep aerodynamic stresses low (<10 MPa) and thus to prevent fragmentation of stony meteoroids with standard strength properties. This scenario results in a strong meteoroid deceleration, a deflection of the trajectory to a steeper impact angle (40-60 degrees), and an impact velocity of 350-600 ms(-1), which is insufficient to produce a shock wave and significant shock effects in target minerals. Aerodynamic and crater modeling are consistent with field data and our microscopic inspection. However, these data are in conflict with trajectories inferred from the analysis of infrasound signals.

In this paper we investigate the formation of the Cretaceous-Paleogene (K-Pg) boundary layer through numerical modeling. The K-Pg layer is widely agreed to be composed of meteoritic material and target rock from the Chicxulub impact site, that has been ejected around the globe and mixed with local material during final deposition. The observed composition and thickness of the K-Pg boundary layer changes with azimuth and distance from the impact site. We have run a suite of numerical simulations to investigate whether we can replicate the observational data, with a focus on the distal K-Pg layer and the impact glasses at proximal sites such as Beloc, Haiti. Previous models of the K-Pg ejecta have assumed an initial velocity distribution and tracked the ejecta to its final destination. Here, we attempt to model the entire process, from impact to the arrival of the ejecta around the globe. Our models replicate the observed ejecta thickness at proximal sites, and the modeled ejecta is composed of sediments and silicate basement rocks, in agreement with observational data. Models that use a 45 impact angle are able to replicate the total ejecta and iridium volume at distal sites, and the majority of the ejecta is composed of meteorite and target sediments. Sub-vertical impacts generate too little iridium, and oblique impacts of <= 30 degrees generate too much. However, in contrast to observations, models that involve ballistic transport of ejecta lead to ejecta thickness decreasing with increasing distance, and are unable to transport shocked minerals (quartz and zircon) from the Chicxulub basement rocks around the globe. We suggest that much of the K-Pg ejecta is transported non-ballistically, and that the most plausible mechanism is through re-distribution from a hot, expanding atmosphere. The results are important for future investigations of the environmental effects of the Chicxulub impact. (C) 2009 Elsevier Inc. All rights reserved.

A systematic analysis of the frequency-dependent source scaling of regional phase data observed from underground nuclear explosions conducted at the former Soviet Semipalatinsk Test Site, the Chinese Lop Nor Test Site, the Russian Novaya Zemlya Test Site, and the U. S. Nevada Test Site has been conducted in an attempt to derive improved, quantitative constraints on proposed physical mechanisms for S-wave generation by explosion sources. The source scaling results for all these testing areas have been found to be remarkably consistent indicating that the observed Sn and Lg spectra scale with explosion yield in a manner that is very comparable to that of the corresponding direct Pn spectra, which differs significantly only over narrow frequency bands defined by differences in the P-and S-wave source corner frequencies. More specifically it has been found that the observed frequency-dependent source scaling of S/P spectral ratios at each of these test sites is very consistent with the simple phenomenological model proposed by Fisk et al. (2005), in which the S-wave source is obtained from the corresponding Mueller/Murphy P-wave source by scaling the corner frequency by the S/P velocity ratio of the source medium. While these results have not yet led to the identification of a specific physical mechanism for S-wave generation by explosions, they do provide very strong constraints that must be satisfied by any plausible proposed physical mechanism

Possibility for hybrid ion-acoustic solitons to exist in complex (dusty) plasmas is investigated. Rarefactive solitonlike perturbations are damped and slowed down, mainly due to the plasma absorption and ion scattering on microparticles. Nevertheless, the amplitude of the evolving perturbation at any moment is given by the amplitude of the "conservative" soliton for the corresponding Mach number (so far as the conservative soliton exists). That property allows us to interpret the evolving rarefactive perturbation as a "weakly dissipative" hybrid dust ion-acoustic soliton. The weakly dissipative hybrid dust ion-acoustic solitons can be studied experimentally in laboratory complex plasmas.

Based on the analysis into the influence of blasting on the seismic activity in the area of the Tashtagol ore deposit, the paper shows that quantity, energy and concentration of the mining-induced seismic events grows in the blasting site region. The background-values of seismic activity come back in a period between 11 hours to 3 days after the blasting, and the seismic activity intensification depends on the blast energy.

Meteor Crater is one of the first impact structures systematically studied on Earth. Its location in arid northern Arizona has been ideal for the preservation of the structure and the surviving meteoric material. The recovery of a large amount of meteoritic material in and around the crater has allowed a rough reconstruction of the impact event: an iron object 50 to in diameter impacted the Earth's surface after breaking tip in the atmosphere. The details of the disruption, however, are still debated. The final crater morphology (deep, bowl-shaped crater) rules out the formation of the crater by an open or dispersed swarm of fragments, in which the ratio of swarm radius to initial projectile radius C-d is larger than 3 (the final crater results from the sum of the craters formed by individual fragments). On the other hand, the lack of significant impact melt in the crater has been used to suggest that the impactor was slowed down to 12 km/s by the atmosphere, implying significant fragmentation and fragments' separation tip to 4 initial radii. This paper focuses on the problem of entry and motion through the atmosphere for a possible Canyon Diablo impactor as a first but necessary step for constraining the initial conditions of the impact event which created Meteor Crater. After evaluating typical models used to investigate meteoroid disruption, such as the pancake and separated fragment models, we have carried out a series of hydrodynamic simulations using the 3D code SOVA to model the impactor flight through the atmosphere, both as a continuum object and a disrupted swarm. Our results indicate that the most probable pre-atmospheric mass of the Meteor Crater projectile was in the range of 4.10(8) to 1.2-10(9) kg (equivalent to a sphere 46-66 m in diameter). During the entry process the projectile lost probably 30% to 70% of its mass, mainly because of mechanical ablation and gross fragmentation. Even in the case of a tight swarm of particles (C-d <3), small fragments can separate from the crater-forming swarm and land on the plains (tens of km away from the crater) as individual meteorites. Starting from an impactor pre-atmospheric velocity of similar to 18 km/s, which represents an average value for Earth-crossing asteroids, we find that after disruption, the most probable impact velocity at the Earth's surface for a tight swarm is around 15 km/s or higher. A highly dispersed swarm would result in a much stronger deceleration of the fragments but would produce a final crater much shallower than observed at Meteor Crater.

The results of measurements of the volumetric activity of subsurface radon Rare given for several sections of the Earth's crust located within the central part of the East European Platform. The influence of tectonic structures on the spatial zonality of radon emanation and the intensity of its temporal variations is shown. The temporal variations in radon emanation are characterized by periodicity with periods of approximately a day, as well as of 4, 14, and 29 days, and, as correlation analysis shows, they are determined by the cyclic recurrence of tidal deformations and by cyclonic processes in the atmosphere. The high correlation of the mean values of the volumetric activity of subsurface radon with the value of atmospheric pressure is established. The dependence of the volumetric activity of subsurface radon and its temporal variations on the depth within the range of depths 0.8-11.5 m is determined. As a result of laboratory experiments, the nonlinear nature of the dependence of radon emanation on the frequency of vibration action is established. For granites, the intensity of radon emanation is maximal at frequencies of 16 and 32 Hz. The results of complex measurements of the microseismic background and the volumetric activity of subsurface radon carried out in the region of the Nelidovo-Ryazan tectonic structure demonstrate the high correlation between the volumetric activity of subsurface radon and the relative amplitude of the quasi-monochromatic component of the microseismic background with a peak frequency of 16.5 Hz.

Instrumental observations revealed a new type of motion previously not described in the literature, the precessional motions in the structural blocks of the Earth's crust. The precession-nutation motions are caused largely by a complex response of a structural block and the adjacent tectonic structure, acting as a discontinuous zone between blocks, to tidal deformation. Irregular precession with a period of about one day complicated by the half a day period nutation defines a complex loading pattern characteristic of the internal structure of faults adjacent to the block.

Previous investigations of impact-induced atmospheric erosion considered vertical impacts only. Numerical simulations of oblique impacts presented in this paper show that the loss of air strongly depends on trajectory inclination and it increases as the impact angle decreases. The results of numerical simulations over the wide range of impact parameters (projectile sizes from I to 30 km, impact velocities from 15 to 70 km/s, escape velocities from 5 to 11.2 km/s, projectile densities from 1 to 3.3 g/cm(3), normal atmospheric densities varying by three orders Of Magnitude) can be approximated by simple analytical formulae.

An experimentally substantiated explanation is proposed for recently discovered specific regularities between the time of earthquake preparation and the earthquake scale. It is shown that the observed regularity of the time of earthquake preparation, which grows slowly with the scale as compared with what follows from the relations for the self-similar environment, may be governed by the nonlinear scale dependence of specific stiffness of discontinuities that demonstrates a gradual increase in the effective elastic modulus of fault zones as their typical size grows.

Statically isolated conditions in the stratum-borehole hydrogeological system under consideration at periods of >= 3 h are established on the basis of the investigation of barometric and tidal responses of the water level in a borehole located in the territory of the Mikhnevo Geophysical Observatory, Institute of Geosphere Dynamics, Russian Academy of Sciences. The barometric effectiveness, tidal sensitivity of the water level, elastic parameters, and porosity of water-bearing rocks are estimated. A model of the inertial character of the water exchange in the stratum-borehole system is constructed depending on the period of variations with allowance for the borehole design, as well as the water transmissibility and elastic capacity of the aquifer. The results of modeling are in compliance with the dependence of the amplitude transfer function from variations in the atmospheric pressure to variations in the water level. The results of processing the data of high-precision measurements made it possible to refine the transmissibility of the aquifer obtained from the data of experimental filtration works.

The results of synchronous observations of the electric field on the shallow crustal layers of the Earth's crust and the microseismic vibrations are presented. On the basis of the coincidence of the statistics of the electric and microseismic pulses of the relaxation type, and, also, the fact that the indicated pulses accompany each other, the conclusion is reached about the unique source of both pulses. The constrained rotation of the structural block during its relaxation is considered as such a source. A mechanism is proposed for the generation of electromagnetic signals, connected with the separation of electric charges as a result of the rapid change in the stress-strain state of the rocks of a complex hierarchic-block structure. A model developed by the authors, for the generation of electromagnetic signals during the relaxation processes in the Earth's crust of a heterogeneous structure, is presented.

Приведенные в работе результаты инструментальных наблюдений позволили установить не описанные ранее закономерности процесса накопления в горном массиве и инженерных сооружениях малых деформаций. Показано, что воздействие колебаниями малой амплитуды вызывает остаточные перемещения, локализуемые на нарушениях сплошности. Установлена закономерность соответствия знака остаточных деформаций, связанных с динамическим воздействием, знаку квазистатических перемещений бортов нарушения. Показано, что в тех случаях, когда имеет место направленный деформационный тренд, регулярные динамические воздействия могут привести к существенному увеличению наблюдаемой скорости деформации трещины или разломной зоны.

A self-consistent model of the ambipolar diffusion of electrons and ions in dusty plasmas accounting for the local electric fields, the dust grain charging process, and the interaction of the plasma particles with the dust grains and neutrals is presented. The dependencies of the diffusion coefficient on the interaction of the electrons and ions with the dust grains as well as with the neutrals are investigated. It is shown that increase of the dust density leads to a reduction of the diffusion scale length, and this effect is enhanced at higher electron densities. The dependence of the diffusion scale length on the neutral gas pressure is found to be given by a power law, where the absolute value of the power exponent decreases with increase of the dust density. The electric field gradient and its effects are shown to be significant and should thus be taken into account in studies of dusty plasmas with not very small dust densities. The possibility of observing localized coherent dissipative nonlinear dust ion-acoustic structures in an asymmetrically discharged double-plasma and the importance of the ambipolar diffusion in ionospheric dusty plasmas are discussed.

Обсуждается перераспределение пылевых частиц в ионосфере в результате вихревых движений. Изучаются следующие возможности: захват и эволюция пылевых частиц в акустико–гравитационных (АГ) вихрях, формирование пылевых вихрей в результате вовлечения в вихревые движения большого числа пылевых частиц, образование вертикальных пылевых потоков (стримеров). Показано, что возбуждение АГ вихрей на высотах 110–130 км в результате развития неустойчивости АГ волн, связанной с ненулевым балансом потоков тепла за счет солнечного излучения, конденсации паров воды, инфракрасного излучения атмосферы и теплопроводности, приводит к существенному переносу пылевых частиц и их перемешиванию на высотах 110–120 км. Слои пылевых частиц в ионосфере толщиной порядка километра, образующиеся на высотах, меньших 120 км, распределяются по области существования АГ вихревых структур. В результате на высотах 110–120 км могут образовываться пылевые вихри. Оказывается возможным перенос частиц на высоты до 130 км. Одним из механизмов переноса пылевых частиц в ионосфере являются вертикальные потоки (стримеры), генерируемые пылевыми вихрями в результате развития параметрической неустойчивости.

Обсуждается поведение пылевых частиц в атмосферных вихрях Россби и возможность их вертикального и горизонтального переноса. Рассматриваются солитонные решения уравнения Чарни–Обухова в виде суперпозиции дипольного и монопольного вихрей. Проведено численное моделирование поведения пылевой частицы в вихре Россби и получены траектории частиц различной массы. Показано, что частицы размерами меньше или порядка десяти микрометров могут находиться в вихре более двух недель, что позволяет этим частицам переноситься c вихрями на расстояния более 10 000 км.

Over the last few decades, rapid improvement of computer capabilities has allowed impact cratering to be modeled with increasing complexity and realism, and has paved the way for a new era of numerical modeling of the impact process, including Full, three-dimensional (3D) simulations. When properly benchmarked and validated against observation, computer models offer a powerful tool for understanding the mechanics of impact crater formation. This work presents results from the first phase of a project to benchmark and validate shock codes. A variety of 2D and 3D codes were used in this Study, from commercial products like AUTODYN, to codes developed within the scientific community like SOVA, SPH, ZEUS-MP, iSALE, and codes developed at U.S. National Laboratories like CTH, SAGE/RAGE, and ALE3D. Benchmark calculations of shock wave propagation in aluminum-on-aluminum impacts were performed to examine the agreement between codes for simple idealized problems. The benchmark simulations show that variability in code results is to be expected due to differences in the underlying solution algorithm of each code, artificial stability parameters, spatial and temporal resolution, and material models. Overall, the inter-code variability in peak shock pressure as a function of distance is around 10 to 20%. In general, if the impactor is resolved by at least 20 cells across its radius, the underestimation of peak shock pressure due to spatial resolution is less than 10%. In addition to the benchmark tests, three validation tests were performed to examine the ability of the codes to reproduce the time evolution of crater radius and depth observed in vertical laboratory impacts in water and two well-characterized aluminum alloys. Results from these calculations are in good agreement with experiments. There appears to be a general tendency of shock physics codes to underestimate the radius of the forming crater. Overall, the discrepancy between the model and experiment results is between 10 and 20%, similar to the inter-code variability.

The scenario of lithopanspermia describes the viable transport of microorganisms via meteorites. To test the first step of lithopanspermia, i. e., the impact ejection from a planet, systematic shock recovery experiments within a pressure range observed in martian meteorites (5-50 GPa) were performed with dry layers of microorganisms ( spores of Bacillus subtilis, cells of the endolithic cyanobacterium Chroococcidiopsis, and thalli and ascocarps of the lichen Xanthoria elegans) sandwiched between gabbro discs ( martian analogue rock). Actual shock pressures were determined by refractive index measurements and Raman spectroscopy, and shock temperature profiles were calculated. Pressure- effect curves were constructed for survival of B. subtilis spores and Chroococcidiopsis cells from the number of colony-forming units, and for vitality of the photobiont and mycobiont of Xanthoria elegans from confocal laser scanning microscopy after live/dead staining (FUN-I). A vital launch window for the transport of rock-colonizing microorganisms from a Mars-like planet was inferred, which encompasses shock pressures in the range of 5 to about 40 GPa for the bacterial endospores and the lichens, and a more limited shock pressure range for the cyanobacterium ( from 5-10 GPa). The results support concepts of viable impact ejections from Mars-like planets and the possibility of reseeding early Earth after asteroid cataclysms.

In a provocative paper Gasperini et al. (2007) suggest that Lake Cheko, a similar to 300-m-wide lake situated a few kilometres downrange from the assumed epicentre of the 1908 Tunguska event, is an impact crater. In this response, we present several lines of observational evidence that contradicts the impact hypothesis for the lake's origin: un-crater-like aspects of the lake morphology, the lack of impactor material in and around the lake, and the presence of apparently unaffected mature trees close to the lake. We also show that a tensile strength of 10-40 MPa is required for an asteroid fragment to traverse the Earth's atmosphere and reach the surface intact and with sufficient velocity to excavate a crater the size of Lake Cheko. Inferred tensile strengths of large stony meteorites during atmospheric disruption are 10-100 times lower. We therefore conclude that Lake Cheko is highly unlikely to be an impact crater.

Shock wave attenuation rate and formation of central uplifts are not precisely constrained for moderately sized complex impact structures. The distribution of shock metamorphism in drilled basement rocks from the 10.5- kilometer- diameter Bosumtwi crater, and results of numerical modeling of inelastic rock deformation and modification processes during uplift, constrained with petrographic data, allowed reconstruction of the pre- impact position of the drilled rocks and revealed a shock attenuation by similar to 5 gigapascals in the uppermost 200 meters of the central uplift. The proportion of shocked quartz grains and the average number of planar deformation feature sets per grain provide a sensitive indication of minor changes in shock pressure. The results further imply that for moderately sized craters the rise of the central uplift is dominated by brittle failure.

We combine classical concepts from different disciplines - those of alpha-hull and alpha-shape from computational geometry, splitting data into training and test sets from artificial intelligence, density-based spatial clustering from data mining, and moving average from time series analysis - to develop a robust algorithm for reconstructing the shape of a curve from noisy samples. The novelty of our approach is two-fold. First, we introduce the notion of k-order alpha-hull and alpha-shape - generalizations of alpha-hull and alpha-shape. Second, we use white noise to "train" our k-order alpha-shaper, i.e., to choose the right values of alpha and k. The difference of the k-order alpha-hull and alpha-shape from the alpha-hull and alpha-shape is also two-fold. First, k-order alpha-hull and alpha-shape provide a robust estimate of the shape by ignoring outliers. Second, it reconstructs the "inner" shape, with the amount of "digging" into the data controlled by k.

3D simulations of basin-scale lunar impacts are carried out to investigate: (a) the origins of strong crustal magnetic fields and unusual terrain observed to occur in regions antipodal to young large basins; and (b) the origin of enhanced magnetic and geochemical anomalies alone, the northwest periphery of the South Pole-Aitken (SPA) basin. The simulations demonstrate that a basin-forming impact produces a massive, hot, partially ionized cloud of vapor and melt that expands thermally around the Moon, converging near the basin antipode approximately 1 h after the impact for typical impact parameters. In agreement with previous work, analytic calculations of the interaction of this vapor-melt cloud with an initial ambient magnetic field predict a substantial temporary increase in field intensity in the antipodal region. The time of maximum field amplification coincides with a period when impacting ejecta also converge near the antipode. The latter produce antipodal shock stresses within the range of 5-25 GPa where stable shock remanent magnetization (SRM) of lunar soils has been found experimentally to occur. Calculated antipodal ejecta thicknesses, are only marginally sufficient to explain the amplitudes of observed magnetic anomalies if mean magnetization intensities are comparable to those produced experimentally. This suggests that pre-existing ejecta materials, which would also contain abundant metallic iron remanence carriers, may be important anomaly sources, a possibility that is consistent with enhanced magnetic anomalies observed peripheral to SPA. The latter anomalies may be produced by amplified secondary ejecta impact shock waves in the thick SPA ejecta mantle Occurring near the antipodes of the Imbrium and Serenitatis impacts. Together with converging seismic compressional waves, these antipodal impact shocks may have produced especially deep fracture zones along the northwest edge of SPA near the Imbrium antipode, allowing the ascent of magma with enhanced KREEP concentrations.

The data of inclined sounding obtained on July 5, 1999 after explosion of the Proton carrier launcher in the upper atmosphere are discussed. A comparative analysis is performed of the detected disturbances with disturbances recorded during explosion of the Soyuz rocket in the middle atmosphere and with disturbances typical for the standard mode of the rocket flight.

In terms of the Muruntau open pit, the paper addresses the possibility of formation of a rupture structure in host rock, based on the analysis of its surface manifestations.

The paper describes the structural features of rockslides and draws a comparison between the energy efficiencies of fragmentation by a rockslide, breakage by blasting and destruction in a crusher. The authors have reproduced in the laboratory conditions the mechanism of heavy fragmentation of strong rocks under static loads typical of the real rockslides and with retained initial structure of the rock mass.

This study presents the results of the numerical modeling of the Lunar Crater Observation and Sensing Satellite (LCROSS) space experiment, which is scheduled for 2009 by NASA. It is demonstrated that a spacecraft with a mass of 2 tons impacting the Moon at a velocity of 2.5 km/s creates an ejecta plume with a size of more than 100 km and a mass exceeding 100 tons. The detailed characteristics of the ejecta are given and their relation to the impactor structure is investigated.

High-velocity comet and asteroid impacts onto the Moon are considered and the material masses ejected after such impacts at velocities above the second-cosmic velocity for the Moon (2.4 km/s) are calculated. Although the results depend on a projectile type and the velocity and angle of an impact, it has been demonstrated that, on average, the lunar mass decreases with time. The Moon has lost about 5 x 10(18) kg, that is, about one-hundredth of a percent of its mass, over the last 3.8-3.9 billion years. The ejection of lunar meteorites and lunar dust, rich in He-3, is considered as well. The results of the study are compared to the results of earlier computations and data on lunar meteorites.

Case-by-case comparisons of otherwise similar rockslides and rock avalanches that differ in morphology can provide reliable and important data for better understanding rockslide motion. Several groups of rockslide examples with more or less similar failure conditions but different deposit shapes or runouts are described. A common theme of differences in mode of momentum transfer is offered in explanation of the observations.

In the course of experiments, the author has elaborated a model of an active medium whose uniting action embraces all natural realia. Having studied the active medium, humankind will be able to answer many questions of science.

The effect of baric variations of different origins on characteristics of seismic noise is analyzed in the frequency range 0.03-20 Hz. Long period variations in atmospheric pressure caused by cyclones, whose period T ranges from half a day to a few days, are shown to increase the microseismic background amplitude by two to four times in the frequency range 0.03-1 Hz (the coefficient of linear correlation between time variations in the amplitude and atmospheric pressure is K = 0.65 at a significance level of r = 0.95). Short-period baric variations with T similar to 5-30 min associated with the passage of cold fronts lead to a tenfold increase in the microseismic background amplitude in the frequency range 4-8 Hz (K = 0.67 at r = 0.95). In this case, disturbances of seismic background are recorded for 20-60 min after the passage of an atmospheric front and display an exponential drop in the amplitude. In distinction to cyclones, an atmospheric front increases the number of impulsive microseismic events of the resonance type.

Based on the studied features of propagation of seismic waves in a rock mass with a long structural fault, the authors have found the relationships between the seismic wave attenuation and weakening by the fault, the physic-mechanical properties of the fault filler, the fault thickness and the wave incidence angle. It is shown that relative displacements of the fault edges occur due to the difference in the wave parameters in front of and behind the faulting. The obtained data are compared with the "inertia model" calculations and the experimental results.

It is shown that, during Perseid, Geminid, Orionid, and Leonid meteor showers, the excitation of low-frequency dust acoustic perturbations by modulational instability in the Earth's ionosphere can lead to the generation of infrasonic waves. The processes accompanying the propagation of these waves are considered, and the possibility of observing the waves from the Earth's surface is discussed, as well as the possible onset of acoustic gravitational vortex structures in the region of dust acoustic perturbations. The generation of such structures during Perseid, Geminid, Orionid, and Leonid meteor showers can show up as an increase in the intensity of green nightglow by an amount on the order of 10% and can be attributed to the fori-nation of non-linear (vortex) structures at altitudes of 110-120 km.

The MIKHNEVO small aperture array of the NORES type (MHVAR) was installed in the central part of the East European Plat­form (EEP) in 2004. A short description of ar­ray configuration and instrumentation is provided. We consider two aspects of the contribution of the MHVAR data to the recording of seismic events in the EEP. First, we discuss three recent earth­quakes on the EEP and compare focus solutions received by the Geophysical Survey RAS and MHVAR jointly and independently. The travel- time and back-azimuth residuals for MHVAR coincide well with the source-specific station cor­rections, evaluated earlier for the stations within the Platform. The second aspect deals with the location and identification of weak local events at distances of up to 500 km from MHVAR. In 2007, MHVAR independently recorded 623 local events with magnitudes (ML = 0.79-3.24) which are identified as quarry blasts.

Опыт демонстрирует постоянство характерной скорости относительного смещения берегов сейсмогенных разломов. При различных тектонических условиях значение этого параметра изменяется всего лишь в пределах одного порядка величины - от единиц до первых десятков миллиметров в год. Естественно предположить, что такое постоянство определяется не столько условиями нагружения, сколько внутренними свойствами геосреды. В настоящей работе, на основе проведенных лабораторных экспериментов, предложена возможная интерпретация этой фундаментальной эмпирической закономерности.

Представлены результаты анализа данных наблюдений спутника DE-2 над разломами земной коры. Показано, что в отсутствие сейсмической и геомагнитной активности в средних широтах над разломами в ионосфере могут наблюдаться значительные (до 1 мВ/м) низкочастотные (единицы Гц–десятки кГц) электрические поля и потоки высокоэнергичных частиц.

Bacterial spores (Bacillus subtilis), cyanobacteria (Chroococcidiopsis sp.), and lichen (Xanthoria elegans) embedded in martian analogue rock (gabbro) were exposed to shock pressures between 5 and 50 GPa which is the range of pressures observed in martian meteorites. The survival of Bacillus subtilis and Xanthoria elegans up to 45 GPa and of Chroococcidiopsis sp. up to 10 GPa supports the possibility of transfer of life inside meteoroids between Mars and Earth and it implies the potential for the transfer of life from any Mars-like planet to other habitable planets in the same stellar system.

Distributions of slope angles in tectonically active mountain belts point to the development of threshold conditions, where hillslopes attain a critical inclination or height at which they fail readily because of limitations in material strength. It has been proposed that hillslopes adjust to rapid uplift and bedrock incision through an increase in the rate of relief-limiting landsliding rather than gradual slope steepening. Here we test this concept by investigating the relationship between mean local relief H, which we take to be a proxy of long-term erosion rates E, and the occurrence of over 300 of the largest (V > 10(8) m(3)) terrestrial landslides on Earth. We find that nearly two-thirds of these giant landslides have occurred in the steepest 5% of the Earth's land surface, where relief is close to its proposed upper strength limit. They are primarily located in deeply incised valleys, along fault-bounded fringes of active mountain belts, and in volcanic arcs. This distribution coincides with areas of high long-term erosion rates (similar to 4 mm yr(-1)), confirming that giant landslides contribute to rapid denudation of mountains. Most of the eroded volume is concentrated in the smallest, but steepest parts of mountain belts and volcanic arcs. First-order estimates of minimum erosion rates accomplished by the largest landslides are >= 0.01 mm yr(-1) these rates are between 1% and 10% of the Late Pleistocene to Holocene mean erosion rates in a given area. Importantly, the landslide erosion rates show a nonlinear increase with mean local relief, suggesting that the contribution of giant landslides in total and per event increases significantly with increasing overall erosion rates. However, giant landslides also occur in areas of lower-than-average relief ((H) over bar similar to 300-700 m), irrespective of whether threshold hillslopes have developed or not. Factors contributing to these failures include soft rocks, extensive low-angle discontinuities, high rates of fluvial bedrock incision, and tectonically driven deformation and slope loading.

In the late Jurassic period, about 142 million years ago, an asteroid hit the shallow paleo-Barents Sea, north of present-day Norway. The geological structure resulting from the impact is today known as the Mjolnir crater. The present work attempts to model the generation and the propagation of the tsunami from the Mjolnir impact. A multi-material hydrocode SOVA is used to model the impact and the early stages of tsunami generation, while models based on shallow-water theories are used to study the subsequent wave propagation in the paleo-Barents Sea. We apply several wave models of varying computational complexity. This includes both three-dimensional and radially symmetric weakly dispersive and nonlinear Boussinesq equations, as well as equations based on nonlinear ray theory. These tsunami models require a reconstruction of the bathymetry of the paleo-Barents Sea. The Mjolnir tsunami is characteristic of large bolides impacting in shallow sea; in this case the asteroid was about 1.6 km in diameter and the water depth was around 400 m. Contrary to earthquake- and slide-generated tsunamis, this tsunami featured crucial dispersive and nonlinear effects: a few minutes after the impact, the ocean surface was formed into an undular bore, which developed further into a train of solitary waves. Our simulations indicate wave amplitudes above 200 m, and during shoaling the waves break far from the coastlines in rather deep water. The tsunami induced strong bottom currents, in the range of 30-90 km/h, which presumably caused a strong reworking of bottom sediments with dramatic consequences for the marine environment.

A self-consistent model of the ambipolar diffusion of electrons and ions in complex (dusty) plasmas accounting for the local electric fields, the dust grain charging process, and the interaction of the plasma particles with the dust grains and neutrals is presented. The dependence of the diffusion coefficient on the interaction of the electrons and ions with the dust grains as well as with the neutrals are investigated. It is shown that increase of the dust density leads to a reduction of the diffusion scale length, and this effect is enhanced at higher electron densities. The dependence of the diffusion scale length on the neutral gas pressure is found to be given by a power law, where the absolute value of the power exponent decreases with increase of the dust density. The electric field gradient and its effects are shown to be significant and should thus be taken into account in studies of complex plasmas with not very small dust densities. The possibility of observing localized coherent dissipative nonlinear dust ion-acoustic structures in an asymmetrically discharged double plasma is discussed.

Possible cavitation disintegration of polymineral microparticles placed into a liquid as a result of interaction of particles with collapsed cavitation bubbles is shown for the minerals most abundant in gold ore. The bubbles are generated by shock loading of the liquid heated to the boiling temperature. The possibility of cavitation separation of nano-and microscale monomineral fractions from polymineral microparticles is demonstrated.

Sputtering effect was proposed as an explanation of high altitude ionization and luminosity, which are not explained by the classical ablation theory. Fast sputtered particles may create luminous area at the altitudes above the altitude of intensive evaporation. We consider the air-meteoroid interaction by the Monte-Carlo type physical model, which allows us to describe the sputtering of meteoroid surface under impacts of incoming air particles. At the altitude 150 km fast particles carry out about 10-20% of incoming flux energy for high velocity meteors. There are also reflected particles, but the most part of total particle outcome is formed by the particles of the meteoroid material. Presence of fast particles possibly explains a large size of meteors in diffuse stage at high altitudes (above 130 km). The sputtering is negligible in the case of meteor velocities below 30 km/s. Sputtered and reflected particles have relatively high ionization degree, which is larger than ionization degree of surrounding atmosphere. We estimated oxygen radiation, which occurs due to the interaction of sputtered particles with surrounding atmosphere, and compared it with observations.

Impacts of cosmic bodies (stony and comet-like) are considered that "burn out" (or, more strictly, totally evaporate) in the atmosphere, which do not form craters but cause fires and destruction on the Earth's surface. The heights of fragmentation, total evaporation, and deceleration of stony and comet-like meteoroids of different sizes, initial velocities, and impact angles are found from numerical simulations. The possible consequences of such falls are considered. The possible parameters of the Tunguska cosmic body are estimated.

The effect of extended discontinuities in a hard rock mass on regularities of forming explosive fracture zones is considered. The comparison of the numerical and in situ experimental results permits to conclude that, in common with the known effect of seismic blast wave screenage, transformation of the wavefront configuration is of drastic importance. In a number of cases, that results in the generation of complex-structured fracture zones: new fractured zones can form beyond unbroken areas. It is demonstrated that the similar effects may cause redistribution of the blast energy and, as a consequence, the higher seismic efficiency produced by flat charge blasting as compared with concentrated charge blasting.

Приведены результаты долговременного просвечивания литосферы сейсмическими волнами от глубокофокусных Гиндукушских землетрясений. Построены рады времен пробега первой продольной волны на постоянной базе для шести сейсмических станций наблюдений, расположенных на Русской (с/с Обнинск), Сибирской (с/с Ельцовка) платформах, Предуральском прогибе (с/с Арти), Центрально-Уральской мегазоне (с/с Свердловск), Забайкалье (с/с Бодайбо) и Сев. Тянь-Шане (с/с Пржевальск). Продол­жительность временного ряда для этих станций изменялась от 1964-1970 до 2007 года. Ряды времен пробега сейсмических волн для указанных станций характеризуются отрицательным линейным трендом разной величины, обусловленным изменением напряженно-деформированного состояния пород. Сопоставление величины трендов на разных станциях показывает, что изменения напряженного состояния пород литосферы оказываются относительно слабыми в асейсмичных регионах Русской и Сибирской платформ, Уральской мегазоне, и более значительными в условиях сейсмически активных регионов Тянь-Шаня, Забайкалья и Предуральском прогибе. Отмечена корреляция трендов временных рядов среднегодовых значений времен пробега сейсмических волн и временного ряда скорости вращения Земли. Наилучшая корреляция между рядами наблюдается для станций, расположенных на платформах, где сейсмичность и активные геодинамические процессы слабо выражены. В длиннопериодные интервалы торможения и ускорения скорости вращения Земли наблюдаются соответственно уменьшение и увели­чение времен пробега сейсмических волн. На фоне линейного тренда на всех станциях наблюдаются вариации времен пробега с периодами 0.3 года, 0.4-0.6 года, 0.9-1 год, 1.2-1.4 года, 2-3 года, 5-6 лет, 10-12 лет, которые находят соответствие в периодах нестабильности вращения Земли.

We show evidence of very recent ( <= 25 - 40 Myr) geologic activity on the eastern flank of Olympus Mons volcano that includes a suite of fluvial ( channel networks), volcanic ( emplacement of lava flows and dikes), and tectonic ( wrinkle ridges and troughs) processes. The combination and youth of these features confirms the importance of geological activity continuing to the present on Mars.

Asteroids tens to hundreds of meters in diameter constitute the most immediate impact hazard to human populations, yet the rate at which they arrive at Earth's surface is poorly known. Astronomic observations are still incomplete in this size range; impactors are subjected to disruption in Earth's atmosphere, and unlike the Moon, small craters on Earth are rapidly eroded. In this paper, we first model the atmospheric behavior of iron and stony bodies over the mass range 1-10(12) kg (size range 6 cm-1 km) taking into account deceleration, ablation, and fragmentation. Previous models in meteoritics deal with rather small masses (< 10(5)-10(6) kg) with the aim of interpreting registered fireballs in atmosphere, or with substantially larger objects Without taking into account asteroid disruption to model cratering processes. A few earlier attempts to model terrestrial crater strewn fields did not take into account possible cascade fragmentation. We have performed large numbers of simulations in a wide mass range, using both the earlier "pancake" models and also the separated fragments model to develop a statistical picture of atmosphere-bolide interaction for both iron and stony impactors with initial diameters up to similar to 1 km. Second, using a compilation of data for the flux at the upper atmosphere, we have derived a cumulative size-frequency distribution (SFD) for upper atmosphere impactors. This curve is a close fit to virtually all of the upper atmosphere data over 16 orders of magnitude. Third, we have applied our model results to scale the upper atmosphere curve to a flux at the Earth's surface, elucidating the impact rate of objects <1 km diameter on Earth. We find that iron meteorites > 5 x 10(4) kg (2.5 m) arrive at the Earth's Surface approximately once every 50 years. Iron bodies a few meters in diameter (10(5)-10(6) kg), which form craters similar to 100 in in diameter, will strike the Earth's land area every 500 years. Larger bodies will form craters 0.5 kill in diameter every 20,000 years, and craters I kill in diameter will be formed on the Earth's land area every 50,000 years. Tunguska events (low-level atmospheric disruption of stony bolides >10(8) kg) may occur every 500 years. Bodies capable of producing hazardous tsunami (similar to 200 m diameter projectiles) should strike the Earth's Surface every similar to 100,000 years. This data also allows us to assess the completeness of the terrestrial crater record for a given area over a given time interval.

We describe remnants of large (10(7)-10(10) m(3)) Late Pleistocene to Holocene rockslides and rock avalanches that block(ed) rivers and are preserved in the Himalayas, the Tien Shan, and the New Zealand Southern Alps despite rates of uplift and erosion of up to 10 mm year(-1). These natural dams control fluvial response on 10(1)-10(4) year timescales by (a) storing and releasing sediment during forced alluviation and fluvial re-incision; (b) relocating river channels through diversion or seepage; (c) inhibiting river erosion into bedrock; (d) forming persistent long-profile knickpoints and knickslopes associated with steep high-energy (> 10(3) W m(-2)) breach and epigenetic bypass gorges and fluvial hanging valleys; and (e) shaping valley-floor morphology. Sediments indicate that rockslide-dammed lakes may persist up to 10(4) years, before being drained or infilled. Several short-lived (10(0)-10(2) year) historical rockslide dams in the Indian and Nepal Himalayas and the Southern Alps have had marked volumetric impacts on catchment sediment budgets shortly following failure. Therefore, we caution against the linear extrapolation of sediment delivery from prehistoric rockslide dams through time as a response variable. We find reach-scale changes to channel gradient to be prominent and persistent indicators of fluvial response to large rock-slope failures.

Arrival times of P and S waves from local earthquakes in the Kamchatka area of the Kurile-Kamchatka Island Arc are used for calculating a spatial model of the elastic wave velocity distribution to a depth of 200 km. The lithosphere is shown to be strongly stratified in its velocity properties and laterally heterogeneous within the mantle wedge and seismic focal zone. A lower velocity layer ( an asthenospheric wedge) is identified at depths of 70 - 130 km beneath the Eastern Kamchatka volcanic belt. The morphology of the Moho interface and the velocity properties of the crust are studied. The main tectonic structures of the region are shown to be closely interrelated with deep velocity heterogeneities. Regular patterns in the statistics of the earthquakes are analyzed in relation to variations in the elastic wave velocities in the focal layer. A mechanism of lithospheric block displacements along weakened zones of the lower crust and upper mantle is proposed.

The Suusamyr region is located in the northern part of the Tien Shan Range in Central Asia. In 1992, this region was hit by the Ms = 7.3 Suusamyr earthquake triggering several large landslides along the Suusamyr Valley and on the southern slopes of the adjacent Suusamyr Range. One of these landslides had been investigated by geophysical and geotechnical methods in order to determine local trigger factors. The present paper focuses on the influence of geological and morphological factors upon landslide occurrence on a regional scale. The analysis is based on a digital data set including landslides triggered in 1992 and several older landslides as well as various types of digital elevation models (DEMs), ASTER image data, and geological and active fault maps. These data were combined to compute landslide susceptibility (LS) maps using statistical methods, Landslide Factor and Conditional Analyses (LFA, CA), as well as a geotechnical one, the Newmark's Method (NM). The landslide data set was also analyzed with respect to the size-frequency relationship.

The Earth's mesosphere at altitudes of 80-95 km exhibits layered phenomena known as noctilucent clouds and polar mesosphere summer echoes. These structures are believed to be associated with the presence of large quantities of charged dust or aerosol particles. The sign of the charge depends on the material composition of the latter as well as the environment. The characteristics of self-organized structures - solitons on the dust acoustic time scale depend strongly on the sign of the charge, and the structures can appear as either electron (ion) density humps or dips. Such a physical distinction can be used for the identification and diagnostics of noctilucent clouds and polar mesosphere summer echoes.

The results on shock phenomena in dusty plasmas of the Solar System are reviewed. The problems of dust ion acoustic bow shock in interaction of the solar wind with dusty cometary coma and formation of transient atmospheres of atmosphereless cosmic bodies such as Moon, Mercury, asteroids and comets are considered. The latter assumes the evolution of meteoroid impact plumes and production of charged dust grains due to the condensation of both the plume substance and the vapor thrown from the crater and the surrounding regolith layer. Physical phenomena occurring during large meteoroid impacts can be modeled with the aid of active rocket experiments, which involve the release of some gaseous substance in near-Earth space. New vistas in investigation of shock processes in natural dusty plasmas are determined.

Results of various instrumental observations of geodynamic processes in the Earth's crust and geophysical fields at the crust - atmosphere boundary in the Oka area of the Nelidovo - Ryazan tectonic structure and adjacent fractures and in the zone of the Gornyi Altai earthquake of September 27, 2003, are presented. The correlations between the geophysical fields are determined from the results of processing and analysis of microseismic vibrations, the emanation field of natural radon, and variations in the electric field in ground and the magnetic field in the surface atmospheric layer. Tidal deformations of the crust were considered as external effects enhancing the interactions between the geospheres. It is noted that tectonic faults determining the block structure of the crust are recognizable as anomalous variations in the geophysical fields and their high cross-correlation.

Results of laboratory experiments and observation data on postseismic deformations in different regions were used to detect the regularities of formation of slow relative block displacements provoked by dynamic events. It is shown that under a gradual change of the stress-strain state of a rock massif, the asymptotic form of displacement with time is close to the law of a quasi-static flow, and under a drastic change in deformation rate, the relative block displacements are controlled mainly by the laws of friction force change during shear. The results obtained show that the dynamics of forces resisting to shears along block boundaries must be taken into account when constructing geomechanical models of different scales.

The dynamic equilibrium of the ozone layer can be locally disturbed when considerable volumes of methane penetrate into the stratosphere as a result of powerful emissions of methane from the lithosphere. Calculations indicate that, in order to break through the tropopause, the methane emission is bound to be greater than 10(9) m(3); such emissions are related to unique poorly studied phenomena. The performed studies of the methane emergence height (which can increase owing to hydrogen adding, joint emergence of a periodic system of methane bubbles located in the same plane near the Earth's surface, or emergence of two coaxial bubbles released at different times) have demonstrated that the methane maximum emergence height does not change radically.

Several large rockslides and rock avalanches ranging in volume from 10(5) m(3) up to 10(8) m(3) were triggered by underground nuclear explosions at the Novaya Zemlia test site. Rapid filming of rock avalanche formation allowed direct measuring of the velocities of debris spreading. Dynamics of two case studies derived from the real time observations and from the analysis of debris morphology and grain size composition is discussed in details. Factors determining runout of artificial rock avalanches such as variability of debris grain size composition and topography of the transition and deposition zones are examined. Relationships of rock avalanche runout and their volume are determined and compared with those of the natural events of different origin. Critical conditions of slope failure occurrence depending on intensity of seismic effects of the explosions and slope angles are examined as well.

Published data for global impact rate of bolides are compared with the cratering rate on the Moon in the past 100 Ma (assumed to be constant). The comparison shows, that in the limits of used models accuracy, the current meteoroid flux in the Earth-Moon system is approximately the same as in the last 100 Ma. provided most of the small (D < 200 m) craters counted on the young (<= 100 Ma) lunar surface are primary. not secondary craters.

В работе показана принципиальная возможность разрушения озонового слоя, когда озоноразрушающие (водород, вода) поступают в стратосферу в результате дегазации Земли. Определены условия, при которых наиболее вероятно образование озоновых «дыр». Показано, что степень разрушения озона зависит от сезона, широты и высоты. Наиболее глубокие озоновые аномалии могут формироваться в зимне-весенний период.

Представлены результаты анализа пространственно-временной динамики полного электронного содержания в ионосфере Земли методом комплексных естественных ортогональных функций (ЕОФ). Показано, что отклик на геомагнитную активность описывается второй ЕОФ, а сезонная и климатологическая изменчивость – первой ЕОФ. Предложенный метод позволяет разделять наблюдаемую изменчивость ионосферы на отдельные моды данных для исследования отклика среды на возмущения разной природы.

Приведены результаты численного моделирования влияния изменения магнитного поля Земли на структуру и динамику ионосферы и верхней атмосферы.

С помощью математического моделирования демонстрируется принципиальная возможность образования у поверхности земли теплого слоя (метрового слоя эрозионных паров и воздуха с температурами несколько тысяч градусов и плотностью в 2050 раз меньше нормальной плотности воздуха) под действием распространяющегося на большие расстояния излучения огненного шара сильного взрыва при умеренной плотности потока лучистой энергии порядка 1 ГВт  м2 за время порядка 10 мс. Результаты численного исследования согласуются с данными наблюдений эффекта теплого слоя при испытаниях ядерного оружия.

The majority of volcanic products on Mars are thought to be mafic and effusive(1,2). Explosive eruptions of basic to ultrabasic chemistry are expected to be common(3,4), but evidence for them is rare and mostly confined to very old surface features(5). Here we present new image and topographic data from the High Resolution Stereo Camera that reveal previously unknown traces of an explosive eruption at 30 degrees N and 149 degrees E on the northwestern flank of the shield volcano Hecates Tholus. The eruption created a large, 10-km-diameter caldera similar to 350 million years ago. We interpret these observations to mean that large-scale explosive volcanism on Mars was not confined to the planet's early evolution. We also show that glacial deposits partly fill the caldera and an adjacent depression. Their age, derived from crater counts, is about 5 to 24 million years. Climate models predict that near-surface ice is not stable at mid-latitudes today(6), assuming a thermo-dynamic steady state. Therefore, the discovery of very young glacial features at Hecates Tholus suggests recent climate changes. We show that the absolute ages of these very recent glacial deposits correspond very well to a period of increased obliquity of the planet's rotational axis (7).

A 10-km diameter crater named Zunil in the Cerberus Plains of Mars created similar to 10(7) secondary craters 10 to 200 m in diameter. Many of these secondary craters are concentrated in radial streaks that extend up to 1600 kin front the primary crater, identical to lunar rays. Most of the larger Zunil secondaries are distinctive in both visible and thermal infrared imaging. MOC images of the secondary craters show sharp rims and bright ejecta and rays, but the craters are shallow and often noncircular, as expected for relatively low-velocity impacts. About 80% of the impact craters superimposed over the youngest surfaces in the Cerberus Plains, such as Athabasca Valles, have the distinctive characteristics of Zunil secondaries. We have not identified any other large (>= 10 km diameter) impact crater on Mars with such distinctive rays of young secondary craters, so the age of the crater may be less than a few Ma. Zunil formed in the apparently youngest (least cratered) large-scale lava plains on Mars, and may be an excellent example of how spallation of a competent surface layer can produce high-velocity ejecta. (Melosh, 1984, Impact ejection, spallation. and the origin of meteorites, Icarus 59, 234-260). It could be the source crater for some of the basaltic shergottites, consistent with their crystallization and ejection ages, composition, and the fact that Zunil produced abundant high-velocity ejecta fragments. A 3D hydrodynamic simulation of the impact event produced 10(10) rock fragments >= 10 cm diameter, leading to up to 109 secondary craters >= 10 m diameter. Nearly all of the simulated secondary craters larger than 50 m are within 800 km of the impact site but the more abundant smaller (10-50 m) craters extend out to 3500 kin. If Zunil is representative of large impact events on Mars, then secondaries should be more abundant than primaries at diameters a factor of similar to 1000 smaller than that of the largest primary crater that contributed secondaries. As a result, most small craters on Mars could be secondaries. Depth/diameter ratios of 1300 small craters (10-500 m diameter) in Isidis Planitia and Gusev crater have a mean value of 0.08; the freshest of these craters give a ratio of 0.11, identical to that of fresh secondary craters on the Moon (Pike and Wilhelms, 1978, Secondary-impact craters on the Moon: topographic form and geologic process, Lunar Planet. Sci. IX, 907-909) and significantly less than the value of similar to 0.2 or more expected for fresh primary craters of this size range. Several observations suggest that the production functions of Hartmann and Neukum (2001, Cratering chronology and the evolution of Mars, Space Sci. Rev. 96, 165-194) predict too many primary craters smaller than a few hundred meters in diameter. Fewer small, high-velocity impacts may explain why there appears to be little impact regolith over Amazonian terrains. Martian terrains dated by small craters could be older than reported in recent publications.

The Flims rockslide is the largest landslide in the Alps, with an estimated volume of 12 km(3). It resulted from a prehistoric high-speed movement of a large limestone mass. Several main factors influenced the mobility of the Flims rockslide: (i) the steep slopes of the Rhine River valley that blocked the spreading of the rock debris out of the limits of Rabiusa and Carreratobel tributary valleys; (ii) the resisting forces taking place at the base of the rockslide by friction and substratum obstacles; and (iii) the rock mass evolving to a granular state, as observed in the deposits, in which coherence of the original rock massif has been preserved. We expect that most of the energy was consumed by impacting on the opposite slope, forcing the rock mass to stop. Lateral parts and some portions of debris, which entered valleys of the right tributaries of the Rhine River, created tongues by rock avalanche motion, indicating transport velocity. These rock masses eroded the valley fill to create a large mixed mass at the toe of the rockslide deposits. Thus, the Flims rock slope movement can be classified as a rockslide to its middle section and as rock avalanches at its lateral margins. A slab-on-slab model is proposed to characterize transformation of the rock mass during transport, with different stages of motion. Beginning as a rockslide, a delaminating process took place to produce a multislab shearing motion. Shearing and fracturing create dilatancy of the sliding rock debris, with spreading constrained by topographic effects. Dynamic disintegration processes explain the production of fine particles and are at the origin of the granular state of the deposits. Lateral sections of the debris mass continued to flow in the absence of topographic constraints.

New three-dimensional hydrodynamic simulations of hypervelocity impacts into the crust of Titan were undertaken to determine the fraction of liquid water generated on the surface of Saturn's largest moon over its history and, hence, the potential for surface-modification of hydrocarbons and nitriles by exposure to liquid water. We model in detail an individual impact event in terms of ejecta produced and melt generated, and use this to estimate melt production over Titan's history, taking into account the total flux of the impactors and its decay over time. Our estimates show that a global melt layer at any time after the very beginning of Titan's history is improbable; but transient melting local to newly formed craters has occurred over large parts of the surface. Local maxima of the melt are connected with the largest impact events. We also calculate the amount of volatiles delivered at the impact with various impact velocities (from 3 km/s for possible Hyperion fragments to 11 km/s for Jupiter family comets) and their retention as a possible source of Titan's atmosphere. We find the probability of impact ejecta escaping Titan with its modern dense and thick atmosphere is rather low, and dispersal of Titan organics throughout the rest of the Solar System requires impactors tens of kilometers in diameter. Water ice melting and exposure of organics to liquid water has been widespread because of impacts, but burial or obscuration of craters by organic deposits or cryovolcanism is aided by viscous relaxation. The largest impactors may breach an ammonia-water mantle layer, creating a circular albedo contrast rather than a crater

It is well documented that lateral heterogeneities in the earth can introduce serious errors in seismic event locations derived from radially symmetric earth models, in particular, for small events recorded only by sparse networks of regional stations. It should be possible to significantly improve the seismic location accuracy for such events by applying travel-time calibration information specific to the regions where the sources and stations are located. This article describes a research investigation directed toward regional travel-time calibration of 30 International Monitoring System (IMS) stations in eastern Asia. For this calibration an initial 3D velocity model covering the entire region was constructed from several submodels. Seismic travel times in this complex 3D velocity model have been computed by using a raytracing algorithm based on a finite-difference approximation to the eikonal equation, which is believed to be accurate to within 0.3-0.5 sec over the regional distance range of interest. A new regional tomography algorithm has also been implemented which solves the fully nonlinear problem by iterating over linear inversion steps in which event hypocenters, model velocities, and ray paths can all be updated. Extensive testing and validation of the final tomographically refined velocity model have been performed with data from numerous ground truth (GT) explosions and earthquakes throughout the region, and it has been demonstrated that this model predicts P-wave travel times with associated root-mean-square (rms) errors on the order of 1 sec across the study region. Finally, a completely new multistation kriging method, which satisfies seismic reciprocity constraints, has been formulated and applied to derive empirical corrections to account for remaining unmodeled error, further reducing the rms error to approximately 0.7 see. These results support the conclusion that our new 3D velocity model for this region represents a significant improvement over the default IASP91 model and will provide improved seismic location capability, in particular, for events recorded by sparse networks of regional stations.

Dust ion-acoustic shocks in a Q machine device are considered. For their description the so-called hydrodynamic ionization source model is used. The model is appropriate for the description of the laboratory experiments in a Q machine device and contains the most important basic mechanisms responsible for the formation of the dust ion-acoustic shocks. A comparative analysis of various dissipative processes occurring on ion-acoustic time scales during the excitation and propagation of nonlinear dust ion-acoustic perturbations in a complex (dusty) plasma is performed in terms of a purely kinetic approach and a hydrodynamic approach. It is found that the most important dissipative processes are the charging of dust grains, the absorption of ions by grains, the transfer of the ion momentum to the grains, and Landau damping.

We present experimental results of a study of electromagnetic field generation during underground detonation of high explosive charges in holes bored in sandy loam and granite. Three components of electric field (vertical component in air and two horizontal components in the soil) and three components of the magnetic induction were recorded during the field experiments. Test conditions and physicomechanical properties of the soil exert significant influence on the parameters of electromagnetic signals generated by underground explosions with masses of 2-200 kg. The electric and magnetic field experimental data are satisfactorily described by an electric dipole model with the source embedded in layered media. We used the solution for a field produced by stationary vertical and horizontal electric dipoles placed near the interface between two layers with different conductivity. The magnitude of the field source was estimated on the basis of the records of electromagnetic signals obtained at different distances from the borehole. For an underground explosion of a TNT charge with a mass of 2 kg carried out in granite the maximum estimated value of the electric dipole component is about 10(-7) C m. This estimate is more than an order of magnitude greater than that obtained for an explosion of the same mass carried out in sandy loam.

The cratering event produced by the Deep Impact mission is a unique experimental opportunity, beyond the capability of Earth-based laboratories with regard to the impacting energy, target material, space environment, and extremely low-gravity field. Consequently, impact cratering theory and modeling play an important role in this mission, from initial inception to final data analysis. Experimentally derived impact cratering scaling laws provide us with our best estimates for the crater diameter, depth, and formation time: critical in the mission planning stage for producing the flight plan and instrument specifications. Cratering theory has strongly influenced the impactor design, producing a probe that should produce the largest possible crater on the surface of Tempel 1 under a wide range of scenarios. Numerical hydrocode modeling allows us to estimate the volume and thermodynamic characteristics of the material vaporized in the early stages of the impact. Hydrocode modeling will also aid us in understanding the observed crater excavation process, especially in the area of impacts into porous materials. Finally, experimentally derived ejecta scaling laws and modeling provide us with a means to predict and analyze the observed behavior of the material launched from the comet during crater excavation, and may provide us with a unique means of estimating the magnitude of the comet's gravity field and by extension the mass and density of comet Tempel 1.

A comparative analysis of the most important dissipative processes occurring during the excitation and propagation of dust ion-acoustic shocks in a Q machine device, among which are the charging of dust grains, the absorption of ions by grains, the transfer of the ion momentum to the grains, and Landau damping, is performed. The relative roles played by dissipative processes in different types of laboratory experiments with complex plasmas are estimated.

Multi-ring impact basins have been found on the surfaces of almost all planetary bodies in the Solar system with solid crusts. The details of their formation mechanism are still unclear. We present results of our numerical modeling of the formation of the largest known terrestrial impact craters. The geological and geophysical data on these structures accumulated over many decades are used to place constraints on the parameters of available numerical models with a dual purpose: (i) to choose parameters in available mechanical models for the crustal response of planetary bodies to a large impact and (ii) to use numerical modeling to refine the possible range of original diameters and the morphology of partially eroded terrestrial craters. We present numerical modeling results for the Vredefort, Sudbury, Chicxulub, and Popigai impact craters and compare these results with available geological and geophysical information.

The transition from the Earth's solid inner core to liquid outer core is the location where the inner core grows(1) and from which compositional convection in the outer core originates(2,3). Most seismological models of the Earth describe the inner-core boundary as sharp(4,5) and simple(6,7,8), although experimental data requiring the presence of a thin transition layer at the bottom of the outer core have been reported(9). The density jump at the inner-core boundary - an important parameter determining gravitational energy release(10) and constraining the compositional difference between the inner and outer core - is also not well known. Estimates of this density jump obtained using free-oscillation eigenfrequencies give low values(11-13) of 0.25-1.0 g cm(-3), whereas a method using the amplitude ratio of core-reflected phases yielded values of 0.6 - 1.8 g cm(-3) ( refs 14 - 17). Here we analyse properties of waves precritically reflected from the Earth's inner core (PKiKP phases) that show significant variability in amplitude, consistent high-frequency content and stable travel times with respect to a standard Earth model(4). We infer that the data are best explained by a mosaic structure of the inner core's surface. Such a mosaic may be composed of patches in which the transition from solid inner to liquid outer core includes a thin partially liquid layer interspersed with patches containing a sharp transition.