This paper presents the results of precise measurements of temperature and pore pressure in the “reservoir–well” system during the development of iron ore deposits of the Kursk Magnetic Anomaly (KMA) via blasting. For the observation period from October 2021 to June 2024, variations in compressibility, permeability and temperature in the upper Albian-Cenomanian confined aquifer, which is used for district water supply, were determined. The general trend in a decrease in water temperature was traced (from 12 °C to 11.4 °C). It was accompanied by an increase in the hydrostatic head (from 3.7 m to 7.4 m). Water temperature in the upper aquifer was measured for 9 industrial explosions in the mine and for 30 explosions in the quarry. For one explosion in the mine and five explosions in the quarry the coseismic changes in water temperature with amplitudes of 0.06–0.09 °C were established, while changes in pore pressure in the “reservoir–well” system were 0.4–2.2 kPa. Local changes in the permeability of the reservoir in the vicinity of the well (the skin effect) are considered to be the main factor that controls the coseismic response of temperature during industrial explosions. As the reservoir permeability increases, the water temperature in the “reservoir–well” system can decrease and vice versa. The same pattern was observed according to regime measurements performed in 2022–2023. The recorded coseismic responses of water temperature in the upper aquifer in the high-frequency range are similar to the effects observed during propagation of seismic waves originated from earthquakes in the low-frequency range at different sites all over the world for the seismic energy density of 0.05–0.45 J/m3. The observed variations in aquifer temperature in the “reservoir–well” system under episodic dynamic impacts are of particular interest from the point of view of activating hydrogeochemical processes that accompany the development of iron ore deposits.

Исследованию механизмов деформирования флюидонасыщенных коллекторов посвящено большое количество научных работ. Данные дистанционного прецизионного гидрогеологического мониторинга позволяют объективно оценивать фильтрационные свойства флюидонасыщенных коллекторов. Реакция системы «пласт - скважина» на атмосферное давление, земные приливы и прохождение сейсмических волн от землетрясений проявляется в виде осцилляций уровня подземных вод, косейсмических и постсейсмических эффектов. Гидрогеологические отклики на квазистационарные факторы соответствуют пороупругому деформированию массива горных пород. Эпизодическое сейсмическое воздействие может приводить как к пороупругой, так и к неупругой реакции флюидонасыщенного коллектора. В ближней зоне землетрясений, в области статических напряжений, установлено скачкообразное (ступенчатое) изменение проницаемости, которое может быть связано с различными механизмами. К ним относятся разжижение дисперсного грунта, дилатансия - трещинообразование на контакте пород с разными прочностными характеристиками и другие. В промежуточной и дальней зонах, области динамических напряжений, длиннопериодные колебания, вызванные прохождением поперечных и поверхностных волн, могут приводить к кольматации/декольматации микротрещин и вариациям проницаемости. Формирование целостного представления о режиме деформирования массива горных пород при сейсмическом воздействии направлено на прогнозную оценку возможных изменений фильтрационных свойств флюидонасыщенных коллекторов. A large volume of scientific papers is devoted to the study of the deformation mechanisms of fluid-saturated reservoirs. Precision hydrogeological monitoring data allows to objectively assess filtration properties of fluid-saturated reservoirs. The reaction of the «reservoir-well» system to atmospheric pressure, Earth tides and the propagation of earthquakes seismic waves can occur in the form of the groundwater level oscillations, coseismic and postseismic effects. Hydrogeological responses to quasi-stationary factors are determined by poroelastic deformation of the rock mass. Episodic seismic impact can lead to both poroelastic and inelastic reaction of a fluid-saturated reservoir. In the near-field zone of earthquakes, in the area of static stresses, an abrupt (step-like) change of permeability has been established, which may be associated with various mechanisms. These include liquefaction of dispersed soil, dilatancy - crack formation at the contact zone of rocks with different strength characteristics, and others. In the intermediate and distant zones, areas of dynamic stresses, long-period oscillations caused by the passage of shear and surface waves can lead to microcracks clogging/unclogging and variations of permeability. The formation of a holistic view of the deformation regime of a rock mass under seismic impact is aimed to predictpossible changes of the fluid-saturated reservoirs filtration properties.

Complex measurements being performed with a network of stations at different epicenter distances allowed to register numerous effects in various geophysical fields at the moment of peak activity of the Tonga Volcano 15/01/2022. Monitoring was also performed at the "Mikhnevo" Geophysical Observatory of Sadovsky Institute of Geospheres Dynamics of Russian Academy of Sciences. The aim was to detect the links between disturbances in the atmosphere, changes in ambient seismic noise, and variations in underground water level. For the first time in an aseismic region the reaction of unevenly aged aquifers to a global disturbance in the form of propagating Lamb atmospheric waves (direct and antipodal ones) as they passed around the Earth have been registered. The responses recorded in different geophysical fields were compared to background values of probability density function of power spectral density. A difference in the intensities of the responses of the confined and weakly confined aquifers to two passages of atmospheric fronts from the Tonga volcanic eruption was established. This difference corresponds to the values of barometric efficiency. Delays of the hydrogeological responses with respect to the passage of Lamb waves were observed. Synchronous measurements of hydrogeological responses to passing atmospheric disturbances produced by the Tonga volcanic eruption performed in an aseismic region add to the world database of interacting geospheres and require further consideration involving the analysis of available experimental data.

The authors analyze seismic and hydrogeological data recorded after a large-scale blast on 22 September 2021 in Lebedinsky open pit mine, Kursk Magnetic Anomaly. In blasting of four groups of blocks, the maximum values of PPV are determined at five observation points arranged at the epicentral distances of 1.7–4.9 km, as well as the amplitudes of the hydrogeological response are assessed in two observation wells in overlying rock mass. The main parameters of the blast-induced seismic effect are used to calculate maximum PPV from the earlier found relation. The divergence of the recorded and theoretical data is observed in the near field of the blast in the first group of blocks, at the reduced distances of 106–198 m/kg 1/3 . In blasting in sedimentary rocks at the reduced distances of 405–512 m/kg 1/3 , the difference in the wavefield is observed. The research findings can be used in drilling-and-blasting control.

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.

Представлен анализ результатов сейсмической и гидрогеологической регистрации массового взрыва, проведенного 22.09.2021 г. в Лебединском карьере Курской магнитной аномалии. При взрыве четырех групп блоков определены значения максимальной скорости смещения грунта в пяти пунктах наблюдений, расположенных на эпицентральных расстояниях 1.7 - 4.9 км, и амплитуды гидрогеологических откликов обводненной надрудной толщи в двух наблюдательных скважинах. Основные параметры взрывов, оказавшие наибольшее сейсмическое воздействие на массив, использованы для расчета максимальной скорости колебаний в волне по установленной ранее зависимости. Расхождения между зарегистрированными и расчетными параметрами отмечены в ближней зоне взрыва первой группы блоков, разрабатываемых в рудно-кристаллическом массиве на приведенных расстояниях 106- 198 м/кг1/3. При осуществлении взрывов в осадочных отложениях на приведенных расстояниях 405 - 512 м/кг1/3 прослежено отличие в формировании волнового поля. Полученные данные могут быть привлечены для контроля технологии буровзрывных работ. The authors analyze seismic and hydrogeological data recorded after a large-scale blast on 22 September 2021 in Lebedinsky open pit mine, Kursk Magnetic Anomaly. In blasting of four groups of blocks, the maximum values of PPV are determined at five observation points arranged at the epicentral distances of 1.7-4.9 km, as well as the amplitudes of the hydrogeological response are assessed in two observation wells in overlying rock mass. The main parameters of the blast-induced seismic effect are used to calculate maximum PPV from the earlier found relation. The divergence of the recorded and theoretical data is observed in the near field of the blast in the first group of blocks, at the reduced distances of 106-198 m/kg1/3. In blasting in sedimentary rocks at the reduced distances of 405-512 m/kg1/3, the difference in the wavefield is observed. The research findings can be used in drilling-and-blasting control.

The results of a computer interpretation of the LANDSAT satellite image of a natural–technogenic geosystem (the Degelen area of the Semipalatinsk test site (STS)) are presented in this article. The data are analyzed together with the materials of geological mapping of the study area and information of the underground large-scale explosions. The block–hierarchical divisibility of the rock mass is reflected in the lineament pattern. The extended lineaments identified at the highest threshold of expression are fragmentarily confirmed by faults and are considered boundaries that determinate of the block configuration. High values of the density fields of small lineaments of the sublatitudinal and SW–NE directions relative to the density field of the SE–NW direction correspond to the activation of the region at the neotectonic stage. A lineament zone of SW–NE strike traces the main deep Degelen–Irtysh fault. The SW–NE direction of the elongation lines of the rose diagrams of small lineaments is determined by the modern stress field. A comprehensive analysis of the geological and geomorphological structure, statistical characteristics of the fields of small lineaments, and the technogenic impact on the massif was used to rank the blocks into natural and natural–technogenic. The technogenically disturbed areas are identified according to the anomalies in the density of small lineaments, which can be considered the main ways radionuclides migrate with underground water.

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.

In this work, we study the reaction of an aquifer lying in the roof of an iron ore deposit located near the town of Gubkin, Belgorod region, during massive explosions. The considered reservoir of pore-fractured type is composed mainly of shales and quartzites, which are characterized by different physical, mechanical, and filtration parameters. A comprehensive analysis of the hydrogeological responses of the aquifer and seismic data to the passage of seismic waves from massive explosions reveals differences in the response of water-saturated reservoirs, characterized by a difference in the structure of the pore-fractured space.

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.

The results of joint processing of hydrogeological and seismic data obtained at the Large-Scale Research Facilities "Mid-Latitude Geophysical Observation Complex "Mikhnevo" for a 12-year observation period are presented in the article. Responses of the "reservoir-well" system to the passage of seismic waves from distant earthquakes with magnitudes of 6.3-9.0, recorded at the epicentral distances from 1863 to 16507 km, have been identified in the database. Maximum values of groundwater level variations and ground velocity under seismic impact have been determined. The power-law dependence of the levels amplitudes of confined and weakly confined aquifers on the maximum vertical ground velocity has been established. A spectral analysis of 6-hour intervals (3 hours before and 3 hours after earthquakes) of seismic and hydrogeological data was performed. The frequencies corresponding to the maximum values of ground velocity and groundwater level variations were determined in the normalized spectra. The intervals within which the extremes of the hydrogeological responses are traced at background values of the ground velocity are identified in the low-frequency range. The amplitude-frequency characteristics of the "reservoir-well" systems differ under seismic impacts at epicentral distances up to 4901 km. The responses of the systems to earthquakes at epicentral distances of 11024-14026 km are similar.

Abstract—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.

Гидрогеологические отклики флюидонасыщенного коллектора описываются двумя возможными типами моделей: статической и динамической [8]. Модель статической деформации предполагает необратимые изменения свойств коллектора, вызванные распространением разрывов вдоль разлома, сопряженного с очагом землетрясения. Модели динамической деформации основаны на теории пороупругости [3]. К одному из факторов, влияющему на состояние флюидонасыщенных коллекторов, относится сейсмическое воздействие, связанное с землетрясениями, происходящими на разных эпицентральных расстояниях от пунктов наблюдений. В качестве индикатора изменения фильтрационных свойств коллекторов рассматриваются вариации уровней подземных вод и порового давления, вызванные прохождением сейсмических волн от разных типов источников – природных и техногенных [2]. Данные регистрации сейсмического воздействия на флюидонасыщенный коллектор могут быть использованы для определения пороупругих свойств с учетом объемной и девиаторной деформации. В данной статье представлены предварительные результаты расчета порового давления на основе пороупругой модели, представленной в работе [7]. Объектом исследований является водонасыщенный карбонатный коллектор, вскрытый в скважине, расположенной на территории геофизической обсерватории ИДГ РАН «Михнево» (ГФО «Михнево»). Выделенные гидрогеологические эффекты в напорном водоносном горизонте использованы для сопоставления с теоретически рассчитанным поровым давлением по сейсмическим данным регистрации удаленных землетрясений.

Abstract—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.

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)·10–7 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.