Nepeina, Kseniia Sergeevna

Nepeina K.S., An V.A.

The paper presents information on the registration of underground nuclear explosions (UNEs) of the Semipalatinsk test site (STS) at the Balapan site (Bal) from 1969 to 1988. Two stations of the Unified Seismic Observation Service (ESSN USSR) - Uzhgorod (UZH) and Vladivostok (VLA), since the epicentral distances for them are closest to each other Δ~36°. Records of the register of specific UNEs have been preserved in the archives of the Institute of Geospheres Dynamics of the Russian Academy of Sciences. Academician M.A. Sadovsky (IDG RAS). Body wave magnitudes (mb) range from 5.6 to 6.2. For them, at equidistant stations, the travel time of the P-wave (tp0) was obtained. Corrections were made to the data on the registration and travel time curves were formed for the UZH-Bal, VLA-Bal and local traces for the range Δ~36.0-36.6°. Velocity Vp is equal ~10 km/s.

Rybin A., Bataleva E., Nepeina K.

The identification of hidden areas of active faults in the Earth’s crust that can generate earthquakes is the most urgent problem in assessing the seismic hazard of various regions. The main goal of this study was a detailed study of the geophysical characteristics in the zone of individual segments of active faults in the Northern Tien Shan with electromagnetic geophysical methods. The structural line of the Issyk-Ata fault is clearly, but fragmentary, revealed on the surface by geological methods, since the tectonic disturbance is hidden by loose deposits of the Cenozoic age. The results of inversion of detailed magnetotelluric soundings in the fault impact zone of the fault made it possible to determine the position of the upper edge, width, depth, strike and inclination of the fault zone. At the stage of complex construction of 2D geoelectric models of the Issyk-Ata fault zone, the results of field profile soundings by the method of surface electrical resistivity tomography were used. To study the dynamics of the constructed block model of the fault zone, we considered variations in the following electromagnetic parameters that reflect the response of the geomedium to a change in its stress–strain state: impedance and tipper components, apparent resistivity and impedance phase, time–frequency series, and anisotropic properties. Based on this, estimates of the correlation between variations in electromagnetic parameters and lunar-solar tides and the spatiotemporal distribution of seismicity were made. This work was supported by the Russian Science Foundation under grant No. 22–27-00567.

Rybin A., Bataleva E., Zabinyakova O., Nepeina K.

In 2023, monitoring geophysical studies were carried out using the electrical resistivity tomography (ERT) method along three profiles that cross the strike zone of the Issyk-Ata fault in the transverse direction. A detailed study was carried out of the observed variations in apparent electrical resistivity, which characterize the change in the electrical properties of the upper part of the Earth's crust section with a 40-minute discretization in time. Using the analysis of difference pseudo-sections of apparent resistivity, constructed based on the results of ERT monitoring, the most informative pseudo-depth interval from the point of view of geoelectric activity was determined for all three monitoring profiles. Accordingly, for a pseudo-depth of 24 m on each monitoring profile, an assessment was made of the geodynamic activity of these sections of the Issyk-Ata fault based on an analysis of the magnitude of two parameters: the amplitude of apparent resistivity variations and the correlation coefficient of electrical resistivity variations with lunar-solar solid tides. High values of these parameters, in our opinion, determine the location of modern active fault zones.

Nepeina K., Bataleva E., Alexandrov P.

This study focuses on microscale anisotropy in rock structure and texture, exploring its influence on the macro anisotropic electromagnetic parameters of the geological media, specifically electric conductivity (σ), relative permittivity (ε), and magnetic permeability (μ). The novelty of this research lies in the advancement of geophysical monitoring methods for calculating cross properties through the estimation of effective parameters—a kind of integral macroscopic characteristic of media mostly used for composite materials with inclusions. To achieve this, we approximate real geological media with layered bianisotropic media, employing the effective media approximation (EMA) averaging technique to simplify the retrieval of the effective electromagnetic parameters (e.g., apparent resistivity–inversely proportional to electrical conductivity). Additionally, we investigate the correlation between effective electromagnetic parameters and geodynamic processes, which is supported by the experimental data obtained during monitoring studies in the Tien Shan region. The observed decrease and increase in apparent electrical resistivity values of ρk over time in orthogonal azimuths leads to further ρk deviations of up to 80%. We demonstrate that transitioning to another coordinate system is equivalent to considering gradient anisotropic media. Building upon the developed method, we derive the effective electric conductivity tensor for gradient anisotropic media by modeling the process of fracturing in a rock mass. Research findings validate the concept that continuous electromagnetic monitoring can aid in identifying natural geodynamic disasters based on variations in integral macroscopic parameters such as electrical conductivity. The geodynamic processes are closely related to seismicity and stress regimes with provided constraints. Therefore, disasters such as earthquakes are damaging and seismically hazardous.

РЫБИН А.К., ЗАБИНЯКОВА О.Б., БАТАЛЕВА Е.А., НЕПЕИНА К.С.

Представлены результаты исследования разломной структуры, полученные с использованием комплекса электромагнитных методов -электротомографии и магнитотеллурического зондирования. Работы выполнены с целью детального изучения положения пространственных гео-электрических неоднородностей и аномалий повышенной проводимости. Построены геоэлектрические модели верхней части разреза (осадочного чехла и фундамента) для двух профилей, секущих зону динамического влияния Иссык-Атинского разлома. Полученные в результате двумерной инверсии аномалии низкого сопротивления коррелируют с положением отдельных сегментов разломной структуры. Получены оценки электромагнитных параметров в разломной зоне и определены элементы ее залегания.

Nigmatullin R.R., Bataleva E.A., Nepeina K.S., Matiukov V.E.

The research is based on the typical measurement calibration procedure of magnetotelluric soundings (MTS) prior to deep Earth exploration. We suggest the testing and new possibilities of the using MTS equipment calibration. We used two Phoenix MTS station boxes with different magnetic coil sets and mixed sets of coils for verification (check-up) stations calibration and the identity sessions. As a result of the experiments carried out and careful running over sorting of standard functions (exponential, power-law, polynomial), the verification of the proposed method was performed. Eventually this study proposes a “universal” fitting curve after one-station calibration curves to be normalized and are compared to another (etalon) station calibration curves (written in the form of two polynomials ratio). This procedure can be generalized for the case x → f(x), where f(x) is known function. It enables to fit all these 4 typical normalized curves (two for amplitudes (mV) and two for phases (degrees)) by the ratio of fourth degree function containing 9 fitting parameters C0-7 and B0, simply calculated as numeric constants through linear least squares method (LLSM).

Rybin A., Nepeina K.

The magnetotelluric soundings (MTS) are a common tool in applied geophysics. The guidelines for electromagnetic (EM) monitoring should be updated because of new tools and software developed. Some techniques paragraphs have outdated sections. Some essential equipment requirements and its’ allowable parameters, MTS acquisition, are defined. We involve Research Station RAS patents (RU 175972 U1, 2017; RU 2701876 C1, 2018) to increase the long-term stability of electrical parameters of non-polarizable electrodes. We consider the irreversible rock deformations form sources of the electromagnetic field of endogenous origin as geodynamic processes. We offer MTS with an additional algorithm with electromagnetic field separation for studying the endogenous component of EM field as a lower half-space impedance. We explain the technology of MTS in seismically active zones with remote access on the example of the Tien Shan. We introduce these guidelines acquiring data system for the joint seismic-and-electromagnetic monitoring for the modern geodynamic processes. We show a result diagram for the energy characteristic of the endogenous component of EM field.

Баталева Е.А., Непеина К.С.

Nepeina K.S., Rybin A.K., Kaznacheev P.A.

Abstract The project of the joint seismic-and-electromagnetic monitoring in low-ambient noise areas is aimed at studying the phenomena associated with the deformation of the Earth’s crust. The arrangements set of the geophysical monitoring in low-ambient noise areas is proposed. The paper describes in detail the technological scheme being of monitoring of the modern geodynamic activity with a magnetotelluric soundings method and a small seismic array presented as the seismic gradient system (SGS). Technical explanations, safety rules, equipment calibration and maintenance, and the technological schemes of the method of obtaining and archiving data are given. Maintenance procedures using SGS with geophones in Tien Shan to determine the endogenous component of the seismic field are described. We investigate a common workflow chart for SGS and main programs for the data caption and data processing. The proposed scheme has been tested and requires the application and adoption to the passive geophysical monitoring routine.

Nepeina K.S., An V.A.

This paper presents the travel times of P waves for 8 Yucca Flat (Nevada Test Site NTS) explosions from 1979 to 1984, with magnitudes mb = 4.9–5.9. Travel times were obtained by revising seismograms from the archives Sadovsky Institute of Geosphere Dynamics for the subsystem “Ozherel’e” (Necklace) of peripheral points Zerenda, Vostochniy, Chkalovo of the large-base seismic array system (SAS) of the geophysical observatory Borovoye. This system has been operating since 1979 on the territory of Kazakhstan. By the example of registration of underground nuclear explosions at the Yucca site of the Nevada Test Site (NTS), local travel time curves and linear trends in the P wave travel time in the range of epicentral distances 89.3110°–90.3701° are investigated. We estimate of the velocities of effective P waves for the Yucca-“Ozherel’e” and peripheral points.

Rybin A.K., Bataleva E.A., Aleksandrov P.N., Nepeina K.S.

Abstract—Electromagnetic investigation of stress-strain state dynamics in the geological medium is based on the analysis of two groups of physical phenomena. The first group includes phenomena associated with the dynamics of electrical properties of rocks caused by a change in their fracturing, porosity, fluid content, structure and texture, temperature and pressure, etc. The second group covers the effects of generation of endogenous (geodynamic) sources of electromagnetic field under irreversible deformations of the geological medium. In this paper, we present the practical results of the studies of the Earth’s natural electromagnetic field that have been carried out at the Research Station of the Russian Academy of Sciences in Bishkek over 40 years of operation of the Bishkek Geodynamical Test Site of the Research Station and aimed at gaining new insights into the present-day geodynamics of the Tien Shan lithosphere. The results of the experimental study of the first group of phenomena are based on the analysis of temporal changes in the magnetotelluric transfer functions. In this analysis it is assumed that the present-day geodynamic processes including catastrophic ones, e.g., earthquakes, trigger the crack formation processes which, in turn, changes the pore-fracture space of the rocks and causes fluid redistribution in them, thus resulting in the changes in the electrical conductivity of the geological medium. The practical results of the studies of the second group of phenomena are based on the notion that the geodynamic processes induced in the Tien Shan crust by irreversible deformations of rocks create sources of electromagnetic radiation leading to the variations in the endogenous electromagnetic field which can be observed on the ground.

Nepeina K.S., An V.A.

The paper presents information from the digitized register of underground nuclear explosions (UNE) of the Nevada test site from 1960 to 1975 stations of the Unitied Geophysical Survey USSR (EGGN USSR), preserved in the archives of the Institute of Geosphere Dynamics of the Russian Academy of Sciences named after M.A. Sadovsky (IDG RAS). Particular attention is paid to the records of those explosions that were registered by one, two or at most three stations. Such reports were checked for the presence of UNE records on seismograms in the archives of the IDG RAS and the Geophysical Survey RAS (FRC GS RAS). For these explosions at the found stations, the travel time of the primary body wave (tp) was obtained. Tables of registration times and travel times for various phases of body waves are compiled. This material is intended to be the publication of a part of the consolidated catalog of registered UNEs of the Nevada test site to replenish the database on the travel times of seismic waves collected over the past two decades.

Nepeina K.S., An V.A.

This research fulfills additional information about the lithosphere below Southeastern Asia and the northern Pacific. The area is interesting for researchers because of the Kuril–Kamchatka subducted lithosphere. The availability to study an underground structure is complicated, because of Pacific Ocean. The significance of this research concerns epicentral distances ~54°–70° or ~6000–7000 km. During the Cold War of the 20th century and the classification of information between the largest nuclear states the Soviet Union (USSR) and the United States of America (USA), data on the registration of nuclear explosions were not published, however, underground nuclear explosions (UNE) were recorded. Thanks to an employee of the laboratory 5-s of the Institute of Physics of the Earth named after O.Yu. Schmidt of the USSR Academy of Sciences Kh.D. Rubinstein is kept at the Institute for the Dynamics of Geospheres of the Russian Academy of Sciences named after Academician M.A. Sadovsky (IDG RAS). Only after 1985 reports from some seismic stations of the former USSR began to be published in the operational reports of the United Geophysical Survey of the Russian Academy of Sciences (GS RAS). As it has not been yet published anywhere, we collect them and obtain the travel times were by revising seismograms from the archives IDG RAS and GS RAS for five Kuril–Kamchatka seismic stations (Bering, Esso, Severo-Kurilsk, Kurilsk). The 48 Unites States UNE at Pahute Mesa (at Nevada Test Site) from 1968 to 1990 are used for travel time curve building. We measure P waves travel times (tp) on historical seismograms for the ray travel path between Pahute Mesa tests and Kuril–Kamchatka stations. The body-waves magnitudes (mb) vary from 5.3 to 6.5. We obtain arrivals for: 1 UNE at Bering station, 7 UNE at Esso station, 45 UNE at Petropavlovsk, 18 UNE at Severo-Kurilsk and 12 at Kurilsk. We build a travel time function using linear regression algorithm as tp=k·Δ°+b, where Δ° is the epicentral distance, k and b are arbitrary constants. We show that travel time deviations, associated with nonlinearity of the Earth. We estimate the effective velocities of P waves for the Pahute Mesa – Kuril–Kamchatka travel path as coefficient k in the linear equation. Effective velocity is equal to 7.5 km/s.

Nepeina K.S., Matiukov V.E.

The paper presents a practical implementation of the task of visualizing additional geophysical information for analyzing the results of azimuthal magnetotelluric (MT) monitoring. Since some patterns of a sharp change in the sign of relative apparent resistivity variations (Δρ) for MT monitoring points depending on ongoing seismic events, as well as lunar-solar tides, were found in previous studies, it became necessary to give illustrative examples proving such cases. For this, we propose to improve the technique for constructing additional graphs containing such parameters of seismic events as: source depth, distance between the source and the observation point, azimuth and energy class, in accordance with the observation time. All parameters are obtained from published seismic catalogs. A method for displaying pseudosections Δρ, combined with a hypocenter distribution plot, in Surfer program is shown. An example of a graph containing simultaneously information about the distance and azimuth of the event relative to the monitoring point, in the form of rotated arrows, is given. Such graphical constructions are maximally automated, and allow the interpreter to confirm the arguments in favor of the spatial-temporal dependence of the variations of electromagnetic parameters on the events occurring in the observed earth's interior.

Nepeina K., Bataleva E.

This work is aimed to develop a new approach to study the relationships between the spatial distribution of the electrical conductivity and earthquake hypocenters in seismically active regions such as the Tien Shan. The basis of a complex deep complex model (up to 30 km depth) of the Tien Shan lithosphere is a fault-block model. The joint analysis of the geoelectric model and seismicity provides important information for understanding the distribution of deep electrical conductivity, which is an indicator of active geodynamic processes and provides indirect estimates of the stress-strain state of the geological media. The purpose of our investigation is to extend the study of the relationship between hypocenter depth distribution and geoelectric boundaries on a 2D cross-sections in the Central Tien Shan. This paper shows complex models, built for several meridional magnetotelluric soundings (MTS) profiles located (74.3° E and 75.2° E). We use seismic bulletins for 5 years (2015–2019) and select earthquakes nearest to the MTS profile lines. Based on our previous studies, we are interested in the behavior of seismicity with energy classes K  8 separately. We calculate relative coordinates (latitudes) to the kilometers from the starting point of the profile. As a result, the graphs present colored 2D cross-section with profile distance (R) and earthquake hypocenters into the depth marked by dots. The analysis of this study indicates the presence of a certain relationship: the earthquakes hypocenters clustering attach to the boundaries of objects and outline geological bodies, or are located inside certain zones.

Ma X., Huang Z.

Altakhaineh A.R., AlTalafeeh A., Al-Ziadat M.

PurposeThis study aims to explore the challenges faced by BA students in the Applied English program at the University of Jordan during their practicum experience, focusing on the first semester of the academic year 2022/2023. It seeks to shed light on training environment issues and workplace skills while considering the cultural and economic context of Arab countries, particularly Jordan.Design/methodology/approachThe study employed a qualitative research design using semi-structured focus group discussions. A sample of 24 students were selected through convenient sampling, ensuring accessibility as the researchers are also instructors at the same university. Data collection emphasized ethical considerations, including informed consent and ensuring privacy and confidentiality.FindingsThe study identified significant challenges related to the training environments and the alignment of tasks with learning objectives. Familial and cultural factors were found to influence the students’ experiences, highlighting the importance of context-specific support. Recommendations were provided to enhance the practicum experience by improving training site selection, refining tasks and offering targeted support systems. Additionally, the study highlights the potential of virtual training environments as a future area of exploration.Originality/valueThis research is among the first to address practicum challenges faced by BA students in the Arab region, with a specific focus on Jordan. By situating findings within the cultural and economic contexts of the region, the study provides unique insights for tailoring support systems and training programs. The results contribute to a better understanding of how to prepare graduates for successful careers in similar contexts.

Jubaedah N.E., Parnadi W.W.

Abstract Electrical Resistivity Tomography (ERT) is a well-known standard geophysics technique for identification of geological phenomena such as faulting. The resolving power of this method is constrained by electrode spacing, device used, electrode configuration, resistivity contrast, and so on. On faulting, fault types are assumed to influence greater than the other parameter. In this research, we carried out a simulation study to detect the resolving power of ERT system using available software in public domain. Three different electrode configurations were used, namely Wenner, Schlumberger, and Dipole-dipole. We varied electrode spacing and resistivity contrast and fault types to yield optimal result. The results of this research are the most optimal model for identifying fault zones was a model that used a Dipole-dipole array with an electrode spacing of 1 m. The smaller the electrode spacing and the greater the number of cells in modelling, it produces a higher resolution modelling cross-section, so that the inversion results are more accurate to the models.

Takele T., Husein M., Diriba D., Assefa G.

Zhou Y., Wu Z., Liang Q., Xu H., Wang H., Xue W.

Scientific and reasonable emergency response initiation mechanisms can provide important support for decision making regarding the emergency management of urban floods. However, there is a lack of a unified paradigm on how to calculate the threshold for emergency response initiation and reasonably initiate emergency response. Therefore, this study proposes a loss-driven urban flood emergency response initiation framework from the perspective of combined disasters. A discrimination mechanism of the emergency response initiation level was established based on the optimal threshold and loss function. And the rainfall event that occurred in Zhengzhou, China, on July 20, 2021, was taken as an example to realize real-time emergency response discrimination and initiation driven by forecast data. Results showed that the initiation time of the Level I emergency response using the proposed method was 9.5 h earlier than the time of the government release, thereby significantly increasing the preparation time for flood management personnel. In addition, the results of the optimal threshold selection indicated that the Natural Breakpoint method was the optimal method for loss threshold partitioning, with the comprehensive evaluation index (CEI) being 3.56–9.53% higher than those of the K-means, Equal Interval, and Quantile method. These results constitute a reference for urban emergency management and related research.

Guo Q., Mao Y., Yan L., Chen W., Yang J., Xie X., Zhou L., Li H.

The nonferrous metal mines in China are rapidly depleting due to years of mining, and it has become difficult to identify new mineral resources in the periphery of the old mining area. In order to deal with this situation, advanced technologies and equipment must be deployed. The borehole transient electromagnetic method (TEM) has become a key technology due to its deep investigative capabilities within conductive geological structures. In the present study, in order to meet the exploration needs at depths of less than 3000 m, surface-borehole TEM exploration was used to analyze the characteristics of electromagnetic signals generated by a long wire source and a large loop source, providing essential data for the development of key technologies, such as sensor parameter design and signal gain optimization of the TEM system in the borehole. This study discussed in detail two key technical problems as follows: firstly, the efficient synchronization mechanism between the ground transmitter system and the borehole electromagnetic signal acquisition system ensured the accuracy and timeliness of data acquisition; and secondly, the realization of mass storage technology, which effectively solved the problem of mass storage and real-time transmission of data in a deep borehole environment. The effectiveness of the surface-borehole TEM systems with a long wire source and a large loop source was verified by tests in real mines. The surface-borehole electromagnetic signal acquisition system developed in this study effectively collected electromagnetic signals in the borehole, and the results accurately reflected the stratigraphic information of mineral resources in the study area. This study can pave a new technical path for the exploration of deep and peripheral areas of non-ferrous metal mines and provide valuable experience and insights for mineral resource exploration in similarly complex geological environments.

Jelbi M., Mridekh A., Taia S., Kili M., El Mansouri B., Magrane B.

Hydrogeophysical methods have been used in conjunction with new numerical models (statistical and other) in recent years within intricate alluvial aquifers. Understanding aquifer distribution and improving groundwater quality knowledge in the context of huge databases is made feasible by the numerous descriptive statistics approaches (such as Principal Component Analysis (PCA), clustering, and moment calculations) and regression modeling. The study area database includes physicochemical data collected throughout multiple periods and over 2600 vertical electrical sounding (VES). Numerous studies have revealed that the water table is dropping and the quality of the water is declining in this area. To illustrate the spread of mineralization, we used a four-phase technique. The occurrence of four geoelectrical levels, as demonstrated by our results, suggests that the deep deposits are rather homogeneous when compared to the shallow surface data. Additionally, there may be a statistical relationship between the hydrochemical data and the two upper geoelectrical levels. It was, as a consequence, feasible to forecast a distribution map for the mineralization that was consistent with the geological information from earlier work by developing a regression relation between apparent resistivity and electrical conductivity. The acquired results provide new opportunities for understanding large-scale database exploitation, enhancing our understanding of intricate aquifers, and integrating hydrogeophysical and hydrochemical data in predictive modeling.

Nwabufo E.

Li R., Pan Y., Zhang X., Dai W., Liu B., Li J.

In response to nonrenewable energy consumption and environmental pollution, the development of electric vehicles has accelerated. The safety of electric vehicles has garnered considerable attention. There are numerous incalculable foreign objects on the road that may collide with or scratch the battery-pack's frontal, resulting in battery-pack system damage or even explosion. This poses a significant risk to the safety of passengers and drivers. In this paper, a diversity of mechanical safety prediction models for battery-pack systems are proposed. These models support data-driven structural optimization of the battery-pack system by utilizing the numerical results of the bottom shell deformation. These simulation-based prediction models combine response surface method and machine learning algorithms. First, a nonlinear finite element model of the battery-pack system is established. The efficacy of the model is verified using constrained modal analysis in a variety of commercial software packages. Second, the collision simulations are executed and the data in various collision conditions are collected. Different sample sizes are used to develop various response surface models and machine learning models. The machine learning algorithms adopt support vector machine, Gaussian process regression, and neural network models. Third, the prediction accuracy of multiple prediction models is investigated according to error functions. The results show that the neural network model can predict the most accurate deformation under the condition of low speed frontal impact. The prediction average absolute percentage error of the neural network model is only 0.34% within the design domain, and only 2.54% outside the design domain. The proposed prediction model can be used for reliable design of the battery-pack system in electric vehicles. It also can be employed to design the early warning system of the battery-packs.

Spichak V. ., Goidina A. .

This paper presents the attempt to estimate the contribution of thermal processes in the Earth’s crust to the generation of seismicity by the example of the seismically active region of the Chuya depression and the Kyrgyz ridge of the Northern Tien Shan. For this purpose, we use the models of temperature, petrophysical characteristics, and elastic moduli constructed in the previous works. The silica content model based on seismic tomography data is used to build a lithotype model. The constructed thermal conductivity model is utilized, along with the temperature model, to create a depth model of heat flow density. Based on the density, elastic moduli, and temperature models, the shear and thermoelastic stress models in the rocks are constructed. Their comparison with the distribution of earthquake hypocenters suggests that on the scale of the seismically active zone of the Chuya depression and the Kyrgyz ridge of the Northern Tien Shan, seismicity is mainly determined by the thermomechanical effect resulting from the hot ascending flow of acid magma from the upper mantle beneath the Muyunkum–Narat median mass.

Spichak V.V., Goidina A.G.

Abstract—The paper presents an attempt to estimate the contribution of thermal processes in the Earth’s crust to earthquake generation. As a case study, the seismically active junction zone of the Chu depression and Kyrgyz ridge of the Northern Tien Shan is considered. The analysis is based on the previously constructed models of temperature, petrophysical characteristics, and elastic moduli. The silica content model derived from seismic tomography data is used to build a lithotype model. The thermal conductivity model is constructed and used in conjunction with the temperature model to create a depth model of the heat flow density. The shear stress and thermoelastic stress models derived from density, elastic moduli, and temperature models are compared with the distribution of earthquake hypocenters in the region. The comparison suggests that on the scale of the seismically active junction zone of the Chu depression and the Kyrgyz ridge of the Northern Tien Shan, seismicity is mainly determined by thermomechanical effect induced by hot ascending flow of acid magma rising from the upper mantle beneath the Muyunkum–Narat median massif.

Sahito Z., Wassan S.H.

This study examines and explores the challenges, issues, and problems with their solutions regarding Science, Technology, Engineering, and Mathematics (STEM) education along with the awareness enjoyed by science teachers. The selection of papers for this study was done through systematic literature review techniques. The 11 themes were generated through the thematic analysis of the papers that is, STEM education and its awareness; its challenges, issues, and problems; its curriculum; inquiry and learning environment; technologies; learning and models of integration; a blended learning approach; students’ problem-solving abilities and skills; its implementation and evaluation; it’s research and current trends; and interdisciplinary collaboration and intervention. Policy and planning, infrastructure, and the state of society were found the main factors of the poor conditions of STEM education. STEM research studies suggest that a curriculum with a blended learning approach has to be integrated by interventions of models depicting technological and inquiry-based environments to bring awareness among teachers, which strengthens the students’ problem-solving abilities and skills.

Nepeina K.S., An V.A.

The paper presents information on the registration of underground nuclear explosions (UNEs) of the Semipalatinsk test site (STS) at the Balapan site (Bal) from 1969 to 1988. Two stations of the Unified Seismic Observation Service (ESSN USSR) - Uzhgorod (UZH) and Vladivostok (VLA), since the epicentral distances for them are closest to each other Δ~36°. Records of the register of specific UNEs have been preserved in the archives of the Institute of Geospheres Dynamics of the Russian Academy of Sciences. Academician M.A. Sadovsky (IDG RAS). Body wave magnitudes (mb) range from 5.6 to 6.2. For them, at equidistant stations, the travel time of the P-wave (tp0) was obtained. Corrections were made to the data on the registration and travel time curves were formed for the UZH-Bal, VLA-Bal and local traces for the range Δ~36.0-36.6°. Velocity Vp is equal ~10 km/s.

Rybin A., Bataleva E., Nepeina K.

The identification of hidden areas of active faults in the Earth’s crust that can generate earthquakes is the most urgent problem in assessing the seismic hazard of various regions. The main goal of this study was a detailed study of the geophysical characteristics in the zone of individual segments of active faults in the Northern Tien Shan with electromagnetic geophysical methods. The structural line of the Issyk-Ata fault is clearly, but fragmentary, revealed on the surface by geological methods, since the tectonic disturbance is hidden by loose deposits of the Cenozoic age. The results of inversion of detailed magnetotelluric soundings in the fault impact zone of the fault made it possible to determine the position of the upper edge, width, depth, strike and inclination of the fault zone. At the stage of complex construction of 2D geoelectric models of the Issyk-Ata fault zone, the results of field profile soundings by the method of surface electrical resistivity tomography were used. To study the dynamics of the constructed block model of the fault zone, we considered variations in the following electromagnetic parameters that reflect the response of the geomedium to a change in its stress–strain state: impedance and tipper components, apparent resistivity and impedance phase, time–frequency series, and anisotropic properties. Based on this, estimates of the correlation between variations in electromagnetic parameters and lunar-solar tides and the spatiotemporal distribution of seismicity were made. This work was supported by the Russian Science Foundation under grant No. 22–27-00567.

Rybin A., Bataleva E., Zabinyakova O., Nepeina K.

In 2023, monitoring geophysical studies were carried out using the electrical resistivity tomography (ERT) method along three profiles that cross the strike zone of the Issyk-Ata fault in the transverse direction. A detailed study was carried out of the observed variations in apparent electrical resistivity, which characterize the change in the electrical properties of the upper part of the Earth's crust section with a 40-minute discretization in time. Using the analysis of difference pseudo-sections of apparent resistivity, constructed based on the results of ERT monitoring, the most informative pseudo-depth interval from the point of view of geoelectric activity was determined for all three monitoring profiles. Accordingly, for a pseudo-depth of 24 m on each monitoring profile, an assessment was made of the geodynamic activity of these sections of the Issyk-Ata fault based on an analysis of the magnitude of two parameters: the amplitude of apparent resistivity variations and the correlation coefficient of electrical resistivity variations with lunar-solar solid tides. High values of these parameters, in our opinion, determine the location of modern active fault zones.

Rybin A., Bataleva E., Nepeina K.

The identification of hidden areas of active faults in the Earth’s crust that can generate earthquakes is the most urgent problem in assessing the seismic hazard of various regions. The main goal of this study was a detailed study of the geophysical characteristics in the zone of individual segments of active faults in the Northern Tien Shan with electromagnetic geophysical methods. The structural line of the Issyk-Ata fault is clearly, but fragmentary, revealed on the surface by geological methods, since the tectonic disturbance is hidden by loose deposits of the Cenozoic age. The results of inversion of detailed magnetotelluric soundings in the fault impact zone of the fault made it possible to determine the position of the upper edge, width, depth, strike and inclination of the fault zone. At the stage of complex construction of 2D geoelectric models of the Issyk-Ata fault zone, the results of field profile soundings by the method of surface electrical resistivity tomography were used. To study the dynamics of the constructed block model of the fault zone, we considered variations in the following electromagnetic parameters that reflect the response of the geomedium to a change in its stress–strain state: impedance and tipper components, apparent resistivity and impedance phase, time–frequency series, and anisotropic properties. Based on this, estimates of the correlation between variations in electromagnetic parameters and lunar-solar tides and the spatiotemporal distribution of seismicity were made. This work was supported by the Russian Science Foundation under grant No. 22–27-00567.

Guo X., Fan N., Liu Y., Liu X., Wang Z., Xie X., Jia Y.

AbstractOcean mining activities have been ongoing for nearly 70 years, making great contributions to industrialization. Given the increasing demand for energy, along with the restructuring of the energy supply catalyzed by efforts to achieve a low-carbon economy, deep seabed mining will play an important role in addressing energy- and resource-related problems in the future. However, deep seabed mining remains in the exploratory stage, with many challenges presented by the high-pressure, low-temperature, and complex geologic and hydrodynamic environments in deep-sea mining areas, which are inaccessible to human activities. Thus, considerable efforts are required to ensure sustainable, economic, reliable, and safe deep seabed mining. This study reviews the latest advances in marine engineering geology and the environment related to deep-sea mining activities, presents a bibliometric analysis of the development of ocean mineral resources since the 1950s, summarizes the development, theory, and issues related to techniques for the three stages of ocean mining (i.e., exploration, extraction, and closure), and discusses the engineering geology environment, geological disasters, in-situ monitoring techniques, environmental protection requirements, and environmental effects in detail. Finally, this paper gives some key conclusions and future perspectives to provide insights for subsequent studies and commercial mining operations.

Zhao Z., Luo Z., Sun H., Li H., Liu Q., Liu H.

Capillary rise tests were conducted on soil columns containing of three layers of sandy soils with coarser over finer over coarser sandy soil to investigate the effect of the relatively finer soil interlayer. The capillary rise height, rate, and water distribution were observed in laboratory tests of four layered soil columns, with two homogeneous (without the interlayer) soil columns serving as the controls. The final maximum height of the capillary rise in the soil column with the interlayer was larger than that of the column without the interlayer when the interlayer was laid around the water entry value of the underlying soil. The water content was not continuous in the entire soil profile with the interlayer, and a small matric suction gap was observed in the relatively fine soil between the soil column with and without the interlayer.

Ziganshin E., Nourgaliev D., Bayuk I., Kadyrov R., Nguyen T.H.

Carbonate rocks have a wide variety of pore shapes and different types of grains, which greatly affect the elastic properties and characteristics of the reservoir. This causes certain difficulties in petroelastic modeling. One of the problems is the scale of the input data, which is then used to build the rock physics model. The paper presents the results of studying three core samples of carbonate rocks of the Upper Devonian and Lower Carboniferous age, which are located in the South Tatar arch (Volga-Ural oil and gas basin (Russia)). To evaluate the structural characteristics of the pore space, the effective medium theory is used. The input data are the results of laboratory studies that include measurements of the velocities of longitudinal and transverse waves, porosity, and thin section and computed tomography analysis. When using the computed tomography, the core samples are analyzed at different resolution (12–37 µm/voxel). The tomography studies of pore space at different scales provide rather different values of porosity and pore aspect ratio. The tomography-based porosity estimations also differ from the experimentally measured porosity (up to 10%). The pore space characteristics provided by different datasets are used to build a rock physics model for the studied rocks that helps to estimate the elastic wave velocities with three different methods of effective medium theory (self-consistent approximation, differential effective medium (DEM), and the Kuster–Toksöz method). A comparison of the velocity estimations with their experimental analogs for dry rocks may indicate the presence of microcracks whose size is beyond the tomography resolution. Improved rock physics models incorporating both pores and microcracks are then used to predict the elastic wave velocities of fluid-saturated rock in a wide porosity range. It is demonstrated that the predicted values significantly differ (up to 30%) from those provided by the rock physics (RP) models constructed without the support of the tomography results. Moreover, other types of models are considered in which the difference in experimental and theoretical velocities is attributed to changes in the host matrix properties as compared to the calcite polycrystal, which are caused by various reasons.

Vargas C.A., Caneva A., Solano J.M., Gulisano A.M., Villalobos J.

We applied multi–temporal 1D magnetotelluric (MT) surveys to identify space–time anomalies of apparent resistivity (ρa) in the upper lithosphere in the Antarctic Peninsula (the border between the Antarctic and the Shetland plates). We used time series over several weeks of the natural Earth’s electric and magnetic fields registered at one MT station of the Universidad Nacional de Colombia (RSUNAL) located at Seymour–Marambio Island, Antarctica. We associated resistivity anomalies with contrasting earthquake activity. Anomalies of ρa were detected almost simultaneously with the beginning of a seismic crisis in the Bransfield Strait, south of King George Island (approximately 85.000 events were reported close to the Orca submarine volcano, with focal depths < 20 km and MWW < 6.9). We explained the origin of these anomalies in response to fluid migration near the place of the fractures linked with the seismic swarm, which could promote disturbances of the pore pressure field that reached some hundreds of km away.

Watson C.S., Elliott J.R., Amey R.M., Abdrakhmatov K.E.

Earth observation (EO) data can provide large scale, high-resolution, and transferable methodologies to quantify the sprawl and vertical development of cities and are required to inform disaster risk reduction strategies for current and future populations. We synthesize the evolution of Bishkek, Kyrgyzstan, which experiences high seismic hazard, and derive new datasets relevant for seismic risk modeling. First, the urban sprawl of Bishkek (1979–2021) was quantified using built-up area land cover classifications. Second, a change detection methodology was applied to a declassified KeyHole Hexagon (KH-9) and Sentinel-2 satellite image to detect areas of redevelopment within Bishkek. Finally, vertical development was quantified using multi-temporal high-resolution stereo and tri-stereo satellite imagery, which were used in a deep learning workflow to extract buildings footprints and assign building heights. Our results revealed urban growth of 139 km2 (92%) and redevelopment of ~26% (59 km2) of the city (1979–2021). The trends of urban growth were not reflected in all the open access global settlement footprint products that were evaluated. Building polygons that were extracted using a deep learning workflow applied to high-resolution tri-stereo (Pleiades) satellite imagery were most accurate (F1 score = 0.70) compared to stereo (WorldView-2) imagery (F1 score = 0.61). Similarly, building heights extracted using a Pleiades-derived digital elevation model were most comparable to independent measurements obtained using ICESat-2 altimetry data and field-measurements (normalized absolute median deviation < 1 m). Across different areas of the city, our analysis suggested rates of building growth in the region of 2000–10,700 buildings per year, which when combined with a trend of urban growth towards active faults highlights the importance of up-to-date building stock exposure data in areas of seismic hazard. Deep learning methodologies applied to high-resolution imagery are a valuable monitoring tool for building stock, especially where country-level or open-source datasets are lacking or incomplete.

Rybin A.K., Bataleva E.A., Aleksandrov P.N., Nepeina K.S.

Abstract—Electromagnetic investigation of stress-strain state dynamics in the geological medium is based on the analysis of two groups of physical phenomena. The first group includes phenomena associated with the dynamics of electrical properties of rocks caused by a change in their fracturing, porosity, fluid content, structure and texture, temperature and pressure, etc. The second group covers the effects of generation of endogenous (geodynamic) sources of electromagnetic field under irreversible deformations of the geological medium. In this paper, we present the practical results of the studies of the Earth’s natural electromagnetic field that have been carried out at the Research Station of the Russian Academy of Sciences in Bishkek over 40 years of operation of the Bishkek Geodynamical Test Site of the Research Station and aimed at gaining new insights into the present-day geodynamics of the Tien Shan lithosphere. The results of the experimental study of the first group of phenomena are based on the analysis of temporal changes in the magnetotelluric transfer functions. In this analysis it is assumed that the present-day geodynamic processes including catastrophic ones, e.g., earthquakes, trigger the crack formation processes which, in turn, changes the pore-fracture space of the rocks and causes fluid redistribution in them, thus resulting in the changes in the electrical conductivity of the geological medium. The practical results of the studies of the second group of phenomena are based on the notion that the geodynamic processes induced in the Tien Shan crust by irreversible deformations of rocks create sources of electromagnetic radiation leading to the variations in the endogenous electromagnetic field which can be observed on the ground.

Nepeina K.S., An V.A.

This research fulfills additional information about the lithosphere below Southeastern Asia and the northern Pacific. The area is interesting for researchers because of the Kuril–Kamchatka subducted lithosphere. The availability to study an underground structure is complicated, because of Pacific Ocean. The significance of this research concerns epicentral distances ~54°–70° or ~6000–7000 km. During the Cold War of the 20th century and the classification of information between the largest nuclear states the Soviet Union (USSR) and the United States of America (USA), data on the registration of nuclear explosions were not published, however, underground nuclear explosions (UNE) were recorded. Thanks to an employee of the laboratory 5-s of the Institute of Physics of the Earth named after O.Yu. Schmidt of the USSR Academy of Sciences Kh.D. Rubinstein is kept at the Institute for the Dynamics of Geospheres of the Russian Academy of Sciences named after Academician M.A. Sadovsky (IDG RAS). Only after 1985 reports from some seismic stations of the former USSR began to be published in the operational reports of the United Geophysical Survey of the Russian Academy of Sciences (GS RAS). As it has not been yet published anywhere, we collect them and obtain the travel times were by revising seismograms from the archives IDG RAS and GS RAS for five Kuril–Kamchatka seismic stations (Bering, Esso, Severo-Kurilsk, Kurilsk). The 48 Unites States UNE at Pahute Mesa (at Nevada Test Site) from 1968 to 1990 are used for travel time curve building. We measure P waves travel times (tp) on historical seismograms for the ray travel path between Pahute Mesa tests and Kuril–Kamchatka stations. The body-waves magnitudes (mb) vary from 5.3 to 6.5. We obtain arrivals for: 1 UNE at Bering station, 7 UNE at Esso station, 45 UNE at Petropavlovsk, 18 UNE at Severo-Kurilsk and 12 at Kurilsk. We build a travel time function using linear regression algorithm as tp=k·Δ°+b, where Δ° is the epicentral distance, k and b are arbitrary constants. We show that travel time deviations, associated with nonlinearity of the Earth. We estimate the effective velocities of P waves for the Pahute Mesa – Kuril–Kamchatka travel path as coefficient k in the linear equation. Effective velocity is equal to 7.5 km/s.

Bataleva E.A.

The results of monitoring studies of the fault structures of the Northern Tien Shan are presented, where regime (regular) observations by the magnetotelluric sounding method are carried out over the state of the geological environment under the influence of geodynamic processes. Fault zones identified from geological and electromagnetic data appear in the upper part of the section as subvertical objects with high electrical conductivity due to increased fracturing and have a good correlation with lunisolar tidal effects. The relationship between the behavior of geophysical fields variations and the stress-strain state of the Earth's crust in the seismically active regions of the Tien Shan is considered based on the analysis of correlations between the components of lunar-solar tidal influences, variations in electromagnetic parameters, and the distribution of seismic events.

Qi T., Zhang F., Pei X., Feng G., Wei H.

Water inrush disasters poses a great threat to the safe exploitation of coal resources. To solve this problem, the transient electromagnetic method (TEM) was proposed to accurately detect the water accumulation in the goaf. The electromagnetic response characteristics of different water-filled goaves were studied by electromagnetic field theory, numerical simulation and field verification. Through the models of 100% water accumulation, 50% water accumulation, 0% water accumulation, 100% water accumulation with collapsed rock, 50% water accumulation with collapsed rock and 0% water accumulation with collapsed rock goaf, the characteristics of induced voltage attenuation curves were studied. Meanwhile, the relationship between the attenuation voltage value and area of the transmitting coil, the depth of the goaf, the background resistivity, and the delay time were also simulated. The results illustrate that the attenuation curve of induced voltage presented a regular exponential decay form in the 0% water accumulation model but existed abnormal exaltation for voltage in water-filled model. Through the linear fitting curve, it can be seen that the abnormal intensity of the induced voltage becomes stronger as the distance between the measuring point and the center of the target decrement. Moreover, the abnormal amplitude of the induced voltage increases with the rise of the water accumulation and collapsed rock will weakly reduce the low-resistivity anomalous effect on the water-accumulated goaf. In addition, the response value of the attenuation voltage increased as the area of the transmitting coil increases, but decreased with increasing delay time and increasing background resistivity and depth of the target body. The field detection results of the Majiliang coal mine also confirmed the theoretical analysis and the numerical simulation.

Lin T., Zhou K., Cao Y., Wan L.

• Air-core coil sensors are important magnetic measurement tools for surface geophysical technology. • Detailed design process of induction coil and air-core coil sensor is presented. • Optimization methods for air-core coil sensors in TEM and SNMR applications are reviewed. • Research prospects of sensor technology in surface geophysical exploration are examined. In the field of surface geophysical detection, electromagnetic technologies represented by transient electromagnetic methods (TEMs) and surface nuclear magnetic resonance (SNMR) use air-core coil sensors as magnetic detection devices because of their high sensitivity, simple fabrication, robustness, and low cost. To clarify the application of air-core coil sensors in these fields, we review the design process and research directions of these devices. First, we introduce the detection principles and parameters of induction coils. Second, we summarize the structure, equivalent model, amplitude–frequency characteristics, and noise level of air-core coil sensors. Third, the characteristics of the air-core coil sensors used in TEMs and SNMR are introduced respectively, and the optimization of parameters such as the noise level, sensitivity, and size of these magnetic detection devices according to actual application conditions is then discussed in detail. Finally, we propose directions for future research based on existing problems in the use of air-core coil sensors, and provide ideas for their further development in geophysical detection.

Bataleva E.

The results of geophysical monitoring of seismically hazardous regions are of undoubted interest for studying the deep structure of the lithosphere, regional seismicity, modern geodynamics, etc. The work used experimental material, including the results of magnetotelluric monitoring and the catalogs of the KNET (Kyrgyzstan Telemetered Network), KRNET (Kyrgyz Republic Digital Network) and ISC (International Seismological Center) networks obtained in the seismically active zones of the Bishkek Geodynamic Proving Ground (Northern Tien Shan). The analysis of electromagnetic monitoring results of the Northern Tien Shan seismic generating zone was carried out in a wide frequency range. The data on the parameters of the electromagnetic field of the Earth’s crust in the Northern Tien Shan are generalized and systematized. Based on the analysis of these data, the dependence of the response of seismic events in electromagnetic parameters on the distance of earthquake epicenters was studied. The most likely reason for the occurrence of anomalous changes in the electromagnetic field is the activation of deformation processes during the preparation of strong earthquakes. The results of the time-frequency analysis are presented and the features of manifestation are considered depending on the location of the hypoand epicenters of seismic events and their magnitude. Regularities have been established in the behavior of tipper variations for remote and regional earthquakes for the first quarter of 2016 with an energy class from 6 to 10.

Nevedrova N.N., Sanchaa A.M., Shaparenko I.O.

Abstract In this paper we present the results of our studies of sections of the Uimon basin in Gorny Altai (Russia) using a complex of electrical prospecting methods. The areas of Baratal Formation at the surface have been investigated. This areas explored in order to understand the stages of formation of the depression. In addition, the possibilities of the electrotomography method for regular observations in seismoactive regions are shown. Comparison of the amplitudes of the resistivity variations based on repeated ERT measurements in different zones of the Terekta fault indicates the activity of its eastern part, which is expressed in significant resistivity variations exceeding 100%. At the same time, the variations in the northwestern part of the fault, reaching 15% on average, are many times smaller.

Mukhamadeeva V.A.

Abstract The article presents the results of electromagnetic monitoring and geomagnetic observation during increased seismic activity in eastern part of Bishkek geodynamic range (Northern Tien-Shan) in 2017. It includes brief description of seismic conditions of the territory being researched, as well as analyses of the correlation between changes in geophysical field parameters and the earthquakes.

Tang H., Wei W., Song X., Liu F.

In this article, we formulate an anisotropic elastoplastic Cosserat continua model for shear failure in stratified geomaterials. Considering the dip angle between local and global coordinates of a formation, a Cosserat elastic anisotropy constitutive matrix under plane strain condition is derived, and cohesion anisotropy is reflected using a microstructural tensor combined-stress invariant method. A Cosserat continuum finite element model and consistent algorithm are developed to consider the characteristics of elastic anisotropy, strength anisotropy, and strain softening. The simulation of a stratified geomaterial sample under uniaxial compression condition shows that the elastic anisotropy has an evident influence on the deformation pattern. It is also demonstrated that dip angle could significantly impact macroscopic failure modes, uniaxial compressive strength, and macroscopic equivalent elastic modulus. The stability analysis of a layered slope demonstrates that the strength anisotropy has a considerable influence on the overload safety factor of the slope and can be a trigger of the formation of shear bands in such slopes. Furthermore, the dip angle of the structural plane also affects the stability of the stratified slope, which is controlled by both the block and structural surface. By comparing the numerical results of the classical continuum model and the Cosserat continuum model, it is proved that the numerical model considering the elastoplastic anisotropy and strain softening under the Cosserat continuum theory overcomes the ill-posedness of mesh sensitivity and maintains the well-posedness of the strain localization problem. Thus, the proposed model is useful for modeling shear failure in stratified geomaterials. • An anisotropic elastoplastic Cosserat model for stratified geomaterials is presented. • Elastic and strength anisotropy, strain softening are included in the model. • The microstructural tensor combined-stress invariant is used for cohesion anisotropy. • Stability of stratified slope is controlled by both the block and structural surface. • The ill-posedness of the strain localization problem is overcome with the model.