Introduction. The widespread distribution of limestones in the Republic of North Ossetia - Alania predetermined the active development of karst on its territory. Karst research is an important scientific task, the solution of which is necessary to ensure human safety. Materials and methods. Based on the results of field research in 2023 and during the interpretation of high - resolution satellite images (Landsat, Sentinel, GeoEye and WorldView-1,2), the parameters and distribution zones of karst subsidence in the Kurtatinsky Gorge were identified. A systematic analysis of the karst hazard was carried out based on structural, geological and geomorphological data, as a result of which a corresponding map was compiled. Results and discussion. The highest density of karst subsidences (15-20 subsidences per 0.01 km2) is observed on the rounded, flattened summit surfaces of the Bakhty-Laparyrag and Khoshkharanrag ridges, composed of Cretaceous rocks of the Barremian stage (K1br). On the Khosavdrag ridge with a similar geological structure, but with a more dissected topography, subsidence is sporadic and located mainly on the structural steps of the slopes. In the lower flattened parts of the slopes, karst subsidence is not observed due to the active accumulation of demolished loose clastic material. The diameter of individual karst subsidences ranges from 5-7 to 60 m, the depth does not exceed 4 m, and there is a wide distribution of subsidences associated with small erosion forms. Almost all subsidences are located north of the watershed line of the Kurtatinsky Gorge, and this reduces the danger of karst for the study area. But due to the high density of subsidence, it is in the upper reaches of small erosion forms that the formation of a summit interception is possible due to the activation of regressive erosion. The territory was divided into five categories based on the following factors: rock composition and parameters of their occurrence, steepness, density of karst subsidence. The greatest karst hazard is typical for the Bakhty-Laparyrag and Khoshkharanrag ridges. The settlements of GornyKartsa and Gusyr are located in the safe zone. Conclusion. The formation and development of karst in the Kurtatinsky Gorge is largely influenced by the nature of the relief relative to the composition of the rocks. Planning and implementation of measures to protect infrastructure facilities is required. Particular attention should be paid to the safety of the road network of the Kurtatinsky Gorge, which crosses an area of high karst danger. The results of the study can be useful for effective land use planning, development of measures to prevent and reduce the risks of karst manifestation, as well as for ensuring safety in mountain regions.

It is generally recognized that the formation of the fold-and-thrust tectonic structures of mobile belts on continents is associated with crushing and narrowing of the Earth’s crust as a result of collision of lithospheric plates. The deformation of the Caucasian lithosphere in the neotectonic time is generally consistent with these ideas. However, the block differentiation of the Caucasian lithosphere introduces specific features in the directivity of modern vertical and horizontal movements. In this paper, we analyze vertical movements of the Caucasus estimated by means of high-precision leveling over more than a century and consider their spatial correlation with tectonics, seismicity, stress-strain state, and geophysical fields. A clear relationship indicating the deep tectonic nature of the long-term uplifting of the Caucasus crust is revealed. Due to the differentiation of the Arabian plate movement, the territory of the Caucasus is divided into provinces that differ from each other in the pattern of modern movements, in the orientation of faults, and in the stress-strain state. The seismic regime in these provinces also has differences in the number of seismic events and focal mechanisms of the earthquakes. We propose a model of the deformation mechanism of the Greater Caucasus, which takes into account the long-term trend of the Caucasus uplifting in the conditions of general shortening of the Earth’s crust. The results of the analysis are used as a basis for discussion of a probable mechanism of tectonic evolution of the Greater Caucasus in the neotectonic time, which can be used in the assessment of seismic hazard in the North Caucasus.

This paper analyzes and reviews the rapid uplifts of the Earth’s crust in the Caucasus that occurred over the last century. The uplifts were registered by precise repeated state leveling and reflected on officially published maps of vertical movements of the Earth’s crust. This study summarizes information on the region’s vertical movements over more than a century. The present study describes the technology for creating maps of recent vertical movements of the Earth’s crust using precision leveling data. This paper summarizes cases of recording uplifts of the Earth’s surface in other regions of the world in connection with seismic activity. The authors carried out intercomparison of vertical movements with tectonics, seismicity, and geophysical fields, which discovered their apparent mutual correspondence. This indicates the deep tectonic nature of the observed uplifts of the Earth’s crust. Spatial and temporal agreement with the distribution of strong earthquakes showed a natural relationship. It has been shown that strong earthquakes are confined to the boundaries of zones of rapid uplift. They occur predominantly in areas of transition between uplifts and subsidence. The results obtained demonstrate the role of the study and observations of vertical movements of the Caucasus in assessing periods and areas of increased seismic hazard.

Актуальность работы. В статье представлены результаты работ, направленных на развитие сети деформационного ГНСС-мониторинга восточных ветвей Владикавказского разлома на территории Республики Северная Осетия-Алания. Территория республики отличается высокой плотностью геодезических сетей: государственных, научных и коммерческих. Однако представленные ранее исследования не предусматривали использование государственных геодезических пунктов, а также построение на их основе равномерно распределенной по территории республики геодезической сети. Целью исследования, в рамках настоящей статьи, являлось формирование геодезической сети для деформационного ГНСС-мониторинга восточной части и отдельно узла сочленения Восточной и Западной ветвей Владикавказского разлома. Методы исследования. Сформированный полигон основывается на государственных геодезических пунктах, скальных центрах, заложенных коллективом авторов, и пунктах постоянно действующих сетей. Выполнены исследования по совершенствованию методики оценки точности ГНСС-измерений, связанные с особенностями горных физико-географических условий. Методика полевого контроля точностных характеристик комплектов ГНСС-аппаратуры, позволяет без эталонных построений в полевых условиях осуществлять контроль по одиночной базовой линии. Результаты исследования. Важным аспектом является применение методики к новым типам ГНСС-антенн, ранее не исследованных, включая choke-ring, а также антенн китайского производства с китайскими платами CHCNAV, которые в настоящий момент все чаще применяются на территории РФ. Обработка наблюдений по разработанному алгоритму позволила сравнить номинальные параметры ГНСС-антенн с их фактическими характеристиками и учесть фактические положения фазового центра. В сентябре 2023 г. на территории сформированного Осетинского геодинамического полигона выполнен первый цикл наблюдений за СДЗК средствами ГНСС. Первые результаты показали, что основное количество СКО положения пунктов в плане группируется в диапазоне 2–3 мм, а по высоте в диапазоне 3–5 мм. Средние значения СКО в плане и по высоте составили 3 мм и 6 мм соответственно.

This work constructs a seismic regime model for the eastern sector of the Arctic Zone of the Russian Federation (AZRF) based on a newly developed, comprehensive integral earthquake catalog for the region, using a uniform magnitude scale from 1980 to 2020. The model parameters are calculated using a novel high-contrast mean-position method, where values are determined within large-radius circles but are assigned to the mean position of epicenters. A quantitative verification method, the L-test, based on the likelihood function, demonstrates that the model aligns well with the initial data. The magnitude–frequency distribution reconstructed from the model corresponds well with observations, both in terms of slope and the number of earthquakes. The epicenters of the largest earthquakes (M ≥ 6) from both the 1982–2020 period and the 1900–1981 period, according to the Kondorskaya–Shebalin catalog, are located in areas with high expected recurrence of such earthquakes as calculated by the model.

Modern satellite positioning and navigation technologies are not applicable in specific areas such as the exploration of oil and gas deposits by means of directional drilling techniques. Here, we can rely solely on natural geophysical fields, such as the Earth’s magnetic field. The precise underground navigation of borehole drilling instruments requires a seamless, near-real-time access to operational geomagnetic data. This paper describes the MAGNUS BD hardware-software system, deployed at the Geophysical Center of the Russian Academy of Sciences, that provides the efficient accumulation, storage, and processing of geomagnetic data. This system, based on the Big Data (BD) technology, is a modern successor of the MAGNUS processing software complex developed in 2016. MAGNUS BD represents one of the first cases of the BD technology’s application to geomagnetic data. Its implementation provided a significant increase in the speed of information processing and allowed for the use of high-frequency geomagnetic satellite data and expanding the overall functionality of the system. During the MAGNUS BD system’s deployment on a physically separate dedicated cluster, the existing classical database (DB) was migrated to the Arenadata database with full preservation of its functionality. This paper gives a brief analysis of the current problems of directional drilling geomagnetic support and outlines the possible solutions using the MAGNUS BD system.

This paper is devoted to the review of currently functioning seismological agencies, seismic monitoring networks created, developed and supported by them, as well as earthquake catalogs produced. Particular attention is focused on international and national seismological centers and seismic networks. A historical insight about the first observations made by seismic networks completes the picture. The basic parameters of the main seismic networks and the principles of functioning for seismological centers are considered. The key characteristics of seismic catalogs that determine the criteria for their quality are discussed. The system-analytical approach to solving the urgent problem of creating the most complete and representative earthquake catalogs with a unified magnitude scale by integrating data from international, national and regional catalogs in the studied region is presented.

Актуальность работы. В статье представлены результаты работ, направленных на развитие сети деформационного ГНСС-мониторинга восточных ветвей Владикавказского разлома на территории Республики Северная Осетия-Алания. Территория республики отличается высокой плотностью геодезических сетей: государственных, научных и коммерческих. Однако представленные ранее исследования не предусматривали использование государственных геодезических пунктов, а также построение на их основе равномерно распределенной по территории республики геодезической сети. Целью исследования, в рамках настоящей статьи, являлось формирование геодезической сети для деформационного ГНСС-мониторинга восточной части и отдельно узла сочленения Восточной и Западной ветвей Владикавказского разлома. Методы исследования. Сформированный полигон основывается на государственных геодезических пунктах, скальных центрах, заложенных коллективом авторов, и пунктах постоянно действующих сетей. Выполнены исследования по совершенствованию методики оценки точности ГНСС-измерений, связанные с особенностями горных физико-географических условий. Методика полевого контроля точностных характеристик комплектов ГНСС-аппаратуры, позволяет без эталонных построений в полевых условиях осуществлять контроль по одиночной базовой линии. Результаты исследования. Важным аспектом является применение методики к новым типам ГНСС-антенн, ранее не исследованных, включая choke-ring, а также антенн китайского производства с китайскими платами CNCNAV, которые в настоящий момент все чаще применяются на территории РФ. Обработка наблюдений по разработанному алгоритму позволила сравнить номинальные параметры ГНСС-антенн с их фактическими характеристиками и учесть фактические положения фазового центра. В сентябре 2023 г. на территории сформированного Осетинского геодинамического полигона выполнен первый цикл наблюдений за СДЗК средствами ГНСС. Первые результаты показали, что основное количество СКО положения пунктов в плане группируется в диапазоне 2–3 мм, а по высоте в диапазоне 3–5 мм. Средние значения СКО в плане и по высоте составили 3 мм и 6 мм соответственно Relevance. This article presents the results of work aimed at developing a deformation GNSS monitoring network for the eastern branches of the Vladikavkaz Fault in the Republic of North Ossetia-Alania. The region is characterized by a high density of geodetic networks, including state, scientific, and commercial networks. However, previous studies did not incorporate the use of state geodetic points or the establishment of a geodetic network uniformly distributed across the republic. The aim of the study, engineering and geodetic work in forming a geodetic network for deformation GNSS monitoring in the eastern and western branches of the Vladikavkaz fault. Research methods. The formed polygon is based on state geodetic points, rock centers laid by the team of authors, and points of permanent networks. Research was conducted to improve the methodology for assessing the accuracy of GNSS measurements, considering the specific mountain physical and geographical conditions. The field control methodology for GNSS equipment accuracy allows for in-field control using a single baseline without reference constructions. Research results. Similar experiments were previously conducted in flat terrain conditions. An important aspect is the application of the method to new types of GNSS antennas that have not been previously studied, including choke-rings, as well as Chinese-made antennas with Chinese CNCNAV boards, which are currently increasingly used in the Russian Federation. Processing observations using the developed algorithm made it possible to compare the nominal parameters of GNSS antennas with their actual characteristics and take into account the actual positions of the phase center. In September 2023, the first observation cycle for modern crustal movements using GNSS was conducted at the newly established Ossetian geodynamic polygon. The initial results indicated that most of the standard deviations for point positions in plan view were in the range of 2–3 mm, and in height, 3–5 mm. The average standard deviations values in plan view and height were 3 mm and 6 mm, respectively

This article is the continuation of a study by authors to create the most complete and representative earthquake catalogs with a unified magnitude scale. The catalog created of the Ossetian sector of the Greater Caucasus (the territory of the Republic of North Ossetia–Alania and adjacent areas) was formed by the aggregation of all available data from Soviet, modern Russian, and Georgian catalogs, as well as the data from the International Seismological Centre. The integration was carried out using the author’s approach based on the modified nearest neighbor method. The integrated catalog of the Ossetian sector of the Greater Caucasus contains 16,285 events for the period 1962–2022. For all events, magnitude estimates are reduced to a unified “proxy-MW” scale. The integration of data from various sources made it possible to significantly replenish the beginning of the aftershock sequence of the Racha earthquake with MW = 7.0, which occurred on 29 April 1991. There has been a change in the level of registration over time. Thus, there is a significant lack of events for the periods 1967–1970 and 1988–1991; starting from 1995, the catalog is complete for magnitude 3.2, and since 2005 for magnitude 2.2. The integration of Soviet and modern Russian and Georgian catalogs made it possible to significantly increase the completeness and representativeness of seismic events in the studied Ossetian sector of the Greater Caucasus. This once again demonstrates both the fundamental importance of merging seismic data from global, national, and regional catalogs and the effectiveness of the author’s developed method.

The method of analyzing data known as Discrete Mathematical Analysis (DMA) incorporates fuzzy mathematics and logic. This paper focuses on applying DMA to study the morphology of time series by utilizing the language of fuzzy mathematics. The morphological characteristics of the time series, such as background, slopes, and vertices, are considered fuzzy sets within the domain of its definition. This allows for the use of fuzzy logic in examining the morphology of time series, ultimately leading to the detection of anomalies.

The article is a continuation of the research on creating the most complete and representative earthquake catalogs by combining all available data from regional, national, and international seismological agencies and reducing magnitudes to a uniform scale. The task of identifying and removing duplicates that arise during the merging process is solved using the authors’ modification of the nearest neighbor method. It is evident that the intelligent merging of different earthquake catalogs for the same territory will improve the completeness and representativeness of events in the final integrated catalog. In this article, the earthquake catalog of the western sector of the Arctic zone of the Russian Federation (AZRF) covering the period 1962–2022 was created by merging three regional Russian catalogs and the ISC catalog. The ratio of magnitude types in the catalog for different seismic networks was analyzed, and magnitude estimates were unified based on the obtained ratios. For analyzing seismic activity in the western AZRF, it is recommended to use earthquakes from the period 1998–2020 when the catalog was significantly cleaned from explosions and other events of the “non-earthquake” type.

The present paper continues the series of publications by the authors devoted to solving the problem of recognition regions with potential high seismicity. It is aimed at the development of the mathematical apparatus and the algorithmic base of the FCAZ method, designed for effective recognition of earthquake-prone areas. A detailed description of both the mathematical algorithms included in the FCAZ in its original form and those developed in this paper is given. Using California as an example, it is shown that a significantly developed algorithmic FCAZ base makes it possible to increase the reliability and accuracy of FCAZ recognition. In particular, a number of small zones located at a fairly small distance from each other but having a close “internal” connection are being connected into single large, high-seismicity areas.

This paper represents the final part of a series of studies aimed at creating the most reliable and representative earthquake catalog covering the Russian and European Arctic. The earthquake catalog of the Gakkel and Knipovich ridges, as well as the Svalbard Archipelago with a unified magnitude scale, was formed based on the combination of four regional Russian catalogs and the ISC catalog. The merging of catalogs was carried out using the modification of the author’s methodology, which allowed for the identification of records in different datasets related to the same seismic event. The modification was introduced due to significant changes over time in the source catalogs. The unified proxy moment magnitude scale was formed based on regression analysis of the different magnitude estimates provided by various agencies. The integrated catalog included 17,922 earthquakes that occurred during the period 1962–2022. Analysis of the integrated catalog showed that the level of registration in the studied area significantly varies over space and time. Before 1995, the catalog contained only strong and moderate earthquakes, and the magnitude of complete registration Mc was 5.0 in the Gakkel Ridge, 4.7 in the Knipovich Ridge, and 4.5 in the Svalbard Archipelago. The number of recorded events increased in the period 1995–2011, and Mc decreased to 4.0 in the Gakkel and Knipovich ridges and to 2.8 in the Svalbard Archipelago. The best level of registration in the Svalbard Archipelago and the Knipovich Ridge was achieved after 2012, when Mc reached 1.7 and 2.8, respectively. In the Gakkel Ridge, despite a noticeable increase in the number of reported events from 2012, the magnitude of complete registration did not improve and was 4.0. The presented integrated earthquake catalog is intended for a wide range of studies of the seismic regime of the Arctic.

The results presented in this paper are obtained as part of the continued development and research of clustering algorithms based on the discrete mathematical analysis. The article briefly describes the theory of Discrete Perfect Sets (DPS-sets) that is the basis for the construction of DPS-clustering algorithms. The main task of the previously constructed DPS-algorithms is to search for clusters in multidimensional arrays with noise. DPS-algorithms have two stages: the first stage is the recognition of the maximum perfect set of a given density level from the initial array, the second stage is the partitioning of the result of the first stage into connected components, which are considered to be clusters. Study of qualities of DPS-algorithms showed that, in a number of situations in the first stage, the result does not include all clusters which have practical sense. In the second stage, partitioning into connected components can lead to unnecessarily small clusters. Simple variation of parameters in DPS-algorithms does not allow for eliminating these drawbacks. The present paper is devoted to the construction on the basis of DPS-algorithms of their new versions, more free from these drawbacks.

The global challenge for the mining sector is the problem of “decarbonization” of coal mining. The modeling of emission flows of coalmine methane is stipulated by the need to prove the environmental effect of the implemented technological changes. For longwall geotechnology, the dynamics of methane concentration in the gas–air mixture extracted by the degassing system reflects the complex relationship between emission and geomechanical processes in the rock mass. In this regard, the aim of the work was to improve the methods for assessing the steps of caving the main roof when mining gas-coal seams. The method of work consisted of processing experimental data (smoothing—Loess, three-dimensional interpolation, regression—the method of least squares) to obtain reliable response functions in three-dimensional space. When developing algorithms in the Python language, the Vi Improved text editor was used. Graphical representation of the results was carried out in “Gnuplot”. As a result of modeling, it was found that the increase in the span of the main roof from 83 to 220 m (S = 1340–1120 m) in the distance range of 120 m in front of the stoping face line and up to 50 m behind it (L = −120–50 m) leads to an alternating cyclicity of local extrema of the dynamics of methane release, according to a polynomial dependence. This fact is a consequence of the implementation of deformation-wave processes in geo-environments, which produce cyclic nonlinearities in the nature of the aero-gas regime of mine methane emissions into anthropogenically disturbed rock masses. In addition, the influence of the situational geomechanical conditions of the excavation area in the goaf was clarified. This makes it possible to reliably identify the caving steps of the main roof.

The objective of this study was to create a representative earthquake catalog for the Eastern Sector of the Arctic zone of the Russian Federation that combines all available data from Russian and international seismological agencies, with magnitude reduction to a uniform scale. The article describes the catalog compilation algorithm, as well as formalized procedures for removing duplicates and choosing the optimal magnitude scale. Due to different network configurations and record processing methods, different agencies may register/miss different events. This results in the absence of some events in different earthquake catalogs. Therefore, merging the data of various seismological agencies will provide the most complete catalog for the studied region. When merging catalogs, the problem of identifying duplicates (records related to the same seismic event) necessarily arises. An additional difficulty arises when distinguishing between aftershocks and duplicates since both are events that are close in space and time. To solve this problem, we used a modified nearest neighbor method developed earlier by the authors. The modified version, which is focused on identifying duplicates and distinguishing between duplicates and aftershocks, uses a probabilistic metric in the network error space to determine the epicenters and times of seismic events. In the present paper, a comparison and regression analysis of the different magnitude types of the integrated catalog is carried out, and based on the obtained ratios, the magnitude estimates are unified.

The introduction of modern methods for the mathematical processing of geological data is one of the promising areas of study and development in the field of geosciences. For example, today mathematical geology makes it possible to reliably identify astronomical cycles by measuring the scalar magnetic parameters of rocks (magnetic susceptibility). The main aim of this study is to develop a mathematical tool for identifying stable oscillation cycles (periods) in the dataset of the magnetic susceptibility of rocks in a geological section. The author’s method (algorithm) is based on the concept of discrete mathematical analysis—an innovative mathematical approach to the analysis of discrete geological and geophysical data. Its reliability is also demonstrated, by comparison with the results obtained by classical methods: Fourier analysis, Lomb periodogram, and REDFIT. The proposed algorithm was applied by the authors to analyze the material of field geological studies of the Zhelezny Rog section (Taman Peninsula). As a result, stable cycles were determined for the Pontian and Lower Maeotian sedimentary strata of the Black Sea Basin (Paratethys).

Early aftershocks contain important information about the physics of earthquake occurrence and postseismic relaxation processes. However, the standard catalogs of early aftershocks are usually incomplete. Many events can be missed in the main shock coda, some of which are strong enough due to the extremely high noise level. Under these conditions, the process of event identification becomes largely stochastic. Due to different network configurations and record processing methods, different agencies may register/miss different events, thus merging catalogs can improve the completeness of the aftershock sequence. When merging catalogs, the problem of identifying duplicates (records related to the same seismic event) arises. The main difficulty is discriminating aftershocks and duplicates, since both are events close in space and time. The problem is analogous to the problem of discriminating aftershocks and independent events. The solution methods are usually similar too. In this paper, we apply the nearest neighbor method modified for our problem. This method has become widespread in recent years in the problem of identifying aftershocks, and a probabilistic metric in the space of network errors in determining the epicenters and times of seismic events. It is applied for automatic identification of duplicates when merging catalogs of aftershocks for the Tohoku earthquake. An analysis of the space-time structure of duplicates and aftershocks shows their significant difference, which makes it possible to successfully solve the problem. In a sample from the global Advanced National Seismic System (ANSS) catalog (M> 4), were found more than 700 events missed by the Japan Meteorological Agency (JMA) seismic network, which is one of the best in the world. Among the misses, there are several events with M> 6 in the first hours after the main shock. Duplicate identification reliability is >97%. The method can be used to improve the completeness of aftershock sequences. The reliable identification of duplicates allows, in addition, to study the correspondence of the magnitudes determined by different agencies. Therefore the present method is an effective tool for creating merged catalogs of earthquakes with a uniform magnitude.

This paper continues the series of publications by the authors on the recognition of areas prone to the strongest, strong, and significant earthquakes using the FCAZ system-analytical method. The areas prone to earthquakes with M ≥ 5.5 in the eastern sector of the Arctic zone of the Russian Federation were recognized. It is shown that certain potential high seismicity zones are well confined to the boundaries of the Eurasian, North American, and Okhotsk tectonic plates. In addition, according to the results of the FCAZ recognition, some areas located at a sufficient distance from the main tectonic structures of the studied region were also recognized as highly seismic. The results of the study, among other factors, justify the use of the assessment of the completeness magnitude in the catalog for choosing the set of recognition objects for the FCAZ method.