In this study, the authors used complex seismotectonic, geological and geophysical methods when carrying out scientific research, identifying unfavourable engineering geological conditions for the designed mining facility located in the cryolithozone, as well as when determining the level of basic seismic hazard and performing seismic microzonation. The seismotectonic methods consisted in establishing the relationship between the distribution of local earthquake epicentres and active geological structures. The geophysical studies employing the methods of near-surface seismic tomography and electrical resistivity tomography allowed obtaining of detailed and reliable information on the features of the engineering geological structure of the studied site required to assess the influence of soils on the seismic wave attenuation of possible earthquakes in the region, thus solving the issue of seismic microzonation. Seismotectonic studies consisted in determining the level of basic seismic hazard and were based mainly on previous field studies summarised in a number of published works, some of whose conclusions were used in this article. The analysis of geophysical data allowed the authors to establish probable location of the distributions of ice and ice-rich permafrost, as well as the heterogeneity of soil conditions that affect their behaviour under dynamic loads. The calculated values of probable earthquake intensities allowed the authors to determine the level of maximum earthquake intensity at the designed industrial sites of the mining and refining facility.

Magnetic exploration is the most informational and economical method of prospecting and exploration of iron-ore deposits. In rough-terrain and remote areas without any infrastructure, problems associated with ground-based methods can be avoided by using modern unmanned technologies that allow conducting geophysical surveys in a more efficient way. An unmanned aeromagnetic survey complex (aerial vehicle, UAV) Geoscan 401 was used to assess the possibility of using UAVs for aeromagnetic surveying of iron-ore deposits. Our experimental study was conducted in the well-studied area of the largest iron-ore deposit of South Yakutia. The UAV capacities were confirmed by comparing the aeromagnetic survey data with the available data obtained by ground magnetic exploration of the study area. By analysing magnetic fields, we established that the anomalies detected by the ground and aeromagnetic surveys were fully identical. Furthermore, a weak anomaly was discovered in the northeastern part of the study area (it was not reflected in the magnetic field from the ground survey data). Recalculation of the vertical gradient of the magnetic field shows that the anomaly is caused by a blind ore body. Its upper edge is located at a depth of 200–250 m from the day surface. In calculations for a data array without gradient intervals, a mean square error (MSE) amounts to 1.01 nT. An absolute error in the heights of the working and control flights did not exceed 1.5 m. Both the preliminary and control measurements were performed very efficiently. Profiles for UAV surveys were spaced by 100 m. A 1.0 km2 site was covered by one flight within approximately 20 minutes. The Geoskan-401 UAV is useful for obtaining orthophotos, topographic maps and 3D models of the surveyed territory as required for further studies consistent with the magnetic surveys. The aeromagnetic surveys were followed by trenching to verify the newly discovered anomalies. Based on the results of this experimental study, the forecast resources of the Sutam deposit should be increased by almost 250–350 million tons, i.e. plus 15 % to the previously explored and approved reserves of the Sutam field.

The results of the interpretation of seismological, geologic–structural, seismotectonic and macroseismic data obtained for the focal zone of the strong Ulakhan-Chistay earthquake (Ms=5.7), which occurred January 20, 2013 in the Chersky seismotectonic zone , on the Eurasia-North America lithospheric plates boundary, are presented. The shock occurred in the zone of a large Ulakhan fault, which is visible in satellite images and can be seen in the topography between the Indigirka and Kolyma Rivers at a distance of 1,500 km. Statistics of seismic observations in the last century and at the beginning of this century show that in the zone of influence of the Ulakhan fault within the crust (~ 35 km thick) at a depth of 7-30 km, more than 14 thousand local events were noted. The epicentral intensity of more than ten of them reached 6–8 on the Russian scale (MSK-64). In addition to high seismicity, additional geodynamic indicators of the reactivation of the Ulakhan fault in modern time were identified, in particular, high heat flux, icing processes, paleo-and modern seismic dislocations, etc.The macro effects of this event on an area of 300 thousand square kilometers were studied in three Arctic regions of Yakutia and in the south of the Magadan region and its epicenter is located by the proximity to the well-preserved paleoseismodislocation Uryun – Takh – Takh, which arose more than a thousand years ago and is clearly visible in the search sistem of Google. As a result, a structural-dynamic model of the Ulakhan fault zone is proposed, explaining the occurrence of the Ulakhan – Chistay earthquake on the basis of the kinematic scheme of the Omulevsky block, which is undergoing extrusion by a collision between the Eurasian and North American lithospheric plates in Northeast Asia.

––The first comprehensive seismotectonic study was performed in the Olenek and Vilyui areas of the Yakutian kimberlite province, which was aimed at elucidating the geodynamic activity of neotectonic structures of the Siberian craton and assessing the environmental hazard of groups of kimberlite fields. Based on the degree of activity and trend of geodynamic processes, we have developed regional principles for the classification of neotectonic structures of the Siberian craton and its fold-thrust framing with the rationale for their differentiation into classes. The active segments of the Verkhoyansk and Baikal–Patom fold–thrust belts are analyzed, which have a dynamic effect on the mode of tectonic deformations of the adjacent sections of the Siberian Platform, where groups of kimberlite fields are localized. The revealed patterns of seismotectonic destruction processes made it possible to establish the intensity and types of the Earth’s crust stresses and strains in the reactivation zones of the marginal sutures of the Siberian craton. Applying mathematical statistics methods permitted a quantitative analysis of the geodynamic parameters of the geologic environment in the Olenek and Vilyui areas of the Yakutian kimberlite province, based on the significant factors responsible for activation of the recent structures as manifestations of a single stress accumulation/discharge process in the Earth’s crust. Using the set of seismotectonic data, we have differentiated the activation zones according to the stress–strain intensity in the Earth’s crust and have assessed the potential environmental hazard of groups of kimberlite fields in the Yakutian diamondiferous province.

Quantitative estimates of present-day lateral ground surface displacement rates in southern Yakutia were obtained during recent years by setting up the first (and the only so far) stations of continuous GPS observation at the town of Neryungri (NRG) and at the town of Chul’man (CHL3). Both stations are in the southern margin of the Eurasian plate, near the system of active structures that separate it from the Amur plate. For an estimate of relative displacement we chose a period of joint operation at these two GPS stations, viz., from June 29, 2015 to December 1, 2016. The rate of displacement at Neryungri as calculated for a 5-year term (between October 27, 2011 and October 1, 2016) was 21.83 ± 0.73 mm/yr in the east–west direction and 12.26 ± 0.25 mm/yr in the north–south direction based on the ITRF2014 frame. The resulting values are little different from the theoretical rates of motion for the Eurasian plate at this point. The difference between measured rates and those for the well-known kinematic model for the Eurasian plate as developed in this study is |0.5| mm/yr for the east component and |1.0| mm/yr for the north component; these values are in agreement with results of other authors (Kreemer et al., 2014; Ashurkov et al., 2016). The accuracy of determination for the rates of lateral ground motion at CHL3 should enhanced by making measurements synchronously with the NRG2 station.

This paper presents seismogeodynamic analysis of modern structures located in the Lena river delta. These structures are key elements in the tectonic evolution of the shelf–continent transition zone in the Arctic segment of the boundary between the Eurasian and North American lithospheric plates. The geological structure of the Lena river delta is predetermined by the junction of the ancient Siberian platform and the Mesozoic Laptev Sea plate. These two large geoblocks of the crust, which differ in age, are separated by a fragment of the Kharaulakh segment of the Verkhoyansk fold system. In our study aimed to reveal regularities in seismotectonic destruction of the crust, we analyzed the geological and geophysical data on the crustal structure, active faults, modern structural plan, dynamic characteristics of the modern relief, and hydrological features characterizing of the flow redistribution in the Lena riverbed. A system of active faults identified in the Lena river delta shows a contrasting kinematic plan of the junction zone of the main geostructures. According to the analysis results, shear faulting is a dominant factor of impact on the morphologic features and seismogeodynamic activation of the modern structures. A regional right-lateral strike-slip fault of the sublatitudinal strike is traced as a major structural boundary that cuts the Lena river delta into several geodynamic segments. Seismotectonic destruction of the crust in the segments differs in types (transpression, transtension and compression). The above-mentioned fault is not only the main element of the kinematic plan of the newest structures in the Lena river delta – it controls the general structural pattern and seismotectonic parameters of active fault zones in the entire northern sector of the Verkhoyansk marginal suture. The seismogeodynamic analysis results obtained in our study provide a reliable basis for estimating potential seismic hazard of the modern structures in the Lena river delta and updating the available seismic zoning maps of the shelf–continent transition zone in the Arctic segment of the boundary between the Eurasian and North American lithospheric plates.

The article presents the results of the first integrated geological and geophysical studies of the Sarma paleoseismic dislocation (PSD). Based on interpretation of sections of trench walls, analysis of shallow geophysics data (electric survey, seismic survey, ground-penetrating radar), and morphological profiling of microforms of the seismogenic relief, a conclusion has been reached on transpressional deformations. The displacement planes of the main reverse faults and thrusts dip to the northwest; minor ones, to the southeast. The kinematic characteristics of seismic movements indicate the formation of dislocations in the Primorsky fault zone under subhorizontal compression conditions.

Our comprehensive study of the Russian Arctic region aims to clarify the features and types of seismotectonic deformation of the crust in the Arctic–Asian Seismic Belt, specifically in the zones of strong earthquakes in the Laptev Sea Segment, the Kharaulakh Segment, and the Chersky Seismotectonic Zone. We have analyzed modern tectonic structures and active fault systems, as well as tectonic stress fields reconstructed by tectonophysical analysis of the Late Cenozoic faults and folds. The investigated neotectonic structures are ranked with respect to the regional classification principles. Changes in the crustal stress–strain state in the lithospheric plate boundaries between the Eurasian, North American, and Okhotsk Sea Plates are analyzed, and regularities of such changes are discovered. A set of models has been constructed for the studied segments of plate boundaries with account of the dynamics of the regional geological structures. The models can give a framework for the assessment of potential seismic risks of seismogenerating structures in the Russian Arctic region.

—The paper presents results of a seismogeological study based on analysis of seismic data and historical facts about the seismic activity of the Khambinskii fault zone. According to the data obtained, a genetic type of dislocations on conjugate faults (Gusinoe Ozero and Orongoi paleoseismogenic structures) is related to reverse faults with a strike-slip component. Geophysical studies of the Gusinoe Ozero structure have determined the dip of the fault plane toward the mountain framing of the depression and its outcrop at the bottom of the seismic scarp. The significant seismic potential of the Khambinskii fault is responsible for the maximum intensity of shocks in the nearby cities and settlements of southeastern Transbaikalia. The seismic fault activity has been confirmed by the historical earthquakes of 1856 and 1885, the M = 5 earthquake that occurred on 2 October 1980, and at least two prehistoric earthquakes. The latest of the latter occurred no earlier than ~4 ka and had M = 7.0–7.3, while the earliest was even more intense and took place in the first half of the Holocene, no later than ~6 ka.

For a quantitative assessment of the current horizontal velocity of the surface displacement of the crust in southern Yakutia in recent years, was organized the first and only points of permanent GPS observations in the city of Neryungri (NRG) and the city of Chulman (CHL3). Both points of observation are located within the southern margin of the Eurasian plate, near the system of active structures separating it from the Amur plate. To estimate the relative displacement, the period of joint operation of these two GPS points was chosen, namely from June 29, 2015 to December 1, 2016. The rate of displacement of the point in Neryungri, calculated for a 5-year period (from 27.10.2011 to 01.10.2016), was 21.83±0.73 mm/year in the East-West direction and 12.26±0.25 mm/year in the North-South direction in the international reference basis ITRF2014. The obtained values differ slightly from the theoretical values of the velocity of the Eurasian lithospheric plate at the specified point. The difference of the measured velocities with velocities according to the known kinematic model of the Eurasian plate obtained in this paper is |0.5| mm/year for the Eastern component and |1.0| mm/year for the Northern one and corresponds to the assessment of other authors [Kreemer et al., 2014]. To improve the accuracy of determining the speed of horizontal displacements of the earth's crust at the station CHL3, it is necessary to continue measurements synchronous with the station NRG2.

Для количественной оценки современных горизонтальных скоростей смещения поверхности земной коры в Южной Якутии в последние годы были организованы первые и пока единственные пункты постоянных GPS наблюдений в г. Нерюнгри (NRG) и в г. Чульман (CHL3). Оба пункта наблюдений располагаются в пределах южной окраины Евразийской плиты, вблизи системы активных структур, отделяющих ее от Амурской плиты. Для оценки относительного смещения был выбран период совместной работы этих двух GPS пунктов, а именно с 29 июня 2015 по 1 декабря 2016 гг. Скорость смещения пункта в г. Нерюнгри, рассчитанная за 5-летний период (с 27.10.2011 г. по 01.10.2016 г.), составила 21.83±0.73 мм/год в направлении восток–запад и 12.26±0.25 мм/год в направлении север–юг в международной отсчетной основе ITRF2014. Полученные значения незначительно отличаются от теоретических значений скорости движения Евразийской литосферной плиты в указанной точке. Разность измеренных скоростей со скоростями согласно известной кинематической модели Евразийской плиты, полученной в данной работе, составляет |0.5| мм/год для восточной компоненты и |1.0| мм/год – для северной и соответствует оценке других авторов [Kreemer et al., 2014]. Для повышения точности определения скорости горизонтальных смещений земной коры на станции СHL3 необходимо продолжить синхронные со станцией NRG2 измерения.

Research objective - determination of the quantitative indicators of seismic wave attenuation on the area of geotechnical landscapes with contrasting properties and the forecast of the seismic intensity impact within the area of study of the linear engineering structure in conditions of permafrost zone. During the research tasks were performed: study of the geotechnical structure of the area, registration of the microseismic disturbance, acceleration graph of the industrial explosions and powerful man-caused sources of the seismic waves. Main hypothesis of the study - contrast saving of the seismic properties of for-mation from geotechnical landscapes of rooted slopes and above floodplain river terrac-es in conditions of the permafrost zone. During the research complex of geophysical and seismological researches was performed, drawing of the geotechnical section confirmed by the drilling data. Results of the study confirmed main hypothesis - major difference of seismic properties of frost soils foundations for joint landscapes has been established.

In order to obtain some clarity in the matter of assessing the seismic effects from industrial explosions of the state rock massif. Variations of the electrical properties of rock mass before and after explosions were studied by electro tomography. The monitoring studies on the experimental profile selected across the strike one of the regional faults that cut across the career field of the Neryungri was conducted. Observations were made before the explosion, immediately after the explosion, and subsequent observations at intervals of one hour. The electrical resistance increases in the rock mass of tectonic disturbance on the geological structure, which located on the side of the explosion. The electrical resistance decreases in the fault zone, some changes in the electrical resistance of the hanging geological structure. It has been found that the spatial orientation of the fracturing of the rock mass affects the pattern of change in the geoelectric properties of the rock mass. The electrical properties changes in the rock mass from the location of the explosion block in concern to the direction of fracture of the rock mass. In the case when the front of the blast wave propagates along the strike of fractures, the fractures open and the intensity of moisture migration increases significantly, which involve a significant decrease in electrical resistance not only in the zone of tectonic disturbance but also in the underlying geological structure. When the wave front propagates perpendicularly to the stretch of rock mass fractures, cracks also close and moisture migration along the cracks caused by changes in the stress-strain state of the rock mass, is not significant, which is reflected in a slight change in the geoelectric properties of the rock mass in the section of the profile under study.

The studied region is located at the junction between the Pacific and Central Asian seismoactive belts. Macroseismic data on earthquakes of this region are available for the last 150 years, while instrumental seismological observations began in the mid-20th century; however, the recurrence interval of strong earthquakes can be up to several centuries and even thousands of years. In this respect, many areas of the Amur region had been believed to be nearly aseismic until earthquakes occurred there. Paleoseismogeological studies of recent years have allowed the character of Holocene displacements to be estimated for some of the main regional structures. As a result, the main tendencies of the Late Quaternary geological evolution of the region remain uncertain and the potential seismogenerating structures are not completely known. Therefore the problem of revealing new zones and periods of seismic activity is topical for the entire Amur region. The importance of this problem is related to the weak degree of study of the region by contemporary methods of active tectonics, the intensive development of engineering infrastructure, which is vulnerable to seismic impacts, and the necessity of long-term seismic forecasting. The present work provides the results of paleoseismogeological studies of the active faults in the Amur region. On the basis of new data on the magnitude potential of seismogenerating structures based on the magnitudes of historical earthquakes and instrumentally recorded ones, we have estimated the seismic effects from strong deep-focus earthquakes and the attenuation coefficients and calculated radii of the first three isoseismals for crustal earthquakes. By using the methods of statistical modeling, we distinguish the periods when seismic effects increased from earthquakes with 2 ≤ M ≤ 6. It is shown that seismic hazard assessment should take into account the dynamics of the seismic regime, caused by the change of the earthquake source depth. It is found that the epicenters of earthquakes with 5 ≤ M ≤ 6 form non-crossing seismic zones in different phases of changes in the Earth’s annual rotation.