The current study aimed to identify possible prerequisites for the discovery of deep thermal waters along the southern shore of Baikal Lake between the villages of Mangutai and Solzan. The results of morphotectonic and structural mapping during the present investigation revealed that the NW-SE trending South Baikal, Utulik, and Coastal faults, particularly in their junctions with the NE-SW and NNE-SSW trending faults, are the most favorable for groundwater discharge. The infrared unmanned aerial vehicle survey carried out along the coastal strip for 37 km at night, discovered several anomalies. For this purpose, anomalies associated with green vegetation, locations where rivers enter Lake Baikal, areas where warm water flows from natural coastal water reservoirs, and anomalies generated by industrial activity were excluded. Finally, increased fracture density at m2 and m3 units, permeable faults, and the most apparent thermal anomalies indicated the most promising locations for further investigation. The anomaly close to the village of Utulik, where hot water may contain sufficient radon for therapeutic purposes, was defined as a priority. The overall results, as well as the structural and lithological similarity between the research area and other promising sites on the eastern coast of Lake Baikal, point to the presence of a geothermal reservoir at depth in the sediments of the Utulik-Solzan depression and the adjacent part of Lake Baikal. Other research are required to appraise geothermal resources and make judgments about future searches for thermal waters.

Many large deltas and other areas, underlain by unconsolidated sediments, are heavily populated but impacted by various natural deformational processes. The causes and mechanisms of the deformation are often obscure because of difficulties in the identification of their geological source. We used an unmanned aerial vehicle (UAV) to survey an area of up to several km2 to detect and map surface discontinuities with displacements of a few centimeters, which can indicate the presence of initial geological deformations. We encountered such offsets in the alluvial fans on the northwestern coast of Lake Baikal, overlying the damage zones of several faults. These deformations at the different sites are referred to as primary or secondary co-seismic ruptures, brittle creep, or cryogenic fissures, which have specific origins. They are located a few hundred meters from a principal fault plane, from junctions of faults, and in the peripheral parts of alluvial fans, making these areas potentially haz-ardous. We analyzed the digital surface models of local segments of one of the delta plains between 2020 and 2021 and established that its periphery has subsided by an average of 5-10 cm. In areas of accumulation of the river sediment, the thickness of coarse clastic deposits has increased by approximately the same amount. Locally and in the coastal zone, the vertical surface changes are larger. In the axial parts of some seismically induced gravitational failures, the subsidence reached 33 cm over a period of 11 months and 19 days. Our results show that sediments of alluvial fans are very susceptible to various tectonic and exogenous deformational processes. The interpretation of the ultra-high resolution UAV's images can help the recognition the low-amplitude brittle deformations at an early stage of their development. Therefore, such UAV surveys are critical in the discernment of neotectonic activity and its related hazards over short observation periods.

Seismogenic deformations of Cape Shartlay represent a very young fault system on the northwestern coast of Lake Baikal. Their study is providing an important opportunity to measure earthquake magnitudes, to identify areas where earthquakes are more likely to occur, and to estimate the probability of earthquake occurrence as applied to seismically active Baikal region. In this connection, the present work was aimed at characterizing in detail the structure, displacements, and reconstruction of the rupture propagation model. The study is based on photogrammetric processing and interpretation of the unmanned aerial survey data, as well as on morphostructural analysis of the displacement profiles and georadiolocation (GPR) data. It has been found that seismogenic ruptures of Cape Shartlay formed under prevailing extension conditions during no less than two earthquakes with magnitudes Mw≥7.0, Ms≥7.2. Seismic rupture propagation was primarily northward. The main rupture with displacement amplitude of more than 2 m contributed 39 to 93 % to the total surface displacement depending on the amount of dislocations on the transverse profile. It is shown that the length of a certain rupture increased almost instantaneously, then displacements along some of the ruptures stopped. A significant elongation of ruptures is primarily due to their merging. The present-day seismogenic zone is highly permeable. According to the tectonophysical model of formation of inner structure of the fault zone, the development of the seismogenic rupture system of Cape Shartlay corresponds to the late disjunctive stage. This means that the rupturing process in this segment of the North Baikal fault may not have stopped yet, and the lack of large earthquakes in the instrumental record implies the accumulation of stress in its southern part. The obtained results provide an opportunity to reconstruct the development of large fault zones by studying the displacement profiles and, therefore, to localize more precisely the places where future earthquakes may occur.

During the exercises of the search and rescue team of the Main Directorate of the Ministry of Emergency Situations of Russia for the Khabarovsk Territory, according to the international methodology for response and rescue operations INSARAG, simulation training was carried out during the sanitary evacuation of victims of emergencies with the development of practical skills in implementing SOPs and under control using checklists. During the training, using standard equipment, we used a previously tested free ECG simulator program — Six Second ECG and simple mannequins.

The geomorphic expression of active faulting and distinction of paleoseismic events in areas that are rapidly obscured by erosion/sedimentation still remains a considerable scientific problem. The present article discusses the revealing of surface faulting ruptures and their parameters to identify capable faults without trenching and to estimate the magnitude of earthquakes. The case study was at Cape Rytyi, located in Baikal-Lena Nature Reserve on the northwestern shore of Lake Baikal. Based on unmanned aerial photography, GPR, and structural observations, we mapped and investigated the relation between geomorphological forms and ruptures. The obtained results show that past landslides and paleoruptures at Cape Rytyi and its surroundings are associated with at least two earthquakes. The Mw of the earlier event was 7.3 (Ms = 7.4); the Mw of the later one was 7.1 (Ms = 7.3). The paleoruptures in the distal part of the delta of the Rita River and on the southeastern slope of the Baikal Ridge were included in the seismogenic rupture zone, which traces some 37 km along the Kocherikovsky fault. The approximate intervals in which earthquakes occurred are 12–5 ka and 4–0.3 ka, respectively. The applied analysis methods can be useful for paleoseismology and assessing seismic hazards in similar regions elsewhere.

On the example of the Rita River delta and alluvial fan of the Shartlai River located on the northwestern coast of Lake Baikal, we show the possibilities of ultra-detailed aerial photography, which allows tracing surface discontinuities with displacements from a few centimeters. The software package "Agisoft Metashape" was applied for analyzing the multi-temporal digital elevation models with the same spatial resolution of 1,67 cm/pixel to fix possible changes in the earth's surface over the year for the local area of earthquake-induced ground failures at Cape Rytyi. It has been established that most of this part has sunk by an average of 5–10 cm per year, and in the axial parts of the faults, subsidence has reached 33 cm. The greatest accumulation of sediments (up to 40 cm thick in some places) occurred on the shore, which is mainly due to the geological activity of the waves of Lake Baikal. Based on the relationship between ruptures and alluvial fans of different ages, we concluded at least two rupturing paleoearthquakes at Cape Shartlai. On the author's geoportal "ActiveTectonics", we uploaded some materials of unmanned aerial photography and geological objects in the form of orthophotomaps, digital elevation models and 360° panoramas that significantly expands the possibilities of data perception which are the basis for scientific results and conclusions.

Delta subsidence is one of the key problems of human life as these areas are developed quite fast. The process is natural and depends on many factors, the influence of which has not yet been sufficiently studied. This study is aimed to identify changes in the earth’s surface of the lakeside part of the Rita River delta on the northwestern coast of Lake Baikal, where a zone of seismically induced gravitational ruptures were recently mapped. To assess topographic changes, we used the calculation of the difference in multi-temporal digital surface models (DSM) obtained in two local areas from ultra-high resolution unmanned aerial photography in 2020 and 2021. We established that the subsidence of the lakeside part of the delta occurred on average by 5–10 cm over 11 months and 19 days. These values are associated with natural sediment compaction. In places of their accumulation, aggradation occurs by similar values, compensating the balance of deposits. In the seismically induced gravitational failures in the absence of alluvium, subsidence reached 33–37 cm, which indicates active endogenous and exogenous processes in the Kocherikovsky fault zone. The largest negative and positive vertical topographic changes up to 40 cm occurred within the beach and were associated with wave-cutting activity. The most extreme swampy part of Cape Rytyi experienced the maximum subsidence per a year. The greatest accumulation of alluvium occurred in the southern section of the Rita River delta in a settling expressed in the surface and coinciding with the zone of recent ruptures, as well as in an accumulative flow that overlaps the zone of surface deformations. With the exception of this part, discontinuities are well exhibited on DSM that means they continue to develop despite intensive sedimentation. Comparison of multi-temporal DSM and DTM by calculating the difference in elevation for each node (pixel) of the model is a promising and inexpensive method for monitoring surface deformations.

We present new data on mud volcanism accompanied by gas emissions in Lake Baikal. Rupture deformations of the bottom with traces of erupted liquefied sediments were found at depths of 105.0–163.6 m in Malaya Kosa Bay and Goryachinskaya Bay in the North Baikal depression. The deposits, outcropped in the extended scarps and mud craters, are mainly represented by highly porous clays. Scarps of boulder–pebble sediments are occasionally encountered. The areas of mud volcanism are attributed to the zone of the North Baikal fault, indicating its current activity. Clays and the soft sediments covering them are disturbed, which indicates the recent eruption of gas-saturated fluid and mud. Cone-shaped edifices about 5 × 5 cm in size with a crater in a top were found in sediments at depths of 157–162 m in Goryachinskaya Bay. Similar gas plumes were revealed in Solontsovaya Bay along straight-line faults opposite the paleoseismic dislocation of the same name. It is necessary to continue studying the revealed shallow-water manifestations of mud volcanism and rupture deformations of the bottom by integrated geological and geophysical studies.

In 2021 and 2022 unmanned aerial photography of the deltas of the Goloustnaya and Buguldeyka Rivers, located on the northwestern shore of Lake Baikal, were performed. Using the photogrammetric method implemented in the “Agisoft Metashape” software, ultra-high-resolution orthomosaics and digital surface models (DSM) were built. When deciphering the obtained materials, technogenic surface changes that are not associated with land development in recent decades were found. The involvement of historical data made it possible to identify traces of anthropogenic activity in the river deltas belonging to the Soviet-era of the country’s development. In the Goloustnaya River delta, which is now almost uninhabited over a larger area, and represents a steppe with islands of relict poplars, the locations of the houses of the Zarechny and Podkamenny uluses, which existed from pre-revolutionary times until 1958, were revealed. The boundaries of these settlements and agricultural land belonging to their inhabitants and collective farms were reconstructed. In both deltas, traces of large-scale logging works, unique photographs of which are presented for the first time in this article, were preserved on the surface. Places of accumulation of sunken forests on the shores of Lake Baikal and in some channels of the Goloustnaya River were revealed. On practice, the obtained data can be used in historical reconstructions, for example, when creating models of the arrangement of deltas in the Soviet-era for regional museums in modern villages and visitor centers of the Pribaikalsky National Park. The results may also be useful in environmental surveys combined with timber extraction in order to clean the bottom of water bodies.

The paper presents the application results of geophysical methods (micro-near-field time-domain electromagnetic sounding and ground penetrating radar profiling) performed in 2022 to determine the volume of homogeneous industrial waste in collection ponds using the example of the phenol lake within the city limits of Ulan-Ude , The Republic of Buryatia. The boundaries and volumes of industrial waste disposal were determined, and the position of the overlying and bottom beds of the phenol pound were recorded. The migration channel of hydrophilic chemical pollutants from the bed of the studied object was identified and the reservoir was installed to collect, over the years of infiltration processes, fluid saturated with hydrophilic chemical pollutants from the phenol pound. 3D models of the industrial waste deposits in the phenol lake and 3D models of the identified collector were built. It was concluded that the used set of geophysical methods was effective for solving similar engineering, environmental and geoecological problems.

We present materials of aerial photography of Cape Rytyi, a unique and most mysterious place on the northwestern shore of Lake Baikal. Photogrammetric survey was carried out using a DJI Phantom 4 Pro V2.0 UAV and provided an orthophoto and a digital terrain model of an 11.074 km(2) area. When deciphering the images obtained in the Rita River deltaic sediments composing the cape, surface ruptures trending north and northeast at 30-150 m from the shore of Lake Baikal were discovered. The ruptures are a clearly localized zone 2.9 km in total length. The performed analysis showed that the structural features of the zone obey the general laws of the development of faults resulted from prevailing extension. It has been established that the formation of the ruptures was predetermined by tectonics and is a secondary effect of resonant oscillations from the M = 5.2 earthquake of 08.13.1962, the epicenter of which was located similar to 35 km southeast of Cape Rytyi, in the Morskoi fault zone. The seismic event initiated the formation of surface ruptures, which led to a gravitational subsidence of coarse deposits of the fan in the shore zone. It is concluded that the development of modern geomorphologic forms in the peripheral part of the Rita River fan on land is similar to the formation of an underwater topography in the region of the Selenga River delta. It occurs under the influence of seismogenic rupturing and following gravitational movements, which intensify in a water-saturated environment and are subsequently complicated by erosion processes.

The first results of a thermal imaging survey of geological objects located along the coast of Lake Baikal are presented. The studies showed that the temperature of the well known Zmeinyi and Zagza thermal springs recorded on infrared images obtained using UAV at a flight of 30–70 m is 10–12.5°C lower than on the ground. In the daylight hours, the areas with green vegetation are the coldest; the rocky areas, including bedrock outcrops, are the hottest. In mid-September, the difference in the temperature between these areas reaches up to 20–21°C. Under night-time (morning before sunrise) conditions, the situation changes in the opposite direction, and the temperature difference is up to 8–9°C. Thermal anomalies of the Earth’s surface were discovered for the first time on the basis of the established patterns of the temperature distribution in the zone of the Primorskii Fault, in the area of the Sarma River. These anomalies can be associated with a deep source of heat that emanates through fractures, as evidenced by the comparison of the optical imaging of the granite outcrop with its heat map. The results obtained offer a challenge for the development of technology to search for endogenous heat sources in fault zones on the basis of the thermal imaging carried out by unmanned aerial vehicles.

In here, we present the results of the GPR study of the modern rupture zone discovered earlier in the periphery of the Rita River delta flowing into Lake Baikal. The research was aimed at subsurface imaging of dislocation geometry using the Logis-Geotech OKO-2 radar equipped with the ABDL Triton antenna. As a result, the characterizations have been obtained for six 73 to 197 m long profiles across the rupture zone. All disturbances visible on the aerial photography materials are highlighted on the radargrams by the oblique reflection event due to a decrease in the signal amplitude. The rupture zone has two large segments – northeastern and submeridional, – which differ in zone width, number of discontinuities, dip angles, and displacement amounts. The deformation features can be attributed to different amounts of a plastic loamy aggregate of coarse deposits in different parts of the Rita River delta that is indirectly confirmed by weaker signal amplitudes on the northeastern segment. Based on present and previous studies, we proposed that the M=5.2 earthquake occurred on August 13, 1962, in Lake Baikal initiated the gravitational sinking in the Rita river delta edge by subsidence along gently sloped rupture surfaces on one segment and along steeply sloped ones on the other. It is necessary to identify and monitor such phenomena to prevent the development of emergencies associated with the collapse of the coasts of large water reservoirs.

In connection with a series of sensible earthquakes in the Baikal-Mongolian region at the end of 2020 – beginning of 2021, the population of the area has increased interest in the zones of possible earthquake sources and their seismic potential. In this regard, we carried out a detailed mapping of paleoseismogenic deformations within one of the most mysterious places on Lake Baikal – Cape Rytyi and its vicinity crossed by the zone of the Kocherikovsky active fault. Along the ruptures in the rear part of the Rita river delta, based on displacement measurements of the original surfaces on the hypsometric profiles, the vertical displacements are reconstructed and compared with ground penetrating radar data. It has been established that the deformations in the studied area are associated with at least two paleoearthquakes. The maximum movement at the first one was 7,9 m, at the second one – 5,0 m. The magnitude estimates calculated from the known equations using these displacements were: MW of the earlier event 7,3, MS = 7,4; MW of the later event is 7,1, MS = 7,3. It is noted that the preservation of seismogenic scarps, their dip angles and the degree of burial strongly depend on the initial landscape and can differ even within a few hundred meters for a single rupture. This fact must be taken into account when conducting paleoearthquake studies and determining the rupture parameters.

A 48 km long zone of surface deformation produced by the Ms = 7.3 intracontinental earthquake of 2003 in Gorny Altai is studied in its five segments between the Aktru and Irbistu rivers, where ruptures show the greatest offsets and distinct structural patterns. A total of 554 coseismic ruptures of five slip geometry types are analyzed in terms of length, orientation, and relative percentage. The rupture patterns are discussed with reference to previously published evidence and compared with other strike-slip zones worldwide.

The results of a high-resolution aerial survey at selected areas in the Zunduk fault damage zone trending northeast along the coastline of the Maloe sea of Lake Baikal from Cape Yadyrtuj are presented. The research was carried out within the framework of the problem of studying the seismotectonics of the shores of Lake Baikal to map the youngest surface ruptures. Based on the images obtained using DJI «Phantom 4 Pro V 2.0» unmanned aerial systems (UAS), we generated orthomosaics and digital terrain models, interpretation of which allowed us to reveal recent ruptures in alluvial fans. The largest number of them is concentrated on the Oto-Khushun Cape, where the development of disturbances as feathering structures occurs at the intersection of the Zunduk fault trending NE–SW and a proposed fault trending NNW–SSE in the water area of Lake Baikal. It explains the block structure of the rupture network in the southwestern part of the cape. Ground penetrating radar profiling showed that the surface ruptures penetrate to a depth of at least several meters. Since the last rupturing earthquake in the Zunduk fault zone is supposed to have occurred 12000–14000 years ago, the ruptures mapped in recent sediments are the result of creep events. The mechanism of their formation is associated with the periodic effect of weak seismic loads on the granular medium, as a result of which micro-slip and subsequent growth of ruptures occur. Taking into account the high rates of erosion and sedimentation within the mountain alluvial fan, as well as the persistence of disturbances in recent sediments, it can be assumed that this process is relatively constant. Identification of such brittle deformations and monitoring of their development in river deltas and outflow cones of watercourses will make it possible to predict possible places of the collapse of the coastal areas of Lake Baikal during moderate and strong earthquakes, as well as to study the dynamics of coastal development – an important component of the abiotic part of the lake ecosystem

ABSTRACT Palaeoseismology studies the footprints of ancient earthquakes to improve the knowledge about the modern seismicity of the territory. A ground‐penetrating radar (GPR), among other geophysical methods, is used for quick determination of shallow stratigraphy – displaced, oblique layers within the fault zone. GPR data interpretation from diverse and complex reflection patterns of the fault zone heavily depends on the interpreter's experience. The range of different fault zone parameters in which this method can be successfully applied has not yet been investigated. We used a numerical simulation of GPR data to determine how GPR images the elements of faults (fault plane, hanging wall, footwall) in comparison with other reflections. Furthermore, we studied which parameters have the most significant impact on GPR wave patterns. We performed a series of numerical models of a fault, changing its geometry with increasing complexity from elementary models to realistic ones. The resulting synthetic profiles allowed finding specific GPR signatures from the fault plane, the hanging wall and the footwall. We collected field GPR data from two different fault zones and examined them for verification.

The article considers the results of GPR studies of the Zunduksky fault section activated between the Cape Oto-Khushun and the Zunduk River, activated in the late Quaternary. The aim of this work is to clarify the kinematic type, determine the vertical displacement amplitudes, and dip angles of the Zunduksky active fault activated in the late Quaternary, as well as determine the maximum magnitude of the earthquake that could occur as a result of the activation of the fault. The work was carried out by OKO-2 GPR with a shielded antenna AB-90 and ABDL-Triton. In addition to the main method, morphostructural analysis of the ledge was used. As a result of the work performed, it was found that the Zunduksky fault in the Late Quaternary was activated under tectonic extension with predominant fault displacement kinematics. The one-act vertical displacements along the seismic fracture change from SW to NE from 6.9 to 1.6 m. When the Late Quaternary ledge of the Zunduksky fault formed, the plastic component of the displacement had a certain value, the contribution of which is from 18 to 78 % of the total displacement. Paleo-earthquake magnitudes calculated from the maximum vertical displacement are Mw = 7.3 and Ms = 7.5.