Variations of Si, Na, Li, activity are considered²³⁴U and activity relationships²³⁴U/²³⁸U in thermal and cold groundwater, as well as chilled hydrotherms from active faults in the SE coastal territory of Middle Baikal. For the Maksimikhinsky polygon, the data of hydrogeochemical monitoring in 2013-2015 are presented with interpretation in terms of chemical hydrogeodynamics: temperature, depth of groundwater reservoir and opening-closing of microcracks for circulating water. When comparing the series of hydrogeochemical monitoring with the series of earthquakes K=10.5-12.7 of the Goryachinskaya seismic activation of Middle Baikal, the increased sensitivity of the responses to earthquakes of the station of cooled hydrotherms from the transition zone of the lower hydrogeodynamic stage compared to the responses of fractured cold waters of the upper stage is revealed. Maksimikha groundwater reservoir is considered as a representative reservoir located along the lateral of the South Baikal depression, in the Yambuyskaya transtensional zone. The coseismic hydrogeodynamics of the Maksimikha reservoir 2013-2015 refers to the time interval preceding the landmark Goloust earthquake in the South Baikal Depression on September 05, 2015 in the seismogeodynamic cycle 2008-2020, which corresponded to the conditions of maximum crustal compression of the Kultukha reservoir localized in the main structure of the Baikal rift system.

Results of review studies of micronutrients and activity ratios are presented²³⁴U/²³⁸U (ОА4/8) in ground and surface waters of Listvyansky, Buguldeysky and Olkhon-Priolkhon polygons of the integrated monitoring organized since 2020. At the Listvyansky test site, a wide interval of OA4/8 values from 1.67 to 2.5 was obtained in the Obruchevskoi fault zone near the B. Koty settlement, and at the Buguldeysky and Olkhon-Priolkhon test sites, an interval of OA4/8 values from 1.25 to 2.70 in the Primorsky fault zone was obtained. These values characterize the general deformation regime in large active faults in the central part of the Baikal rift zone. The water of the river. Buguldeika River water differs in trace element composition and OA4/8 values from the water of its tributary Kurtun due to the location of the basins of these rivers in the rocks of the exposed basement of the Siberian Platform and its sedimentary cover, including evaporitic carbonate deposits. Groundwater has been identified on Olkhon Island that differs in elemental composition from deep Baikal water.

Using the developed geoinformation system "Prediction" the analysis of information available from mass media about two destructive earthquakes in Turkey, which occurred on 06.02.2023, was carried out. Seismogeological conditions of preparation modes and manifestation of seismogenic ground deformations in the epicentral regions of two Turkish earthquakes, the epicenters of which occurred in the southwestern segment of the East Anatolian fault, were analyzed. The possibilities of recognizing the signs of preparation of these earthquakes by means of medium-term forecasting tools developed for the Baikal rift zone, which are important for assessments of seismic hazard and seismic risk, are discussed. Based on the analysis of the consequences of large-scale destruction of residential and industrial infrastructure in Turkey, the reasons for the huge damage to the country's economy caused by earthquakes are considered, which are largely due to unfavorable seismotectonic conditions and urbanization problems resulting from insufficient compliance with the necessary requirements and norms of earthquake-resistant construction.

This study is focused on analog modeling of the stick-slip process along an existing large fault in an elastic-viscoplastic model subjected to loading at a constant strain rate. Based on our model results and data from (Ma et al., 2012, 2014), we distinguish stable, meta-stable, and meta-instable stages of the stick-slip process (the latter includes the early and late sub-stages). Our experiments show that the fault is periodically reactivated by segmentation. We analysed this mechanism from one fault reactivation to another, and identified regressive and progressive trends of segmentation. The regressive segmentation takes place during the stable and meta-stable stages of the stick-slip process. Under regressive segmentation the number of active segments and their lengths are reduced. The progressive segmentation is initiated at the early meta-instable sub-stage of the stick-slip process. Its activity is desplayed by an increase in the number of active segments to a certain critical density, while their pattern becomes more chaotic. In the late sub-stage, number of segments decreases as they rapidly grow and join with each other to form larger active segments, up to full reactivation of the entire fault.

For comparison with the model results, we interpret rock deformation monitoring records before the Bystroe earthquake. Our analysis confirms specific features of the anomalous rock deformation that are similar to the strain features observed along the model fault during the meta-instable stage. There are evidence to suggest that meta-instability of a fault is a potential candidate to short-term precursor of earthquakes.

The results of monitoring the concentration of the thermophilic element Si in fresh subthermal and cold groundwater of the Kultuksky polygon with a temperature range at the outlet from temperature values close to 0 °С to 20 °С are given. A consecutive zonal increase of Si concentration in the groundwater reservoir of the polygon with the center at station 40 is revealed. In the groundwater of this station, a minimum temperature of 25 °C on September 17, 2014 (before the earthquakes of 2014-2015) and a maximum temperature of 60 °C on January 23, 2021 (11 days after the strongest Khubsugul earthquake, Mw=6.8) are obtained by silicon (chalcedony) geothermometer. It is assumed that groundwater flowed from the reservoir region with higher temperature during the strong Kultuk seismic activation (August 27, 2008 - January 04, 2011) and was replaced by groundwater with lower temperature during the weak Tolbazikhinskaya activation (June 24, 2011 - October 11, 2012) while reaching the temperature minimum by 2014. Then, groundwater inflow with higher temperature was again revived during preparation and implementation of the Baikal-Khubsugul seismic activation, which was marked by strong earthquakes in 2020-2022.

The results of monitoring of thermophilic trace element Li and related macrocomponents Cl and S in groundwater of st. 27 of the Kultuk polygon. The dependence of their variations on earthquakes and aftershocks of the Baikal-Khubsugul activation in 2020-2022 is established. According to Na/Li geothermometry, activity ratio ²³⁴U/²³⁸U and activity ²³⁴U are designated groundwater sources in the reservoir with temperatures up to 100 °C or more under crustal tension and sources with temperatures up to 8 °C under crustal compression. During the development of a complete seismogeodynamic cycle of crust compression and stretching, the stabilization phases, as well as the phases of increasing and decreasing groundwater temperature are deciphered.

In the summer of 2017-2018, landscape-geochemical and socio-geographical studies were carried out in the Selenga River delta (southeastern coast of Lake Baikal). The land use structure here is dominated by hayfields and pastures. The study area is important for the development of meat and dairy farming in Buryatia; cereals, legumes, cold-resistant silage crops, potatoes and other vegetables are grown here. In the delta of the Selenga River various types of soils of the alluvial department (Fluvisols), Folic Podburs, Gray Metamorphic (Gray Metamorphic) and Folic Gray soils have been formed. Fertile soils of high floodplain with chernozems (Chernozems) and dark humus soils (Phaeozems) are used for arable land. Agricultural lands of terraces with Gray and Folic Gray soils are used for pastures. Soils of low floodplain of overwatered meadows are included into agricultural turnover. It is established that soils of the most part of agricultural lands are characterized by satisfactory agronomic condition. Upper horizons of gray (Gray) soils of forests and chernozems (Chernozems) of steppes in natural state are characterized by high concentrations of humus. In permanently used soils in agriculture its content decreases, in fallow lands - it is restored. Reaction of environment (pH vodn) of soils is mainly neutral. It was found that the soils of the Selenga River delta are predominantly of light granulometric composition. It was found that gray soils quickly degrade and lose fertility when forests are cleared and used for arable land. Steppe soils show good resistance to agricultural use. Soils of fallow lands and arable lands in areas formerly occupied by forests are infertile and need nitrogen and potassium fertilizers. Soils recently brought into agricultural use need phosphorus and potassium fertilizers. Chernozems and gray soils of natural landscapes, as well as agrozems (Anthrosols) of areas formerly occupied by steppe are in good and satisfactory agronomic condition. In the vicinity of the village of. High concentrations of some heavy metals in alluvial soils exceeding MAC have been established near Kabansk village. Increased content of oil products, phosphates, fluorides and heavy metals in the Selenga River waters was detected. Coastal waters of Lake Baikal at the mouth of the Selenga River still meet sanitary and hygienic requirements. The alluvial soils of the Selenga River delta act as a geochemical barrier to the migration of pollutants into Lake Baikal.

In the western part of the South Baikal depression, the spatial and temporal distribution of earthquake epicenters is characterized by quasi-periodic seismic activations. The strongest earthquakes have occurred in 1999 (Yuzhno-Baikal, Mw = 6.0), 2008 (Kultuk, Mw = 6.3) and 2020 (Kudarinsk, Mw = 5.4). Since 2013, we have monitored the ratio of activities ²³⁴U/²³⁸U (ОА4/8) in groundwater as an indicator of fracture opening/closure promoting/preventing water circulation in active faults in a depression. Based on the monitoring results, we defined the concept of a complete seismic-geodynamic cycle as a change of crustal compression by crustal stretching, occurring within 12 years with a sequential increase in seismic hazard levels.