The article is devoted to earthquakes and seismicity, brief information about the formation and development of seismology is given. There are three stages in the formation of seismology as a science: descriptive: covering the second half of the 19th century; the development of seismology in the system of geological sciences; and the stage of development of seismology in the system of physical and mathematical sciences. Distinctive features of earthquakes from other natural disasters are given, their classification according to various criteria – according to the depth of the focus, according to the mechanism of manifestation, and so on. The connection of earthquakes with the fault-block structure of the territory is noted. The purpose of this work is to present general information about earthquakes, their types, seismicity criteria, and in assessing the current state of the problem of earthquake prediction. The main methods are comparative analysis and generalization of theoretical data and practical manifestations of earthquakes in different regions, etc. When studying the seismicity of the region, earthquake catalogs, stock materials and published scientific papers were used. On the example of the study of earthquakes in different regions, it was noted that their seismicity is mainly associated with the structural and tectonic features of the territory. Based on the study of earthquakes that occurred in different regions in the 20th century, their unpredictability and the impossibility of predicting their centers, time and strength are stated. At the same time, in the future, the forecast of earthquakes is not excluded with constant monitoring in order to identify anomalous phenomena, organize, collect, systematize, analyze and process seismic data, including earthquake precursors.

The paper presents the results of a computational experiment aimed at obtaining criteria for the selection of geological structures for the creation of a natural gas underground storage in the hydrated state in permafrost aquifers. The advantages of this method of underground gas storage are greater compactness and stability of the storage, because the gas in the hydrated state occupies a much smaller volume than in the free state at the same temperature and pressure. A mathematical model of gas injection through a single well into a horizontal aquifer is presented, which takes into account all the basic physical and thermodynamic features of the process under consideration, including gas compressibility, the Joule-Thomson effect, adiabatic expansion, non-isothermal filtration of water and gas, mass transfer between gas, water and hydrate. This model is used to estimate the dynamics of the distribution of hydrate saturation, water saturation, pressure and temperature in the aquifer at different intensity values of gas injection and filtration-capacitance properties of the reservoir. In addition to porosity and permeability, the selected reservoir (depleted gas or aquifer) is characterized by initial values of pressure, temperature and water saturation. The variable parameters are the reservoir porosity and the volume flow rate of the injected gas. The results of the calculations showed that aquifers should be chosen for the creation of underground gas storage facilities in a hydrated state, depending on their reservoir properties and hydrodynamic characteristics. In further studies, it is necessary to evaluate the thermal interaction of such storages with the surrounding rocks. To do this, the proposed mathematical model should be generalized in a twodimensional formulation. The results obtained and the mathematical model can be used to develop the scientific foundations of underground storage technology not only for natural gas, but also for associated petroleum gas, as well as greenhouse and toxic gases in a hydrate state.

The problem of forest fires is becoming more and more visible both globally and locally. Fires in Yakutia are a serious problem. Boreal forests play an important role in global warming and carbon dioxide circulation. Changes in the fire regime and climate in this region have already begun, and this has an impact on carbon dynamics on a regional and global scale. Increasingly, satellite data is being used to study fires. In recent years, so-called “Big Data” has been used in the processing of satellite data. In order to correctly assess the magnitude of the threat, it is necessary to develop an effective methodology for assessing post-fire performance. Data from the MODIS Collection 6 sensor were chosen for research because of their greater availability and sufficient spatial resolution for our work. We used data for the period from 2001 to 2019 from the FIRMS fire archive. This article presents a method for determining some of the characteristics of fires using Big Data and the Google Earth Engine platform. Algorithms created to determine the main post-fire characteristics were applied on the example of the Verkhoyansk region of Yakutia. The results are given on the example of fires in Verkhoyansky district of Yakutia in the period 2001 – 2019. For the analysis, data from the FIRMS program from the Modis and VIIRIS instruments, as well as Landsat data were used.

On the basis of a quantitative and comparative geographical analysis of the landscape structure of the Orulgan Ridge, information was obtained on the regional features of the Orulgan Ridge. The Orulgan Ridge, stretched in submeridional direction along the Lena River. Lena, occupies the most elevated northwestern part of the Verkhoyansk mountain system. The length of the ridge in the latitudinal direction is 270 km, in the longitudinal direction – up to 400 km. The set of features of the joint manifestation of the climatogenic and cryolithogenic factors is well differentiated along the main watershed of the ridge, which makes it possible to distinguish three rather contrasting slopes confined to the basins of the Lena, Omola and Yana rivers. An analysis of the results of calculating landscape-morphological indicators for the main basins of the ridge made it possible to establish differences in landscape structure and diversity. Based on the study of their landscape structure, we came to the conclusion that the differences in them are significant, which, in our opinion, corresponds to the criteria for distinguishing regional complexes at the level of physiographic subprovinces: western Prilenskaya, northeastern Priyanskaya, and eastern Priyanskaya. Based on the data obtained, similar landscape models can be developed in the future for other provinces of the mountains of Northeast Siberia.

The article discusses the results of a geological study (search and evaluation) of sapropel deposit in the subsurface area “Lake Kubalakh” (38 km of the Vilyui motorway). The identification of sapropel deposits of the lake includes a complex of various studies, such as geological and hydrogeological description of the object of study, sounding drilling, testing, topographic and geodetic and laboratory work.
Probing manual drilling was carried out from the ice in order to clarify the boundaries of the deposit, to obtain data on the properties, conditions of occurrence, and capacities of deposits. The sounding network of the lake consisted of five cross-sections with a lake area of 34.89 hectares, located in parallel through 180 meters. A picket line is laid across 40 meters. At each picket, the deposits were probed with simultaneous determination of sapropel power, water depth and the nature of the mineral bottom.
The results of the study revealed that zoogenic-algal, mixed-algal and diatom sapropel species are developed in the subsurface area. The thickness of the deposits varies from 0.3 to 2.60 m, averaging 1.66 m. The main sapropel deposit is concentrated at the northern end of the lake. Agrochemical indicators of sapropel deposits: ash content – 38.8, humidity – 80.52, organic matter – 30.85 %; total nitrogen – 0.89, potassium oxide – 0.17, calcium oxide – 4.32, phosphorus oxide – 0.16 % on ABC. The concentration of 9 trace elements-metals, including cadmium, arsenic, mercury, lead is set within the permissible concentrations. Studies on ⁴⁰K, ²²⁶Ra, ²³²Th and ¹³⁷Cs have shown the radiological safety of sapropel deposits of the lake. Bacteriological studies of sapropels have shown the absence of pathogens of salmonellosis, anthrax, anaerobic and pseudomonas microflora, pathogenic proteus, E. coli.
The estimated geological reserves of sapropels amounted to 525.8 thousand m³, the balance reserves of sapropel deposits in category C₁ – 301.2 thousand m³.

The article deals with the specifics of the regional centers of the Far Eastern Federal District. The complex and contradictory nature of its socio-economic development in the post-Soviet period is pointed out. At the same time, a clear strengthening of the process of regionalization was noted – the practice of dominance in the social and economic aspects of the regional center. The influence of the regional center goes far beyond the administrative role, forming a sharply dominant center – the regionopolis. This process is also understood as a more complex process of metropolization projected onto the regional level. The definitions and essence of the latter are noted. Based on the analysis of the shares of some statistical indicators (population, investments in fixed capital, the presence of basic backgrounds of organizations, the commissioning of residential buildings, retail trade turnover) from the collections “Regions of Russia. Main socio-economic characteristics of cities” for 2010, 2011, 2013, 2015, 2017, 2019 the conclusion is made about the strengthening of regionalization in all regions of the Far Eastern Federal District. This, in turn, is a consequence of the complex process of spatial polarization. Its strengthening was due to the increase in the factors of competitiveness of regions in market conditions. There is an obvious contradiction in the federal district – the actual formation of a mega-region (a supra-agglomeration form of urbanization) not due to the complexity of the economy, the latest technologies, the creative class, but due to the privatization and marginalization of the territory, accompanied by spatial compression. The conclusion is made about the objective nature of regionalization, the administrative impact on which is potentially dangerous due to possible incorrect management decisions. At the same time, the emerging new picture of socio-economic development creates new opportunities in the Far Eastern Federal District.