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The Permian-Triassic magnetostratigraphy of the central East European platform has been updated using evidence from the Zhukov Ravine, Slukino, and Okskiy Siyezd reference continental redbed sequences. The new data reveal five rather than four polarity subzones in magnetozone R₃P, which thus can be ranked up to orthozone RnP. The upper Permian strata of the Zhukov Ravine and Okskiy Siyezd sections contain intervals of anomalous paleomagnetic directions similar to those revealed earlier in roughly coeval rocks from the Nedubrovo section in the Vologda region. The anomaly may be of regional extent and may correspond to quite a long (thousands of years) span of geomagnetic field stability near the Paleozoic-Mesozoic boundary, which fits the subequatorial dipole field in the first approximation. The paleomagnetic results were used to constrain the position of three new Permian-Triassic paleomagnetic poles of the East European platform, corrected for inclination shallowing: PLat = 54.8°, PLong = 173.6°, dp / dm = 2.6°/4.0° (Zhukov Ravine); PLat = 47.6°, PLong = 164.3°, dp / dm = 3.0°/4.8° (Slukino); PLat = 52.7°, PLong = 153.6°, dp / dm = 3.7°/5.4° (Okskiy Siyezd).

Many attributes and inversion transformations solving the problem of extracting information on the elastic properties of a medium are based on the Zoeppritz equation or its approximations calculated for a boundary between two half-spaces. In a real medium, a seismic signal is in interference as a result of reflection from the top and bottom of individual thin layers or units whose elastic properties differ from those of the adjacent rocks. In such media, there is a discrepancy between experimental and theoretical dependences of the reflection coefficient amplitude developed for half-spaces. For a homogeneous thin layer, the change in the frequency response of the reflection coefficient is associated with the reflection coefficients of the layer top and bottom interfaces and the wave traveltime within the layer at the same time. A detailed analysis of the reflection coefficient amplitude of a homogeneous thin layer using the spectral decomposition technology allows us to isolate only the change in the reflection coefficients, regardless of the thickness. The proposed method for predicting the elastic properties of thin layers is based on the analytical derivation of the reflection coefficient of a homogeneous thin layer, according to which there is a parabolic relation between the squared reflection coefficient amplitude and the squared frequency. The approximation coefficient at the zero degree of the argument mainly characterizes the properties of a medium, unlike the first- and second-degree coefficients, which depend both on the properties and on the thickness of the layer. Therefore, it makes sense to use the approximation coefficient at the zero degree of the argument as an attribute of the wavefield to predict the elastic properties of thin layers in the interwell space. A good example of a relatively homogeneous thin layer is a narrow riverbed. Determining the properties of the rock filling the channel feature helps identify more sandy areas promising for further development of the field.

The methodology for building a 3D density model of the Earth’s crust and upper mantle for a crustal block in the South Kamchatka Peninsula is presented. The model is derived from the interpretation of the Bouguer anomaly values and data obtained by deep seismic soundings and electrical prospecting methods. 3D image creation can be viewed as a several phase procedure. At the first step, the area of interest is investigated through a network of intersecting profiles utilized for subsequent modeling depth density sections using the parameter scanning procedure. The a priori data include materials of geophysical surveys and geological, and petrophysical studies as well as results of depth estimation at singular points by the Euler deconvolution method. The next step involves formation of a 3D density matrix from the cross-section models. Coordinates in the cross-section planes are defined in the square grid nodes and converted to plane rectangular coordinates (the SK-42 reference system). A file of the cross-sectional database of density values is thus produced. For area shaving a sparse network of cross-sections, an additional database is derived from grid files of densities mapped horizon-wise. This ultimately results in the creation of the unified databases. A 3D network of cubic unit cells for three-dimensional (voxel) representation of density of the geologic medium is calculated. The model of density of unit cube with edge measuring 4 km was constructed for entire investigated block of the Earth’s crust. The model was detailed by decreasing successively the unit cube edges to 2.0, 1.0, and 0.5 km. The 3D modeling results are presented as block diagrams and density isosurface maps in horizontal slices at different depths. The block diagrams show isosurfaces with densities typical of deep subsurface boundaries and structures. The isosurfaces for densities of 2.75 and 2.90 g/cm³ reflect the morphology of the roof of the crystalline basement, and the lower-upper crust boundary, respectively, while the isosurfaces of 3.20 and 3.33 g/cm³ represent feasible shape of the crust-upper mantle contact. The lower-density zone ubiquitously observed in the investigated crustal block is caused by rock destruction along the deep fault. It is identified in the model with 1 km cubic unit cell side and encompasses the feeding systems of volcanoes, namely: Sopka Asacha (Asacha Volcano), Mutnovskaya Sopka (Mutnovsky Volcano), Gorelaya Sopka (Gorely Volcano), and Vilyuchinskaya Sopka (Vilyuchansky Volcano).The model with a 0.50 km cubic unit cell side shows a 2.85 g/cm³ isosurface, which delineates a column-shaped high-density region. A higher density revealed in the block is assumed to be associated with basite intrusions. 3D density models based on cross-section modeling provide additional information for geodynamic reconstructions, allowing a rough estimation of the geometry of concealed geologic features and their volumes, and can be utilized in 3D modeling to build initial models.

The flow in the far turbulent wake behind a body of revolution is studied with the use of a three-parameter turbulence model, which includes differential equations of the turbulent energy balance, transport equation for the turbulent energy dissipation rate, and turbulent shear stress equation. Local equilibrium algebraic truncation of the transport equation for the turbulent shear stress yields the known Kolmogorov-Prandtl equation. Under a certain constraint on the values of the empirical constants and for the law of time scale growth consistent with the mathematical model, this equation is a differential constraint of the model or an invariant manifold in the phase space of the corresponding dynamic system. The equivalence of the local equilibrium approximation and the condition of the zero value of the Poisson bracket for the normalized turbulent diffusion coefficient and defect of the longitudinal component of velocity is demonstrated. Results of numerical experiments are reported; they are found to be in good agreement with theoretical predictions.

New experimental data have been obtained on the Workman-Reynolds freezing potential of water and the electric current from an external source through the ice melting front. A new model of the phenomenon is proposed, which takes into account the capture of protons and hydroxide ions by interstices of the ice lattice acting as charge traps. The model provides a semi-quantitative explanation of the observed features of the phenomenon.

The prerequisites and modeling of possible outburst floods in the valley of the Bodomdara River (Tajikistan) are considered using detailed field data. According to the route survey results, Lake Bodomdara Upper is a supraglacial lake, which assumes possibility of its outburst leading to a cascade outburst flood. The depression of Lake Bodomdara Lower is relatively stable, and its outburst is possible without cascade flooding at anomalously high temperatures, upon snowmelt combined with extreme rainfall. Two probable scenarios are considered: (I) the outburst of Lake Bodomdara Lower (its volume comprised 328 000 m³ according to the bathymetric survey of 2020) and (II) the cascade outburst flood of Lake Bodomdara Upper (700 000 m³). Digital elevation model (DEM) ALOS PALSAR (12.5 m) and DEM based on images from an unmanned aerial vehicle for the Bodmodara River alluvial fan were used for predicting flood consequences. The outburst flood hydrographs for scenarios I and II were obtained using the lake outburst model developed by Yu.B. Vinogradov and an empirical formula, respectively. The material increment was estimated in the transport-shift model of mudflow formation. The resulting hydrograph was applied for zoning the Bodomdara and Shahdara river valleys with a total length of 75 km based on the FLO-2D model. According to the modeling, the maximum water discharge at the top of the alluvial cone of the Bodomdara River will reach 143 m³/s under scenario I and 348 m³/s under scenario II.

Many elements of the natural environment are areal objects that change their position and shape at all scales of variability. For sea ice, such elements can be fast ice, drifting ice, polynyas, ice massifs, boundaries of multi-year ice. In other earth sciences, these are the boundaries of glaciers, permafrost, snow cover, forest zone, various isolines of meteorological and oceanological fields (isotherms, isobars, etc.). To analyze such objects, approximations in the form of a grid area (rasterization) or a system of sections are usually used. In this article, we suggest a direct analysis of these objects based on operations with vector polygons. An efficient algorithm for calculating the probability (frequency of occurrence) of an unlimited number of polygons has been developed and tested. A criterion for selecting one of the real edges of a polygon as an analogue of the isoline of probability of intersections of polygons is proposed. The developed method has been tested using data on the fast ice of the Kara Sea taken from the digital ice charts developed by the Arctic and Antarctic Research Institute for 1998-2020. As a result, the maps of fast ice probability for the cold season of each year and for a given time of the year for the entire considered period have been obtained. Based on these data, the operational characteristics of fast ice have been estimated, and a tendency for a decrease in the area of fast ice during the considered period has been revealed. For the beginning of May (period of the maximum development of fast ice), analogues from factual observations characterizing extreme, median, and quartile probability isolines of fast ice occurrence have been found.

The results of studies of the methane content in the active layer and upper permafrost horizon in the areas of the Marre-Sale station (western Yamal Peninsula) and the Pechora River mouth are presented. Data on the methane content in Quaternary permafrost and ground ice of different geneses and data on methane emission from the surface of typical tundra in Marre-Sale are analyzed. The highest methane content in sediments of both the active layer and the upper permafrost is characteristic of boggy floodplains and waterlogged depressions on the surface of the marine terrace. In well-drained landscapes, methane is virtually absent in sediments of the active layer. In the upper permafrost, its content 5-6 times higher than in the overlying active layer. A large amount of methane (on average, about 2 mL/kg) is contained in loamy clay marine sediments at the base of the Marre-Sale section, as well as in the massive ice. The distribution of methane in permafrost and ground ice is close to a lognormal distribution. Significant methane flux (up to 10.7 mg/(m² ·h ) has been determined for highly moistened surfaces occupying about 45-50 % of the area of a typical tundra.

Conditions of the origin, existence, and melting of the superimposed ice are considered for Bellingshausen Ice Dome on Fildes Peninsula of King George (Waterloo) Island near Antarctic Peninsula. Every year, accumulation of superimposed ice on the ice dome reaches about 15 cm. In years with positive mass balance on the ice dome, the thickness of superimposed ice increases. The maximum measured thickness of perennial superimposed ice on the ice dome is equal 145-150 cm reaching 300 cm in some places. Significance of the superimposed ice in the ice mass balance of Bellingshausen Ice Dome in different years during the observation period from 2007 to 2021 is estimated. It is argued that regime field observations are necessary for finding seasonal boundary of the superimposed ice as the altitude of the equilibrium line.

Doctor of Geographical Sciences, chief researcher of the Laboratory of General Geocryology of the Melnikov Permafrost Institute, Siberian Branch of the Russian Academy of Sciences, Aleksey Aleksandrovich Galanin passed away on September 8, 2022. A well-known specialist in geomorphology, evolutionary geography, and paleogeographic reconstruction of periglacial landscapes of the northeast of Russia in Pleistocene and Holocene, Aleksey Galanin will be remembered as a talented researcher with lively mind, enthusiasm, and passion for science, a warm-hearted and wonderful person.