The article concerns the research of neotectonics and modern seismic activity of the Western Transbaikalia. The region is located on the southeastern flank of the Baikal rift system and is the western boundary of the Amur Plate, representing a transition region between the influence of the Indo-Asian collision, which determines compression deformations and extension during rifting. The purpose of the study is the geodynamic zoning of Western Transbaikalia using computer lineament analysis (LESSA technology) of a digital elevation model (DEM). This analysis made it possible to identify three regions within the study area with different structural patterns: Ust-Selenginsky, Western, and Eastern, which differ in geodynamic settings, the nature of seismicity, the history of relief development, the time and style of neotectonic deformations at  different  stages  of  rifting. The  boundaries  of  the  regions  are  marked  by  extended morpholineaments, gradient zones of density of small lineaments, and thickening of structural lines, coinciding with geological deep faults and zones of deformation localization. The most active fragments of lineaments were identified and their possible kinematics were determined. A zone of concentration of submeridional morpholineaments and supposed plastic flow has been determined, which predetermined the geodynamic history of the region and the possible position of the western paleoboundary of the Amur Plate at the early stage of passive rifting. The role of extended morpholineaments of meridional and NNW strike on the localization of strong earthquakes has been revealed. The influence of the Daurian megaarch on the distribution of extended lineaments of NNW strike is noted.

This paper presents the results of experiments to reproduce the process of stick-slip along a pre-existing stick-slip discontinuity in an elastoviscoplastic model. There are numerous examples of this process being reproduced experimentally to look for signs of the preparation of pulsed displacement along a fault, which could be interpreted as a harbinger of an impending earthquake in nature. In these experiments, rocks and other materials with high elasticity and susceptibility to brittle fracture were used as models. The results presented in this article were obtained using elastoviscoplastic models. The authors are not aware of the use of such models in the experiments described. The model materials were an aqueous paste of montmorillonite clay and wet river sand. As a result of the experiments, characteristic stages of deformation of the near fault zone were identified, one of which corresponds to slow sliding of the material with aperiodic displacement fluctuations. Digital image analysis was used to identify areas of both excess and deficient displacement along the strike of the model fault.

The goal of this study was to develop a method for analyzing signal records from a group of stations acquired during microseismic monitoring using a neural network to identify the moments of first arrivals. The novelty of the proposed method lies in the use of Wavelet Scattering for feature extraction, which significantly simplifies the model training process compared to traditionally used convolutional neural networks. The Transformer architecture used in the model allows for information exchange between an arbitrary number of recording stations, thereby determining arrival times at individual stations based on information from the entire group. The model was trained on fully synthetic data. This approach, compared to training on real data, may lead to a model with better generalization capabilities, as synthetic data reflect the mechanics of the generation and propagation of elastic waves without being influenced by local conditions and signal registration features. Several data augmentation strategies were explored, including adding noise to increase the model’s robustness to noise. The best balance between noise robustness and model accuracy was achieved by adding Gaussian noise with random standard deviation. The results of this study can be used in the development of deep learning models trained on both synthetic and real seismic records.

The paper presents a comparative analysis of the reconstructed ionospheric parameters based on the data of receiving VLF signals at the Mikhnevo and Ul’yanovka observatories during the solar flare on 07/03/2021. It is shown that the developed method for reconstructing ionospheric parameters is applicable to paths of various lengths. A further development of the technique is proposed, which could ensure the reconstruction of the ionospheric parameters on a single-frequency path from measurements at two points.

The LWPC radio-physical model is intended for calculating the propagation of VLF-LF radio waves in the earth-ionosphere waveguide channel. It is an open-access program. Thus, many ionosphere and atmosphere geophysics researchers use the program as a tool for verifying the models by comparing theoretical results with the radio-field measurements. However, it is necessary to know what accuracy LWPC provides and what the influence of various model parameters is in order to obtain correct conclusions. This information is not available in the program user’s guide, so this work makes an attempt to compensate for this shortcoming. Analysis of considered variants allowed us to draw the following conclusions. The accuracy of the model is ~0.1–0.5 dB for amplitude and 1° – 5° for phase and depends on the path (coordinates of the transmitter and receiver and frequency). The program reaches this accuracy when specifying the ionosphere with a step of 100–150 km along the path. Replacing the built-in models of the ground conductivity and the Earth’s magnetic field by actual versions does not have a significant impact on the calculation results. The fundamental difference was obtained by replacing the collision frequencies, which are based on the standard exponential altitude dependence, with values calculated according to the distribution of neutral medium parameters. In this case, the difference in amplitudes reaches several decibels, and phases – several tens of degrees.

The eruption of the Hunga-Tonga-Hunga-Hapai volcano on January 15, 2022, and associated explosive events recorded by seismic and acoustic instruments across the planet caused significant and prolonged effects in the atmosphere and ionosphere. Measurement data obtained using a record number of ground observation sites and space-based systems provided an unprecedented amount of geophysical information. Analysis of seismic and atmospheric-ionospheric disturbances allowed to determine the value of the volcanic activity index for the Hunga-Tonga-Hunga-Hapai eruption VEI = 6, which places it among the largest volcanic eruptions ever recorded. Unique or rarely observed events are the height of volcanic cloud rise to the mesosphere boundaries, record thunderstorm activity, the scale, amplitude and duration of atmospheric, stratospheric and ionospheric disturbances registered over the entire planet, the strongest infrasound signals observed in the world for the last 30 years. The synchronous registration of low- frequency variations of the geomagnetic field and the amplitude of the Shuman resonance signals made it possible to determine the propagation velocities of Lamb waves, acoustic-gravity and infrasound waves, to determine the phases of eruptions responsible for the generation of various types of atmospheric and ionospheric perturbations and the propagation velocity of the corresponding perturbing agents. At the same time, a comprehensive analysis of the dynamics and mechanisms of global geophysical perturbations caused by the eruption is impeded by the absence of a complete model of a multiphase high-energy underwater eruption, the difficulty of joint analysis of the entire set of revealed geophysical effects of the eruption with the use of existing models of the atmosphere and ionosphere. It is obvious that understanding of the whole complex of global geophysical disturbances on the planet caused by the eruption provides unique material for studying the processes of geospheres interaction, which is a combination of interdependent and actively interacting physical phenomena.

The results of three-dimensional numerical modeling of the oblique impacts of ten-kilometer water comets with velocities of 20 to 50 km/s at an angle of 45° onto a solid surface and into an ocean up to 6 km deep are presented. The maximum masses of ocean water, comet and soil matter ejected into the atmosphere, as well as the masses of water, impactor and soil matter remaining in the atmosphere 10 minutes after the impact are calculated. The mass of vaporized ejecta is determined.

This article, based on currently available materials, submits for consideration an overview of the part of the soviet nuclear testing work, in which employees of the Special Sector of the Institute of Chemical Physics of the USSR Academy of Sciences took an active part, in the direction of the development of unique measurement methods and equipment, as well as in conducting tests and obtaining results.