The problem of cyclic shear of granular material sample in the framework of discrete element method (DEM) was considered. The realization of the shear closed to homogeneous one allows calculating the components of the stress tensor of representative medium volume depending on given microproperties of the discrete particles and on the interaction conditions between them. It was shown that the coaxiality condition of the stress and strain tensors under the shear of macrovolume is satisfied. The dilatancy curve was plotted. An analysis of the stress state and the behavior of the dilatancy shows that an increasing of loading cycle number leads to the stabilization of deformation process in which the stationary deformation regime occurs. The correlation between the obtained numerical solutions and the data of laboratory experiments carried out earlier was found.

The paper presents the results of a complex investigation on an exhumed section of a tectonic fault being a part of the Buguldeisky disjunctive node of the Baykal Rift Zone. The chemical composition of 81 samples taken at the day surface was determined, and their petrographic description was performed. Applying the hierarchical clustering algorithm in the analysis of chemical composition of the samples made it possible to distinguish three groups that characterize fault walls, composed of amphibolite and granite. Also the core of the fault was detected, which is characterized by an insertion of a ferruginous- carbonate material. The petrographic description of the samples confirms the correctness of identifying three groups and allows, additionally, to reveal the dynamometamorphic transformations of minerals localized in the fault core which were produced by high-amplitude seismogenic slips. In the fault core, the rock was subjected to strongest cataclastic deformations with a local frictional heating up to 1000° C. A geoelectric section was constructed across the strike of the fault based on the electrical tomographic measurements. A conductive zone 20 m wide is distinguished in the geoelectric section, which is spatially consistent with the zone of the fault core. Based on a comprehensive study of the exhumed segment, the elements of its occurrence were determined (strike azimuth is 70°, dip angle is 60°), which indicates that the exhumed segment belongs to the Morsky fault.

Current studies of solar-terrestrial relationships and the possible impact of space weather on seismic activity are based on statistical analysis without detailed consideration of possible physical mechanisms that results in unclear or contradictory conclusions. It is proposed to consider the hypothesis of electromagnetic triggering of earthquakes by a sharp burst of telluric currents in the lithosphere, including seismogenic crust faults, due to interaction of X-ray radiation of a solar flare with the «ionosphere- atmosphere-lithosphere» system. This hypothesis is based on the field and laboratory experiments carried out in Russia over the past forty years that convincingly demonstrated a possibility of triggering of earthquakes by injection of electric current into the crust faults. A mathematical model and a computer code for numerical estimates of telluric currents generated by solar flare radiation are presented. The numerical estimates performed show that solar flares can generate telluric currents in the conducting layers of the Earth's crust with a density comparable to the densities of currents generated in the crust by artificial pulsed power sources capable to trigger earthquakes. Consequently, the triggering of seismic events is possible not only by artificial sources of electric current, but also by ionospheric disturbances caused by strong solar flares. This model can be used to assess the seismic hazard during the period of strong variations in space weather parameters, in particular, pulsed changes in the geomagnetic field caused by strong solar flares of X-class.

The modes in the modified Lorentz dynamic system, which describe the distribution of the speed and temperature of convective rolls with thermophysical parameters of the neutral gas of the ionosphere F region under an external harmonic effect on the neutral gas temperature are investigated. The neutral gas model is built in the approximation the thermophysical parameters constant in a convective cell. The external influence on the dynamic system is carried out by changing the parameters of the horizontal and vertical temperature distribution of the convective rolls.

The results of calculations of deformation, fragmentation and deceleration of asteroids 1.5–5 km in size in the atmosphere of Venus are presented. The fraction of energy lost by asteroids during their passage through the atmosphere and the effective dimensions of an asteroid (or a cloud of its fragments) at the moment of impact on a solid surface are determined. It is shown that asteroids 1–2 km in size reach the surface of Venus in the form of a cloud of fragments with a diameter of 5–20 km, the kinetic energy of which is 10– 1000 times less than the initial energy of the asteroid. Such impacts do not appear to result in the formation of classical single craters or crater fields, but may be responsible for the formation of dark and bright spots (splotches) observed on the surface of Venus.

The data of instrumental observations performed at the Center for Geophysical Monitoring of Moscow, IDG RAS during the explosive eruption of the Hunga-Tonga-Hunga-Haapai volcano on January 15, 2022, are presented. It is shown that the volcanic explosion caused a series of wave disturbances in the atmosphere. Acoustic-gravity waves were recorded as Lamb waves with a source at the epicenter of the explosion. It is shown that the periods of acoustic-gravity waves passage were accompanied by synchronous disturbances not only of the electric field strength, but also of the concentration of microparticles. The characteristic frequencies of these perturbations closely match to the frequency range including the Brunt–Väisälä frequency.

The use of well bundles of converged charges makes it easier and more accurate to achieve the effect of directional blasting than the traditional method of directional blasting, since almost any charge configuration is possible to realize. The paper considers the simulation of blasting action based on the numerical gridless Lagrangian method, which is called the method of smoothed hydrodynamic particles.