The analysis of geological information indicates the presence in the fault zone of segments radically different in structure, material composition and, as a result, frictional characteristics. In this work, on the basis of numerical calculations, we consider the role of regions with different properties during the development of a dynamic fault initiated in the area of a heterogeneous tectonic fault. It is shown that the characteristic size of frictional inhomogeneities on the slip plane and the density of their arrangement largely determine the features of the fracture propagation, including such poorly studied stages as its start and stop. The initiation of a rupture of a local area can be caused by various reasons – a change in pore pressure, the impact of seismic vibrations from remote events, and intergeospheric interactions. After initiation on one of the «locked» segments, a dynamic fracture can propagate even at a relatively small level of shear stresses compared to the peak contact strength. The condition for this is the presence on the fault plane of other contact regions with properties of frictional weakening. In this case, it turns out to be necessary to ensure the conditions of initiation only in a local area, and then the dynamic shear can be maintained by a stress wave radiated from the surface of a propagating discontinuity.

The behavior of complex dynamical systems is highly variable. This fully applies to seismicity and to the manifestation of earthquake precursors. Even in those cases where there are grounds for assuming the presence of precursor effects, they are often extremely difficult to distinguish against the strong background variability of the corresponding systems. Asimple method for detecting of the desired systematic component in the behavior of dynamical systems is suggested and implemented. Examples of seismoionospheric effects are considered using data from the Kokubunji ground-based vertical sounding station (Tokyo, Japan) and the seismicity regime in the vicinity of strong (M7.0+) earthquakes in Kamchatka. It can be assumed that the proposed approach can be effective in many other cases.

The estimates of the Q-factor parameter based on the registration of the amplitudes of P- and S- waves along the profile of the «Mikhailovsky» quarry – «Mikhnevo» SAA from two quarry blasts were obtained. The registration was carried out by three-component sensors, which made it possible to estimate the Q values by three components. Two methods were used – the estimation of the amplitude attenuation coefficient and the ratio of the amplitudes of the spectral components depending on the distance. These two approaches were widely used earlier for the interpretation of the deep seismic sounding (DSS) data. As a result, the average values of the Q-factor parameter were obtained by two methods – Q for P-waves is about 376 and for S-waves: Q = 1068 and Q = 897

Strong induced earthquakes remain one of the most sensitive information issues for society, causing people’s concern. In addition, the study of induced earthquakes provides chances to identify cause-and- effect relationships in the process of preparation and origin of the seismic event, to establish parameters that can be used to control the ongoing processes. The article summarizes the results of recent years working on the occurrence of strong induced earthquakes in the mining areas in the conditions for initiating dynamic slip-type events (type II) are described. Changes in Coulomb stresses on the fault plane are analyzed, as well as various factors that can cause such changes. It is shown that if the Coulomb stress changes reach several tenths of MPa on the fault plane of a significant size, significantly exceeding the area of the earthquake nucleation zone, then even a small value of one percent of the natural stress level may be sufficient to initiate seismogenerating movements along the stressed fault. Calculations performed for large quarries occupying about 20 km2 (like the Bachatsky quarry in Kuzbass) have demonstrated that the extraction and movement of rock masses in such an area can bring closer the moment of occurrence of an earthquake with a magnitude of M ~ 6, already prepared by the natural evolution of the mountain massif. At the same time, the formation of large rock dumps during the development of such large quarries does not contribute to the initiation of large seismic events. An extensive network of underground workings in the vicinity of a tectonic fault has a noticeable effect on the effective rigidity of the massif and on the possibility of fault slip. However, the practice of laying chambers with destroyed rock significantly reduces the likelihood of such a negative scenario. The issue of discrimination of natural and man-made events is also considered, since it is important not only for public opinion, but also for the separation of the area of responsibility of state structures and insurance companies, on the one hand, and companies exploiting the subsoil, on the other. The identified types and parameters of anthropogenic impacts will help to reasonably determine restrictions on certain types of work, which, in turn, will reduce the likelihood of catastrophic earthquakes in mining areas. In addition, the potential of induced earthquakes should be taken into account when assessing seismic hazards, especially in areas where responsible energy and engineering facilities are located.

A numerical model for calculating explosive detonation in boreholes is described. The model provides for the possibility of converting ejecta from the explosion crater into discrete particles (dust and stones) and calculating the motion of these condensed particles and their interaction with the gas flow within the framework of the equations of motion of multiphase media. The results of the calculation of 1000 kg TNT explosions in several boreholes 15 m deep are presented. These calculations demonstrate the formation and evolution of a gas and dust cloud, the change in the mass of particles of different sizes in the air with time, and their spatial distribution. A numerical analysis of the behavior of a gas and dust cloud in the wind field after completion of its rise was carried out, and the first approximation of dependence of the surface concentration of fine particles on time was obtained at distances up to several kilometers from the quarry wall. According to the calculations, the excess of the maximum permissible concentration of suspended particles in the atmosphere at downwind distances exceeding 500 m from the pit will not be achieved under the conditions of the considered problem

The paper aims to analyze and compare the effects and mechanisms of influence on the D and E regions of the ionosphere of the Sun’s X-ray radiation and charged particle precipitations. The work investigates mid- latitude effects, which have not received sufficient coverage in the scientific literature. We analyze changes in the parameters of radio signals received at the IDG RAS Mikhnevo Observatory from European VLF transmitters for a series of events in September 2017, when an X8.2-class X-ray flare and subsequent proton precipitation were observed. Both events lead to an increase in the electron density in the lower ionosphere, but differ in their impact on radio signal parameters. The impact of X-ray radiation leading to an increase in the amplitude of radio signals is observed only in the daytime. The impact of proton rashes is manifested as a nighttime decrease in amplitude.

This article describes the details of area survey with multirotor UAV. We performed geomagnetic and air photography with multispectral camera. Air survey was supplemented with ground stationary and on-foot measurements. Attention brought to the cold weather and snow cover of the region of interest at time of the fieldwork, as well as the environmental effect on the equipment and particular issues with its utilization. In the end we evaluated the direct and indirect effect on the results of both magnetic and multispectral surveying.