Based on the results of physical modeling, the interaction of an air shock wave caused by a surface explosion of an explosive charge with a warm layer is considered. It is shown that the presence of a heating layer causes a strong effect associated with a qualitative change in the pressure diagram in the shock wave, a decrease in the amplitude of the compression wave and an increase in its duration.

The article attempts to trace the evolution of some basic provisions of the model of the geophysical medium by M.A. Sadovsky in the works of the employees of the IDG RAS. Rich experimental material accumulated over many years of participating in nuclear weapons tests served as a foundation for developing the dynamics of rock mass deformation at different hierarchicallevels. It is shown that many modern approaches and current results anyway were predicted in the works of M.A. Sadovsky. The key role of fault zones in the evolution of deformation processes in the Earthʼs crust is demonstrated. The development of a new scientific school «Geomechanics of Faults» opens up new possibilities in solving fundamental and applied problems in the physics of the solid Earth.

The paper presents a brief historical overview of laboratory experimental studies initiated at the Schmidt Institute of Physics of the Earth of the Russian Academy of Sciences in the first half of the 1970s on the initiative of academician M.A. Sadovsky and reproduced certain aspects of rock failure during the seismic process using models. The background and main directions of research are noted. Data on individual experiments are presented, the main attention is focused on the methodology. The basic information about a large-scale experiment on deformation and destruction of blocks of rocks of meter size on a 50-ton press is given. The experiment was conducted in the 1980s under the methodological and organizational guidance of the IPE RAS (Sobolev G.A.) with the involvement of a wide range of related organizations and specialists. The methodology and results of experiments on the seismic gap model, experiments on slider models of faults with trigger initiation and experiments on small samples with a complex stress state are described. The experimental results supported the main ideas of the avalanche-unstable fracturing formation model proposed at the IPE RAS in 1971.

The article presents the history of the organization of IPKON RAS on the basis of the Sector of Physical and Technical Mining Problems at the O.Yu. Schmidt Institute of Physics of the Earth of the USSR Academy of Sciences, headed by Academician M.A. Sadovsky.

The problem of stress redistribution in a rock mass in the cross of two parallel workings is considered within the framework of a non-local gradient model. The constitutive equations describe plastic intergranular shifts and local heterogeneity. Two independent displacement fields are used to describe the kinematics in the plane case. As a result, the model contains a structural parameter that includes the length dimension and describes local bends of elementary volumes. Examples of numerical simulations of the development of plastic deformation zones nearby the opening contour of the rock mass are given, and areas of increased stress concentration are determined. It is shown that taking into account local bends, on the one hand, leads to a decrease in plastic shifts nearby the opening contour, and on the other hand, to a deeper penetration of areas of high stress concentration into the rock mass.

The results of comparative analysis of modern volumetric deformations and seismicity in fault zones of seismically active (Kopetdag, Kamchatka) and weakly seismic (South-East of Tatarstan) regions are presented. It is shown that there is an inverse relationship between the energy characteristics of deformation and seismological processes in space and time. It is concluded that the observed antiphase behavior of energy characteristics is due to the alternate realization of the volumetric and shear parts of the accumulated potential energy of the medium. It is suggested that the presence of more intense volumetric deformations of fault zones of platform, weakly seismic regions is due to a decrease in the share of realization of the shear component of deformation energy due to reduced seismic activity in these regions.

The study of the fragmentation phenomenon and divisibility of rocks is of great importance for understanding the essence of the seismic process, solving the problems of the mining industry, and identifying the parameters and mechanisms of fault-fracture tectonics. A fundamentally significant contribution to the development of this direction was made by Academician Mikhail Alexandrovich Sadovsky. Usually, the problem of divisibility is сonsidered in the context of fault-fracture tectonics, but divisibility is determined not only by linear structures (faults, lineaments), but also by the existence of three-dimensional geological provinces with structural and material content characteristic only of these provinces. This type of divisibility is practically not studied. The article describes the areas of areal rifting: the Provinces of basins and ridges (North America), the Selengino-Vitim zone (Western Transbaikalia), the Sunda shelf (the Malay Archipelago), which are elements of the volumetric divisibility of the earth›s crust and at the same time have an internal divisibility of a higher rank. The study is based on a comparative structural and tectonic analysis using both author›s and literary material. The objects considered in the article form tectonically isolated lenticular planar geological bodies with an individual morphostructure, geological history and geodynamic conditions of formation. They are bounded by fault zones and are represented by structural paragenesis of brittle-plastic diffuse (dispersed) shear, which is characterized by the fragmentation of rock masses into a system of linearly ordered uplifts and troughs. The existence of such morphostructural ensembles (paragenesis) reflects the 3D tectonic divisibility of the crustal scale.

Substantiation of technologies for opening and developing solid mineral deposits, seismic zoning of territories for the purposes of large-scale construction is carried out using geomechanical models, so their validation is an urgent task. The article discusses some aspects related to the choice of the size and orientation of the computational domain, as well as the quantitative assessment of the stress field components outside the zone of influence of the target object. Based on a comparative analysis of the linear dimensions of tectonic blocks of the first and second scale levels of the Altai-Sayan folded region, the hierarchy coefficient according to M. A. Sadovsky k = 3.17–3.22 was found, which is proposed to be used in designing nested geomechanical models for the region of the main iron ore deposits of Gornaya Shoria. A method for quantitative assessing the parameters of the external stress field has been developed and tested on real geotechnical objects of various scales (Solikamsk mine and coal seam in the extraction section of the Vorkutinskaya mine). The method is based on solving inverse boundary value problems using direct (measuring hydraulic fracturing) and indirect (passive seismic tomography using the coordinates of the hypocenters of dynamic events and the times of the first arrivals recorded by mine seismic stations) data. The implementation of this method made it possible to determine the principal horizontal stresses in the external stress field of the Solikamsk mine of 14 and 24 MPa, indicating an overthrust geodynamic regime in the vicinity of this geotechnical object.

This paper presents the results of experiments to reproduce the stick-slip process along a model fault and to induce fault edge movement by fluid and electrical effects. A special feature of the experimental setup used is an extended movable block, which allows to significantly increase the area of the interblock contact filled with dry fine-grained sand. This makes it possible to study the spatial pattern of the development of active deformation zones of the contact zone by solving the problem of locating acoustic emission sources. Particular attention has been paid to the study of the response of the contact zone to the injection of water into it and to the direct application of electric current. As a result of the experimental studies, spatiotemporal patterns of the response of the model fault to an increase in shear load and fluid and electrical effects have been determined. It is shown that the effect of electric current causes an increase in acoustic emission activity throughout the area between the electrodes, except for the emission activation area at the water injection stage. It was found that the electrical action can lead to the initiation of dynamic motion with the activation of spatial areas manifested in previous action stages.

Seismotectonic domains are the basis for seismic hazard assessment at the level of General Seismic Zoning (GSZ). A fragment of a seismotectonic domain map is analyzed. It is shown that domains do not always represent homogeneous combinations of seismic and tectonic features, as was assumed when they were formulated. Sometimes domains represent a very high degree of generalization, combining quite heterogeneous areas. At the same time, it is shown that it is unjustified to completely abandon generalizing seismotectonic models and rely only on maps of active faults. It is suggested that clearly expressed individual features of strong earthquakes, including those of close magnitudes, impose restrictions on the possibilities of seismic hazard assessment.

A new approach is proposed to estimate the amplitude of shock waves and compression waves in the atmosphere caused by explosive sources: industrial explosions, powerful explosions of concentrated charges, explosions of condensed chemical explosives and explosions of gas mixtures. As a result of generalization of the data of instrumental observations, the possibility of using M.A. Sadovskyʼs formulas to describe the mechanical effect of shock waves in the atmosphere for all the above sources is shown by taking into account the dependence of the scale coefficients of the law of energy similarity and the TNT equivalent of the explosion on the volumetric energy density in the source, which makes M.A. Sadovskyʼs formula universal for calculating the parameters of the mechanical action of explosive charge explosions with any state of matter, different properties and energy characteristics. The data obtained can be used to prevent the negative consequences of the use of explosive technologies in the national economy and during experimental explosions of explosives.

Computer modeling methods are used to examine the possibility of the formation of the Australasian tektite strewnfield as a result of an asteroidal impact on an island of volcanic origin with a hill. It is shown that, when an asteroid hits a mountain, the angle of dispersion of high-speed ejecta increases, which can explain the large size of the Australasian tektite strewnfield. The absence of a found crater-source of tektites is explained by the fact that such an impact would result in the formation of an underwater crater, which is more difficult to detect than one located on land.

One of the fundamental problems of astrophysics and geophysics is the study of processes in the external and internal magnetosphere and ionosphere of the Earth related to energy transfer in the system of solar wind - magnetosphere and plasmasphere - ionosphere. The most important agent of energy transfer in this system is plasma flows interacting with the background plasma and magnetic field. Their direct study using spacecrafts is not possible with today›s technical capabilities. Under these conditions, active plasma experiments are of paramount importance. This direction is being successfully developed in IDG RAS, and the foundation for setting experiments, development of initial data and the necessary technical and measuring instruments is the experience of many years of research in the field of explosion physics, conducted in the Special Sector of the Institute of Chemical Physics of RAS, and then in the Special Sector of the Institute of Physics of the Earth RAS and in the Institute of Geospheres Dynamics RAS under the leadership of Academician M.A. Sadovsky. The results of the experiments conducted in cooperation with scientific organizations of the Russian Federation and the USA made it possible for the first time in a real geophysical environment to carry out complex multipoint measurements of plasma parameters both inside the plasma flow and remotely. The analysis of the results of the experiments showed that their schemes, parameters of explosive plasma generators, diagnostic equipment allowed to study the most important and still being the subject of active study the effects of interaction of natural ionospheric plasma flows with the background medium and geomagnetic field, their spatial and temporal distribution, main parameters and results of influence on the geophysical environment.

At the end of the 20th century, the International Monitoring System (IMS) was created, which arose in connection with the emergence of the Comprehensive Nuclear-Test-Ban Treaty. Academician of the Russian Academy of Sciences Mikhail Aleksandrovich Sadovsky, who participated in a number of preparatory meetings and headed the Soviet delegation at one of the key meetings of experts on the seismic method of detecting nuclear explosions, made a great contribution to the formation of the terms of the Treaty with his knowledge and authority. M.A. Sadovsky was not only a recognized scientific authority in the field of the mechanical action of an explosion, but was also directly involved in organizing observations of nuclear explosions at experimental sites. The results obtained under the supervision of Academician M.A. Sadovsky laid the foundation for the development of seismic methods for monitoring nuclear tests. The main goal of the International Monitoring System is formulated as «facilitating the detection of any nuclear explosion» and for a long time this task remained mainly in the theoretical plane. However, the current political situation has transferred these issues from routine procedures to the newly emerging urgent tasks of timely and reliable detection of possible nuclear tests. The article describes the work that was carried out at the turn of the century in the course of selecting locations for seismic stations that later became part of the international monitoring system (IMS). The main principles and algorithms for selecting locations for seismic stations are considered based on an analysis of the experience of work on selecting sites for IMS stations in Russia. A step-by-step analysis of the basic approaches used in organizing the IMS seismic network can be useful in creating new observation systems to solve various problems.