Response of cracking processes in variations of geophysical fields

This paper discusses a range of issues related to the interpretation of time variations of geophysical fields as a response of the geophysical environment to lunar-solar tidal influences and seismic events under conditions of submeridional compression. A model linking the mechanism of crack formation and generation of geophysical fields has been proposed. The concept of the energy characteristics of a seismic field of deep underground (endogenous) origin along the seismic wave field observed on the Earth's surface for three mutually perpendicular components has been introduced. The results of field studies of simultaneous recording of a seismic wave field by a three-component gradient system and a magnetotelluric field at monitoring sites of the Bishkek Geodynamic Proving Ground (BGPG in Northern Tien Shan) are presented. The test area is situated in an active intracontinental mountain Central Asian Orogenic Belt with the frequent seismicity. For the experiment purposes, we select the Ukok regime monitoring point in the Kochkor basin of Kyrgyz Tien Shan. Because the location is characterized by low-level of seismic noise and the technical-and-industrial influence. The applicability of such a joint approach in geophysics is discussed. According to the results of the experiments performed, we establish a possible causal relationship between lunarsolar tides and activation of the deep underground (endogenous) source. Based on the correlation analysis of gravitational tidal effects, and the results of magnetotelluric monitoring, the azimuthal dependence of the electrical conductivity of the medium was revealed. We detect characteristic changes in the studied electromagnetic parameters, which we identify as a result of the redistribution of fluids between the fracture systems, were. The joint analysis of data from regime magnetotelluric observations and seismicity distribution confirms the high sensitivity of the method to changes in the stress-strain state of the geological environment. The confinement of seismic events to zones with high gradients of variations of apparent electrical resistivity is shown. The work may be of interest to specialists in the field of Earth Sciences, dealing with the interpretation of experimental data from geophysical test sites. (C) 2020 Elsevier B.V. All rights reserved.