The solution of forward problems of magnetotelluric sounding for a case of one-dimensional piecewise gradient environments is received. Two problems are considered: the problem of calculating the impedance on the Earth's surface for a gradient model of the upper half-space (Earth's atmosphere) and the problem of determining the magnetotelluric impedance for layered, piecewise-gradient models of the geological medium, which allow mathematical modeling of the magnetotelluric response functions and study the interaction of electromagnetic field and gradient models of lithosphere media. Such models extend the possibilities of development of the theory and practice of magnetotelluric research, first of all, when solving inverse problems, which is associated with the advantage of analytical solutions over numerical solutions of inverse problems of geophysics in terms of sharp reduction of their dimensionality. The main focus of the work is on the study of geodynamic processes in passive electromagnetic monitoring, the foundations of which are laid in the article (Alexandrov, Rybin, Zabinyakova, 2018).
The article deals with the inverse problem of determining the transient resistance of the main pipeline insulating coating. For this, UAV measurements of the magnetic induction vector modulus of the magnetic field excited by the system of electrochemical cathodic protection of pipelines are used. The solution method is based on Tikhonov's method for finding the extremal of the regularizing functional. The developed algorithm is implemented in software. The results of computational experiments are presented.
This study focuses on microscale anisotropy in rock structure and texture, exploring its influence on the macro anisotropic electromagnetic parameters of the geological media, specifically electric conductivity (σ), relative permittivity (ε), and magnetic permeability (μ). The novelty of this research lies in the advancement of geophysical monitoring methods for calculating cross properties through the estimation of effective parameters—a kind of integral macroscopic characteristic of media mostly used for composite materials with inclusions. To achieve this, we approximate real geological media with layered bianisotropic media, employing the effective media approximation (EMA) averaging technique to simplify the retrieval of the effective electromagnetic parameters (e.g., apparent resistivity–inversely proportional to electrical conductivity). Additionally, we investigate the correlation between effective electromagnetic parameters and geodynamic processes, which is supported by the experimental data obtained during monitoring studies in the Tien Shan region. The observed decrease and increase in apparent electrical resistivity values of ρk over time in orthogonal azimuths leads to further ρk deviations of up to 80%. We demonstrate that transitioning to another coordinate system is equivalent to considering gradient anisotropic media. Building upon the developed method, we derive the effective electric conductivity tensor for gradient anisotropic media by modeling the process of fracturing in a rock mass. Research findings validate the concept that continuous electromagnetic monitoring can aid in identifying natural geodynamic disasters based on variations in integral macroscopic parameters such as electrical conductivity. The geodynamic processes are closely related to seismicity and stress regimes with provided constraints. Therefore, disasters such as earthquakes are damaging and seismically hazardous.
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