## 2 Materials and Methods
### Geodynamic Process Reflexion in the Physicoelectric Properties of Rocks  
The variations in electrical resistivity are closely related to the process of rock deformation [57, 58]. Deformation begins with the closure of fractures in the rock sample, and the extent of sample deformation nonlinearly depends on pressure. Simultaneously, the resistivity of the rock decreases due to the conductive surface increasing. As deformation progresses, elastic deformation exhibits a linear dependence on stress, leading to a linear decrease in resistivity. Increasing stresses initiate the development of both existing and newly formed cracks. Further stress buildup results in the release of accumulated elastic energy and a sharp increase in the number of cracks. At this point, an uncontrolled process of brittle fracture ensues, accompanied by a decrease in stresses and a sharp increase in resistivity. Thus, irreversible geodynamic processes manifest as the disruption of rock continuity and the formation of cracks, either without visible displacement or with displacement within their planes due to mechanical impacts caused by tectonic and non-tectonic forces [57, 58].  
Fracturing is a significant process occurring in all rocks under various geological conditions. The formed cracks are filled with fluids and particles from the deformable rock, altering the overall physical and mechanical properties of the rock [59]. In cases where highly conductive fluids fill the cracks, the structural features of the rock no longer play a role, and the electrical resistivity anisotropy coefficient decreases to unity as moisture content increases. However, in other cases, the anisotropy of electrical resistivity provides valuable information about the structural and textural features of the rock, such as layering, shearing, fracturing, etc. [39, 60].  
It is well established that resistivity anisotropy is highly sensitive to changes in rock stress. The anisotropy of electric conductivity correlates with the anisotropy of permeability in rock layers and serves as an indicator of the self-organized structure of the rock itself.  
Figure 3: Polar diagrams showing the variations in apparent resistivity (\(\rho_{k}\)) over time at a fixed point before and after an explosive earthquake. The diagrams depict the dependence of resistivity on the sounding period (T) and azimuth (\(\alpha\)) in degrees (Az). (**a**) represents the data 12 h before the earthquake, while (**b**) shows the data 6 h after the earthquake.  
Isotropy, therefore, represents a special case characterized by a disordered rock structure. To establish a quantitative relationship between the structural-textural and physicoelectric parameters of the rock, it is necessary to construct a phenomenological model of electrical resistivity that considers the structural features of the rock.  
The geophysical literature has developed various types of structural phenomenological models and solutions for its numerical description. However, the calculation of electrical resistivity for such models is limited to transversely isotropic media, primarily due to the limited development of the Maxwell homogenization technique [13; 61], which enables the transition from the local physicoelectric parameters of the media to macro-parameters.