Application of Independent Finite Element Modeling for Estimating the Effect of Simplest Landforms on Results of Inversion of Electrical Resistivity Tomography Data (Example of a Trench with the Triangular Cross-Section)

Abstract

In solving the problems of shallow depth electrical prospecting of the daylight surface, the topography is a factor that has a significant impact on the results of the inversion of electrical resistivity tomography data. Verification of the results of inversion of the field data is a laborious task due to the complex structure of the original geological medium. At the same time, the development of computer numerical simulation methods allows obtaining electrical resistivity tomography data for simple models of the medium. The results of estimating the effect of the simplest landforms on the results of the inversion of electrical resistivity tomography data obtained by numerical simulation by the example of the model of a trench with the triangular cross-section are presented. Numerical simulation is performed based on the finite element method by an inversion-independent technique. It is determined that the inversion of the tomography data for the trench in a homogeneous half-space produces false anomalies, with the maximum located under the axis of the trench. It is shown separately that in the presence of real inhomogeneity at this position, it can, depending on its resistance, be masked (compensated) by the false anomaly, or strengthen it. If the trench is in a two-layer medium, then there is a distortion of the boundary between the layers at some interval under the trench, repeating the trench shape.