Dispersion of Rayleigh Surface Waves and Electrical Resistivities Utilized to Invert Near Surface Structural Heterogeneities

Abstract

The single-station Rayleigh surface wave group velocities and electrical resistivities are two data sets that we cooperatively employ to image the near surface (< 40-m) anomaly structures. We numerically simulate the corresponding field measurements where the anomaly structures are assumed to have two-dimensional (2D) variations. The surface waves are represented by fundamental mode dispersion curves, and the electrical resistivities are assumed to be measured by using direct currents. We consider two types of anomaly structures, i.e., cavity and ore body. These two heterogeneities are easily distinguished from the surrounding geomaterial by their distinct physical properties. The cavity is characterized by low seismic velocity and high electrical resistivity, while the ore body is characterized by high seismic velocity and low electrical resistivity. The Rayleigh surface wave data is assumed to be collected throughout the classical common-shot gather. Multiple electrodes, multiple core cables, and multiple arrays are assumed to be used in the electrical survey. Both surface wave group velocities and electrical resistivities are shown to properly invert the anomalous structures in the subsurface. The surface wave group velocities have good horizontal resolution, while the corresponding vertical resolution is somewhat lower. The electrical resistivities have good resolution for shallow structures, but the resolution becomes somewhat reduced with increasing depth. Doi: 10.28991/HEF-2022-03-01-01 Full Text: PDF