Using Resistivity Measurements to Determine Anisotropy in Soil and Weathered Rock

Abstract

This study uses electrical resistivity measurements of soils and weathered rock to perform a fast and reliable evaluation of field anisotropy. Two test sites at New Concord, Ohio were used for the study. These sites are characterized by different landform and slightly east dipping limestone and siltstone formations of Pennsylvanian age. The measured resistivity ranged from 19 Ω∙m to 100 Ω∙m, and varied with depth, landform, and season. The anisotropy was determined by a comparison of resistance values along the directions of strike and the dip. Measurements showed that the orientation of electrical anisotropy in the shallow ground may vary due to fluid connection, which is determined by the pore geometry in soil and rock, as well as by the direction of fluid movement. Results from this study indicated that a portable electrical resistivity meter is sensitive and reliable enough to be used for shallow ground fluid monitoring.

Numeric Validation of the Inversion Model of Electrical Resistivity Imaging Method using the Levenberg-Marquardt Algorithm

“…ERI has wide applicability for near surface investigations related to civil infrastructure, hydrogeology, environmental assessment, and archeology due to its ability to differentiate materials based on electrical properties. Factors such as mineral composition, porosity, water content, and salt concentration influence field measurements [4,5]. By detecting electrical property contrasts, ERI can delineate subsurface lithological contacts, solution cavities, contaminant plumes, and structural features without cumbersome drilling [2,6].…”