Analysis of non-ideal remote pole in Electrical Resistivity Tomography for subsurface surveys

Abstract

One of the most used geophysical measurement techniques for soil reconstruction is the Electrical Resistivity Tomography. In many different application fields, the reconstruction of the subsurface must be accurate and precise in order to properly identify the underground target. In many practical cases this will allow to decrease the costs thanks to an easier and more accurate plan of the excavation survey. There are different array geometries that could be used in Electrical Resistivity Tomography depending on the area of investigation. Some of them uses a remote electrode (also known as remote pole) ideally located at infinite distance from the other electrodes. Obviously, since the length of the cable is finite, it is not possible to deploy the remote pole at the theoretical infinite distance. Thus, it is fundamental to understand how this error influence the subsurface reconstruction. Starting from a previous work, this paper compares the output of a Monte Carlo simulation with the results of a measurement survey carried out on an Etruscan tumulus. The location of the remote pole has been changed starting at 50 m up to 150 m from the center of the linear array. The results of both simulations and measurement campaign emphasizes the effects of a non-ideal remote pole in terms of apparent resistivity of the subsurface and colormap-based soil reconstruction.

Considerations on the Electrode-Spacing-to-Electrode-Diameter Ratio in Electrical Resistivity Tomography (ERT): An Operational Approach

“…In particular, a wrong deployment of the electrodes along the ERT line or the finite distance of the remote pole in case of a pole-dipole (PD) array can generate artefact that can be interpreted as subsoil anomalies (see for instance [19]- [23]).…”