3D and Boundary Effects on 2D Electrical Resistivity Tomography

Abstract

Electrical resistivity tomography (ERT) is one of the most widely used geophysical methods in geological, hydrogeological, and geo-environmental investigations. Although 3D ERT is now available, 2D ERT remains state-of-the-practice due to its simplicity in fieldwork and lower space requirements. 2D ERT assumes that the ground condition is perpendicular to the survey line and outside the survey line is homogeneous. This assumption can often be violated in conditions such as geologic strikes not perpendicular to the survey line and topographic changes or buried objects near the survey line. Possible errors or artifacts in the 2D resistivity tomogram arising from violating the 2D assumption are often overlooked. This study aimed to numerically investigate the boundary effects on 2D ERT under various simplified conditions. Potential factors including resistivity contrast, depth and size of buried objects, and electrode spacing were considered for the parametric studies. The results revealed that offline geologic features may project onto the 2D tomogram to some extent, depending on the aforementioned factors. The mechanism and implications of boundary effects can be drawn from these parametric studies.

Geophysical Survey as a Tool to Reveal Subsurface Stratification at a Small Agricultural Headwater Catchment: A Case Study

“…Also, the 2D transects which are perpendicular to each other can capture the 3D structures differently. For instance, the presence of the brook may result in differences in the transects BFB5 and BFC3 and cause the discrepancies in the intersection C [24]. The highly variable geology of the catchment and inclinations of the subsurface layers may also manifest differently to the perpendicular cross-sections.…”

Special Issue: Selected Papers from IEEE ICASI 2019

“…Y. C. Hung et al [6] reported on "3D and Boundary Effects on 2D Electrical Resistivity Tomography". Electrical resistivity tomography (ERT) is one of the most widely used geophysical methods in geological, hydrogeological, and geo-environmental investigations.…”

The application of the 2D/3D electrical resistivity tomography (ERT) method in investigating the carbonate karst of the Zakrzówek Horst

“…In the case of monitoring tasks, the 4D technique is applied, where measurements are repeated in the time domain (Lapenna & Perrone 2022). In the 2D technique, where measurements are performed along the linear profile it can be difficult to identify the spatial extent of heterogeneities in geological structures (Aizebeokhai 2010, Hung et al 2019. Therefore, measurements based on the 3D technique provide more accurate and reliable results, especially in the case of inhomogeneities existing under the surface.…”