Resistivity Method
Electrical resistivity imaging is becoming increasingly popular due to the availability of automated data acquisition devices and user-friendly inversion software, which allows it to produce images of the subsurface quickly and efficiently. It has been used to look at areas with complicated geology, such as volcanic and geothermal zones, landslides, seismotectonic structures, hydro-geologic phenomena and environmental issues, and the deposition and flow of impact melt and breccias (Colangelo et al., 2008; Lapenna et al., 2005; Steeples, 2001 ). In this section, we focus on the application of the resistivity method in investigating the Bosumtwi impact crater.
Aning et al. (2013 ) used the multi-electrode gradient array to conduct a 2D electrical resistivity tomography (ERT) survey at several places around the crater. The authors discovered three formations with distinct resistivity signatures: low resistivity regions from the lake’s shore to uphill with resistivities of 64 Ω.m representing lake sediments; moderately high resistivity regions with values between 128 Ω.m and 200 Ω.m interpreted as impact-related breccias such as dikes, allochthonous or parautochthonous depending on their geometries; and finally, the model clearly distinguished the resistive basement metamorphic formations. Using the ERT model, the authors were also able to determine faults and fractures and the thickness of post-impact lake sediments and breccias. Based on their findings, they concluded that the multi-core cable’s take-outs could be changed to suit the needs of a specific survey, underlining the technique’s applicability in impact cratering investigations and geo-electrical imaging studies in general.
Habimana et al. (2020 ) used electrical resistivity imaging in conjunction with seismic refraction methods to map the subsurface structure of the suevites north of the Bosumtwi impact crater in Ghana to establish their depth extent, in-situ resistivity, and P-wave velocity. According to the authors, the suevite deposits were discovered at a depth of 12 meters. The findings also revealed that the subsurface consists of two or three layers: unconsolidated topsoil, clayey soil, and fractured claystone.