Application of 2D and 3D geoelectrical resistivity imaging for engineering site investigation in a crystalline basement terrain, southwestern Nigeria

Orthogonal set of 2D geoelectrical resistivity field data, consisting of six parallel and five perpendicular profiles, were collected in an investigation site using the conventional Wenner array. Seven Schlumberger soundings were also conducted on the site to provide ID layering information and supplement the orthogonal 2D profiles. The observed 2D apparent resistivity data were first processed individually and then collated into 3D data set which was processed using a 3D inversion code. The 3D model resistivity images obtained from the inversion are presented as horizontal depth slices. Some distortions observed in the 2D images from the inversion of the 2D profiles are not observed in the 2D images extracted from the 3D inversion. The survey was conducted with the aim of investigating the degree of weathering and fracturing in the weathered profile, and thereby ascertaining the suitability of the site for engineering constructions as well as determining its groundwater potential.