Integrated geophysical subsurface characterization for construction site suitability of the proposed central library at achievers university, Owo, Nigeria

Abstract This study used integrated geophysical methods to characterize the subsurface for construction site suitability of a proposed structure at Achievers University, Owo, Nigeria. The Audio-Magnetotelluric (AMT), Vertical Electrical Sounding (VES), and Electrical Resistivity Tomography (ERT) were employed to probe the subsurface conditions and identify potential weak zones along three traverses established nearly perpendicular to the strike direction of the area. The AMT survey identified relative resistivity readings (0.01–0.42), identifying low resistivity zones indicative of conductive formations suitable for groundwater housing at depth and weak zones unsuitable for construction in the near-surface region. VES results showed four geo-electric layers with varying resistivity, indicating competent to highly competent topsoil across the study area with a resistivity value range of 411.4–3858.1 Ohm-m. ERT further delineated the shallow subsurface, revealing potentially unstable topsoil overlying competent weathered bedrock and fresh basement. Based on the findings from this study, a deep foundation is recommended to ensure the structure rests on the competent basement, providing optimal support for any engineering project. This integrated geophysical approach offers critical insights for optimizing construction strategies at the proposed site, with additional geotechnical analysis recommended.