Geophysical Verification of Minor Fault Mechanics using Vertical Electrical Sounding survey in Ibadan and Ijebu-Ode, Southwestern Nigeria

Abstract

Understanding and mapping minor fault systems is essential for tectonic hazard assessment and sustainable subsurface resource management. This study applies the Vertical Electrical Sounding (VES) method to identify and characterize minor faults in Ibadan and Ijebu-Ode, southwestern Nigeria, regions previously underexplored in this context despite their proximity to known major fault zones from the Atlantic Ocean. Using the Schlumberger electrode array along four profiles in Ibadan and five in Ijebu-Ode, resistivity data were acquired and interpreted through geophysical inversion. The results revealed two main subsurface terrains: sedimentary and crystalline rocks. Specific curve types (KH, HKH, KHKH) indicated fractured or faulted basement zones, with fault-related resistivity anomalies detected at depths ranging from 1.0 to 53.1 m. These findings highlight the tectonic sensitivity of the study areas and underscore the importance of integrating such data into regional seismic risk mapping and groundwater development plans. Further multi-method geophysical validation is recommended to confirm the structural interpretations.