Geoelectrical characterization of subsurface instabilities: Implications for mass movement risk management in Bafoussam, Western Highlands of Cameroon

Abstract

• Geoelectricity maps subsurface resistivity to identify mass movement risk zones. • Iso-resistivity maps show deep low zones (>70 m) and compacted high surface layers. • The susceptibility map identifies zones prone to geological/geophysical instability. • Bafoussam is prone to landslides, collapses, flooding, and erosion. • The phenomena grown by human activities linked to infrastructural development. Mass movements represent a major geological hazard in the city of Bafoussam (western Cameroon), exacerbated by rapid urbanization and heavy rainfall. This study aims to delineate areas susceptible to mass movements by integrating geomorphological observations with geoelectrical data. A multi-criteria analysis was conducted using Geographic Information Systems (GIS), incorporating conditioning factors such as lithology, slope and land use. To enhance the reliability of the susceptibility model. Vertical Electrical Soundings (VES) using the Wenner/Schlumberger array were performed across strategic locations. The geoelectrical results revealed three main lithological domains: highly resistant surface domain layer (ρ > 262 Ω.m) corresponding to lateritic soil and dry basement rocks; a moderate resistant domain (85 < ρ < 262 Ω.m) associated with weathered materials; and a low-resistivity zone (ρ < 85 Ω.m) indicating saturated clay-rich layers or fractured water-bearing rocks. The correlation between electrical sounding curves (predominantly K and KH types) and geomorphological data allowed for the identification of potential sliding surfaces at depths ranging from 5 to 15 meters. The resulting integrated susceptibility map classifies the study area into three risk zones: stable, moderately susceptible, and highly susceptible. These findings provide a critical decision-making tool for urban planning and natural hazard mitigation in Bafoussam and other highlands around sub-Saharan Africa.