Self Potential (SP) and Resistivity Methods of Discriminating Lithologies in a Landslide Areas of Ohafia Town, Nigeria

Abstract

This research presents the application of geophysical self-potential (SP) and resistivity methods in evaluating subsurface phenomenon in Ohafia Area. Two communities were covered with three profile lines of 200 m spread occupied in each location. The data were acquired using ABEM SAS 300C Terrameter and later processed with EarthImager 1D inversion modelling software. Self-Potential values ranged from -107.8 to 112.3 mV in Amaekpu and -100 to 150 mV in Elu area. Positive SP values indicated lithologies with low permeability while negative SP values showed permeable lithologies. Six geologic layers were inferred for Amaekpu area while seven layers were inferred from Elu area. Layer 1, 3 and 5 are low permeable lithologies while Layer 2, 4 and 6 are permeable intervals in Amaekpu. In Elu, Layers 1, 3, 5 and 7 are having low permeability while Layers 2, 4 and 5 are highly permeable lithologies. Lithologic intervals inferred from inverted resistivity data which include sands, sandstones and gravels conformed with regions having negative SP values. Similarly, depth intervals identified as topsoil, siltstones and clay conformed with positive SP values.