Investigation of fault zone and its environmental impact in Ilorin, North Central, Nigeria

Abstract

A series of Seismic activities are being experienced in some part of Nigeria with the obvious threat to lives and properties. This study therefore investigated and identified localized fault zone believed to be pathway to seismic activities in Ilorin. For this purpose, high resolution aeromagnetic data of Ilorin, obtained from Nigerian Geological Survey Agency were processed and interpreted using Geosoft Oasis Montaj 6.4.2 data processing and analysis software package. The Reduced to Equator (RTE)-Residual Magnetic Anomaly (RMA) maps were obtained from step by step filtering of magnetic intensity maps, the geological features were examined using Analytic Signal Amplitude (ASA). Lineaments were extracted from Total Horizontal Derivatives (THD) map.The process was then subjected to depth continuation process to obtain localized fault zones The Upward continuation process employed, showed the region of consistent high magnetic amplitude or increasing amplitude on the upward depth continued map of the study area as region of deep depth to magnetic sources, indicating intrusion. The minor or localized faults were captured with decreasing magnetic amplitude at UC height of 5000 m at the depth of 2,500m in the area under study. The superposition of the lineaments obtained from THD map on the RTE-RMA and geological maps revealed ductile and brittle deformations and a set of dextral localized faults of varied orientations. These identified localized faults within the study area could serve as pathway to Seismic activities leading to earth tremor as a threat to human existence.