Electromagnetic Characterization of the Fracture System within Older Granite of North Central Nigeria

Abstract

A VLF electromagnetics survey was carried out on the whole land area of the Federal College of Education, seated on the older part of the basement complex of north-central Nigeria. VLF machine, model EM/6, was used to collect data along 8 VLF profiles at a station spacing of 66 m across the strike of the geological formation. Fractures, sheared and faulted zones were reported all over the area, with the prominent ones concentrated at the north–western corner, which diminished progressively toward southwest direction of the site. The in-phase and quadrature component plots revealed conductivity high of +130% and 86% respectively around the northwest while the lowest conductivity occurred toward the eastern part of the campus. Consequently, northwestern side appears the most promising water-bearing zone.