Journal de géologie et géophysique
Libre accès

Abstrait

Characterization of Buried Targets at an Experimental Geophysical Site Using Ground Magnetic Geophysical Methods

Joseph Omeiza Alao*, Kolawole Muyideen Lawal, Bala Bello Muhammad Dewu, Jimoh Raimi

The ground magnetic investigation is fast becoming a powerful geophysical tool to resolve environmental challenges. It involves the application of basic geophysical methods and principles to detect environmental contaminants. This article presents the outcomes of the investigation carried out at Ahmadu Bello University Geophysical Test Site (ABUGTS) to simulate a broad range of features usually encountered in environmental contexts to enhance the understanding of the subsurface information. The Total Magnetic Field (TMF) of the natural subsoil of the site was obtained before the installation of buried targets to identify the possible existing buried materials that could alter or influence geophysical data. Laboratory test was carried out on the buried targets to determine the magnetic susceptibility, electrical conductivity, density, volume and mass. Interpretation of the data acquired before installing the buried targets shows no significant variations in the earth’s total magnetic field within the site. Minor and insignificant magnetic anomalies were distributed across the site without buried targets, which may simply be attributed to the inhomogeneous nature of the site consisting of both consolidated and loose subsurface. The TMF obtained after the buried targets indicates significant magnetic field variations with four major and three minor magnetic anomalies in different locations. The large buried ferromagnetic objects show strong signals and smaller ferromagnetic objects generate minor anomalies with the precise prediction of the buried target position. A magnetic anomaly map of the site indicates significant magnetic distortion in the places where the buried targets were installed. However, the magnetometer fails to capture some targets, which may be due to the size and depth of the target. The magnetic method is a very powerful, convenient, cheap, and time-saving geophysical tool for investigating buried targets and is more effective in detecting large metallic targets.