A Comparative Study Of Source Location And Depth Estimates From Total Intensity And Reduced-To-The Pole Magnetic Data

Abstract

Locations and depths to magnetic sources can be estimated from the maxima of the horizontal gradient magnitude (HGM), the analytic signal amplitude (ASA) and the local wave number (LWN) of the total intensity magnetic field. In this study, a synthetic magnetic field due to four buried dipoles was analysed to show that estimates of source location and depth can be improved significantly by reducing the data to the pole prior to the application of the HGM, ASA and LWN functions. Furthermore, results show that estimates from the HGM and the ASA are comparable and better than those from the LWN because the LWN uses second derivatives and therefore, is very susceptible to noise in the data. The aeromagnetic map of part of Ilesha area, southwestern Nigeria was also analysed to demonstrate the effectiveness of the RTP process. Key words: dipole anomaly, horizontal gradient magnitude, analytic signal, local wave number, source location, source depth Ife Journal of Science Vol. 7(1) 2005: 91-100