Using the ASVI to invert for remanently magnetised bodies

Abstract

Magnetic inversion programs such as mag3d from UBC have proven to be very useful for generating realistic 3D susceptibility models from surface Total Magnetic Intensity (TMI) data. However, these programs do not perform well when the observed data includes the response of bodies which are strongly remanently magnetised. This failure occurs because the forward model algorithm used in the inversion only generates the induced response, so the remanent component in the TMI has to be modeled using the induced response for an unrealistic distribution of susceptibility. In this paper we investigate the effectiveness of inverting the analytic signal of the vertical integral (ASVI) for synthetic and real TMI data using mag3d. For both data sets we find that the inversion of the ASVI data produces a model which is much more realistic than that obtained by inverting the original data.