A fast and accurate numerical approach for electromagnetic inversion.

This paper deals with the solution of Maxwell's equations to model the electromagnetic fields in the case of a layered earth. The integrals involved in the solution are approximated by means of a novel approach based on the splitting of the reection term. The inverse problem, consisting in the computation of the unknown underground conductivity distribution from a set of modeled magnetic eld components, is also considered. Two optimization algorithms are applied, based on line- and global-search methods, and a new minimization approach is presented. Several EM surveys from the ground surface are simulated, considering the horizontal coplanar (HCP) and perpendicular (PRP) magnetic dipolar congurations. The numerical experiments, carried out for the study of river-levees integrity, allowed to estimate the errors associated to these kind of investigations, and conferm the reliability of the technique.