Advances in electromagnetic modeling based on integral equation methods and their application to 3D inversion of time-domain airborne data

Thirty-five years ago, Gerald W. Hohmann, late Professor of Geophysics at The University of Utah, published a seminal paper on 3D electromagnetic (EM) modeling using the integral equation (IE) method. This achievement subsequently inspired a considerable body of research in 3D EM modeling and inversion. Over the decades, the IE method evolved from the academic intrigue of EM fields scattering from simple 3D bodies into a practical tool of EM modeling and inversion for arbitrarily complex 3D geoelectrical structures. In this paper, we demonstrate that recent advances in the IE method have made it practical to rigorously invert entire surveys of time-domain airborne electromagnetic (AEM) data to 3D conductivity models with hundreds of thousands of cells within several hours on a workstation