3-D joint inversion of electrical and magnetometric resistivity data

Abstract

The DC electrical resistivity (DC) and magnetometric resistivity (MMR) are two geophysical techniques applied in exploration of mineral resources and in solving environmental and engineering problems. Conventionally, these two techniques are used separately to infer the subsurface conductivity. Since each of these methods has its own relative merits and limitations, a joint use is expected to provide complementary information, and possibly reduce the survey costs as well. In this paper, we present a unified algorithm to compute the potential and magnetic fields that arise from buried source electrodes. This is done in two consecutive steps by solving a Poisson's equation for a scalar electrical potential and a magnetostatic equation for a vector magnetic potential, respectively. The inverse problem is formulated as an optimization in which both observed potential and magnetic field data are fit to a certain degree, and at the same time, the recovered model has a minimum structure. The standard Gauss-Newton algorithm is used to obtain the model pertubation at each iteration. The code is verified with a synthetic model.