Two‐dimensional joint inversion of magnetotelluric and dipole‐dipole resistivity data

Abstract

This paper describes 2-D joint inversion of MT and dipole‐dipole resistivity data with the emphasis on the computer algorithm. The algorithm produces a 2-D model composed of a large number of rectangular blocks, each of which has constant resistivity. The solutions to two forward problems are based on the finite‐element method. The computation time for the partial derivatives of MT responses is reduced by using the reciprocity relation and the concept of a fictitious source. The smoothness‐constrained least‐squares method, together with the modified Gram‐Schmidt method, is also to stabilize the solution and avoid spurious resistivity features. Synthetic and field data examples show that the 2-D joint inversion can be effective for improving the resolution attained by the 2-D interpretation of a single kind of data set.