EM2INV — A finite difference based algorithm for two-dimensional inversion of geoelectromagnetic data

Abstract

The paper presents an efficient finite difference based 2D-inversion algorithm, EM2INV, for geoelectromagnetic data. The special features of the algorithm are • optimal grid generation based on grid design thumb rules, • finite domain boundary conditions, • interpolation matrix that permits generation of response at observation points different from grid points, • Gaussian elimination forward matrix solver, that enables reuse of already decomposed coefficient matrix, • super-block notion that reduces the number of blocks with unknown resistivities and, in turn, the size of Jacobian matrix and • bi-conjugate gradient matrix solver for inverse problem which circumvents the need of explicit Jacobian matrix computation.