A FORTRAN-77 computer program for three-dimensional inversion of magnetic anomalies resulting from multiple prismatic bodies

Abstract A computer program in FORTRAN 77 is presented for three-dimensional inversion of total field magnetic anomalies resulting from multiple prisms with arbitrary magnetizations and orientations. The program is based on the nonlinear optimization technique of the Marquardt algorithm. The equations for the anomalies and derivatives with respect to various parameters of the prismatic bodies are programmed to minimize computing time. The derivatives are computed by analytical methods as the computation time is smaller than that required by numerical methods. Approximate equations allow rapid calculation of the magnetic anomalies and derivatives. Efficient methods are developed for three-dimensional inversion of magnetic anomalies by an appropriate use of the exact and approximate equations. The method is applied for inversion of the total field aeromagnetic anomalies over Mahanadi Basin, Orissa, and aeromagnetic anomalies over the western part of Cuddapah Basin, Andhra Pradesh, India.