A FORTRAN-77 COMPUTER-PROGRAM FOR 3-DIMENSIONAL INVERSION OF MAGNETIC-ANOMALIES RESULTING FROM MULTIPLE PRISMATIC BODIES

A computer program in FORTRAN 77 is presented for three-dimensional in version of total field magnetic anomalies resulting from multiple pris ms with arbitrary magnetizations and orientations. The program is base d on the nonlinear optimization technique of the Marquardt algorithm. The equations for the anomalies and derivatives with respect to variou s parameters of the prismatic bodies are programmed to minimize comput ing time. The derivatives are computed by analytical methods as the co mputation time is smaller than that required by numerical methods. App roximate equations allow rapid calculation of the magnetic anomalies a nd 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 tot al field aeromagnetic anomalies over Mahanadi Basin, Orissa, and aerom agnetic anomalies over the western part of Cuddapah Basin, Andhra Prad esh, India.