LIMAT: a computer program for least-squares inversion of magnetic anomalies over long tabular bodies
A popular method for the inversion of magnetic anomalies in total vertical or horizontal field over thin sheet thick dike and vertical fault is presented. The magnetic anomaly over thin sheet may be expressed as a polynomial of the form FX2 + C1FX + C2F + C3X3 + C4X2 + C5X + C-6 The initial parameters of the source are obtained from the coefficients C-1,C-2,..., C-6 by inverting a 6 x 6 matrix. The thick dike and the vertical fault are an ensemble of thin sheets. So the same initial solution obtained for the thin sheet model can be used for the thick dike and the vertical fault. Besides, in this method the computer calculates the initial solution by using all the discrete magnetic anomaly values and the corresponding distances as an input. The initial solution thus obtained is modified in an iterative process using non-linear least-squares regression by employing Marquardt's algorithm. The regional value that is subjective in manual interpretation is also adjusted in this method to obtain a close fit. A computer program in FORTRAN 77 is presented and used to interpret synthetic and practical data and the efficacy of the results are discussed. (C) 2002 Elsevier Science Ltd. All rights reserved.
inversion thin sheet thick dike vertical fault fortran 77