SEPARATION OF REGIONAL AND RESIDUAL MAGNETIC-FIELD DATA

We present a method for separating regional and residual magnetic fiel ds using a 3-D magnetic inversion algorithm. The separation is achieve d by inverting the observed magnetic data from a large area to constru ct a regional susceptibility distribution, The magnetic field produced by the regional susceptibility model is then used as the regional fie ld, and the residual data are obtained by simple subtraction. The adva ntages of this method of separation are that it introduces little dist ortion to the shape of the extracted anomaly and that it is not affect ed significantly by factors such as topography and the overlap of powe r spectra of regional and residual fields. The proposed method is test ed using a synthetic example having varying relative positions between the local and regional sources and then using a field data set from A ustralia. Results show that the residual field extracted using this me thod enables good recovery of target susceptibility distribution from inversions.