Automatic inversion of magnetic anomalies caused by 2D listric fault sources with arbitrary magnetisation

An automatic inversion technique is presented to analyse the magnetic anomalies produced by 2D fault sources having nonplanar fault planes. This technique provides a means to analyse the magnetic anomalies of the structure measured in any component (i.e., vertical, horizontal or total). The present technique uses the polynomial functions to describe the fault plane, the coefficients of which become the unknown parameters to be estimated from the magnetic anomalies along with the other shape parameters, namely, the depths to the top and bottom of the fault structure, the location of the fault edge, besides intensity and direction of magnetisation. This technique initialises the model space based on some characteristic anomalies and their positions on the anomaly profile and subsequently updates them iteratively following the predefined convergence conditions. The closeness of fit between the recovered and assumed theoretical models of a fault structure from the analysis of noise-added vertical magnetic anomalies justifies the strength and applicability of the proposed technique. The observed total magnetic anomalies along an EW profile across the western margin of the Perth Basin, Australia are interpreted and the results are compared with the available/reported information.