Automated airborne EM anomaly picking and 3D model fitting

Abstract

A number of algorithms for the transformation of airborne EM data to 3D conductivity distributions have been developed in the past few years. This paper describes a MATLAB implementation of the Annan spectral method to permit the automatic detection and fitting of vortex and current gathering responses from discrete targets. The method used consists of 1) AEM System definition 2) pre-calculation of a large number of system specific AEM responses for target geometries of interest 3) Conversion of data to stitched 1D CDI through EMFlow with conversion to equivalent step response data 4) response – background separation 5) successive brute force fitting of every "possible" anomaly to every successive line segment of data 6) selection and refinement of acceptable models based on error criteria This paper presents results of the application of the method to fixed-wing Geotem data from Queensland and Sweden.