Determination of the Distance to Magnetic Sources Using Tensor Data

Semiautomatic interpretation methods are widely used to produce initial geophysical models, which can then be refined by forward modelling and inversion. Airborne measurements of the gradients of the magnetic field have been made routinely for some time now, and tensor datasets are becoming more common. Existing semi-automatic interpretation techniques that determine the distance to potential field sources use the field and its gradients. These techniques are extended to use tensor data, which provide different types of analytic signal amplitude, and hence different methods of source-distance calculation. The solutions that are obtained can then be used to cross-check each other. If measured tensor data are not available, the tensors may be calculated from the total magnetic intensity data, which can also produce satisfactory results. The method is demonstrated using airborne data from South Africa.