Abstract
A numerical method is used to calculate the electromagnetic fields associated with a three-dimensional conductivity anomaly. A uniform field oriented in various directions relative to the anomaly is used as the source. The transfer functions and related perturbation and induction arrows associated with the fields are calculated. The results show that the perturbation arrows do not well describe the anomalous currents for the three-dimensional model considered, but can give a method of outlining the spatial extent of the anomaly. The induction arrows may be used in the traditional way to indicate the flow of anomalous currents and point toward conductivity inhomogeneities. Two methods of calculating the induction arrows are compared.
