Inversion using Euler deconvolution of the magnetic gradient tensor

Abstract

While the routine measurement of the magnetic gradient tensor is some way off, in certain circumstances it is possible to calculate the gradient tensor from total magnetic intensity (TMI) information. Such circumstances include anomalies being no more than about 20 percent of the local Earth?s field, where the field departs from being a true potential field, and adjacent lines being well levelled. Euler deconvolution requires solving at least four simultaneous homogeneous equations to yield the location in 3D and the Euler structural index of the source. Combining two or more adjacent tensors provides an over-determined system which allows the covariance to be estimated and gives a measure of uncertainty. This method extracts a wealth of information on the location and geometry of magnetic sources. However, the method is sensitive to departures of the TMI from being a true potential field, for very strong anomalies, in which case conversion to a true potential can be performed using an iterative method involving calculating components from the TMI and projecting the components onto the local field direction.