Simultaneous estimation of total magnetization direction and spatial orientation of a magnetic source

The interpretation of magnetic anomalies is not a trivial task not only because of the difficulties in allowing for a possible existence of remanent magnetization, but also due to the nonlinear dependence of the magnetic anomaly upon the source geometry. For the sake of simplicity, the magnetization is usually assumed to be induced only while trying to estimate the interpretation model geometry. Alternatively, the spatial orientation of the source may be assumed known in order to estimate the total magnetization. We present a method to simultaneously estimate the total magnetization direction and the spatial orientation of the source. The method is based on the approximation of the anomalous field by the series derived from expansion of the magnetic potential in multipoles, keeping moments up to 2nd order. Because the parameters to be inverted are the source moments, the method has the advantages of being linear and appropriate to interpret anomalies produced by a broad class of sources. This class comprises the finite-volume bodies, homogeneously magnetized in direction, but not necessarily in modulus, and whose spatial distribution of magnetization modulus presents three orthogonal symmetry planes.