3D magnetization vector inversion for SQUID-based full tensor magnetic gradiometry

Following recent advances in superconducting quantum interference devices (SQUIDs), airborne full tensor magnetic gradiometry (FTMG) is emerging as a practical geophysical exploration method that is intended to recover information about remanent magnetization. In this paper, we introduce 3D regularized inversion of FTMG data that recovers the total magnetization vector in each cell of the 3D earth model. If a priori information about the susceptibility or remanent magnetization is available, the 3D inversion can be constrained to recover the remanent magnetization vector. If a priori information is not available, it is possible to recover attributes such as the amplitude, components, and angle of the magnetization vector relative to the inducing field. We present a case study for data acquired over a dike swarm in South Africa that compares our 3D FTMG inversion for magnetization with a 3D total magnetic intensity (TMI) inversion for a positively-constrained susceptibility distribution. Given the significant remanent magnetization present, the 3D FTMG inversion for magnetization recovers results that are most consistent with the known geology.