University of Tasmania, Australia

The rapid inversion of EM

In recognition of the need for rapid, integrated interpretation, an approximate 3D TEM inversion algorithm has been under development at CODES during the past 3 years (VPem3D version 1; Schaa and Fullagar, 2008). The algorithm relies on the concept of magnetic moments, which are time-weighted integrals of the TEM decay. In effect the moment transformation converts the 3D TEM inversion problem into a 3D magnetic inversion problem. The underlying assumption is that the net TEM response can be reproduced via superposition of the responses of single sub-volumes i.e. that EM interactions between volume elements can be ignored. This assumption is usually acceptable at late times, and it is the late time signature which is normally most important in exploration.

The aims of this project are to further advance the development of rapid approximate inversion of TEM data and to fully develop practical tools for integrated interpretation of multiple data sets in the “VP environment”. In parallel with the improvements to the algorithm, there is a need to develop a user friendly interface, which has sufficient functionality to expedite constrained 3D inversion. It is proposed to adapt and improve the existing VPmg user interface, VPview version 1, to fulfil this role.