Large‐scale inversion of ZTEM data

Abstract

A ZTEM survey is an airborne electromagnetic survey which records the vertical magnetic field that result from natural sources. The data are transfer functions that relate the local vertical field to orthogonal horizontal fields measured at a reference station on the ground. The transfer functions depend on frequency and provide information about the 3D conductivity structure of the Earth. While the airborne nature of the survey means that large survey areas can be surveyed quickly and economically, the high number of cells required to discretize the entire survey area at reasonable resolution can make the computational costs of inverting the entire data set all at once prohibitively expensive. Here we present a workflow methodology that can be used to invert large natural source surveys by decomposing the large inverse problem into smaller more manageable problems before combining the tiles into a final inversion result.