Large-scale 3D Inversion of EarthScope MT Data

Abstract

We have developed efficient workflows for large-scale 3D MT inversion which address two common problems encountered in 3D MT inversion: computational time and memory requirements. To minimize computational time, our modelling is based on a parallel implementation of the integral equation method. To minimize memory requirements, we have implemented a receiver footprint which dramatically reduces the memory needed for storing Fréchet derivatives for large 3D models. We have applied our 3D MT inversion methodology to EarthScope data acquired over the western United States. In this paper, we present the first 3D earth models of the upper mantle beneath Yellowstone National Park as independently revealed by both 3D MT inversion and 3D seismic tomography. These earth models show a highly conductive region associated with the plume of hot material rising from the mantle towards the Yellowstone volcano. The plume is identified as a west-dipping conductive structure in the 3D conductivity model of geometry similar to the low velocity structure in the 3D P-wave velocity model.