Large-scale 3D integral equation based inversion of EarthScope MT data using a variable sensitivity domain

Moving sensitivity domain that varies with frequency was implemented and tested in a parallel magnetotelluric (MT) integral equation inversion. This approach reduces computation time and memory requirements. We assess the robustness of the approach by model tests and apply it to the inversion of EarthScope MT data collected over the Northwestern US. Prominent features obtained by this inversion include resistive structure associated with the Juan de Fuca slab subducting beneath the northwestern United States and the conductive zone of partially melted material above the subducting slab corresponding to the Cascade volcanic arc. We also observe extensive areas of moderate-to-high conductive asthenosphere below 100 to 200 km and high-conductive body associated with the Yellowstone mantle plume.