Three-dimensional electrical conductivity structure of the contiguous US from USArray MT data

Knowledge about the electrical conductivity structure of the Earth's interior is a key to understanding its thermo-chemical state and evaluate the impact of space weather events. USMTArray is a high quality data set of magnetotelluric measurements that addresses both of these problems. Covering ~70% of the contiguous United States on a quasi-regular 70 km spaced grid, this unique publicly available data led to the development of several regional 3D electrical conductivity models. However, an inversion of the entire data set demands novel multi-scale imaging approaches that can handle and take advantage of a large range of spatial scales contained in the data. We present a 3D electrical conductivity model of the contiguous United States derived from the inversion of ~1100 USArray magnetotelluric stations. The use of state-of-the-art modeling techniques based on high-order finite-element methods allows us to take into account complex coastline and reconstruct Earth’s conductivity across many scales. The retrieved electrical conductivity variations are in overall agreement with well-known continental structures such as the active tectonic processes within the western United States (e.g., Yellowstone hotspot, Basin and Range extension, and subduction of the Juan de Fuca slab) as well as the presence of deep roots (~250 km) beneath cratons.