The United States Magnetotelluric Array and the National Impedance Map

Reviews of Geophysics
By: , and 

Links

Abstract

The United States Magnetotelluric Array (USMTArray) data set, collected in the years 2006–2024, consists of more than 1,700 long-period magnetotelluric stations covering the entirety of the contiguous United States on a quasi-regular 70 km grid. Funding across multiple federal agencies was critical to sustaining this effort to its completion. Important components of the project included active guidance and participation from the MT community, the open and timely availability of all data, and the application of consistent instrumentation and robust data processing. Together with parallel advancement in the development of publicly available three-dimensional (3D) inversion codes, the USMTArray has revitalized the US magnetotelluric community and increased the visibility of magnetotellurics within the Earth-science community. Taken as a whole, these data are visualized as the National Impedance Map, which, together with a 3D synthesis conductivity model of the nation, reveals the electrical architecture of the contiguous US. USMTArray data are used by researchers worldwide for fundamental and applied studies, including investigations of continental architecture and evolution, estimation of hazards to critical infrastructure due to geomagnetic storms, and assessment of the nation's undiscovered geothermal and mineral resources. We here review the history and development of the project, discuss the challenges and successes in its execution, present the National Impedance Map and synthesis conductivity model, and highlight the breadth of research stemming from this rich data set.

Suggested Citation

Kelbert, A., Bedrosian, P.A., Schultz, A., Egbert, G.D., Pellerin, L., Love, J.J., Frassetto, A., and Murphy, B., 2026, The United States Magnetotelluric Array and the National Impedance Map: Reviews of Geophysics, v. 64, no. 2, e2024RG000850, 57 p., https://doi.org/10.1029/2024RG000850.

Study Area

Publication type Article
Publication Subtype Journal Article
Title The United States Magnetotelluric Array and the National Impedance Map
Series title Reviews of Geophysics
DOI 10.1029/2024RG000850
Volume 64
Issue 2
Publication Date May 01, 2026
Year Published 2026
Language English
Publisher American Geophysical Union
Contributing office(s) Geology, Geophysics, and Geochemistry Science Center
Description e2024RG000850, 57 p.
Country United States
Other Geospatial conterminous United States
Additional publication details