Magnetotelluric data across the Southern San Andreas Fault Zone, California

The Southern San Andreas fault (SSAF) poses one of the largest seismic risks in California. However, structural properties around Coachella Valley remain enigmatic. In 2019, we collected magnetotelluric soundings (MT) to help inform depth-dependent fault zone geometry, fluid content and porosity. This project was led by the Institute of Geophysics and Planetary Physics at the University of California San Diego in partnership with U.S. Geological Survey and funded in large part by the Southern California Earthquake Center (SCEC). The MT data were collected using Zonge International 32-bit ZEN data loggers with ANT-4 magnetic induction coils and Borin Ag-AgCl electrodes with 50 m dipoles. The ZEN was programmed to record continuously for ~8 hours at 256 samples per second with 10-minute burst sampling at 4096 samples per second in between for a total recording time of about 20 hours per site. This dataset consists of 27 wideband MT soundings, including time series and transfer functions estimated using the robust remote reference code EMTF (Egbert, 1997; DOI: https://doi.org/10.1111/j.1365-246X.1997.tb05663.x).