CORRELATION OF GEOTHERMAL FEATURES SOUTHEAST OF THE SALTON SEA WITH FAULT SYSTEMS USING SUBSURFACE GEOPHYSICS

Southeast of the Salton Sea, hundreds of geothermal structures, such as mud pots and mud volcanoes, have been hypothesized to correspond to an unconfirmed extension of the San Andreas Fault (SAF). To further examine this hypothesis, we investigate the relationship between subsurface geophysical anomalies associated with the known geothermal structures in the southeastern Salton Sea region and the speculated extension. Our integrated study includes very low frequency electromagnetic measurements (VLF), ground-based magnetic surveys, and GIS analysis. We combine our geophysical survey results with fault maps and remote sensing data in order to correlate the presence of geothermal features in the region with potential fault systems.

Using historical data in addition to our own remote sensing-based research, we have generated a new database of geothermal mud structures in the region. VLF measurements can indicate the presence of fluids along faults or shear zones, while magnetic profiles may locate fault planes through contrasts in magnetic susceptibility. In February 2020, we conducted two VLF and ground-based magnetics surveys, one and two km in length, trending west to east within the Imperial Wildlife Area Wister Unit. By employing ground-based magnetic and VLF geophysical surveying techniques using the GEM System’s proton magnetometer and VLF attachment, we aim to support or reject the hypothesized potential fault zone, which is expected to run northwest to southeast. Evidence of subsurface faulting is expected in the form of magnetic anomalies and Fraser-filtered peaks in the processed data from VLF surveys. Initial interpretations indicate that faulting may be present in our survey area. We are planning to carry out additional remote sensing analysis to investigate the time-dependent evolution of the geothermal features through interferometry.