A multi-scale magnetotelluric (MT) investigation of the Salton Trough

Pieter-Ewald Share, Steven Constable, Jared Peacock, & Samer Naif

Published September 10, 2023, SCEC Contribution #12773, 2023 SCEC Annual Meeting Poster #094

All three plate tectonic margin types are embedded in the Salton Trough lithosphere. The southern San Andreas fault system (SSAF, transform) and associated localized incipient rifting (divergent) are abutted to the west by the Peninsular Ranges, a remnant of Farallon slab subduction (convergent). All these systems contribute to a region of complex structure and strain, rich in aqueous fluids and melts, and play key roles in the potential for volcanic activity and for destructive earthquakes along the critically strained SSAF. Our new project seeks to image this tectonically complex region using multi-scale and amphibious magnetotelluric (MT) arrays (sites 100s m to 10s km apart). From these data, electrical conductivity information extending from the surface into the uppermost asthenosphere will be derived. At the largest scale (>10 km), these data address questions on variations in the local lithosphere-asthenosphere boundary and dehydration of the subducted slab. Mid-scale (1 – 10 km) deployments focus on crustal and uppermost mantle composition, the partitioning of fluids, partial melt, and by inference strain, and the evolution of these properties from transform to incipient rifting areas. At the finest scales (sites <1 km apart), the conductivity images highlight fault zone porosity, fluid content and geometry and how these variables differ between creeping and locked fault strands. By exploiting the unique resolution capabilities of MT these multi-scale images will, in combination with existing geoscientific knowledge, provide a new and more holistic understanding of Salton Trough tectonics and its related geohazards.

Key Words
Salton Trough, Structure and Strain, Magnetotellurics, Complex Tectonics

Citation
Share, P., Constable, S., Peacock, J., & Naif, S. (2023, 09). A multi-scale magnetotelluric (MT) investigation of the Salton Trough. Poster Presentation at 2023 SCEC Annual Meeting.

Related Projects & Working Groups
San Andreas Fault System (SAFS)