Imaging the Upper Mantle Seismic Structure Beneath Southern California

A. Christian Stanciu, & Eugene D. Humphreys

Published August 15, 2019, SCEC Contribution #9856, 2019 SCEC Annual Meeting Poster #314

Upper mantle seismic imaging using body waves provides high resolution constrain on lateral variation in structure at depths bellow ~55 km. While tomographic imaging methods have been consistently improving over the last few decades, current imaging quality is still affected by problems arising from ray-tracing assumptions, anisotropy, use of ray theory, and errors in estimations of crustal travel times. We address these problems and present new high-resolution images of the P, S, and Vp/Vs seismic structure of the upper mantle beneath southern California. These models include accurate crustal corrections estimated using SCEC’s crustal velocity model. Our models resolve higher amplitudes for the mantle seismic structures than previously published models, and find the thickness of the Transverse Ranges anomaly to be reduced by 10%. Our preferred interpretation of the fast mantle structure beneath the Transverse Ranges is a descending remnant of the Farallon slab that drives southern California northward and contributes to rifting in the Salton Through. Seismically slow asthenosphere beneath the Salton Trough is the result of high temperature and presence of partial melt.

Key Words
seismic imaging, tomography, Transverse Ranges, Farallon

Stanciu, A., & Humphreys, E. D. (2019, 08). Imaging the Upper Mantle Seismic Structure Beneath Southern California. Poster Presentation at 2019 SCEC Annual Meeting.

Related Projects & Working Groups
SCEC Community Models (CXM)