New Insights on the Crustal Lithology and Seismo-Tectonics of Southern California From Joint Gravity and Full-Wave Inversion

Session: Full-Waveform Inversion: Recent Advances and Applications
Type: Oral
Date: 4/29/2020
Time: 03:15 PM
Room: 120 + 130
Description: 

Accurate and self-consistent models of wave speed and density variations are essential for understanding the compositions and physical properties of the crust and mantle and their seismic behavior. Traditionally, gravity and seismic data are inverted for density and wave speed either separately or jointly via velocity-density scaling. A caveat of this practice is that the velocity-density relation varies substantially with rock types, so the empirical relationships are not universally applicable. Here we report a new joint inversion method using Bouguer gravity and full-wave sensitivities to both density and wave speed perturbations to image subsurface structures. Application of the method to Southern California demonstrates that the joint inversion increases the model resolution and reduces the trade-offs between shear wave speed and density and between shallow and deep structures compared to those of seismic-only or gravity-only inversions. Low density and intermediate Vp/Vs ratio beneath the Transverse Ranges suggest that the granitic roots of the mountains extend to ~15 km depth, where crustal seismicity may be conditioned by brittle deformation of mechanically weak granite under these mountains.

Presenting Author: Yang Shen

Authors