Strong SH-to-Love Wave Scattering off the Southern California Continental Borderland

Chunquan Yu, Zhongwen Zhan, Egill Hauksson, & Elizabeth S. Cochran

Published October 21, 2017, SCEC Contribution #7972

Seismic scattering is commonly observed and results from wave propagation in heterogeneous medium. Yet deterministic characterization of scatterers associated with lateral heterogeneities remains challenging. In this study, we analyze broadband waveforms recorded by the Southern California Seismic Network and observe strongly scattered Love waves following the arrival of teleseismic SH wave. These scattered Love waves travel approximately in the same (azimuthal) direction as the incident SH wave at a dominant period of ~10 s but at an apparent velocity of ~3.6 km/s as compared to the ~11 km/s for the SH wave. Back projection suggests that this strong scattering is associated with pronounced bathymetric relief in the Southern California Continental Borderland, in particular the Patton Escarpment. Finite-difference simulations using a simplified 2-D bathymetric and crustal model are able to predict the arrival times and amplitudes of major scatterers. The modeling suggests a relatively low shear wave velocity in the Continental Borderland.

Yu, C., Zhan, Z., Hauksson, E., & Cochran, E. S. (2017). Strong SH-to-Love Wave Scattering off the Southern California Continental Borderland. Geophysical Research Letters,. doi: 10.1002/2017GL075213.