SCEC Award Number 19152 View PDF
Proposal Category Individual Proposal (Integration and Theory)
Proposal Title SCEC Simulation Validation for Southern California Basins using Ground Motion Recordings
Investigator(s)
Name Organization
Jonathan Stewart University of California, Los Angeles
Other Participants Chukwuebuka C. Nweke
SCEC Priorities 4b, 4d SCEC Groups GM, EEII
Report Due Date 03/15/2020 Date Report Submitted 03/13/2020
Project Abstract
 Cybershake-based ground motions are being actively considered for engineering application in the greater Los Angeles area (Crouse and Jordan, 2016; https://data2.scec.org/ugms/) and nationally (Moschetti et al. 2017). One of the principal motivations for this application is a belief that Cybershake-based estimates of basin effects on long-period ground motions in Southern California and elsewhere are more accurate than those from semi-empirical ground motion models (GMMs), such as those from the NGA-West2 project. The two estimates are indeed different, with the severity of the basin effect being stronger in the Cybershake simulations.

We plan to extend previous validation approaches applied for ShakeOut and Broadband Platform simulations for application to Cybershake simulations, with a particular emphasis on long-period site effects. We intend to apply this approach for the specific purpose of testing Cybershake-based basin amplification estimates.
Intellectual Merit The project will inform the degree to which basin effects in Southern California are captured by SCED 3D simulation procedures. Misfits will be useful to identify areas in which simulation procedures can be improved through subsequent research. This will provide fundamental insights into factors controlling site response in complex basin structures.
Broader Impacts The project has partially funded a post-doctoral scholar from an under-represented group in science and engineering. It has increased his visibility in the SCEC community and significantly enhanced his professional development.
Exemplary Figure Trend of site terms with differential depth using Southern California data. The site terms represent average misfit of GMM from observed ground motions at Southern California sites. “Observations” for this figure are for small magnitude events as recorded from earthquakes and as computed from simulations. Differential depth is basin depth (depth to 1.0 km/s shear wave isosurface) minus average depth conditioned on VS30.