SCEC Award Number 22160 View PDF
Proposal Category Collaborative Proposal (Integration and Theory)
Proposal Title Reconciling Bias in Moderate Magnitude Earthquake Ground Motions Predicted by Cybershake Simulations
Investigator(s)
Name Organization
Chukwuebuka Nweke University of Southern California Jonathan Stewart University of California, Los Angeles
Other Participants Minhao Wu
SCEC Priorities 4a, 4b, 4e SCEC Groups GM, EEII, Seismology
Report Due Date 03/15/2023 Date Report Submitted 04/01/2023
Project Abstract
 Earthquake simulation platforms are are an attractive toolset for predicting ground motion in areas where data is scarce. Recent studies have used simulations to investigate ground motions associated with historical and/or expected high-impact earthquakes. These simulations are gaining attention as a resource for engineering design, but their accuracy needs to be validated before they can be fully embraced. One approach to validate simulated ground motions is to simulate earthquakes with well-recorded data and assess their residuals against said data to identify any bias. A study by Nweke et al. (2022) conducted simulations for 13 moderate magnitude earthquakes in southern California and found a positive bias (under prediction) in ground motion levels relative to the observed data. This current study aims to understand the source of this bias by evaluating ground motion residuals and exploring its dependence on parameters like magnitude, rupture distance, and source depth. Currently, additional events are being analyzed to see if the bias persists. The goal of this work is to develop a refined simulation methodology that is better able to capture the absolute levels of ground motions observed for earthquakes, thus building additional confidence in the application of the simulation approach for high impact scenarios.
Intellectual Merit This research (and project) is directly related to the Ground Motion Simulation Validation (GMSV) Technical Activity Group (TAG). The determination of the source of the observed bias between simulations and recorded ground motion data will provide a means to update/enhance the estimates derived from physics-based simulation platform to more closely align with reality. This will pave the way for the adoption of simulated ground motions in engineering design applications.
Broader Impacts This research project is providing the PI, who is a member of an underrepresented group in earthquake engineering and seismology, a means to further his research endeavors and also provide training to a graduate student who has overcome personal adversity to attain a terminal degree. This project is also supporting a strong collaboration between researcher scientists and engineers who are working towards developing a tool that will help improve the resiliency of infrastructure design and development.
Exemplary Figure Figure 9. Site amplification for different shear wave velocity profiles.