SCEC Award Number 24062 View PDF
Proposal Category Individual Research Project (Single Investigator / Institution)
Proposal Title Frequency-Based Validation of Site Response for Physics-Based Ground Motion Simulations in Northern California
Investigator(s)
Name Organization
Chukwuebuka Nweke University of Southern California
SCEC Milestones A2-1, D3-2, D3-3 SCEC Groups GM, EFP, Seismology
Report Due Date 03/15/2025 Date Report Submitted 03/24/2025
Project Abstract
 Simulated ground motions are essential for seismic hazard and structural response analyses, particularly in regions where observational data is limited. While extensive validation efforts have been conducted in Southern California, the performance of physics-based simulations for moderate-magnitude events in Northern California remains less explored. This study presents a validation of simulated ground motion in Northern California by comparing simulated ground motions generated from 1D simulation with observations. The residuals are compared with the residuals for similar moderate magnitude events in southern California which were simulated and prepared in the same way as northern California events. The comparison shows a distinct difference in the residual trends and bias level between northern California and southern California. Although no reason or feature was found for the cause of the difference, the potential answer could be addressed by running the 3D simulations in both regions and checking if trend and level of the bias still exists or diminishes.
SCEC Community Models Used Community Velocity Model (CVM), Community Fault Model (CFM)
Usage Description The CVM and CFM were used in combination with the broadband platform and the SW4 code to execute earthquake simulations and generate simulated waveforms at numerous sites.
Intellectual Merit The validation of earthquake simulations using an expanded catalog of field recorded data (on a 1-to-1 level) will allow for targeted enhancements of the simulation protocol (i.e., identify where and what components of the platform, tools, resources need to be improved and how). We have explored a rigorous robust investigation of sources of misfit/bias using residual analysis to identify and isolate governing features that need improvement. This will help advance the adoption of physics-based simulations for engineering applications on a grand scale.
Broader Impacts This SCEC proposal has benefit the training and progress of a phd student. IT has also provided an opportunity for an undergraduate researcher to participate and contribute to the outcomes of the research endeavors (via the Viterbi SURE program). Moreover, the interaction between the phd student and undergraduate allowed for opportunities of mentorship for hte graduate student which his critical to their development as a future mentor/teacher/researcher.
Project Participants The graduate student that has participated in the efforts associated with the project is Sajan KC. This work was also done in collaboration with Dr. Robert W. Graves and has received insights from Dr. Jonathan P. Stewart. The undergraduate researcher to participate in this Karena Clark from UCLA. We were also fortunate to have a pre-collegiate researcher name Lucky Guevarra who also participated in the research effort through the Viterbi K-12 SHINE program.
Exemplary Figure Figure 7: Average total residual considering all recordings and recordings within 50 km for simulations without site adjustment and with GP site adjustment.
Linked Publications

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