SCEC Award Number 22051 View PDF
Proposal Category Individual Proposal (Integration and Theory)
Proposal Title Optimizing Simulation Parameters for SCEC BBP SDSU Module Based on SEAS GOF
Investigator(s)
Name Organization
Kim Olsen San Diego State University
Other Participants Ke Xu, PhD student.
SCEC Priorities 4a, 4b, 4c SCEC Groups GM, EEII, CS
Report Due Date 03/15/2023 Date Report Submitted 03/03/2023
Project Abstract
 The purpose of this project is to estimate optimal modeling parameters for the SCEC Broadband Platform (BBP) validation events using the SDSU BBP module for spectral accelerations (SAs) and smoothed Fourier Amplitude Spectra (SEAS). We use trial-and-error modeling to adjust the high-frequency attenuation exponent f_dec and Q_0 factor in the relation Q(f)=Q_0 f^(f_dec), as well as the spectral decay parameter κ in the local site term P(f)=exp⁡(-πκf). After applying the new set of parameters, the average bias from the observations is reduced in most validation events. Furthermore, the trends of SAs deviations are also flattened in the acceptable frequency band from 0.1 Hz to 10 Hz for some events, which provides a better and more consistent fit after merging with the low-frequency synthetics. Based on our results, we have changed the recommendation for the parameters in the newest release (22.4.0).
Intellectual Merit By careful parameter adjustment it is possible to optimize and improve the bias against observations for earthquake ground motions.
Broader Impacts The project supported a PhD student at SDSU for a year. By estimating refined, region-specific parameters, it is possible to generate enhanced ground motion prediction and seismic hazard analysis.
Exemplary Figure Figure 5. Comparisons of old and revised RotD50 SA GOF averaged for all stations with 64 stochastic BBP realizations for the southern Sierra Nevada region (2019 M6.4 Ridgecrest A, 2019 M5.4 Ridgecrest B, and 2019 M7.1 Ridgecrest C. Credits: Fabio Silva and Ke Xu.