SCEC Award Number 17137 View PDF
Proposal Category Individual Proposal (Integration and Theory)
Proposal Title SDSU BBP Module Extension: Ground Motion Correlation, Duration, and Multi-Segment Ruptures
Investigator(s)
Name Organization
Kim Olsen San Diego State University
Other Participants Rumi Takedatsu, Research Assistant
SCEC Priorities 4b, 4c, 4d SCEC Groups CME, GM, EEII
Report Due Date 06/15/2018 Date Report Submitted 11/05/2018
Project Abstract
 The SDSU module, merging low-frequency deterministic signals with high-frequency scattering func-tions (Olsen and Takedatsu, 2015), participated in and passed the SCEC Broadband Platform valida-tion exercise, where the focus was on validating simulated median pseudo-spectral accelerations for large earthquakes in western and eastern US and Japan, as well as NGA-west1 GMPEs. Here, we pre-pare the SDSU module for the next generation seismic hazard analysis.

We have incorporated inter-frequency correlation in the FAS domain as a post-processing method into the current SDSU Broadband ground motion generator module. Using our improved method, the BB results for 7 western U.S. events with Mw5.0-7.2 show that the empirical inter-frequency cor-relations of EAS are well predicted in the SDSU module for a large number of realizations from a single event with unbiased goodness-of-fit of the spectral accelerations in the presence of correlated synthetics. This in itself is an important step toward validating the BB codes in FAS rather than SA space. A further validation of the correlated synthetics comes from an improved fit of the RotD100/RotD50 ratio, a proxy metric proposed by Burks and Baker (2014).

We have updated and validated the SDSU BBP module in terms of ground motion duration. 50-realization significant duration estimates from the updated SDSU module were generally improved of the WUS and Japanese events. Finally we verify a multi-segment rupture implementation of the SDSU module with 1- and 3-segment Landers approximations.

Finally, we have participated in the weekly BBP group efforts toward validating the codes for addi-tional events.
Intellectual Merit The efforts on validating the BBP durations led to refined methodology for comparing data and synthetics, by realizing that the current process was insufficient and resulted in biased results.
Broader Impacts Better prediction of ground motions allows the earthquake community to estimate the losses and damage in future earthquakes. Specifically, it has been shown that ground motion correlation has a significant impact on the loss estimation. In addition, more accurate estimation of ground motion duration is important for building design. Improvements to the BBP modules, such as the SDSU module here, allows the broader community to use more accurate code for ground motion modeling.
Exemplary Figure Figure 2.