Group B, Poster #192, Earthquake Engineering Implementation Interface (EEII)

Evaluation of the Impacts on Risk Assessments for Distributed Infrastructure Systems from Ground Motion Median, Variability, and Spatial Correlation in CyberShake Simulations

Yajie Lee, Christine A. Goulet, ZhengHui Hu, & Scott Callaghan
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Poster Presentation

2023 SCEC Annual Meeting, Poster #192, SCEC Contribution #13298 VIEW PDF
The SCEC CyberShake platform provides 3D physics-based simulations that better capture the local source, path, and site effects for probabilistic hazard assessment than traditional ground motion models (GMMs). Previously, we examined the impact of CyberShake Study 15.12 simulations on Probabilistic Seismic Risk Assessment (PSRA) of the underground transmission water pipeline network for the City of Los Angeles. Significant differences in estimated pipeline network seismic risks – measured by the expected number of pipeline repairs – were found between CyberShake and GMMs, with significant implications on public policies concerning seismic risks and on estimates of resources needed for to adequately plan and mitigate the risks to meet system-wide resilience criteria.

Physics-based earthquake simulations and traditional GMM-based approaches differ in three main characteristics: median ground motions for a given source and site, ground motion variability, and spatial correlation. All these characteristics can significantly influence system-level risk estimates of a spatially distributed system. To further understand the causes of the differences in the resulting risk outcomes, in this study, we utilize a common set of earthquake ruptures and the identical pipeline damage models for all system risk calculations, using the earthquake simulations from CyberShake Study 22.12 and the empirical GMMs, respectively. To separate the impacts from ground motion median, variability, and spatial correlation, we conduct a suite of progressive risk analyses in several steps, with each step designed to incorporate one ground motion characteristic at a time. These analyses will allow us to systematically investigate the role of each of the ground motion components on the system risk results and provide an increased understanding of the CyberShake approach compared with the traditional GMM-based approach in characterizing regional ground motion inputs for seismic risk assessments of spatially distributed infrastructure, and guide future research and necessary validations of the technology for crucial real-world applications.