Spatial correlations in CyberShake physics-based ground motion simulationS

Jack W. Baker, & Yilin Chen

In Preparation 2018, SCEC Contribution #7963

Spatial variations in strong ground motion have a significant impact on performance of distributed infrastructure in earthquakes, and implied risk to portfolios of insured buildings in a region. Currently, spatial ground motion variations in future earthquakes are predicted empirically, and calibrated using ground motion observations from densely recorded earthquakes. While useful, that calibration process requires strong assumptions about stationarity and anisotropy of correlations. This paper reports preliminary results from an effort to perform analogous spatial variation estimation using physics-based simulations from the CyberShake platform. This platform contains simulated ground motions from tens of thousands of earthquake rupture scenarios, at locations throughout Southern California, providing a synthetic ground motion catalog that is much richer than we could ever hope to achieve from recordings. That richness allows significant relaxation of stationarity and anisotropy assumptions, and provides new insights regarding the role of source and path heterogeneity on the spatial correlation of ground motion amplitudes. The results show that the geological condition and directivity of earthquake propagation have significant impact on spatial correlation. Additionally, this work serves as a new dimension of ground motion simulation validation, as the estimated correlations can be compared to results from past earthquakes.

Citation
Baker, J. W., & Chen, Y. (2018). Spatial correlations in CyberShake physics-based ground motion simulationS. Oral Presentation at Eleventh U.S. National Conference on Earthquake Engineering.

Related Projects & Working Groups
Ground Motion Simulation Validation