Spatial Correlations in CyberShake Physics‐Based Ground‐Motion Simulations

2019 ◽  
Vol 109 (6) ◽  
pp. 2447-2458 ◽  
Author(s):  
Yilin Chen ◽  
Jack W. Baker
Keyword(s):  
Ground Motion ◽  
Prediction Models ◽  
Spatial Correlations ◽  
Ground Motion Simulation ◽  
Source Effects ◽  
Simulation Validation ◽  
Geological Conditions ◽  
Simulated Ground Motions ◽  
Strong Ground

Abstract When studying the performance of distributed infrastructure in earthquakes, spatial variations in strong ground motion have a significant impact. Currently, prediction models for spatial ground‐motion variations in future earthquakes are calibrated using ground‐motion observations from densely recorded earthquakes. Although useful, that calibration process requires strong assumptions about stationarity and isotropy of correlations. This article reports results from conducting analogous spatial variation estimation using physics‐based simulations from the CyberShake platform. This platform contains simulated ground motions from hundreds of thousands of rupture realizations, 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 isotropy assumptions, and provides new insights regarding the role of source and path heterogeneity on the spatial correlation of ground‐motion amplitudes. The results suggest that geological conditions, source effects, and path effects have significant impacts on spatial correlations. In addition, this work serves as a new dimension of ground‐motion simulation validation, because the estimated correlations can be compared to results from past earthquakes.

scholarly journals Hybrid broadband ground motion simulation validation of small magnitude earthquakes in Canterbury, New Zealand

2020 ◽  
Vol 36 (2) ◽  
pp. 673-699 ◽  
Author(s):  
Robin L Lee ◽  
Brendon A Bradley ◽  
Peter J Stafford ◽  
Robert W Graves ◽  
Adrian Rodriguez-Marek
Keyword(s):  
New Zealand ◽  
Ground Motion ◽  
High Frequency ◽  
Motion Simulation ◽  
Small Magnitude ◽  
Ground Motion Simulation ◽  
Simulation Methodology ◽  
Simulation Validation ◽  
Broadband Ground Motion Simulation ◽  
Broadband Ground Motion

Ground motion simulation validation is an important and necessary task toward establishing the efficacy of physics-based ground motion simulations for seismic hazard analysis and earthquake engineering applications. This article presents a comprehensive validation of the commonly used Graves and Pitarka hybrid broadband ground motion simulation methodology with a recently developed three-dimensional (3D) Canterbury Velocity Model. This is done through simulation of 148 small magnitude earthquake events in the Canterbury, New Zealand, region in order to supplement prior validation efforts directed at several larger magnitude events. Recent empirical ground motion models are also considered to benchmark the simulation predictive capability, which is examined by partitioning the prediction residuals into the various components of ground motion variability. Biases identified in source, path, and site components suggest that improvements to the predictive capabilities of the simulation methodology can be made by using a longer high-frequency path duration model, reducing empirical V s30-based low-frequency site amplification, and utilizing site-specific velocity models in the high-frequency simulations.

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