Poster #135, Fault and Rupture Mechanics (FARM)

Numerical modelling of rupture dynamics constrained by past seismicity for ground motion prediction

Elif Oral, Jean-Paul Ampuero, Javier Ruiz, & Domniki Asimaki
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Poster Presentation

2021 SCEC Annual Meeting, Poster #135, SCEC Contribution #11235 VIEW PDF
Predicting ground motion by physics-based modelling, particularly at magnitudes and distances that lack empirical data, has been an attractive avenue for seismic hazard assessment studies. In the proximity of a fault, both source- and site-related complexities control the final ground motion; understanding the impact of these complexities on ground motion, therefore, matter to reason and constrain the associated variability of ground motion. Initial stress heterogeneity is one of the acknowledged source-related complexities to account for, and we hypothesize that it results from the superposition of residual stresses left by past seismicity. Here we develop a new method to generate initial s...tress heterogeneity that is governed by the regional statistics of past seismicity, including the Gutenberg-Richter frequency-magnitude distribution and the hypocentral depth distribution. Our modelling conforms with fracture mechanics theory and applies scale-dependent fracture energy, and we calibrate rupture models to satisfy empirical earthquake scaling laws and ground motion prediction equations. We validated our method through Mw 7 earthquake models suitable for California and investigated the impact of background seismicity on rupture dynamics and near-field ground motion. Our results, with 3 Hz resolution, suggest a notable spatial variation of ground motion metrics close to faults due to background stress heterogeneity. The outputs of our study promises to disentangle source and site effects on near-field ground motion with the use of regional statistical data.