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Validate simulated fault displacements from dynamic rupture against the observed in the 1992 Landers earthquake

Yongfei Wang, & Christine A. Goulet

Published April 19, 2021, SCEC Contribution #11005

Coseismic fault displacements in large earthquakes have caused significant damage to structures and lifelines located on or near fault lines. Fault displacements represent an important seismic hazard, especially for distributed infrastructure systems that may cross faults in multiple locations. Predictive fault displacement models are sparse and poorly constrained partly due to the scarcity of detailed fault displacement observations. Advancements in physics-based dynamic rupture simulation methods make them an attractive approach to address this important problem. Dynamic ruptures construct the earthquake rupture evolution and seismic wave propagation under plausible physical conditions. They can therefore be used to quantify fault displacement through physical causative parameters. When used with appropriate constitutive models to characterize the bulk medium around the fault, dynamic rupture models can also capture off-fault inelastic distributed fault displacements. In this project, we first validate a suite of models against well-documented case histories, and we then extend the simulations to predict displacements for scenarios and events we have not yet experienced. Our initial validation is based on the 1992 Landers M7.3 earthquake for which we compare simulations to on- and off-fault displacement data. We also perform a validation of ground motions against recordings from the event, to ensure that all physics important to modeling have been properly parameterized and that the results are defensible. In the predictive step, we aim to provide a range of expected displacements that capture several aspects of modeling uncertainties. For the Landers scenario, we developed an ensemble of spontaneous dynamic rupture models with varying imposed stresses and geometrical fault roughness profiles, resulting in a suite of 48 simulation datasets. We present the validation results and provide insight on the uncertainty of resulting ruptures including their magnitude, length, propagation velocity and displacement distributions.

Wang, Y., & Goulet, C. A. (2021, 04). Validate simulated fault displacements from dynamic rupture against the observed in the 1992 Landers earthquake. Oral Presentation at SSA 2021 Annual Meeting.