Near Source High-Frequency Ground Motion from Physics-based Dynamic Earthquake Rupture Simulations

Kyle B. Withers, Shuo Ma, Yongfei Wang, Thomas Ulrich, Dunyu Liu, Benchun Duan, Alice-Agnes Gabriel, Elif Oral, Luis A. Dalguer, Christine A. Goulet, Domniki Asimaki, & Jean-Paul Ampuero

Published September 11, 2022, SCEC Contribution #12108, 2022 SCEC Annual Meeting Poster #217

This work uses a group modeling approach to simulate ground motions from physics-based dynamic earthquake rupture simulations. Our purpose is to supplement sparse empirical ground motion data, to ultimately help inform seismic hazard assessment. Using a collaborative approach composed of six modeling groups, we focus our efforts at near-source distances, comparing simulated metrics with empirical predictions at frequencies up to ~3 Hz. We begin with an analysis of our synthetic results compared with ground motion models (GMMs) and are compiling a database of source ruptures and corresponding synthetic ground motion information for use in engineering efforts and other research studies.

We first focus on strike-slip earthquakes, across a magnitude range where the ruptures are spontaneously nucleated, allowing ruptures to die-out naturally. Each modeling group uses their preferred method of initial friction, fault geometry, and stress conditions to simulate ruptures, but we impose common constraints of some predictor variables (such as site conditions), to enable uniform comparison with empirical models. This method allows a diverse set of ruptures and ground motions and highlights the impact of various choices of parameter combinations on ground motion trends. We are finding that the averaged ground motion results have similar characteristics with that of predicted GMMs, including distance trends at both long and short distances from the simulated earthquakes. The median and within-event variability of the data are analyzed, and generally found to be consistent across the modeling groups, with variations correlated with choice of individual modelers’ initial conditions. This finding illuminates the importance of considering multiple source characteristics in the earthquake source generation, and further motivates continued exploration of various input conditions that impact both median and variability. We are continuing to note inconsistencies in behavior across the modeling results, towards helping guide selection of parameters in simulation setup.

Citation
Withers, K. B., Ma, S., Wang, Y., Ulrich, T., Liu, D., Duan, B., Gabriel, A., Oral, E., Dalguer, L. A., Goulet, C. A., Asimaki, D., & Ampuero, J. (2022, 09). Near Source High-Frequency Ground Motion from Physics-based Dynamic Earthquake Rupture Simulations . Poster Presentation at 2022 SCEC Annual Meeting.

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