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

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

Published September 10, 2023, SCEC Contribution #12830, 2023 SCEC Annual Meeting Poster #105

In this project, we form a modeling group targeting improving methods of simulating earthquake ground motions for seismic hazard applications using dynamic rupture simulations. We aim to determine conditions that make broadband synthetic ground motions more reliable in a broader effort towards supplementing empirical models with simulation-derived information. Each modeler within our group uses their preferred simulation code to generate ruptures across a range of magnitudes and computes the resulting ground motions at a selection of spectral acceleration periods. We focus on near-source distances, where observed ground motion data is lacking, and generate a suite of dynamic rupture simulations at periods relevant to engineering applications. We generate ruptures along strike-slip faults, but we anticipate the approach being extended to other styles of faulting moving forward.

Within this group’s study, we evaluate how earthquake rupture characteristics effect the rupture process, and ultimately influence ground motion behavior. The resulting broadband ground motions are pooled and compared with trends of period and distance with leading empirical ground motion models (GMMs). We analyze characteristics from each modeler individually, as well as with reference to the entire group's average synthetic trends, comparing both the synthetic median and ground motion variability terms, isolated in terms of both intra- and inter-event standard deviations. We find that the aggregate level of ground motion for an active tectonic region compares well using GMMs in terms of both distance decay and median ground motion at long and intermediate periods (e.g., 0.3-1 s). We observe that intra-event variability fluctuates widely with distance, resulting from azimuthal changes in ground motion amplification. As part of this work, we have initiated the creation of a synthetic ground motion database, compiling the ground motion metrics generated here into a uniform format, to provide access and straight-forward selection of records from synthetic events.

Key Words
dynamic rupture, ground motion, validation

Citation
Withers, K. B., Ma, S., Ulrich, T., Gabriel, A., Ampuero, J., Oral, E., Dalguer, L. A., Wang, Y., Goulet, C. A., Duan, B., Liu, D., & Asimaki, D. (2023, 09). Near Source High-Frequency Ground Motions from Physics-based Dynamic Rupture Simulations. Poster Presentation at 2023 SCEC Annual Meeting.

Related Projects & Working Groups
Fault and Rupture Mechanics (FARM)