Generation of Broadband Ground Motion from Dynamic Rupture Simulations: A Group Modeling Approach towards better Characterizing Seismic Hazard for Engineering Applications

Kyle B. Withers, Yongfei Wang, Thomas Ulrich, Alice-Agnes Gabriel, Benchun Duan, Dunyu Liu, Jean-Paul Ampuero, Elif Oral, Luis A. Dalguer, Frantisek Gallovic, Lubica Valentova, & Domniki Asimaki

Submitted September 8, 2024, SCEC Contribution #13648, 2024 SCEC Annual Meeting Poster #185

We employ three-dimensional dynamic rupture simulations to generate a database of synthetic, broadband ground motions over a range of earthquake magnitudes, involving a large group of modelers using different numerical approaches and computational implementations. In regions with limited empirical observations, physics-based synthetic ground motions like these can provide additional records that may help to improve the accuracy of seismic hazard analysis. The simulated ground motions presented here resolve frequencies up to 3 Hz for strike-slip faults, with a future plan to extend to dip-slip faults. This multi-year effort focuses on the source component that influences ground motions in a one-dimensional layered media, so we constrain our initial comparison to near-source distances, where the effect of anelastic attenuation is minimal. We bin the ground motions from our simulated datasets as a function of period and distance from the fault to evaluate the overall amplitude and trends with empirically-based ground motion models (GMMs). The median and variability of the ground motions from each modeling group are compared both individually and collectively. There is generally good agreement among the synthetic ground motions trends with empirical GMMs at periods shorter than 1 s, with some approaches underestimating spectral amplitudes at the higher frequencies. We separate the total standard deviation into the intra- and inter-event terms, permitting deeper insight into the effects of various ground motion amplification components, such as azimuthal variations in the ground motion. We extended our analysis this beyond the typical peak intensity values (PGA/PGV/PSA) and included an additional metric related to duration, CAV (cumulative absolute velocity). Additionally, we compared dynamic rupture synthetics with observed records from the 2023, Kahramanmaraş, Turkey events, finding that the synthetic ground motions capture shape and amplitude of recorded ground-motion pulses well between 0.01-1Hz, but lack in reproducing variability in pulse orientation. This collection of synthetic ground motions has the potential to be useful for a wide variety of users, for both research and engineering applications. An overarching goal is the development of a uniform processing framework, to facilitate distribution of synthetic ground motions and their associated metadata in an open web-service based browser.

Key Words
dynamic rupture, ground motion, validation

Citation
Withers, K. B., Wang, Y., Ulrich, T., Gabriel, A., Duan, B., Liu, D., Ampuero, J., Oral, E., Dalguer, L. A., Gallovic, F., Valentova, L., & Asimaki, D. (2024, 09). Generation of Broadband Ground Motion from Dynamic Rupture Simulations: A Group Modeling Approach towards better Characterizing Seismic Hazard for Engineering Applications. Poster Presentation at 2024 SCEC Annual Meeting.

Related Projects & Working Groups
Ground Motions (GM)