Deterministic ground motions from an earthquake simulator consistent with NGA-West2 ground motion models

Bruce E. Shaw, Kevin R. Milner, Scott Callaghan, Christine A. Goulet, & Fabio Silva

Published September 10, 2023, SCEC Contribution #13014, 2023 SCEC Annual Meeting Poster #184

We use the deterministic earthquake simulator RSQSim to generate complex sequences of ruptures on fault systems used for hazard assessment. We show that the source motions combined with a wave-propagation code create surface ground motions that fall within the range of epistemic uncertainties for the NGA-West2 set of empirical models. The deterministic physics-based approach provides an opportunity for better understanding the physical origins of ground motions. For example, we find that reduced stress drops in shallow layers relative to constant stress drop with depth lead to peak ground velocities in the near field that better match empirical models. The simulators may also provide better extrapolations into regimes that are poorly empirically constrained by data, because physics, rather than data parameterizations, is underlying the extrapolations. Examples include ground motion radiation patterns and directivity for complex multi-fault ruptures, each relevant to modern hazard assessments.

Key Words
Earthquake simulator, ground motion models, deterministic ground motions

Citation
Shaw, B. E., Milner, K. R., Callaghan, S., Goulet, C. A., & Silva, F. (2023, 09). Deterministic ground motions from an earthquake simulator consistent with NGA-West2 ground motion models. Poster Presentation at 2023 SCEC Annual Meeting.

Related Projects & Working Groups
Ground Motions