Using dynamic rupture simulations to improve ground motion models for normal-slip earthquakes

Yair Franco, & Daniel T. Trugman

Submitted August 30, 2026, SCEC Contribution #15135, 2026 SCEC Annual Meeting Poster #TBD

Normal-slip earthquakes are a regular occurrence in the Intermountain West region of the United States. Hazard assessments such as the 2023 National Seismic Hazard Model (NSHM) require the capacity to accurately predict the range of possible ground motions expected during future earthquakes. However, the ground motion data that informs the current NSHM ground motion models (GMMs) is scarce in normal-faulting earthquake observations. Near-fault recordings of large earthquakes are particularly rare. Numerical simulations are sometimes used to provide complementary information for GMMs used in the NSHM, but typically neglect normal-slip earthquakes in favor of reverse-faulting events. This presents an issue of potential mischaracterization of seismic hazard in areas close to normal faults. Here we use SeisSol, a dynamic rupture simulation and wave propagation software package, to study the near-fault ground motion behaviors of normal-slip earthquakes. We analyze differences in intensity and distribution of motion emitted by normal and reverse-slip events of varying fault dips. We also run simulations incorporating a 3D velocity model for the Reno-Carson City area in Western Nevada, an environment with low-velocity basins bounded by active normal faults. We find that for shallowly dipping faults, the strongest horizontal ground motions are concentrated on the footwall side of the fault, while for steeply dipping faults, the strongest ground motions are on the hanging wall side. In simulations incorporating basin effects, we find that dynamic rupture behaviors can vary drastically at shallow depths depending on the density and stress conditions of the surrounding material. These dynamic phenomena affect maximum simulated ground motion intensities. Our results indicate that the dynamics of normal-slip earthquake ruptures can cause a significant effect on maximum ground motion, complicating ground motion prediction in the near-fault regime. This work emphasizes the importance of considering the underlying physics of earthquake rupture in developing next-generation ground motion models.

Key Words
ground motion models, simulation, normal fault, dynamic rupture

Citation
Franco, Y., & Trugman, D. T. (2026, 08). Using dynamic rupture simulations to improve ground motion models for normal-slip earthquakes. Poster Presentation at 2026 SCEC Annual Meeting.

Related Projects & Working Groups
Ground Motions (GM)