Further Validation of a Dynamic Heterogeneous Stress Drop Model to Predict Near-Field Ground Motion for Strike-Slip Earthquakes

Shuo Ma

Published September 8, 2024, SCEC Contribution #13638, 2024 SCEC Annual Meeting Poster #187

The heterogeneous stress drop model that is self-similar, with short-wavelength components tied with rupture length, provides a remarkable fit to the near-field ground motion from Mw 7 earthquakes (Andrews and Ma, 2016). However, for events smaller than Mw 7 with smaller rupture areas (including buried ruptures), the model was found to underestimate high-frequency ground motion. An ad-hoc way of specifying the spatial spectrum for fault aspect ratio was used in previous work. Here I improve the method by rigorously specifying the spatial spectrum for any rupture dimensions and extend the model for smaller magnitudes. Good fits to the GMM for Mw 6.5 and Mw 6.0 events in the frequency range up to 3 Hz are shown. Stress needs to drop as abruptly as possible at rupture front in the numerical scheme. Low-velocity fault zone is also found to contribute to the overall fitting to the GMM for small magnitudes.

Citation
Ma, S. (2024, 09). Further Validation of a Dynamic Heterogeneous Stress Drop Model to Predict Near-Field Ground Motion for Strike-Slip Earthquakes. Poster Presentation at 2024 SCEC Annual Meeting.

Related Projects & Working Groups
Ground Motions (GM)