Physics-based simulations of Cascadia earthquake rupture and tsunamis
Yihe Huang
University of Michigan
- Date & Time
- Location
- Online-only seminar via Microsoft Teams
- Host
- Annemarie Baltay Sundstrom
- Summary
The Cascadia subduction zone is considered to pose great earthquake and tsunami hazards in the Pacific Northwest, but we have a limited understanding about where the earthquake will initiate and how large the earthquake magnitude and tsunami amplitudes can be. I will present physics-based simulations of Cascadia earthquake rupture and tsunamis to discuss the important parameters used to constrain the simulations and their implications. We show in 2-D dynamic rupture simulations that given our current understanding of the shear stress rate in the gap region it is unlikely for Northern Cascadia rupture to stop right above the gap region. By developing for the first time 3-D dynamic Cascadia rupture simulations, we find the level of interseismic shear stress accumulation in the central Cascadia and in the shallow region near trench controls the final rupture size of Cascadia earthquakes. Our rupture simulations can provide a reasonable fit to the 1700 A.D. coastal subsidence data using different combinations of locking depths and initial shear stress distribution. We also use geodetic coupling models and earthquake rupture properties to constrain tsunami simulations of M7.5–9.2 Cascadia earthquakes. While it is often believed that the worst-case tsunami scenario results from the largest M9 earthquake, our results highlight the importance of considering M>8.5 earthquakes for tsunami hazard mitigation, as they can create comparable coastal tsunami amplitudes due to the focusing effect of the concave coastline geometry near Oregon.
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