The Effect of Kinematic Earthquake Rupture on Near-Field Hazards Along the Cascadia Subduction Zone
Abstract
Due to its historic scarcity of large earthquakes, the Cascadia Subduction Zone is a challenging environment for studying both the expected ground motion on land and the coastal effects of potential tsunamis. While forecasting the rupture extent of future earthquakes is always an imperfect study, the long rupture of the 1700 Cascadia earthquake leads to the possibility of future events of a similar size. Past studies have explored the effects of varying fault parameters on tsunami generation, however little has been explored on the role of kinematic rupture on tsunami propagation, particularly in the near field for large (M8+ earthquakes). For the purposes of tsunami modeling, seismically generated deformation is commonly handled as an instantaneous perturbation to the water column. While this approach is sufficient for small ruptures, the Cascadia Subduction Zone has the possibility of rupturing with lengths exceeding 800 km. The long rupture, both spatially and temporally, allows for an assessment of the effects of a kinematic rupture and the comparison with traditional static models. We illustrate the effect of kinematic rupture on the near-field coastal response first through a simplified megathrust environment, and then using a large database of realistic megathrust events along Cascadia. Synthetic events range in magnitude, size, and rupture duration allowing for the exploration of how these factors are affected in the near-field. We identify how the kinematic rupture affects the open-ocean directivity of tsunami energy, and its effect on coastal tsunami amplitudes in the near-field. We merge these observations with the expected peak ground motion on land to provide a comprehensive picture of earthquake hazards for large Cascadia megathrust events.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.T24B..04W
- Keywords:
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- 8118 Dynamics and mechanics of faulting;
- TECTONOPHYSICSDE: 8170 Subduction zone processes;
- TECTONOPHYSICSDE: 8180 Tomography;
- TECTONOPHYSICSDE: 8185 Volcanic arcs;
- TECTONOPHYSICS