Group A, Poster #125, Fault and Rupture Mechanics (FARM)

Dynamic off-fault failure and tsunamigenesis at strike-slip restraining bends: Fully-coupled models of dynamic rupture, ocean acoustic waves, and tsunami in a shallow bay

Shuo Ma
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Poster Presentation

2022 SCEC Annual Meeting, Poster #125, SCEC Contribution #11899 VIEW PDF
Inelastic off-fault deformation can lead to large tsunamigenesis in different tectonic settings. Here a mechanism for tsunami generation by strike-slip earthquakes that involves dynamic off-fault failure at restraining bends is presented. Dynamic rupture on a vertical strike-slip fault is modeled with undrained inelastic off-fault response incorporated by the Drucker-Prager yield criterion. I show that in a local transpressive stress regime dynamic off- fault failure at restraining bends produces significantly larger and more localized surface uplift than is produced by purely elastic dislocation models, resulting in a positive flower and coseismic pop-up structure. The larger uplift is due ...to frictional sliding with a thrust component on conjugate microfractures, modeled by inelastic deformation. The short-wavelength inelastic uplift, largely controlled by bend size, is shown to generate localized tsunami efficiently in a shallow bay by fully coupling dynamic rupture, ocean acoustic waves, and tsunami. Fully-coupled models also indicate that supershear rupture on a vertical planar strike-slip fault does not generate large tsunami as the large kinetic energy of supershear rupture is carried away by ocean acoustic waves. Dynamic off-fault failure at fault complexities, such as restraining bends and compressional stepovers, may need be urgently incorporated in the current tsunami hazard assessments in strike-slip environments.

This work is published in the following paper:

S. Ma, Dynamic off-fault failure and tsunamigenesis at strike-slip restraining bends: Fully-coupled models of dynamic rupture, ocean acoustic waves,and tsunami in a shallow bay, Tectonophysics (2022), https://doi.org/10.1016/j.tecto.2022.229496
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Citation: Ma, S. (2022, 09). Dynamic off-fault failure and tsunamigenesis at strike-slip restraining bends: Fully-coupled models of dynamic rupture, ocean acoustic waves, and tsunami in a shallow bay. Poster Presentation at 2022 SCEC Annual Meeting.
Keywords: restraining bends, off-fault plasticity, strike-slip earthquakes, tsunamigenesis
Relevant SCEC Themes:
Beyond Elasticity
Modeling Earthquake Source Processes
Risk to Distributed Infrastructure