Integrating Three-Dimensional Earthquake Rupture Dynamics, Ocean Acoustic Waves and Tsunami: Effects of Inelastic Failure in the Accretionary Wedge

San Diego State University Foundation, San Diego CA

Investigators

Abstract

Shallow Subduction zones (upper 10 ? 15 km) host earthquakes on shallow-dipping plate interfaces and efficient in generating tsunami. The physics of tsunami generation from earthquake ruptures is, however, not well understood. This research will extend the researcher's previous earthquake rupture models to 3D and integrate these models with ocean acoustic waves and tsunami models. The fully coupled system of earthquake rupture and ocean acoustic waves and tsunamis provides the principal theoretical means for understanding the physics of these earthquakes and tsunami generation. These models can also be used extract useful signals that can be used in differentiating underlying mechanisms and tsunami early warning. This proposal addresses one of the major unsolved problems in earthquake mechanics: the physics of anomalous rupture characteristics and tsunamigenesis in the shallow subduction zone. Why can these earthquakes generate tsunami efficiently but radiate weak high-frequency energy? What gives rise to slow rupture velocity and low moment-scaled radiated energy? Is tsunami generated by large shallow slip near the trench, distributed inelastic deformation in the wedge, or both? Can ocean acoustic waves be used in tsunami early warning? How does time-dependent seafloor deformation affect near-field tsunami? This 3-year research project will include the following activities: (i) Develop an updated Lagrangian finite-element approach to fully couple tsunami and ocean acoustic waves with earthquake rupture in 2D and 3D, and validate it with an existing Eulerian approach. (ii) Simulate along-strike rupture propagation with and without inelastic wedge failure and examine how they may significantly affect tsunami and ocean acoustic waves. Test and extract signals that can be used in tsunami early warning. (iii) Develop dynamic rupture models of representative tsunami earthquakes and simulate waveforms to regional/teleseismic distances. Examine the resolving power of teleseismic, high-rate GPS, and tsunami data.