CAREER: Numerical Investigation of Controls on Megathrust Earthquakes Along the Japan Trench Subduction Zone
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This career project is to integrate research in controls on megathrust earthquakes along subduction zones with teaching in earthquake generation and complexity. A better understanding of the 2011 M9 Tohoku (Japan) earthquake is critical for us to do a better job in forecasting future megathrust earthquakes worldwide. This project aims to address two categories of questions about the earthquake. First, why did the 2011 event happen in the way it did? What physical conditions on the subducting fault control features in rupture propagation and slip distribution inferred from seismic/geodetic data? Second, what is the relationship between the 2011 event and previous large events of M7~8 on the subducting fault? What control generation of large earthquakes of different sizes along the subduction zone? We hypothesize that geometrical complexities on the subducting plane, including bends/kinks of the subducting plane and subducted seafloor features such as seamounts, play the primary role in controlling the 2011 event and megathrust events of different sizes along this subduction zone. We propose to use computer models with constraints from observations to address these questions. We will use a dynamic finite element method code to perform dynamic rupture modeling of the co-seismic process of the 2011 event to address the first category of questions. For the second category, we will use the code to perform earthquake cycle simulations at the subduction zone, with the dynamic relaxation technique to obtain solutions for the quasi-static processes between two adjacent earthquakes by the dynamic solver.What we learn from the 2011 M9 event and the subduction zone in this project can be applied broadly to subduction zones worldwide, including the Cascadia subduction zone along the west coast of the North America continent, to mitigate hazards from future megathrust earthquakes and tsunamis. Addressing the two categories of questions from a physical point of view as we propose is extremely important in advancing our understanding of generation of megathrust earthquakes, and thus in forecasting future megathrust earthquakes along subduction zones. The procedure for earthquake cycle simulations along subduction zones may serve as a powerful tool to assimilate large datasets and to address difficult questions in earthquake science. Course modules on earthquake generation processes and complexities to be developed will bring cutting-edge research results into classrooms of colleges and high schools across the nation. Installation and operation of a seismometer and setup of physical models of spring-slider systems at Texas A&M University will provide hands-on resources for teaching and outreach activities at various levels, and promote awareness of earthquake hazards and understanding of earthquake phenomena.