CAREER: Numerical Investigation of Controls on Megathrust Earthquakes Along the Japan Trench Subduction Zone

这个职业计划是整合研究控制大逆冲断层地震沿着俯冲带与教学地震的生成和复杂性。更好地了解2011年M9东北（日本）地震对于我们更好地预测全球未来的大推力地震至关重要。本项目旨在解决有关地震的两类问题。首先，为什么2011年的事件会以这样的方式发生？从地震/大地测量资料推断，俯冲断层控制破裂传播和滑动分布特征的物理条件是什么？第二，2011年地震与俯冲断层上的7 ~8级大地震有何关系？是什么控制着俯冲带沿着不同规模大地震的发生？我们假设，俯冲平面上的几何复杂性，包括俯冲平面的弯曲/扭结和俯冲海底特征，如海山，在控制2011年事件和沿着该俯冲带的不同大小的巨型逆冲断层事件中发挥主要作用。我们建议使用计算机模型的约束，从观察来解决这些问题。我们将使用动态有限元方法代码来执行2011年事件的同震过程的动态破裂建模，以解决第一类问题。对于第二类，我们将使用该代码在俯冲带进行地震周期模拟，通过动态松弛技术获得两个相邻地震之间的准静态过程的动态求解器的解决方案。我们从2011年M9事件和本项目中的俯冲带中学到的知识可以广泛应用于全球俯冲带，包括北美大陆西海岸沿着的卡斯卡迪亚俯冲带，以减轻未来巨型逆冲断层地震和海啸的危害。从物理学的角度来解决这两类问题，对于我们进一步理解逆冲断层地震的产生，进而预测未来沿着俯冲带的逆冲断层地震，是极其重要的。沿着俯冲带的地震周期模拟程序可以作为同化大型数据集和解决地震科学难题的有力工具。关于地震生成过程和复杂性的课程模块将把尖端的研究成果带到全国各地的大学和高中的课堂上。得克萨斯州农工大学地震仪的安装和操作以及弹簧滑块系统物理模型的建立将为各级教学和外联活动提供实践资源，并促进对地震危害的认识和对地震现象的理解。

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.