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

职业：日本海沟俯冲带沿线巨型逆冲地震控制的数值研究

• 批准号: 1254573
• 负责人: Benchun Duan
• 金额: $ 60万
• 依托单位: Texas A&M University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-08-01 至 2020-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1254573&HistoricalAwards=false
• 关键词: CAREER; Numerical; Investigation; Controls; Megathrust

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.

该职业项目旨在将俯冲带特大逆冲地震控制研究与地震发生和复杂性教学相结合。更好地了解 2011 年东北 M9 级地震对于我们更好地预测全球未来的特大逆冲地震至关重要。该项目旨在解决有关地震的两类问题。首先，为什么2011年的事件会这样发生？从地震/大地测量数据推断俯冲断层控制破裂扩展和滑移分布的物理条件是什么？其次，2011年的事件与此前发生的M7~8俯冲断层大事件有何关系？是什么控制着俯冲带发生不同规模的大地震？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（例如海山），在控制2011年事件和沿该俯冲带的不同规模的巨型逆冲事件中发挥着主要作用。我们建议使用具有观察约束的计算机模型来解决这些问题。我们将使用动态有限元方法代码对 2011 年事件的同震过程进行动态破裂建模，以解决第一类问题。对于第二类，我们将使用代码在俯冲带进行地震周期模拟，利用动态松弛技术，通过动态求解器获得两次相邻地震之间的准静态过程的解。我们从 2011 年 M9 事件和该项目中的俯冲带中学到的知识可以广泛应用于世界各地的俯冲带，包括北美大陆西海岸的卡斯卡迪亚俯冲带，以减轻未来特大逆冲地震和海啸的危害。正如我们所提出的，从物理角度解决这两类问题对于增进我们对特大逆冲地震生成的理解，从而预测未来沿俯冲带的特大逆冲地震极为重要。沿俯冲带的地震周期模拟程序可以作为吸收大型数据集和解决地震科学中的难题的强大工具。待开发的关于地震发生过程和复杂性的课程模块将把前沿的研究成果带入全国各地大学和高中的课堂。德克萨斯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设置将为各级教学和外展活动提供实践资源，并提高人们对地震危害的认识和对地震现象的理解。