Collaborative Research: Subduction Megathrust Rheology: The Combined Roles of On- and Off-Fault Processes in Controlling Fault Slip Behavior

合作研究：俯冲巨型逆断层流变学：断层上和断层外过程在控制断层滑动行为中的综合作用

• 批准号: 2319849
• 负责人: Caroline Seyler
• 金额: $ 9.12万
• 依托单位: University of Southern California
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-01-01 至 2026-12-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2319849&HistoricalAwards=false
• 关键词: Collaborative; Research; Subduction; Megathrust; Rheology

Over the past two decades, the discovery of a broad spectrum of fault slip speeds in subduction zones – from slow tectonic rate creep to episodic tremor and slip to fast earthquakes - has ignited a burgeoning new research direction focused on understanding the physical mechanisms that cause faults to slip fast or slow, and how slower slip might potentially interact with large destructive earthquakes and tsunamis. Advancing our knowledge of subduction fault and earthquake mechanics requires a quantitative and holistic investigation of the deformation behavior of the plate boundary system. The deformation of both material within the fault and the surrounding wall rocks has been shown to be a function of stress, temperature, strain rate, and rock type. At the same time, heterogeneity in the fault zone, due to variations in rock type and conditions along the fault, has emerged as a leading hypothesis to explain the occurrence of slow earthquakes and slow slip events. Therefore, quantifying the deformation behavior of subduction zone rocks has been a growing endeavor for experimentalists.Through experiments and numerical models, this research will specifically address two questions. First, how does rheology along the megathrust - and its heterogeneity - affect fault slip behavior? Second, how does inelastic deformation on- and off-fault affect strain energy accumulation and the occurrence and distribution of locking and slip? New experiments will be conducted on subduction zone rocks that are deformed under pressures and temperatures present at the depths where earthquakes begin. The experimental data will inform numerical models that can bridge scales to include heterogeneity along the fault. The net result of this work will be new quantitative insights into the roles of spatial heterogeneity and rheology in subduction systems over a range of timescales. The project will support training of early career scientists including undergraduate and graduate students, postdocs, and two early career PIs. In addition, the project will develop a modeling short course for subduction zone rheology using newly developed codes. The lessons from the short course will be made publicly available as a set of short videos that include instructions for using the codes as a pathway to maximize their accessibility.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

Over the past two decades, the discovery of a broad spectrum of fault slip speeds in subduction zones – from slow tectonic rate creep to episodic tree and slip to fast earthquakes - has ignited a burgeoning new research direction focused on understanding the physical mechanisms that cause faults to slip fast or slow, and how slower slip might potentially interact with large destructive earthquakes and tsunamis.促进我们对俯冲断层和地震力学的了解需要对板边界系统变形行为进行定量和整体投资。在断层和周围的壁岩石内两种材料的变形已被证明是压力，温度，应变速率和岩石类型的函数。同时，由于岩石类型和沿断层条件的变化，断层区的异质性已成为一种主要假设，可以解释地震慢和慢速事件的发生。因此，量化俯冲带岩石的变形行为一直是实验者的努力。通过实验和数值模型，这项研究将特别解决两个问题。首先，沿着大型质量及其异质性的流变学如何影响断层滑移行为？其次，非弹性变形对应变能积累以及锁定和滑动的发生和分布如何？将在俯冲带岩石上进行新实验，这些岩石在地震开始的深度处的压力和温度下变形。实验数据将告知数值模型，该模型可以桥接尺度以包括沿断层的异质性。这项工作的最终结果将是对空间异质性和流变系统在俯冲系统中在一系列时间尺度上的作用的作用的新定量见解。该项目将支持对早期职业科学家的培训，包括本科生和研究生，博士后和两个早期职业生涯。此外，该项目将使用新开发的代码开发俯冲带的简短课程。简短课程的课程将作为一组简短的视频公开提供，其中包括使用代码作为最大化其可访问性的途径的说明。该奖项反映了NSF的法定任务，并被认为值得通过基金会的知识分子优点和更广泛的影响标准通过评估来进行评估。