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: 2319848
• 负责人: Demian Saffer
• 金额: $ 27.27万
• 依托单位: University of Texas at Austin
• 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=2319848&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.

在过去的二十年里，俯冲带断层滑动速度的广泛发现——从缓慢的构造速率蠕变到阵发性震颤和滑动，再到快速地震——引发了一个新兴的新研究方向，重点是了解导致断层的物理机制。快速或缓慢滑动，以及较慢的滑动如何可能与大型破坏性地震和海啸相互作用。提高我们对俯冲断层和地震力学的了解需要对板块的变形行为进行定量和全面的研究。断层内的物质和周围围岩的变形已被证明是应力、温度、应变率和岩石类型的函数，同时，由于断层的变化，断层带内的不均匀性。沿断层的岩石类型和条件已成为解释慢地震和慢滑移事件发生的主要假设，因此，量化俯冲带岩石的变形行为已成为实验学家不断努力的方向。通过实验和数值模型，这项研究将具体解决两个问题首先，沿着巨型逆冲断层的流变性及其非均质性如何影响断层滑动行为？第二，断层上和断层外的非弹性变形如何影响应变能积累以及锁定和滑动的发生和分布？对在地震开始的深度存在的压力和温度下变形的俯冲带岩石进行的实验数据将为数值模型提供信息，该模型可以弥合沿断层的不均匀性。这项工作的最终结果将是新的。该项目将支持包括本科生和研究生、博士后以及两名早期职业 PI 在内的早期职业科学家的定量培训。使用新开发的代码对俯冲带流变学进行建模的短期课程将作为一组短视频公开发布，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 的法定使命。和通过使用基金会的智力价值和更广泛的影响审查标准进行评估，该项目被认为值得支持。