Collaborative Research: The rheological behavior of gouge at high temperature

合作研究：高温下凿岩的流变行为

• 批准号: 2240735
• 负责人: Heather Savage
• 金额: $ 10.16万
• 依托单位: University of California-Santa Cruz
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-07-01 至 2026-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2240735&HistoricalAwards=false
• 关键词: Collaborative; Research; rheological; behavior; gouge

Major earthquakes are generated along faults in Earth’s tectonic plates as rocks are sheared past each other. Assessing the hazard associated with a fault zone requires understanding the conditions that promote earthquake nucleation. Shearing on faults can occur in an unstable manner, where rapid slip allows an earthquake to nucleate, or in a stable manner, where slip is steady and suppresses earthquake nucleation. Although much work has been devoted to understanding the conditions that lead to earthquake nucleation in the relatively cold portions of Earth’s crust, there is still a considerable gap in knowledge regarding the stability of faults in hotter regions. These hotter regions include the conduits of explosive volcanoes and transform faults in the oceans. Our work will determine the influence of temperature on fault stability to enable accurate assessments of hazard and risk in these regions. This work will also provide training to early-career researchers at the postdoctoral, graduate, and undergraduate levels. The team involved in this research will also work to introduce high-temperature experimental rock physics to groups typically underrepresented in the sciences via international conferences, and they will run a short-course on earthquakes and faulting to be offered to early-career researchers around the world in an in-person and virtual format.We will specifically answer three questions related to fault stability at high temperatures. First, how do extreme temperatures affect the strength and stability of fault materials? To answer this question, we will conduct deformation experiments on fault materials over a wide range of conditions. Second, what microscopic mechanisms control the strength of fault materials, and how do they compete with one another? To answer this question, we will use high-resolution microscopy to compare mechanical measurements with theoretical models based on the microphysics of rock deformation. Third, how do these mechanisms interact to determine fault stability, and what does this mean for the depth range of earthquakes in natural settings? To answer this question, we will assess the relationships among microscopic features, the macroscopic strength, the observed stability, and the rate of deformation. The net result of these observations will be a refined model for the stability of fault zones at high temperatures, which we will then compare to available catalogs of earthquake locations in relatively “hot” regions to test our predictions of the depth range of earthquake nucleation.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.

由于岩石彼此剪切，沿着地球构造板的断层产生了主要地震。评估与断层区相关的危害需要了解促进地震成核的条件。在断层上进行剪切可能以不稳定的方式发生，在这种情况下，快速滑移允许地震到核，或以稳定的方式进行核，其中滑动稳定并抑制地震成核。尽管已经致力于了解导致地球地壳相对冷的相对寒冷部分地震成核的条件，但仍然考虑到较热区域中断层的稳定性仍然存在差距。这些较热的区域包括爆炸火山的吊带和转化海洋中的断层。我们的工作将确定温度对故障稳定性的影响，以便对这些地区的危害和风险进行准确评估。这项工作还将为博士后，研究生和本科生的早期研究人员提供培训。参与这项研究的团队还将致力于通过国际会议向科学中通常不足的小组介绍高温实验摇滚物理学，他们将在地震上进行简短的地震，并为世界各地的早期研究人员提供过失，以面对面和虚拟的方式为世界各地的早期研究人员提供。首先，极端温度如何影响断层材料的强度和稳定性？为了回答这个问题，我们将在各种条件下对故障材料进行变形实验。其次，哪些微观机制控制了断层材料的强度，它们如何相互竞争？为了回答这个问题，我们将使用高分辨率显微镜将机械测量与基于岩石变形的微物理学的理论模型进行比较。第三，这些机制如何相互作用以确定断层稳定性，这对自然环境中地震的深度范围意味着什么？为了回答这个问题，我们将评估微观特征，宏观强度，观察到的稳定性和变形速率之间的关系。这些观察结果的最终结果将是高温下断层区域稳定性的精制模型，然后我们将其与相对“热”区域中地震位置的可用目录进行比较，以测试我们对地震深度范围的预测，这是NSF的法定任务，反映了通过评估的范围来弥补的范围。