Collaborative Research: Seismic cycles and earthquake nucleation on heterogeneous faults: Large-scale laboratory experiments, numerical simulations, and Whillans ice stream

合作研究：非均质断层上的地震周期和地震成核：大规模实验室实验、数值模拟和惠兰斯冰流

• 批准号: 2240375
• 负责人: Gregory McLaskey
• 金额: $ 44.63万
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-05-15 至 2026-04-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2240375&HistoricalAwards=false
• 关键词: Collaborative; Research; Seismic; cycles; earthquake

According to well-established theory, earthquakes may start with very slow movement (or "slip") along a fault, which suddenly accelerates to the violently rapid slip that can generate ground shaking. Slow slip has been seen before large earthquakes, but it is usually different from what the theories predict. Dr. McLaskey and his team will use laboratory experiments and computer models to measure and understand slow slip and tiny earthquakes that happen along faults before a large earthquake. In the laboratory experiments, a ten-foot slab of rock with a cut (fault) embedded in it is compressed and sheared using a giant press, making the fault creep and then slip suddenly in "laboratory" earthquakes. The experiments can test how realistic, non-uniform fault properties—like rough versus slippery sections, or bumps and bends—can play a role in providing warning signs of an impending earthquake. Computer models will be developed to understand and explain data collected during the laboratory earthquake experiments. To check how well these computer models perform, they will be tested against a large collection of data on slow pre-earthquake slip and earthquakes that are ocurring beneath a glacier in Antarctica. As part of this project, three graduate students and at least two undergraduates will receive training in earthquake science (experiments, modeling, and data analysis).Heterogeneous fault properties—bumps, bends, differing lithology, and heterogeneous loading conditions that exist at a variety of scales—are generally not considered in earthquake nucleation theories, but have been shown to strongly influence the way an earthquake initiates. On a heterogeneous fault, neighboring fault patches reach failure at different times, often resulting in the propagation of slow slip fronts that may only be detectable as a gradual decrease in seismic coupling, such as that observed prior to the M 9 Tohoku Earthquake, or from the migration and coalescence of microseismicity. This project explores the behavior of heterogeneous faults late in the earthquake cycle including the propagation of slow slip fronts and their interaction with strong/unstable asperities. These mechanisms may transform models of the way earthquakes initiate and better inform the interpretation of precursory activity. This project employs meter-scale laboratory experiments, where heterogeneous fault properties are imposed at specific locations and the effects on earthquake nucleation and triggering by slow slip fronts are studied in detail. Additionally, theoretical and numerical models for slow slip propagation on heterogeneous faults are developed to extend the laboratory results to length scales and conditions more relevant to natural earthquakes. The models are then tested against a field-scale glacial stick-slip cycle at Whillans Ice Stream, an Antarctic glacier, where aseismic transients affect 100 km-scale glacial stick-slip events and exhibit behavior similar to that observed in the lab.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.

根据良好的理论，地震可能始于断层的运动非常缓慢（或“滑动”），这突然加速到可能会产生地面摇动的迅速迅速滑动。在大地震之前已经看到了慢滑，但通常与理论预测的不同。麦克拉斯基（McLaskey）博士和他的团队将使用实验室实验和计算机模型来测量和理解大地震前发生故障的缓慢滑移和微小的地震。在实验室实验中，使用巨大的压机压缩并剪切了一块十英尺的岩石（断层）岩石（断层），使故障爬行，然后突然在“实验室”地震中滑落。这些实验可以测试逼真的，不均匀的断层特性（例如粗糙与湿滑的部分，或颠簸和弯曲），可以在提供即将发生的地震的警告迹象中发挥作用。将开发计算机模型来理解和解释实验室地震实验期间收集的数据。为了检查这些计算机型号的性能，将对它们进行大量数据的测试，这些数据集和地震缓慢地发生在南极洲的冰川下。作为该项目的一部分，三名研究生和至少两名本科生将接受地震科学（实验，建模和数据分析）的培训。HeleterenogenogentosTurnology Trupt特性（造成量表，弯曲，差异化岩性和异质载荷条件，这些条件在各种规模上都没有在各种规模上存在，但在地震构成的启动中却不在erteareation neartion neartion Teapile中受到强烈影响。在异质断层上，相邻的断层斑块在不同的时间达到失败，通常会导致慢滑动前部的传播，而慢滑动前部的传播可能只能在地震耦合中逐渐降低，例如在M 9 Toohoku地震之前观察到的，或者是从Mictheoku地震之前观察到的。该项目探讨了地震周期后期异质断层的行为，包括慢滑锋的传播以及它们与强/不稳定的垂体的相互作用。这些机制可能会改变地震发起的方式的模型，并更好地告知对前期活动的解释。该项目采用了仪表尺度实验室实验，在特定位置施加了异质断层特性，并详细研究了对地震成核和慢速滑移前部触发的影响。此外，开发了用于异质断层的缓慢滑移传播的理论和数值模型，以将实验室结果扩展到与自然地震更相关的长度尺度和条件。然后，在南极冰川Whillans Ice流的现场尺度冰川滑移周期中对模型进行测试，在该冰川上，Aseismic瞬态影响100 km级的冰川棒滑雪事件，与实验室中观察到的相似的暴露行为相似。该奖项在NSF的法定任务中反映了NSF的法定任务，并通过评估了CRARIA的支持。