Collaborative Research: Laboratory and Theoretical Investigations of the Micro-Mechanical Origins of Rate and State Friction on Tectonic Faults

在地震周期中，由于地球板块构造运动，构造断层缓慢积累应力。然后在地震中灾难性地失败。 模拟地震周期的关键之一是摩擦定律，它既可以应用于地震的快速动态运动，因为断层岩石在摩擦接触中相互摩擦和滑动，也可以应用于地震之间可能需要数百年的缓慢应力积累过程。在普林斯顿大学和宾夕法尼亚州立大学之间的这项合作工作中，将对摩擦滑动进行异常良好的控制测量，同时收集滑动界面和断层泥剪切层的超声波数据。所提出的工作具有重要的社会意义的地震灾害评估，地震预报，并改善，地震nucleation.Rate-and-State摩擦定律的基本理解代表了目前国家的最先进的在实验室和地震物理的数值模拟，包括成核，动态破裂和完整的地震周期。 然而，我们对摩擦记忆效应和滑动速度依赖性的理解仍然主要是经验性的，这限制了我们将实验室测量应用于地震断层和/或解决与从实验室测量预测构造断层行为相关的问题的能力。 为了解决这些缺点，最近在滑动岩石表面和剪切粒状断层泥的超声波监测的进展将提供基本的洞察到构造断层的摩擦行为的物理和微观力学起源。

In the earthquake-cycle, tectonic faults slowly accumulate stress, due to plate tectonic motion of Earth?s surface, and then fail catastrophically in earthquakes. One of the keys to simulating the earthquake cycle are friction laws that can be applied to both the fast, dynamic motion of earthquakes, as fault rocks rub and slide past one another in frictional contact, and the slow processes of stress accumulation between earthquakes that can take hundreds of years. In this collaborative work between Princeton and Penn State Universities, unusually well-controlled measurements of frictional sliding will be conducted while collecting simultaneous ultrasonic data on the sliding interfaces and sheared layers of fault gouge. The proposed work has important societal implications for seismic hazard assessment, earthquake forecasting, and an improved, fundamental understanding of earthquake nucleation.Rate-and-state friction laws represent the current state-of-the-art in the laboratory and for numerical simulations of earthquake physics, including nucleation, dynamic rupture and the complete seismic cycle. However, our understanding of friction memory effects and slip velocity dependence remains primarily empirical, which limits our ability to apply laboratory measurements to earthquake faults and/or to address the problems associated with predicting the behavior of tectonic faults from laboratory measurements. To address these shortcomings, recent advances in ultrasonic monitoring of sliding rock surfaces and sheared granular fault gouge will provide fundamental insights into the physics and micro-mechanical origins of frictional behavior of tectonic faults.