Deciphering the influence of rock properties on fault rupture mechanics

地震是调节断层运动的主要机制。地震破裂的传播速度是决定相关地震危险性的关键参数。最近的观察表明，破裂速度发生在一个连续的时间尺度上，但人们对地震发生的断层的物理条件如何控制破裂速度，从而控制地震危险性知之甚少。本研究项目旨在长期研究断层表面的哪些物理因素，如岩石成分、破坏程度、流体浓度等，对控制破裂速度最为关键，从而更好地评估地震对社会造成的风险，减轻地震危害。

Earthquakes are the dominant mechanism accommodating motion on faults. The speed at which an earthquake rupture propagates is the key parameter determining associated seismic hazard. Recent observations suggest that rupture speed occurs over a continuum of time scales, but there is little understanding of how the physical conditions on the fault where an earthquake occurs control rupture speed, and thus, seismic hazard. This research program aims over the long term to study what physical factors on the fault surface, such as rock composition, degree of damage, concentration of fluids, etc., are most critical to controlling rupture speed, so that we can better assess the risk to society posed by earthquakes, and mitigate seismic hazard. Over the next five years, the proposed research program will concentrate on resolving rupture behavior in the context of bulk fault frictional properties by addressing a critically important question: How do changing frictional properties with depth modulate the rupture velocity on a fault? To address this question, research efforts will be concentrated in three main areas that investigate rupture speed and its relation to fault surface friction over the shallow (< 2 km), intermediate (2-15 km), and deep (15-35 km) portions of fault zones. The program will have a broad impact on the mechanistic understanding of earthquake rupture physics on a basic scientific level, and will provide practical tools for better anticipating and assessing seismic hazard in Canada, and elsewhere. Current methods for estimating seismic hazard are based on limited empirical observations of ground motion with a wide range of outliers, and lack fundamental information about the earthquake rupture itself. Quantifying the link between changing frictional differences on fault surfaces and the changes in earthquake rupture properties is key to developing better seismic hazard estimates. This program will help improve seismic hazard assessment and subsequent societal risk by linking fault properties to rupture speed. In particular, it will contribute to better hazard assessment of anthropogenically induced earthquakes, an increasing concern in Canada due to the proliferation of non-conventional oil and gas recovery techniques.