Deciphering the influence of rock properties on fault rupture mechanics

地震是调节断层运动的主要机制。地震破裂传播的速度是决定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，但很少有人了解如何在断层上的物理条件发生地震控制破裂速度，从而，地震的危险性。这项研究计划旨在长期研究断层表面的物理因素，如岩石成分、损害程度、流体浓度等，对控制破裂速度至关重要，这样我们就可以更好地评估地震对社会造成的风险，减轻地震灾害。 在接下来的五年里，拟议的研究计划将集中在解决破裂行为的背景下，通过解决一个至关重要的问题：如何改变摩擦特性与深度调制破裂速度的故障？为了解决这个问题，研究工作将集中在三个主要领域，调查断裂带的浅（< 2公里）、中间（2-15公里）和深（15-35公里）部分的断裂速度及其与断层面摩擦的关系。该计划将对地震破裂物理学的基本科学水平的机械理解产生广泛的影响，并将为更好地预测和评估加拿大和其他地方的地震危险提供实用的工具。目前估计地震危险性的方法是基于有限的地面运动的经验观测与范围广泛的离群值，并缺乏有关地震破裂本身的基本信息。量化断层面摩擦力差异变化与地震破裂性质变化之间的联系，是更好地进行地震危险性评估的关键。该计划将通过将断层特性与破裂速度联系起来，有助于改善地震危险性评估和随后的社会风险。特别是，它将有助于更好地评估灾害性地震的危害，由于非常规石油和天然气开采技术的扩散，这在加拿大越来越令人关切。

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.