Faulting and healing of the crust throughout the seismic cycle: From microscale physico-chemical processes to a global rheology

在地球的上地壳，地质变形主要是由断裂和断裂调节的。断层运动可能是灾难性的，并会引发地震，但这在时间上是相当罕见的事件：地壳中的大多数断层要么非常缓慢地移动（蠕动），要么在两次地震之间完全锁定。在这个所谓的震间期，由于化学石化过程，裂缝愈合（即恢复强度）并密封（即关闭流体流动路径）。愈合和密封过程与裂缝生长的竞争决定了未来沿断层发生地震的位置和时间。因此，了解岩石是如何愈合和断裂的，以及这些过程之间的反馈，是更好地了解地震产生和相关危害的重要一步。尽管自20世纪70年代末以来，这个问题受到了相当大的关注，主要是通过现象学摩擦本构定律的发展，但在实际的微观机制方面知之甚少，从这些机制中可以观察到经验宏观定律。特别是，包括骨折生长、愈合和密封在内的统一微力学框架仍有待确定。因此，我建议从不同的角度来解决这个问题，通过(1)通过实验确定和量化控制超慢变形和骨折愈合的物理化学过程，以及(2)理论上将这些过程输入到严格的微机械框架中，该框架可用于从实验室推断到现场规模。

In the Earth's upper crust, geological deformation is primarily accommodated by fracturingand faulting. Fault motion can be catastrophic and generate earthquakes, but these are rather rare events in time: most faults in the crust are either very slowly moving (creeping) or completely locked between earthquakes. During this so-called interseismic period, fractures heal (i.e., they regain strength) and seal (i.e., they close paths for fluid flow) due to chemical lithification processes. The competition of healing and sealing processes with fracture growth conditions the location and timing of future earthquakes along faults. Hence, understanding how rocks heal and fracture, and the feedbacks between these processes, is an essential step towards a better knowledge of earthquake generation and the associatedhazards. Despite the considerable attention this problem has received since the late 1970's,mostly through the development of phenomenological frictional constitutive laws, very little isknown in terms of actual microscale mechanisms, from which the observed empirical macroscopic laws couldarise. In particular, a unifying micromechanical framework encompassing fracture gowth, healing andsealing remains to be determined. Therefore, I propose to tackle this problem from a different pointof view, by (1) identifying and quantifying experimentally the physico-chemical processes controllingultra-slow deformation and fracture healing, and (2) theoretically input those processes into a rigorousmicromechanical framework that can be used to extrapolate from the laboratory to field scale.