Reservoir induced seismicity provides a suitable method for studying the roles of fluid in inducing earthquakes. The fault structure plays a predominant role in the occurrences of earthquakes, and the influences of fluid also cannot be disregarded. In this study, we investigate the active Fairy Mount fault in the Three Gorges Reservoir. Since water impoundment in 2003, more than 4000 detectable earthquakes have occurred along the fault. The vast majority of these earthquakes are associated with the fault and water impoundment. To explore the effects of water-fault interactions on induced earthquakes, a permeability structure of the fault zone is established by a series of geological experiments. Fault rocks, including unconsolidated breccias and fault gouges, collected from a presentative outcrop are employed for detailed microstructural and mineralogical analyses. The results reveal a complex internal fault structure and widespread fluid-rock interactions. The hydrogeological property of the fault exhibits a typical conduit/barrier permeability structure. Highly permeable damage zones act as fluid conduits for the infiltration of reservoir water to the subsurface, while the low permeable fault core renders the fault core as a potential fluids storage area to weaken the fault in the shallow crust. In sum, both the pore pressure changes due to water infiltration and the long-term chemical effect of water on the fault plane promote instability of the fault and induce earthquakes.

中文翻译：

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流体与断层带相互作用对浅地壳触发地震的影响

水库诱发地震活动为研究流体在诱发地震中的作用提供了一种合适的方法。断层构造在地震的发生中起主导作用，流体的影响也不容忽视。在这项研究中，我们调查了三峡水库中活跃的仙女山断层。自 2003 年蓄水以来，沿断层发生了 4000 多次可探测地震。这些地震中的绝大多数与断层和蓄水有关。为探究水-断层相互作用对诱发地震的影响，通过一系列地质实验建立了断层带的渗透结构。断层岩，包括松散角砾岩和断层泥，从展示露头中收集的数据用于详细的微观结构和矿物学分析。结果揭示了一个复杂的内部断层结构和广泛的流体-岩石相互作用。断层的水文地质性质表现出典型的管道/屏障渗透结构。高渗透性损伤带作为水库水渗透到地下的流体管道，而低渗透性断层核心使断层核心成为潜在的流体储存区，以削弱浅层地壳中的断层。总之，水入渗引起的孔隙压力变化和水对断层平面的长期化学作用都会促进断层的不稳定并诱发地震。断层的水文地质性质表现出典型的管道/屏障渗透结构。高渗透性损伤带作为水库水渗透到地下的流体管道，而低渗透性断层核心使断层核心成为潜在的流体储存区，以削弱浅层地壳中的断层。总之，水入渗引起的孔隙压力变化和水对断层平面的长期化学作用都会促进断层的不稳定并诱发地震。断层的水文地质性质表现出典型的管道/屏障渗透结构。高渗透性损伤带作为水库水渗透到地下的流体管道，而低渗透性断层核心使断层核心成为潜在的流体储存区，以削弱浅层地壳中的断层。总之，水入渗引起的孔隙压力变化和水对断层平面的长期化学作用都会促进断层的不稳定并诱发地震。而低渗透性断层核使断层核成为潜在的流体储存区，削弱了浅地壳中的断层。总之，水入渗引起的孔隙压力变化和水对断层平面的长期化学作用都会促进断层的不稳定并诱发地震。而低渗透性断层核使断层核成为潜在的流体储存区，削弱了浅地壳中的断层。总之，水入渗引起的孔隙压力变化和水对断层平面的长期化学作用都会促进断层的不稳定并诱发地震。