Reservoir-Induced Seismicity in the Three Gorges Reservoir Area
As a region with little or very low level background seismicity, the impoundment of the Three Gorges Reservoir in June 2003 was related to increasing reservoir-induced seismicity. Analysis of the spatial pattern of seismicity showed that a majority of the seismicity was associated with the heavily fractured, deep crustal Jiuwanxi Fault, especially in regions of permeable Carbonate rocks formations. Analysis of the temporal pattern of the seismicity and a comparison with the filling history of the reservoir showed that the frequency and intensity of induced seismicity started at low level accompanying the impoundment of the Three Gorges Reservoir, and then increased with the increasing of water level and decreased thereafter. The amplitude of fluctuation of water level was found to be related to the frequency and intensity of induced seismicity. The pore pressure diffusion plays an important role in reservoir induced seismicity.