Abstract:Based on geological structure of regions near the Xiannüshan-Jiuwanxi fault zone, we discuss the characteristics of seismic activity in the vicinity of the Three Gorges Reservoir before and after impoundment. The triggering relationship between M4.5 and M4.7 earthquakes occurred on 2014-03 and the influence of the two earthquakes on subsequent small earthquakes is further studied. The results show that the M4.7 earthquake may be jointly triggered by M4.5 earthquake and large pore pressure caused by water seepage. The stress disturbance of M4.5 and M4.7 earthquakes led to the increase of seismic activity in the study area, and about 66.9% of the subsequent earthquakes occurred in the area of Coulomb stress enhancement. Variation of static Coulomb stress caused by two earthquakes led to the increase of seismicity near the Xiannüshan fault zone. The seismicity near Xiannüshan fault zone will be above the background seismicity in the coming period. The activity of Jiuwanxi fault zone is relatively weak, slightly less than background seismicity and in the stage of stress accumulation.
CHANG Ting,ZHANG Lifen,WANG Qiuliang et al. Study on Seismic Activity and Static Coulomb Stress Variation in the Vicinity of Xiannüshan-Jiuwanxi Fault Zone[J]. jgg, 2020, 40(10): 1044-1048.