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通过震源位置和速度结构联合反演方法,利用浙江和福建区域地震台网和珊溪水库台网给出的P波走时资料,得到了珊溪水库地区的三维速度结构,重新确定了珊溪水库地震的震源参数。结果表明:①震中总体呈现NW向分布,NW走向的双溪-焦溪垟断裂可能为珊溪水库地震序列的发震断层。②珊溪水库地震震源深度最大为9.5km,平均为5.4km,小于华南地震区10km的平均震源深度。③水库北、南两岸的地震较浅,震源深度均小于5km,水库淹没区地震较深。水库诱发地震之初的几年中震源深度有一个逐渐变大的过程,这可能是由于库水逐渐往深部下渗,从而进一步诱发了更深处的地震所致。④研究区存在一个低P波速度异常区,低速区位于水库淹没区内的多组断裂交汇部位,地震大多发生在低速异常区内。这可能与水库蓄水后库水下渗有关。
Based on the P-wave travel time data given by Zhejiang and Fujian regional seismograph networks and Shanxi reservoir network, a three-dimensional velocity structure of Shanxi reservoir area was obtained through joint inversion of focal position and velocity structure. Seismic source parameters. The results show that: (1) The epicenter presents an NW distribution, and the NW-trending Shuangxi-Jiao Xi’ao fault may be the seismogenic fault of Shanxi reservoir seismic sequence. ② The shale depth of the Sanxi Reservoir earthquake is 9.5km, averaging 5.4km, which is less than the average focal depth of 10km in the South China Earthquake. ③ The earthquakes in the north and south banks of the reservoir are shallower and the focal depths are less than 5km. The earthquakes in the reservoir inundation area are deeper. During the first few years of the reservoir-induced earthquake, there was a gradual increase in focal depth. This may be due to the deeper infiltration of reservoir water, which further induced the earthquake deeper. ④ There is an anomalous region of low P-wave velocity in the study area, and the low-velocity region is located at the intersection of multiple groups of faults in the inundation area of the reservoir. Most of the earthquakes occur in the low-velocity anomalous region. This may be related to reservoir water infiltration after impounding.