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本文从直达波传播的走时公式出发,根据最小二乘法原理,对丹江水库地震网内记到的直达波到时资料作直线拟合,求出波速比的变化及其范围,并对其精度进行了估算和评定。同时对直达波和虚波的速度及震源深度的精度问题也作了评定。在扣除了观测误差影响以后,从中滤取波速比异常信息,对丹江水库波速比值的正常与异常的可信范围作了估算,说明该区蓄水以来,最大一次Ms=4.7级—宋湾震群型地震和李官桥Ms=3.8级地震发生前存在波速比异常现象,并结合该区的应力状态与中、小地震的震源机制解,发现波速比具有各向异性的性质。最后本文结合该区地形变资料,讨论了水库诱发地震的膨胀(扩容)—流体扩散模式。
In this paper, starting from the travel time formula of direct wave propagation, according to the principle of least square method, the direct wave arrival time recorded in the seismic network of Danjiang Reservoir is linearly fitted, and the variation of wave velocity ratio and its range are obtained. Estimated and assessed. At the same time, the accuracy of the velocity and focal depth of the direct wave and the virtual wave were also evaluated. After deducting the influence of observational error, we get the information of wave velocity anomaly, and estimate the credible range of normal and anomaly of wave velocity ratio of Danjiang reservoir, which shows that the maximum Ms = 4.7 There is an anomaly of wave velocity anomaly before the earthquake group quake and Ms = 3.8 Ms = 3.8 earthquakes. Combined with the stress state of the area and the focal mechanism solution of moderate and small earthquakes, it is found that the wave velocity ratio has the anisotropy. Finally, the paper discusses the expansion (expansion) - fluid diffusion model of reservoir-induced earthquakes in light of the deformation data of the area.