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应用参考资料[1]中提出的方法,测定了唐山7.8级地震前后,震源及其邻近地区微震震源参数(地震矩、应力降、震源尺度)。结果表明:唐山地震前数年,唐山—宁河—滦县一带发生的震级相近的小地震,具有较高的应力降和较小的震源尺度;并自1974年7月以来,唐山地震震源区介质看来出现一个应力加速积累的过程;震后,相应地区内小地震的应力降减小,震源尺度增大,这与海城地震所得结果是一致的。
Using the method proposed in Reference [1], the microseismic source parameters (seismic moment, stress drop and source scale) of the source and its adjacent areas before and after the Tangshan Ms8.8 earthquake were measured. The results show that small earthquakes of similar magnitudes occurred in the Tangshan-Ninghe-Luanxian area in the years prior to the Tangshan earthquake have higher stress drop and smaller source scale. Since July 1974, the focal region of Tangshan earthquake The medium appears to be a process of accelerating the accumulation of stress. After the earthquake, the stress drop of small earthquakes in the corresponding area decreases and the source scale increases, which is consistent with the result of Haicheng earthquake.