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通过对华北第四活跃期高潮期强震发生前中小地震的时、空、强分布图象的研究,发现每次七级以上强震发生前区域地震活动都经历过一个类似的阶段性变化过程,我们称为强震孕育阶段过程。华北地震活动高潮期就是由若干个这样的孕震过程所组成。华北强震孕育过程都可以划分为三个不同的时期,即预备期(A期)、激进期(B期)、逼震期(C期)。这三个时期地震活动具有的特点和某些规律性反映了华北地下介质应力应变的变化过程与现有的破裂机制概念相一致。因此认为强震的孕育不仅取块于区域应力场的作用,而且与区域内中小地震活动的变化和进程密切相关,同时提出一个简单的孕震模式——“阻导模式”。
Through the study of the temporal, spatial and strong distribution of small and medium earthquakes before the strong earthquake at the climax of the fourth active phase in North China, it is found that the regional seismic activity before each strong earthquakes of magnitude seven or more experienced a similar phase change process , We call the geocentric phase of the process. The upsurge of seismic activity in North China is composed of a number of such seismogenic processes. The process of the strong earthquakes in North China can be divided into three different periods: the A period, the B period and the C period. The characteristics and some regularities of the seismic activity in these three periods reflect that the change process of stress and strain of the underground medium in North China is consistent with the existing concept of the rupture mechanism. Therefore, it is considered that the inoculation of strong earthquakes not only takes the role of block in the regional stress field, but also is closely related to the change and process of small and medium earthquakes in the area. At the same time, a simple seismogenic model called “resistive guidance mode” is proposed.