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作者把强震孕育过程中处于一定构造条件下的一系列震群事件,统称为区域震群.分析1967年以来华北区域震群的时空进程发现:大约在唐山大震前5年,在未来大震震中区外围,形成了一个震群活动的空区,在空区外围,则出现了一个震群相对活跃的环形区域.环形区域内的震群表现出与唐山大震孕育过程有关的、逐渐增强的阶跃式活动,并在孕震不同阶段的转折时期相对密集;与此同时,大范围区域震群还经历了远场一近场的往返迁移.大震前后区域震群的这种时空分布与地震活动其它指标的变化有所呼应,它们在一定程度上共同勾画出强震前近场与远场的异常特征.由此认为,研究区域震群的时空特征,有可能为强震预报提供某些线索.
A series of earthquake swarm events under certain tectonic conditions in the process of strong earthquakes gener- ation are collectively referred to as regional swarm of swarms.Analysis of the spatial-temporal process of the swarm of earthquake in North China since 1967 reveals that about 5 years before the Tangshan earthquake, In the periphery of the epicenter, a vacant area of swarm activity is formed, and in the periphery of the vacant area, there is a ring-shaped area with relatively active swarm.The swarm in the annular area is related to the gestation process of Tangshan earthquake and gradually Enhanced step-by-step activities, which are relatively intensive during the turning-points of different stages of seismogenic earthquake. In the meantime, the large-scale regional earthquake swarm also undergoes the near-field far-field migration back and forth. The distribution and the change of other indicators of the seismic activity have echoes, which to a certain extent, jointly delineate the anomalous characteristics of the near-field and far-field before the strong earthquakes.Therefore, it is considered that the spatial and temporal characteristics of the regional swarm in the study area may be the prediction of strong earthquakes Provide some clues.