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渭河盆地是历史上发生过许多大震的地区,例如,1556年华县8级大震就发生在盆地的东部。现在地震活动水平一直很低。自七十年代后期区域台网建成以来,在盆地内部经常记录到震群活动。这种频繁的活动似乎代表了本区地震活动的一个重要方面。 本文系统地研究了1979年以来发生在盆地内部的5次震群活动。总结了它们在震源分布、时间序列、震级频度关系和震源错动等方面的特征。探讨了这些特征与一般地震序列的相似性,比较了这些震群之间的异同。最后,采用1976年以来震群活动的资料,初步探讨了这种活动与邻近地区中强震的可能关系。对震群的成因也提出了初步看法。
The Weihe Basin is a region where many major earthquakes have occurred in history. For example, the Huadian M8 magnitude earthquake occurred in 1556 in the eastern part of the basin. Earthquake activity levels have been low now. Since the completion of the regional network in the late 1970s, earthquake swarm activities have often been recorded within the basin. This frequent activity seems to represent an important aspect of seismic activity in the area. This paper systematically studies five earthquake swarms occurring in the basin since 1979. The characteristics of their distribution in source, time series, frequency relationship of magnitude and source dislocation are summarized. The similarity between these features and general earthquake sequences is discussed, and the similarities and differences between these earthquake swarms are compared. Finally, based on the data of the earthquake swarm activity since 1976, the possible relationship between this activity and the strong earthquakes in the adjacent area is discussed. The origin of the swarm also made a preliminary view.