【摘要】 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。更多还原

【Abstract】 The Weihe Graben is situated in the central part of China. The 1556 Huaxian County earthquake with a magnitude higher than 8 and a series of strong aftershocks occurred in the eastern part of this region. Thereafter, there was no major earthquake activity at all. The present seismicity there is very low. Since the establishment of a regional network of seismic stations in the late 1970’s, only small earthquakes were recorded.In this paper, five earthquake swarms occurred in the graben since 1979 are systematically investigated. The characteristics of their spatial distribution, temporal sequence, and magnitude-frequency relationship are summarized. The similarities between these swarms and ordinary earthquake sequences are discussed, and a preliminary interpretation of the genesis of these swarms is proposed. Finally, the relationship between these swarms and moderate earthquakes occurred in their adiacent region is discussed.更多还原