林邦慧, 胡小幸, 王泽皋. 1966年邢台地区大震前小震的"密集-平静"特征及其初步解释[J]. 华北地震科学, 2006, 24(2): 30-35.
引用本文: 林邦慧, 胡小幸, 王泽皋. 1966年邢台地区大震前小震的"密集-平静"特征及其初步解释[J]. 华北地震科学, 2006, 24(2): 30-35.
LIN Bang-hui, HU Xiao-xing, WANG Ze-gao. THE "DENSE-QUIET" CHARACTERISTIC OF SMALL EARTHQUAKES BEFORE 1966 XINGTAI STRONG EARTHQUAKES AND ITS PRELIMINARY EXPLANATION[J]. North China Earthquake Sciences, 2006, 24(2): 30-35.
Citation: LIN Bang-hui, HU Xiao-xing, WANG Ze-gao. THE "DENSE-QUIET" CHARACTERISTIC OF SMALL EARTHQUAKES BEFORE 1966 XINGTAI STRONG EARTHQUAKES AND ITS PRELIMINARY EXPLANATION[J]. North China Earthquake Sciences, 2006, 24(2): 30-35.

1966年邢台地区大震前小震的"密集-平静"特征及其初步解释

THE "DENSE-QUIET" CHARACTERISTIC OF SMALL EARTHQUAKES BEFORE 1966 XINGTAI STRONG EARTHQUAKES AND ITS PRELIMINARY EXPLANATION

  • 摘要: 利用邢台地震台网的地震目录资料,研究了邢台地区强震前小震的"密集-平静"特点及其空间分布的立体图像,研究结果表明:(1)1966年3月邢台地区发生的几个6级以上强震前小震均有"密集-平静"现象,但明显程度随时间减小,部分4.5级地震前小震也有"密集-平静"现象,但因出现在6级以上地震的余震活动背景上,情况比较复杂,相对平静期的长度,密集期中最大地震的震级均与相应主震震级之间有一定关系,一般来讲,主震震级越大,平静期越长,密集期中最大地震震级也越大。(2)3月22日7.2级主震前,小震的"密集-平静"过程在空间上有清晰的物理图像。3月8日6.8级地震发生后,3月20日在其余震区的两个端部中介质强度较弱的南西端首先达到破裂强度,发生一系列中小地震,对应于主震前的密集期。3月21日~22日主震前小震明显减少,是主震前的相对平静期,而且小震有由南西端向北东方向迁移的趋势。显示震区应力场在迅速地改变,应力由南西端向北东端进一步集中,并促使22日在北东端尖端部位失稳而发生6.7级及7.2级主震。3月26日6.2级强震前小震的"密集-平静"过程在空间上也有类似清晰的物理图像。此外,本文对大震前小震的"密集-平静"特点作初步的解释。

     

    Abstract: The "dense-quiet" characteristic of small earthquakes before Xingtai strong earthquake and its spatial distribution are studied with the data recorded by Xingtai Seismic network.The results show:(1) there was "dense-quiet" phenomenon before all the over 6 magnitude earthquakes in Mar.1966,but its clear level fell with time.The phenomenon was also showed before parts 4.5 magnitude earthquakes.Because they appeared in the aftershocks of over 6 magnitude earthquake,their situation relatively complicated.Compared the quiet period,the magnitude of biggest earthquake in dense period all had some relation with that of the main earthquake.Generally speaking,the larger the magnitude of the main shock,and the longer the dense period,the bigger the magnitude of the earthquake in dense period.(2) The "dense-quiet" process before M7.2 earthquake occurred on Mar.22 was very clear in spatial.distribution.After the occurrence of M6.8 earthquake on Mar.8,a cluster of small earthquakes occurred at the southwest end of the aftershock region,which might be corresponding to the dense period before the main shock.On Mar.21~22,small earthquakes reduce obviously with a tendency to transfer from southwest to northeast,which might be the quiet period before main shock.The transfer of minor earthquakes indicated that the stress field in seismogenic zone changed rapidly,and concentrated from southwest to northeast,and with the destabilization at the northeast end on Mar.22,the M6.7 and M7.2 major shock occurred.The "dense-quiet" process before M6.2 earthquake occurred on Mar.26 was also showed clear image in space.

     

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