新丰江余震震群的“应力窗口”效应与华南地区的地震活动

THE "STRESS WINDOW" EFFECT OF XINGFENG-JIANG AFTERSHOK SEQUENCES AND THESEISMIC ACTIVITY IN SOUTH CHINA

本文取1962至1990年12月广东省新丰江地震的余震序列资料,从应变释放的角度定量地分析新丰江的余震活动特点以及与华南地区中强地震活动的关系,并与理论分析结果对比。发现新丰江地震的余震应变释放过程具有4次明显的应变异常增加,而且。从新丰江地震以来,华南地区发生的所有5.0以上中强地震都与新丰江余震应变释放的明显异常增加相“联系”,新丰江余震震群的出现是华南地区构造应力场增强的背景下余震区应力加强的效应,可以起到监视华南地区5.0级以上中强地震的“应力窗口”作用。 从1986年以来,新丰江地区的余震活动有所加强,其应变释放明显增加,表明华南地区的构造应力场在加强。其地震活动可能达到较高的水平。

With the data of Xingfengjiang aftershock sequences from 1962 to December 1990, the relations between the features of Xingfengjiang aftershock activity and the activity of middle stronge earthquakes in South China are studied by the means of strain release. By comparing the results of the strain release and the theory results, it founds that four obvious abnormality are increases in the strain release process of Xingfengjiang aftershock. Furthermore, all of the middle-stronge earthquakes (Ms≥5.0)took place in South China have something to do with the obvious abnormal incr-昬a'ses of strain release in Xingfengjiang aftershock. The aftershock swarm in Xingfengjiang is the effect of the strengthened stress at the aftershock region under the background of .the strengthened tectonic stress field in South China, which can be regarded as a 'stress window' to watch the formation of middlestronge earthquakes (Ms≥5.0) in South China. From 1986, the activity of Xingfengjiang aftershock has been enhaced and the strain release has been increased obviously. It shows that the tectonic stress field is strengthened in South China and the level of seismic activity may be high.