南黄海北部坳陷丛集地震的环境应力特征

对2001~2002年发生在南黄海北部坳陷的丛集地震的构造背景进行了分析,计算和研究了地震丛集过程中环境应力值的演化,讨论了2002-07-23 ML5.1地震发生的背景及其力学机制。研究结果表明,地震丛集过程的中止与中强地震的发生有关;丛集地震形成的初期和中期的平均环境应力值要高于丛集形成之前但低于ML5.1地震发生前夕,丛集后期的平均环境应力值则因ML5.1地震的发生而有所下降。该研究对于今后利用丛集地震及其环境应力值的变化分析和预测中强地震的发生有重要参考意义。

The Characteristics of Ambient Stress of Cluster Earthquakes in the North Depression of South Yellow Sea

In this paper, the geologic structure of north depression of South Yellow Sea where cluster earthquakes occurred is analyzed and the variation of ambient stress during earthquake clustering is calculated and studied. In addition, the background of and mechanism for the ME5. 1 earthquake on July 23, 2002 is discussed. It is indicated that fhere is a correlation between the pause of clustering process and medium-large earthquake, and that the average ambient stress value during initial term and middle term of cluster earthquake formation is higher than that before cluster earthquake formation but lower than that in the eve of occurrence of ME5. 1 earthquake and the average ambient stress value during upper term of cluster dropped because of the occurrence of ME5. 1 earthquake. The results of this research can provide a significant reference for analyzing and forecasting the occurrence of medium-large earthquakes by using cluster earthquakes and the variation of ambient stress values.