2011年日本9.0级地震前地震空间相关长度增长现象

使用单键群方法研究了2011年3月11日日本本州东北部海域9.0级地震前地震空间相关长度变化。结果表明,在本次地震发生前约两年,5级以上地震的空间相关长度开始出现明显增长,变化趋势可以用幂次率进行很好的拟合。用没有7级以上强震发生的时段内的地震目录,采用相同方法进行了计算,没有发现明显的幂次率增长现象,说明强震前5级以上地震的空间相关长度的幂次率增长是地震孕育过程中震源区的物理性质特征的表现之一。

Growing Phenomena of Seismic Spatial Correlation Length before Japan M9.0 Earthquake in 2011

Using single-link cluster analysis(SLC) method,we studied the variation of seismic spatial correlation length before Japan M9.0 earthquake occurred in the Northeast Coast of Honshu.The results showed that the seismic spatial correlation length of M > 5 earthquakes increased significantly and its trend could be well fitted by power rate in 2 years before M9.0 earthquake.Then we applied this method to the catalog with period of no M7 strong earthquakes occurred from 1996 to 1999 which was selected from historical earthquake activities in the surrounding area of epicenter,and found that there was no significantly increasing process by power rate.The results showed that the seismic spatial correlation length increased by power rate of M > 5 earthquakes which occured before strong earthquake represented the physical property of focal region in the process of strong earthquake preparation.