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Title:: Using b-value Interception Method to Estimate Maximum Aftershock of the Wenchuan M_S8.0 Earthquake

Author(s):: QIAN Xiao-dong; QIN Jia-zheng; (Earthquake Administration of Yunnan Province,Kunming 650224,Yunnan,China)

Keywords:: Wenchuan M_S8.0 earthquake; interception of b value; maximum aftershock; mainshock-aftershock type sequence

摘要:: 利用川滇地区主震—余震型地震序列资料进行统计,结果表明:对于主震—余震型地震序列,在G-R关系中用b值截距方法估算最大余震震级M_m,用线性较好的震级资料得到的结果与实际较为接近; 当主震震级M_S≥4.5时,M_m与最大震级M_max满足关系式M_max=-0.41+1.00M_m±0.40; 根据历史地震资料和中国地震台网中心给出的汶川8.0级地震序列资料,预测汶川地震序列属于主震—余震型,估算的最大余震为(6.4±0.40)级,大于7级的可能性不大。

Abstract:: We analyze the mainshock-aftershock type sequence in the Sichuan-Yunnan region,and estimate the magnitude of the maximum aftershock of every sequence using the method of b-value interception based on Gutenberg-Richter relation. The estimated results close the actual results when the magnitudes of the sequence have good linear relation. The b-value interception M_m and the maximum magnitude of aftershock M_max have the relation M_max=-0.41+1.00M_m±0.40 when the magnitude of mainshock is equal to or more than 4.5. Based on historical earthquake sequences and the Wenchuan M_S8.0 earthquake sequence data from China Seismological Network Center,we predict that the Wenchuan earthquake sequence is mainshock-aftershock type,and the magnitude of maximum aftershock is(6.4±0.40),i.e.,the maximum aftershock is unlikely to exceed seven.