用b值截距估算汶川8.0级地震序列最大余震

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

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Mm,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MS≥4.5时,Mm与最大震级Mmax满足关系式Mmax=-0.41+1.00Mm±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。

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 Mm and the maximum magnitude of aftershock Mmax have the relation Mmax=-0.41+1.00Mm±0.40 when the magnitude of mainshock is equal to or more than 4.5.Based on historical earthquake sequences and the Wenchuan MS8.0 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.