中国大陆余震序列类型的综合判定

Synthetical judgment of types of aftershock sequences in Chin′s Mainland

在对中国大陆294次5级以上地震序列主震后不同时段、11个单项序列参数计算结果的基础上，分别建立不同时段、以不同序列参数为自变量的Fisher判别函数，用于序列类型的综合判定。在Fisher判别函数建立过程中，除以常规序列参数作为函数自变量输入外，还引入主震滑动角参数，以使判别函数在一定程度上包含主震破裂形式的信息。统计结果表明，序列类型识别正确率随资料长度（震后时段）增加而提高。不同类型序列的识别正确率不同，孤立型序列的识别正确率大于0．93，主余型序列的识别正确率为0．73～0．93，多震型序列的正确识别率为0．57～0．86，均明显高于随机投票0．33的自然对应率，因而其序列分类能力应得到正的评分。

Based on calculation results of 11 parameters of 294 aftershock sequences with mainshock magnitude greater than or equal to 5.0 occurred in Chinrs mainland, Fisher discriminant functions in different period since the mainshock, taking different sequence parameters as the independent variables, have been established, which could be used for synthetical judgment of sequence types. Besides routine sequence parameters, the rake of the mainshock has also been introduced into the Fisher discriminant functions to make them containing messages of fracture mode of the mainshock. Statistical results show that the accurate ratio of discriminant on types of aftershock sequences increases with the increment of time period since the mainshock and there is something different for different sequence types. The accurate ratio is greater than 0. 93 for isolated earthquake type, is from 0. 73 to 0. 95 for mainshock-aftershock type and is from 0. 57 to 0. 86 for multiple mainshock type. All of them are highly greater than stochastic corresponding ratio, 0.33, and therefore its forecasting score should be positive.