余震的序列参数稳定性和余震短期发生率预测效能的连续评估——以2014年云南鲁甸6.5级地震为例  

Stability of early-estimation sequence parameters for continuous forecast of the aftershock rate:A case study of the 2014 Ludian,Yunnan M_S6.5 earthquake

作　　者：蒋长胜[1] 吴忠良[1] 尹凤玲[1] 郭路杰[1] 毕金孟 王亚文[1] 

机构地区：[1]中国地震局地球物理研究所,北京100081

出　　处：《地球物理学报》2015年第11期4163-4173,共11页Chinese Journal of Geophysics

基　　金：国家国际科技合作专项项目(2012DFG20510);中国地震局地球物理研究所基本科研业务费专项(DQJB13B19)联合资助

摘　　要：为考察目前国际上广泛使用、对真实地震序列描述最好的＂传染型余震序列模型＂（ETAS）在主震后的序列参数拟合、余震短期发生率预测的效能,本研究以2014年云南鲁甸MS6.5地震序列为例,采用滑动连续拟合与预测的方式,考察了ETAS模型参数的动态变化和余震短期发生率预测的实际效能.连续滑动拟合结果表明,在主震发生后的早期阶段,α值有明显的不稳定变化,在震后5.10天稳定在1.6~2.0;p值在震后25.00天内由1.07逐渐下降至0.78左右,其后稳定在0.72~0.85;b值在震后35.00天内逐渐由0.80增加至0.95,其后稳定在0.93~0.97.对连续滑动预测结果的N-test检验表明,余震发生率预测会出现部分失效现象,1天预测时间窗失效比例约为12%、3天预测时间窗失效比例为6%.建议可在震后早期采用1天的较短预测时间窗,而在序列参数较为稳定时段采用较长的3天预测时间窗.It is particularly important to quantify the effectiveness of the earthquake sequence short-term forecast model and investigate the time variation of the earthquake sequence parameters for construction of the regional earthquake forecasting experience.The epidemic type aftershock sequence（ETAS）model and the ETAS-based thinning algorithm were considered,which are the best seismicity description model and forecast method accepted widely in the world.The Ludian,Yunnan MS6.5earthquake sequence provides new scientific data for such retrospective case study.The ETAS model was fitted to the earthquake sequence of the Ludian,Yunnan MS6.5earthquake for examining the stability of early-estimation sequence parameters and relationships among those parameters,with cutoff magnitude ML2.0,and the starting time fixed by C0=0.049 day,the ending time from 2.00 days to 149.20 days by sliding with 0.05 day steps and a total of2945 time periods in ETAS fitting.The ETAS-based thinning algorithm was used to forecast the future next-day and 3-days aftershock rate in all the time periods,and a statistical method N-test was used to test the efficiency of such a continuous forecasting.The parameters areμ=0.0000,K=0.0103,c=0.0039,α=1.8180 and p=0.8018 for the ETAS fitting in the Ludian,Yunnan MS6.5earthquake sequence,and related triggering ability in generating secondary aftershocks,and the decay rate of aftershocks show no significant differences compared to other earthquake sequences in China mainland.Theαvalue reduced from 3.5~3.8to1.6~2.0in the early stage after the mainshock occurred since the ending time t2=5.05~5.10days;the pvalue from 1.07 down to 0.78 within 25.00 days after the mainshock and remains steady at 0.72~0.85;and the b value increased from 0.80 to 0.95 gradually within 35.00 days after the mainshock,and remains steady at 0.93~0.97.Furthermore,the pandαvalues show a reverse change,the pand b value also show a reverse change within 35.00 days after the mainshock but no obvious correlation after this stage.There is

关 键 词：地震序列 ETAS模型 短期预测 统计检验 

分 类 号：P315[天文地球—地震学]