摘要
针对"时空传染型余震序列"(英文简称ETAS)模型在地震序列参数的早期特征和余震短期概率预测研究中的应用问题,重点考察了不同截止震级Mc选取对结果的影响.以甘肃岷县—漳县6.6级地震序列的震后1.677天内的早期阶段为例,考察了ETAS模型和修正的Omori-Utsu公式的适用性问题,发现ETAS模型AIC值在各截止震级Mc下均小于修正的Omori-Utsu公式的结果,表明其适用效果更好.设定Mc=ML1.0,1.1,…,2.5,分别考察了ETAS模型中α值和p值的稳定性,并与2013年芦山7.0级地震序列进行了对比.结果表明,Mc对α值的影响相对较小,p值影响较大.此外,对基于ETAS模型和"瘦化算法"的余震短期概率预测结果进行了N-test检验,结果表明Mc的设定对余震短期概率预测影响较大,对甘肃岷县—漳县6.6级地震,仅当Mc=ML1.0或ML1.1时可获得较好的预测结果.由此,在真正的"向前"的预测实践中,需要首先考察不同的Mc下的余震预测效果.
The effect of cutoff magnitude Mc of an earthquake catalogue on the result of the analysis of earthquake sequence was investigated using the epidemic type aftershock sequence （ETAS） model to the 2013 Minxian Zhangxian, Gansu, China, Ms6. 6 earthquake sequence. Considering the early stage of aftershock sequence within about 1. 6 days after the mainshock, ETAS model and modified Omori-Utsu relation were used to estimate the earthquake sequence parameters. The AICs of ETAS model are smaller than the modified Omori-Utsu relation for all the considered cutoff magnitude M~., implying that the sequence was better fitted by the ETAS model. Setting different Mc from M~.I. 0 to 2.5 with interval 0.1, the stability of parameter ~ and p was investigated, with the comparison with the 2013 Lushan, Sichuan, Ms7.0 earthquakesequence. The result shows the effect of Mc on the estimation of these parameters, with p more sensitivite to Me. N-test was performed to the probabilistic forecast of aftershocks based on ETAS model and ＂thinning algorithm＂, indicating the effect of Mc on the forecast performance for the Minxian-Zhangxian sequence. Acceptable result was obtained only with Mc-ML 1.0 or Ml.1.1. The analysis cautions that in the practical forward forecas~ of aftershock probabilities, cutoff magnitude is a key factor to be considered.
出处
《地球物理学报》
SCIE
EI
CAS
CSCD
北大核心
2013年第12期4048-4057,共10页
Chinese Journal of Geophysics
基金
国家国际科技合作项目(2012DFG20510)
国家科技支撑计划项目(2012BAK15B01
2012BAK19B01)联合资助
