2010年青海玉树M_s7.1地震序列ETAS模型参数及其变化特征研究  

Analysis of ETAS Model Parameters and Associated Variation Characteristics for 2010 Yushu,Qinghai M_S7.1 Earthquake Sequence

作　　者：余娜[1] 蒋长胜[2] 马玉虎[1] 

机构地区：[1]青海省地震局,青海西宁810000 [2]中国地震局地球物理研究所,北京100081

出　　处：《地震工程学报》2016年第4期609-615,623,共8页China Earthquake Engineering Journal

基　　金：2016年度震情跟踪定向任务(2016010133);青海省科技厅基础研究项目(2013-Z-710)

摘　　要：采用时间序列的"传染型余震序列"(ETAS)模型和最大似然法对2010年4月14日青海玉树M_S7.1地震序列的参数进行了估计。为考察其结果的稳定性,设定不同的截止震级和不同的拟合截止时间分别进行序列参数估算。选用截止震级M_C=M_L1.5对玉树M_S7.1地震序列整体的参数进行拟合,计算获得α=0.948 2,p=1.059 6和b=0.817 3。与中国大陆M>7.0地震序列的平均序列参数相比较表明,玉树M_S7.1地震序列表现为触发次级余震的能力较弱,序列衰减速率较快。研究表明,截止震级M_C对α、k和p值有一定的影响。随截止震级逐渐增大,参数k值逐渐减小,α值总体上有增加的趋势,而对p值的影响较小。在地震序列的早期阶段,ETAS模型参数中的p值和α值在震后14天内随时间的变化幅度较为明显,其后各参数变化相对平稳。The maximum likelihood method is used and the epidemic-type aftershock sequence（ETAS）model is fitted in the analysis of aftershock sequence characteristics of the April 14,2010Yushu（M_S7.1）earthquake that occurred in Qinghai province.To examine parameter stability,ETAS parameters and their standard errors are estimated with different cutoff magnitudes,M_C,and different ending times for the fitting interval.The overall parameters are observed to beα=0.948 2,p=1.059 6,and b=0.817 3with setting M_C=M_L1.5.Compared to other M 7.0earthquake sequences on the continental China,the Yushu M_S7.1earthquake sequence is characterized by a weak triggering capability in generating secondary aftershocks,and a quick decay rate of aftershocks.A systematic approach for using multiple cutoff magnitudes above the magnitude of completeness is adopted in the calculation process to examine stability of the sequence parameters and to analyze the degree to which they are affected.The cutoff magnitude,M_C,is observed to have a certain effect on the value ofα,k,and p（with an increase in M_Cthe value of k decreases,there is a general increasing trend ofα,but less influence on p）.ETAS model parameters with different sequence durations are studied in this paper,together with their temporal variations and stability in the early stage after the shock.There is variation in the range of pandαshortly after the earthquake stops for different cutoff magnitudes within the same earthquake,whereas there is a trend of p andαis towards convergence and stability after stabilization of seismic activity.Furthermore,there is evident change in the temporal variation of ETAS parameters 14 days after the mainshock,when the parameters become relatively stable.

关 键 词：玉树MS7.1地震 余震 地震序列 ETAS模型 

分 类 号：P315.8[天文地球—地震学]