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Title:: The Wenchuan M_S8.0 Earthquake:Strong Aftershock Prediction Based on Attenuation Features of Aftershocks of M≥7 Earthquakes in Sichuan-Yunnan Region

Author(s):: FU Hong; WU Cheng-dong; (Earthquake Administration of Yunnan Province,Kunming 650224,Yunnan,China)

Keywords:: Sichuan-Yunnan region; earthquake sequence; Wenchuan M_S8.0 earthquake; judgment for post-earthquake tendency

摘要:: 通过对川滇地区M≥7地震余震序列活动早期衰减特征的研究,发现序列基本上符合G-R关系,大、小地震成比例,序列中的最大强余震小于或等于用序列拟合计算b值截距得到的最大地震,且误差ΔM≤0.4; 最大强余震多在2个月内发生,序列中较强余震的h值小于1时,其后通常还会发生震级较大的余震,当h大于1时,序列余震震级不会太高; 最大强余震常发生在序列前期释放较弱的地段。将这些共性特征应用于汶川8.0级地震余震的前期跟踪监视中,通过了2个月内余震的衰减趋势和强余震判断结果的外推应用检验。

Abstract:: We study the features of aftershock sequences of M≥7 earthquakes in the Sichuan-Yunnan region,and find the sequences basically conforms to the Gutenberg-Richter relation,and the number of large earthquakes is proportional with that of the small ones.The maximal magnitude of the aftershocks is less than or equal to the magnitude given by the b-valve interception method using sequence data,and the magnitude error ΔM≤0.5.The maximal aftershock usually happens in two months after a mainshock.When the h-value of relatively strong aftershocks in sequences is less than 1.0,the later aftershocks usually have equivalent magnitude; oppositely,when the h-value of relatively strong aftershocks in sequences is larger than 1.0,the magnitudes of later aftershocks are not too large.The maximal aftershock usually happens in the place where early energy release of sequence is weak.We apply these common characteristics to the aftershock monitoring of the Wenchuan earthquake,which passes the extrapolation tests of aftershocks attenuation tendency of the Wenchuan earthquake and its strong aftershock prediction.