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Title:: Characteristics of the 2021 Yangbi,Yunnan M_S6.4 Earthquake Sequence and Prediction of Its Strong Aftershocks

Author(s):: ZHAO Xiaoyan; WANG Guangming; ZHANG Qian; HE Suge; FAN Wenjie; LIU Zifeng; (Yunnan Earthquake Agency,Kunming 650224,Yunnan,China)

Keywords:: the Yangbi M_S6.4 earthquake; seismic sequences; strong aftershocks

摘要:: 利用云南地震台网观测资料,对2021年漾濞M_S6.4地震序列的时空演化特征进行分析,结果表明:漾濞地震序列的空间展布可分为4段,且余震活动衰减非常迅速。通过分析历史地震序列类型、h值、等待时间法、累计频次曲线、初动方向等,判断漾濞M_S6.4地震序列为前震-主震-余震型。利用云南地区6级地震最大余震发震时间统计和震级差分布特征分析,认为漾濞M_S6.4地震最大余震已经发生。最后讨论了漾濞地震序列4级余震偏多的现象及可能的原因。

Abstract:: On the basis of the data of the 2021 Yangbi M_S6.4 earthquake sequence recorded by the Yunnan Earthquake Observation Network,we analyze the temporal and spatial evolution characteristics of the sequence.The spatial distribution of the sequence can be divided into 4 sections and the aftershock-activity attenuate rapidly.Through the analysis of the type of the historical earthquake sequences in this area,the method of h-value,the method of dt-t,the method of the cumulative frequency,and first-motion signs of the earthquake wave,we determine that the Yangbi M_S6.4 earthquake sequence belongs to foreshock-mainshock-aftershock type.According to the statistics of the original time of the historical strongest aftershocks in Yunnan,and the distribution characteristics of the magnitude differences,we conclude that the strongest aftershock of the Yangbi M_S6.4 earthquake has occurred.Finally we discuss the high frequency of M_L≥4.0 aftershocks in the sequence and the possible reasons.