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Title:: Tracking Analysis of Seismic Anomalies of the 2021 Yangbi,Yunnan M_S6.4 Earthquake

Author(s):: FU Hong; LIU Zifeng; HU Xiaojing; LI Zhirong; HONG Min; PENG Guanling; WANG Guangming; NI Zhe; (Yunnan Earthquake Agency,Kunming 650224,Yunnan,China)

Keywords:: the Yangbi M_S6.4 earthquake; foreshock sequence; fixed survey of the crust deformation; underground-fluid anomalies; comprehensive prediction

摘要:: 对云南漾濞M_S6.4地震前出现的前震序列、地震学、定点形变和流体观测异常进行系统梳理和回顾,结果表明:前震序列较为复杂,能找到一些地震学的异常特征,但难以通过这些特征对震后趋势进行正确判断; 定点形变观测异常出现时间早、异常幅度大,可为震级预测提供依据; 流体观测异常出现时间短、异常相对集中,为时间预测提供了更好的支撑; 形变和流体异常与亚失稳后期阶段具有较为相似的时空特征,可能与亚失稳过程有关。前震序列的判断结合区域地震危险性,可能是提高判断准确性更好的方法,合理利用地震孕育不同阶段的异常特征,是做好综合预测需要提倡的方法。

Abstract:: In this study,we made a series of researches and retrospections of the foreshock sequence,as well as the anomalies of seismological,deformation and fluid observations at fixed observational sites before the occurrence of the Yangbi M_S6.4 earthquake.The results are as follows:seismicity of the foreshock sequence is relatively complicated; some seismological anomalies can be extracted from the foreshock sequence.However,it's difficult to make a short-term forecast based on the characteristics of the foreshock sequence.The anomalies of deformation at fixed observational sites arose early and substantially,which could shed light on the prediction of earthquake magnitude.The anomalies of fluid observation prior to the M_S6.4 earthquake were transient and intensive,which could provide better evidence for forecasting of the timing of the mainshock.Features of the anomalies of deformation and underground fluid are much similar in time and space with the features of the fault's later-stage meta-instability,which may be because of the fault's meta-instability evolution.One could improve the accuracy of the earthquake prediction by combining the characteristics of foreshock sequence and regional seismic risk.We suggested that it was a promising method for comprehensive earthquake prediction by reasonably using the characteristics of the anomalies emerged in different seismogenic stages.