基于时-空ETAS模型的新疆伽师地区背景及触发地震活动的探讨  

ANALYSIS ON BACKGROUND AND TRIGGERED SEISMICITY OF JIASHI,XINJIANG,CHINA BASED ON SPATIAL-TEMPORAL ETAS MODEL

作　　者：张盛峰 张永仙[2] 范晓易 ZHANG Sheng-feng;ZHANG Yong-xian;FAN Xiao-yi(School of Earth Sciences and Engineering,Nanjing University,Nanjing 210023,China;Institute of Earthquake Forecasting,China Earthquake Administration,Beijing 100036,China;Jiangsu Earthquake Agency,Nanjing 210000,China)

机构地区：[1]南京大学地球科学与工程学院,南京210023 [2]中国地震局地震预测研究所,北京100036 [3]江苏省地震局,南京210000

出　　处：《地震地质》2021年第2期297-310,共14页Seismology and Geology

基　　金：中国地震局地震预测研究所基本科研业务专项(2020IEF0501);国家自然科学基金(42004038);科技部国家重点研发计划政府间国际科技创新合作重点专项(2018YFE0109700);基本科研业务专项重点实验室基金(2020LNEF04);支撑新时代防震减灾事业现代化建设试点任务之“地震数值预测研究和传统方法评估试点项目”;山东省重点研发计划项目(2018GSF120002)共同资助。

摘　　要：新疆伽师地区历史上发生过多次M_(S)6.0以上地震,2020年1月19日该地区再次发生了M_(S)6.5地震。这些地震属于独立的背景地震活动,还是与已发生的其他地震存在一定的相互触发关系?探索与此问题相关的背景地震活动和触发地震活动特征,对深化这一区域地震活动特征的认识具有重要意义。为此,文中利用时-空ETAS模型对该区1970年1月1日以来的地震序列进行分析,拟合得到了较为稳定可靠的模型参数,给出了区域背景地震活动水平、表示地震活动丛集特征的丛集率指标及包含背景及丛集活动的总活动水平等结果,并利用随机除丛方法将背景地震活动与丛集活动剥离开来,得到了每个地震事件作为背景事件或触发余震事件的概率。结果显示,研究区北部与南部的背景地震活动和触发丛集活动存在明显差异,丛集地震活动为总体地震活动的主要成分;计算结果表明,此次M_(S)6.5地震被触发的可能性达99%,其中2020年1月18日M_(S)5.3地震对其触发贡献最大,达94%;在对其他地震事件具有触发贡献的个体中,2020年4月21日M L4.1地震“干预”其他事件发生过程的平均能力相对较高,达0.505,但需要通过其他手段进一步佐证。文中工作是中国地震局开展的针对此次地震的虚拟科考工作的一部分,所得结果可以为后续深入研究该地震提供帮助。Several earthquakes above M_(S)6.0 occurred in Jiashi,Xinjiang region in China in history.A new M_(S)6.5 event occurred in this area on Jan.19,2020,for which a‘virtual scientific investigation’was carried out by China Earthquake Administration in a short time after the earthquake.In this‘virtual investigation,a vital important question is that which fault controls the occurrence process of this event,and what is the correlation between this event with other previous earthquakes.To understand the solutions of these questions well,the seismologists analyzed different types of monitoring data,the source parameters,focal mechanisms,seismic waves,InSAR data,regional tectonics,seismic activity including the aftershock sequence,abnormalities of CH4 and GPS TEC,etc.Some conclusions can be drawn on the features of this earthquake and the potential of large aftershocks based on analysis of these kinds of data.Statistical seismology tools may provide a significant constraint in the case that some earthquakes cannot be described very well through traditional approaches.Concerning the seismicity in the Jiashi area,whether this earthquake is independent background seismicity,or has a certain triggering relationship to the other previous events,is a main question to be well answered during this research.So,to explore the features of the background events and the triggering ability of the events in this area,we used the spatial-temporal epidemic type aftershock sequence(ETAS)model to fit the seismicity using the earthquake events from Jan.1,1970 to Jun.1,2020 to obtain the spatial and temporal distribution of total seismicity rate,background seismicity rate and clustering seismicity rate.Then the stochastical declustering method based on ETAS model was used to separate all the events into background events and clustering events.The result shows that the clustering seismicity has a main contribution to the total seismicity in this region.The north and south part of the study area show different features of background and tr

关 键 词：新疆伽师地区 M_(S)6.5地震 时-空ETAS模型 背景地震活动 触发地震活动 

分 类 号：P315.2[天文地球—地震学]