2008年3月21日新疆于田MS7.3地震破裂过程研究  

Source rupture process of Yutian,Xinjiang,M_S7.3 earthquake on 21 March 2008

作　　者：冀战波 赵翠萍[3] 王琼[2] 李志海[2] 王海涛[2] 

机构地区：[1]中国地震局兰州地震研究所,中国兰州730000 [2]新疆维吾尔自治区地震局,中国乌鲁木齐830011 [3]中国地震局地震预测研究所,中国北京100036

出　　处：《地震学报》2014年第3期339-349,531,共11页Acta Seismologica Sinica

基　　金：国家自然科学基金(41104037);“新疆新源-和静6.6级地震科考”项目及地震科技星火计划项目(XH13027)联合资助

摘　　要：利用IRIS全球地震台网30°—90°的长周期P波记录,反演了2008年3月21日新疆于田MS7.3地震的破裂过程,得到了此次地震的破裂时空图像,并初步分析了余震分布与主震断层滑动量分布的关系.结果表明,此次地震是一个破裂尺度长100km、宽20km的破裂过程;破裂持续时间约为40s,在第13s时地震矩释放速率达到峰值,断层面上一次大的破裂行为几乎构成了整个地震的破裂过程.地震所释放的标量地震矩为4.23×1019 N·m,其矩震级为MW7.02.由主震断层静态滑动量分布图可以看出,整个破裂区以正断左旋走滑为主,显示出双侧破裂特征,最大滑动量为151cm,位于初始破裂点沿断层出露地表处.精定位后的余震在断层面上的投影结果显示,80%以上ML4.0—4.9余震和全部ML≥5.0余震均发生在初始破裂点附近区域及其南西方向,位于主震破裂滑动位移量迅速减小的区域,反映了震源区介质强度的不均匀性.This paper studied the source rupture process of the Ms7.3 earthquake occurred in Yutian,Xinjiang on March 21,2008,by using digital teleseismic P wave seismograms recorded by long-period seismograph stations of the Global Seismic Network.Then we got the rupture pattern of the earthquake and analyzed the relationship between distribution of aftershocks and fault slip of the main shock.The rupture process inversion result shows that the co-seismic deformation affected a big area （about 100 km× 20 km） and that the total rupture duration is about 40 s.One large rupture behavior on the seismogenic fault almost constitutes the whole rupture process of this earthquake; the scalar moment tensor is 4.23×10^19 N·m and its moment magnitude is Mw7.02.The distribution of static slip on the main-shock fault shows that the rupture zone is dominated by sinistral strike-slip normal motion,suggesting a bilateral rupture process.The maximum slip is 151 cm,which is located at the surface above the initial rupture point.The projection results of the relocated aftershocks on the main shock fault plane show that more than 80 % of the aftershocks with 4.0≤ ML≤4.9 and all of ML≥5.0 aftershocks occurred near the initial rupture point and its southwestern region,where the sliding displacement resulted from the main shock reduces rapidly.It may reflect the heterogeneity of fault medium strength in the source region.

关 键 词：2008年于田M7 3地震 震源破裂过程 矩张量反演 余震分布 

分 类 号：P315.31[天文地球—地震学]