新疆于田地区地震活动与强震间的应力转移  

Seismic Activity and Stress Migration between Major Earthquakes in Yutian Region, Xinjiang

作　　者：王辉[1] 曹建玲[1] 田勤俭[1] WANG Hui;CAO Jian-ling;TIAN Qin-jian(Institute of Eart hquake Forecasting,China Earthquake Administration,Beijng 100036,China)

机构地区：[1]中国地震局地震预测研究所,北京100036

出　　处：《地震》2021年第2期14-28,共15页Earthquake

基　　金：国家自然科学基金(41774111,41974111);国家重点研发计划项目(2018YFE0109700-03)。

摘　　要：新疆于田地区位于青藏高原与塔里木盆地相交会的地方,强震频发。2008年以来,该地区陆续发生的4次M6以上强震都位于阿尔金断裂带南分支的龙木错—郭扎错断裂带附近。这些地震的发生为研究于田地区中强震活动的空间分布及其之间的相互作用及提供了很好的实例。首先,利用小震目录对区域地震活动进行分析,给出了地震活动性参数b值的空间分布。然后,采用分层黏弹性模型研究了区域4次中强地震所造成的区域应力转移。我们发现,于田地区近年来强震活动的时空分布特征可能与区域地壳应力水平的差异有关。康西瓦断裂带上历史强震活跃,但是现今地震较平静,b值较高;而龙木错—郭扎错断裂带附近的b值相对较低,现今强震活动频繁。于田地区4次中强震造成的应力转移则比较复杂,2012年地震受到2008年地震的卸载作用,而2014年和2020年2次地震的发生均受到前序地震的促进作用。综合区域地震活动和强震之间应力转移的分析,可以认为阿尔金断裂带南支的龙木错—郭扎错断裂带上,应力水平仍然相对较高,未来的地震危险性仍然较大。The Yutian region is located at the intersection region of borderland of the Tibet Plateau and Tarim craton.Four major earthquakes all occurred around the southwestern end of the Altyn Tagh Fault zone since 2008.The earthquake sequence provides a great opportunity to study the spatial distribution of regional moderate strong earthquakes and their interaction.Firstly,we analyze the seismicity in the Yutian region using small earthquake catalogue since 1970,and present a spatial pattern of b-value.Then,we calculate stress migration between 4 major earthquakes since 2008 using a layered viscoelastic dislocation model.We found that the migration of major earthquakes in Yutian region may be controlled by crustal stress level.More historical earthquakes were recorded along the Kangxiwar fault,and b-value derived from background seismicity is relative higher.In contrast,b-value along the Longmu Co-Guozha Co fault zone,the southern branch of the Altyn Tagh fault,is relative lower,while strong earthquake occurred frequently in recent years.In addition,the stress transfer caused by the 4 strong earthquakes in Yutian area is complicated.TheΔCFS that produced by the 2008 earthquake have negative effects on the occurrence of the 2012 event.While occurrence of the 2014 and 2020 events are both promoted by previous major earthquakes.Based on the results of seismic activity and stress transfer,it can be concluded that the crustal stress near the Longmu Co-Guozha Co fault zone is still relatively high,hence still with relative higher potential seismic risk in future.

关 键 词：于田地震序列 阿尔金断裂带 地震活动 库仑破裂应力 

分 类 号：P315.7[天文地球—地震学]