新疆天山中段上地幔各向异性研究  

STUDY ON ANISOTROPY OF UPPER MANTLE IN MIDDLE SECTION OF TIANSHAN MOUNTAINS,XINJIANG

作　　者：赵鹏翔 谢江丽 郑雪刚[1] 王伽祺 ZHAO Peng-xiang;XIE Jiang-li;ZHENG Xue-gang;WANG Jia-qi(Earthquake Agency of Xinjiang Uygur Autonomous Region,Urumqi 830011,Xinjiang,China)

机构地区：[1]新疆维吾尔自治区地震局,新疆乌鲁木齐830011

出　　处：《内陆地震》2025年第1期68-76,共9页Inland Earthquake

基　　金：新疆地震科学基金(202217).

摘　　要：新疆天山中段区域内自2016年来发生M_(S)5.0以上地震6次,其中包括呼图壁M_(S)6.2地震以及精河县M_(S)6.6地震,地震活动较为频繁,应力场变化明显。利用新疆天山中段区域内新疆数字地震台网2016-2020年22个宽频地震台站记录的,震中距为85°~130°、M_(S)≥5.5且有清晰SKS或SKKS震相的远震波形数据,使用最小特征值法(EV)、旋转相关法(RC)以及最小切向能量法(SC)3种方法计算台站下方各向异性参数,即快波偏振方向(φ)及慢波延迟时间(δt)。研究结果表明,新疆天山中段区域内上地幔厚度在70~115 km之间;上地幔各向异性方向主要为NE和NW两个方向,这种杂乱无章的结果表明,新疆天山中段区域内地下介质存在较为复杂的各向异性结构;通过上地幔各向异性方向和板块运动方向的对比,发现区域内地幔流动模型为简单的软流圈流动。Since 2016,there have been 6 earthquakes above M_(S)5.0 in the middle Tianshan region of Xinjiang,including the Hutubi M_(S)6.2 earthquake and the Jinghe County earthquake of magnitude 6.6.The seismic activity is relatively frequent and the stress field changes obviously.In this paper,the data of epicenter distance 85°~130°,M_(S)≥5.5 and clear SKS or SKKS seismic phase recorded by 22 broadband seismic stations in Xinjiang Digital Seismic Network from 2016 to 2020 are used.In this paper,the minimum eigenvalue method(EV),rotation correlation method(RC)and minimum tangential energy method(SC)are used to calculate the anisotropy parameters below the station,that is,the polarization direction of fast wave(φ)and the delay time of slow wave(δt).The results show that the thickness of the upper mantle in the middle Tianshan Mountains is 70~115 km.The direction of upper mantle anisotropy is mainly NE and NW,and the results show that there is a complex anisotropic structure in the lower medium in the middle Tianshan region of Xinjiang.By comparing the anisotropy direction of the upper mantle and the direction of plate movement,it is found that the mantle flow model in the region is a simple asthenosphere flow.

关 键 词：各向异性 上地幔 天山中段 

分 类 号：P315.7[天文地球—地震学]