CT理论与应用研究2025，Vol.34Issue(5)：763-774,12.DOI:10.15953/j.ctta.2025.205
中祁连地壳速度结构及地震活动性
Crustal Velocity Structure and Seismic Activity of the Central Qilian Block
摘要
Abstract
The Qilian Orogenic Belt,located at the northeastern margin of the Tibetan Plateau with the Central Qilian Block at its core,plays a significant role in regional tectonic evolution.To reveal the crustal velocity structure of the Qilian Orogenic Belt and investigate the relationship between velocity structure and seismic activity,this study utilized P-wave and S-wave arrival time data recorded by seismic networks in Gansu,Qinghai,and other regions under the China Earthquake Networks Center.A double-difference tomography method was applied to relocate 6,617 seismic events in the study area,and 3D P-wave/S-wave velocity structures as well as velocity ratio distributions were obtained.The double-difference tomography produced several interesting results:(1)The Central-Northern Qilian Fault Zone exhibits distinct segmentation in activity along its eastern and western sectors.The eastern segment is dominated by shallow-seated faulting(0-10km),whereas the western segment features deeper-seated tectonic activity(15-25km).This indicates more pronounced upper crustal thickening in the western sector of the Qilian orogenic belt.Large earthquakes are concentrated in high-velocity anomaly regions of the upper-middle crust,suggesting that brittle crust is more prone to fault rupture.(2)Both velocity structures and velocity ratio distributions show a vertical transition from high to low values,indicating that the upper-middle crust of the Qilian Orogenic Belt is more rigid,whereas the middle-lower crust may include dehydration reactions of hydrous minerals.(3)There is a significant interface separation between the Central Qilian Block and the North Qilian Orogenic Belt in the upper-middle crust,which corresponds well with the south-deep and north-shallow distribution characteristics of sedimentary rock layer thickness in the Qilian Orogenic Belt.关键词
祁连造山带/双差层析成像/地壳速度结构Key words
Qilian orogenic belt/double-difference tomography/crustal velocity structure分类
天文与地球科学引用本文复制引用
梁赐安,沈旭章,李敏娟,刘谨瑞..中祁连地壳速度结构及地震活动性[J].CT理论与应用研究,2025,34(5):763-774,12.基金项目
国家自然基金重点项目(祁连造山带深部结构与晚新生代构造变形研究(42230305)) （祁连造山带深部结构与晚新生代构造变形研究(42230305）
2025年度地震预测开放基金(XH25005D). （XH25005D）
