CT理论与应用研究2025，Vol.34Issue(5)：775-789,15.DOI:10.15953/j.ctta.2025.290
龙门山断裂带地壳三维精细结构成像与构造特征研究
Three-dimensional High-resolution Crustal Structural Imaging and Tectonic Characteristics Study of Longmenshan Fault Zone
摘要
Abstract
Seismic arrival time data from broadband arrays deployed along the Longmenshan fault zone were used to invert three-dimensional fine structure models of VP,VS,and VP/VS at depths less than 24km and earthquake relocation in the Longmenshan fault zone using the consistency-constrained double-difference tomography method.The results are as follows:(1)The Longmen Shan fault zone exhibits a high-velocity zone between the Beichuan-Yingxiu fault and the Maoxian-Wenchuan fault zone.Within the depth range of 0-8km,this high-velocity zone is confined beneath the Longmen Shan fault zone.Between depths of 8-20 km,the high-velocity zone merges with the high-velocity zone associated with the Maoxian-Wenchuan ductile shear zone.At depths ranging from 20-24km,the high-velocity zone becomes concentrated in the central segment of the Longmen Shan fault zone.The Western Sichuan foreland extensional deformation belt on the southeastern side of the Anxian-Guanxian fault maintains consistently low velocities.(2)Earth-quakes within the Longmenshan fault zone are predominantly concentrated at depths ranging from 4 to 16km beneath the Beichuan-Yingxiu fault zone.Seismic activity shows a significant correlation with transitional zones,which signifies shifts between high and low seismic wave velocities as well as regions characterized by elevated velocity ratios.The dip angles of the seismic distribution and velocity anomalies vary across the southern,central,and northern segments of the Longmenshan fault zone.In the northern segment of the Longmenshan fault zone,both high-velocity bodies and earthquakes are concentrated within a depth range of 0-15km,with an almost vertical dip orientation.(3)The combined analysis of tomographic velocity structures and fracture characteristics in the reflection profiles reveals a Y-shaped hidden fault within the seismogenic zone of the Lushan earthquake.The seismogenic area of the Lushan earthquake is overlain by an aseismic zone layer measuring 10-15km thick.关键词
龙门山断裂带/双差地震层析成像/地壳速度结构Key words
Longmenshan fault zone/double-difference seismic tomography/Crustal Velocity Structure分类
天文与地球科学引用本文复制引用
瞿辰,于常青,钱辉,曾祥芝..龙门山断裂带地壳三维精细结构成像与构造特征研究[J].CT理论与应用研究,2025,34(5):775-789,15.基金项目
地球深部探测与矿产资源勘查国家科技重大专项(郯庐断裂带深井多参数观测井群系统工程建设(2024ZD1000401)) （郯庐断裂带深井多参数观测井群系统工程建设(2024ZD1000401）
国家自然科学基金(龙门山断裂带深部结构与断裂剪切带变化特征(4217040898)). （龙门山断裂带深部结构与断裂剪切带变化特征(4217040898）
