Crustal shear wave velocity and radial anisotropy in the Xiaojiang fault zone system (SE Tibet) revealed by ambient noise interferometry

• Published in: Tectonophysics Vol. 792; p. 228594
• Main Authors: Yang, Yuan, Hu, Shaoqian, Yao, Huajian, Fang, Lihua, Wu, Jianping
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 05.10.2020; Elsevier BV
• Subjects: Ambient noise; Ambient noise tomography; Anisotropy; Crustal shear wave velocity; Deformation; Dispersion curve analysis; Fault lines; Fault zones; Geological faults; Interferometry; Lava; Love waves; Permian; Radial anisotropy; S waves; Seismic arrays; Seismic velocities; Seismicity; Shear wave velocities; Southeastern Tibet; Tectonics; Velocity; Water depth; Wave dispersion; Wave velocity; Xiaojiang fault zone system; Tibet; Ambient noise tomography; Southeastern Tibet; Xiaojiang fault zone system; Crustal shear wave velocity; Radial anisotropy
• ISSN: 0040-1951; 1879-3266
• DOI: 10.1016/j.tecto.2020.228594

The Xiaojiang fault zone system (XJFS) is located in the southeastern Tibet with high seismicity. In this study, we invert Rayleigh and Love wave dispersion curves obtained from three dense seismic arrays jointly for high-resolution 3-D crustal average shear wave velocity and radial anisotropy models simultaneously in XJFS. Our model reveals that the upper crust and mid-lower crust generally exhibit negative and positive radial anisotropy, respectively, implying that the deformation pattern is depth-dependent. To the east of the Lvzhijiang Fault, most of the low velocity zones in the mid-crust correspond to the positive radial anisotropy (Vsh > Vsv); the channelized weak zone seems to be continuous across the Red River Fault at depth of 20 km, probably within a thin layer. West of the Lvzhijiang Fault, where it is inferred to be the inner zone of the Permian Emeishan Large Igneous Province, the high velocity zone and positive radial anisotropy in the mid-lower crust can be attributed to the underplating and intruded magmatic rocks. In the upper crust, the high and low velocity zones are mostly belt-shape and follow the north-south direction parallel to the regional major faults; the lateral variation of the radial anisotropy spatially corresponds to the activity of different segments of the Xiaojiang fault zone. Our models depict detailed geometry of the channelized weak zone in the mid-lower crust and provide new insight into the role of major faults in regional tectonics. •High-precision crustal Vs and radial anisotropy models in XJFS (SE Tibet) are derived.•Our models depict detailed geometry of the channelized weak zone in mid-lower crust.•Radial anisotropy is spatially associated with activity of different segments of XJF.