Crustal and uppermost mantle structure of SE Tibetan plateau from Rayleigh-wave group-velocity measurements

作     者：Yonghua Li Jiatie Pan Qingju Wu Zhifeng Ding 

作者机构：Key Laboratory of Seismic Observation and Geophysical Imaging China Earthquake Administration Institute of Geophysics China Earthquake Administration 

出 版 物：《Earthquake Science》 (地震学报（英文版）)

年 卷 期：2014年第27卷第4期

页      面：411-419页

学科分类：070801[理学-固体地球物理学] 07[理学] 0708[理学-地球物理学] 

基　　金：supported by the China National Special Fund for Earthquake Scientific Research in Public Interest(201008001) NSFC(41074067) 

主　　题：SE Tibetan plateau Shear-wave velocity Rayleigh-wave tomography Group velocity 

摘      要：A shear-wave velocity model of the crust and uppermost mantle beneath the SE Tibetan plateau was derived by inverting Rayleigh-wave group-velocity mea- surements of periods between 10 and 70 s. Rayleigh-wave group-velocity dispersions along more than 3,000 inter- station paths were measured based on analysis of telese- ismic wavelbrm data recorded by temporary seismic stations. These observations were then utilized to construct 2D group-velocity maps in the period range of 10-70 s. Tile new group-velocity maps have an enhanced resolution compared with previous global and regional group-velocity models in this region because of the denser and more uniform data coverage. The lateral resolution across the region is about 0.5° for the periods used in this study. Local dispersion curves were then inverted for a 3D shear-wave velocity model of the region by applying a linear inversion scheme. Our 3D shear-wave model confirms the presence of low-velocity zones （LVZs） in the crust beneath the northern part of this region. Our irnaging shows that the upper-middle crustal LVZ beneath the Tengchong region is isolated from these LVZs beneath the eastern and northern part of this region. The upper-middle crustal LVZ may be regarded as evidence of a rnagma chamber in the crust beneath the Tengchong Volcanoes. Our model also reveals a slow lithospheric structure beneath Tengchong and a fast shield-like mantle beneath the stable Yangtze block.