Premium
S wave velocity structure in southwest China from surface wave tomography and receiver functions
Author(s) -
Wang Weilai,
Wu Jianping,
Fang Lihua,
Lai Guijuan,
Yang Ting,
Cai Yan
Publication year - 2014
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.983
H-Index - 232
eISSN - 2169-9356
pISSN - 2169-9313
DOI - 10.1002/2013jb010317
Subject(s) - geology , seismology , surface wave , seismic tomography , structural basin , low velocity zone , receiver function , fault (geology) , mantle (geology) , geodesy , tectonics , geophysics , lithosphere , geomorphology , telecommunications , computer science
Using the surface wave records of 504 teleseismic events at 50 temporary and 92 permanent seismic stations in southwest China, we obtain phase velocity maps at 10, 15, 25, 40, 60, and 75 s at a grid spacing of 0.5° × 0.5° from the interstation correlation method and surface wave tomography. We also obtain the S wave velocity structures beneath three profiles using the joint inversion of receiver functions and surface waves. At short periods (10 and 15 s), high‐velocity zones (HVZs) are found in the Panzhihua‐Emeishan region, the Sichuan basin and the Weixi‐Lijiang region surrounding the low‐velocity zones (LVZs) from Songpan‐Ganzi block to the east of Lijiang, where the elevations are significantly higher. At long periods (40, 60, and 75 s), HVZs are found in the Weixi‐Lijiang region, the Panzhihua‐Chuxiong basin,and the Kunming‐Tonghai region, which form a belt in the center part of the study area. The fast polarization directions on both sides of the belt defined by the shear wave splitting of teleseismic SKS waves vary significantly and indicate that the flow of material from the plateau is blocked in two different depth intervals and leads to different horizontal extents. The long‐period maps and the structures along the three profiles show that LVZs are present in the upper mantle beneath rapidly slipping fault zones, such as the Anninghe‐Zemuhe‐Xiaojiang fault zone, the Red River fault zone, and the Xiaojinhe fault zone, implying that these faults penetrate deep into the mantle.