QIAN Qi-Wei,
WU Jing,
LIU Geng et al
.2017.Anisotropy of middle-upper crust derived from shear-wave splitting in the northeastern Tibetan plateau and tectonic implications.Chinese Journal Of Geophysics,60(6): 2338-2349,doi: 10.6038/cjg20170625
Anisotropy of middle-upper crust derived from shear-wave splitting in the northeastern Tibetan plateau and tectonic implications
QIAN Qi-Wei1,2, WU Jing1, LIU Geng3, SHA Cheng-Ning4, MA Jian-Xin4, BAI Zhan-Xiao4, ZHAO Yan-Jie4, LIU Xiao-Mei1,2
1. Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China; 2. University of Chinese Academy of Sciences, Beijing 100049, China; 3. Institute of Earthquake Science, China Earthquake Administration, Beijing 100036, China; 4. Qinghai Earthquake Administration, Xining 810001, China
Abstract:The northeastern Tibetan plateau(94°E—105°E,32°N—40°N) is the front edge of expansion of this vast high land, which is crucial for understanding the evolution of the plateau. We obtain the shear-wave splitting results from waveforms of local earthquakes(2008—2014)recorded by the digital seismic network of Qinghai Province. First, we apply the HypoDD to relocate the seismic events, and choose those events within the S window (defined by the incidence angle ≤45°) for further analysis. Then, we use the SAM technique to invert the shear-wave splitting parameters. Totally, we obtain splitting parameters of 26 stations. The results show that two major fast shear-wave polarizations exist in Xining and adjacent areas, where multiple blocks converge. This means that seismic anisotropy in middle-upper crust of the area is controlled by both the tectonic stress and active faults. In addition, predominant polarization direction of seismic anisotropy in the crust from Yushu aftershocks is consistent with the principal compressive stress field in this region.
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