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Journal: |
Acta Geologica Sinica 2018 No.10
clicks:121 |
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Title:
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Author:
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Ding Zhifeng,Guo Huili,Wang Xingchen,Chang Lijun,Zhang Fengxue,Yuan Songyong,Zheng Chen |
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Adress: |
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Abstract:
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The China Seismic Array (ChinArray) Program is to image the crust and upper mantle structures and their
relationship to seismic activity in the mainland of China. The first two phases of the Program was
completed in the eastern margin of the Tibetan Plateau in 2016. By using the seismic imaging methods,
we want to explore the relationship between the Plateau and surroundings blocks, and to learn more about
background structures where the strong earthquake occurred. The seismic array in this region includes
1174 broadband portable seismic stations, with the station spacing of 35km and two years observed
period. By using the data of the seismic array stations, we inversed the 3-D seismic velocity structure, the
shape of the Moho discontinuities and the seismic anisotropy of the lithospheric medium in the research
area. The low velocity zone in the lower crust was founded inside the Plateau area. The depth of the Moho
was obtained from the seismic receiver function. They showed the detailed variation of the Moho
discontinuity in the eastern margin of Tibetan Plateau. The velocity structure results showed that the Red
River fault is the border of the blocks in crust, while it has no remarkable variation in mantle beneath the
fault. The bottom of Alasan block might be affacted by the extrusion of the northeastern margin of the
Tibetan Plateau. The seismic anisotropy figure showed that the directions of the splitted fast S waves are
changed near the latitude of 26°N in southeastern margin of Tibetan Plateau. The seismic anisotropy in
northeastern margin of Tibetan Plateau also show the complex deformation figure caused by the process
between Tibetan Plateau and surrounding blocks. These results could be used to build the lithospheric 3-D
velocity model in the eastern margin of Tibetan Plateau. |
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