Seismic Anisotropy in the upper crust beneath the Sanjiang lateral collision zone in the southeastern margin of the Tibetan Plateau revealed by S wave splitting from a temporary array

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Published: Jun 27, 2023
DOI: https://doi.org/10.4401/ag-8867

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Xinyi Li
a:1:{s:5:"en_US";s:68:"Institute of Earthquake Forecasting, China Earthquake Administration";}
https://orcid.org/0000-0001-6414-9195
Yuan Gao

Abstract

The Sanjiang lateral collision zone is a key region to understand the Tibetan Plateau’s tectonic structure and the Tethys-Himalayan’s tectonic evolution. Complex tectonic structures, intense crustal deformation, frequent seismicity, and abundant metal deposits are all present. With the seismic data recorded by a temporary array (SJ-Array) and permanent stations (Nov. 2018 ~ Dec. 2020), this paper adopts the S wave splitting technique to obtain the essential properties of upper crustal anisotropy. In the interested area, it is shown that the dominant polarization of the fast S wave is NNW, with a mean polarization direction of 167.9°. In addition, the study area can be divided into three subzones from the west to the east: A, B, and C, according to the various mean polarizations varying from NNW, NS to NNE. The mean normalized time delay between the two split S waves is 4.0 ms/km, and the range of time delay is from 2.0 to 6.3 ms/km. The largest time delay is located at the east side of the western boundary of the Sichuan-Yunnan rhombus block. Furthermore, there is a strip area of strong anisotropy stretching along the western segment of the Lijiang-Xiaojinhe fault. These all demonstrate the local tectonic differences and indicate that the crustal structure may be strongly controlled by the fault and block boundary strike.

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How to Cite
Li, X. and Gao, Y. (2023) “Seismic Anisotropy in the upper crust beneath the Sanjiang lateral collision zone in the southeastern margin of the Tibetan Plateau revealed by S wave splitting from a temporary array”, Annals of Geophysics, 66(2), p. SE212. doi: 10.4401/ag-8867.
Issue
Vol. 66 No. 2 (2023): Special Issue: Seismic anisotropy and shear-wave splitting: Achievements and perspectives -
Section
Seismic anisotropy and shear wave splitting: Achievements and perspectives
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