Crustal seismic anisotropy in Yunnan, Southwestern China |
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| Authors: | Yu-tao Shi Yuan Gao Jing Wu You-jin Su |
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| Institution: | (1) Institute of Earthquake Science, China Earthquake Administration, Beijing, 100036, China;(2) Earthquake Administration of Yunnan Province, Kunming, 650041, China |
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| Abstract: | Using seismic data recorded by Yunnan Telemetry Seismic Network from January 1, 2000, to May 31, 2005, the polarization directions
of fast shear waves are obtained at 15 seismic stations by SAM technique, which is a systematic analysis method on shear-wave
splitting. The results show that predominant directions of polarizations of fast shear waves at most stations are mainly nearly
in the N–S or NNW directions in Yunnan. The predominant polarization directions of fast shear waves at stations located on
the active faults are consistent with the strike of active faults, directions of regional principal compressive strains from
GPS measurement, and directions of regional principal compressive stress. A few of the stations show that polarization patterns
of fast shear waves are more complicated or inconsistent with the strike of active faults and the directions of principal
GPS compressive strains; these stations are always located at the junction of several faults. We conclude that the predominant
polarization direction of fast shear waves indicates that the direction of the in situ maximum principal compressive stress
is controlled by multiple tectonic aspects, such as the regional stress field and faults. |
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| Keywords: | Shear-wave splitting Polarization of fast shear wave Principal compressive stress Active faults |
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