Lower-crust S-wave velocity beneath western Yunnan Province from waveform inversion of dense seismic observations |
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| Authors: | Xing Gao Youliang Su Weimin Wang Shunping Pei Zhi Guo |
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| Institution: | Institute of the Tibetan Plateau Researches, Chinese Academy of Sciences, Beijing, China |
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| Abstract: | We use teleseismic body waveforms to explore S-wave layered velocity structures beneath 30 portable digital seismic stations deployed around western Yunnan Province. Results show that the Moho depth in this region is ～40 km and decreases in general from north to south, consistent with previous geophysical studies. Associated with this lateral variation of the Moho depth, the lower crust above the Moho discontinuity has a 15–25 km thick zone with an S-wave velocity lower than that of the upper crust. This lower velocity zone might be interpreted as a lower crust weak channel, which may mechanically partially decouple the upper-crust deformation from the underlying mantle. Thus, the inverted S-wave velocity structure could provide new evidence for the lateral flow of lower crust in the build-up of the south-eastern Tibetan plateau. |
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