Inversion of far-field seismic waves at Shidao Seismographic Station

RUAN Ai-guo; LI Jia-biao; HAO Tian-yao; WU Qing-ju; XU Yi

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RUAN Ai-guo, LI Jia-biao, HAO Tian-yao, WU Qing-ju, XU Yi. Inversion of far-field seismic waves at Shidao Seismographic Station[J]. Haiyang Xuebao, 2006, 28(2): 85-92.

Citation:

RUAN Ai-guo, LI Jia-biao, HAO Tian-yao, WU Qing-ju, XU Yi. Inversion of far-field seismic waves at Shidao Seismographic Station[J]. Haiyang Xuebao, 2006, 28(2): 85-92.

RUAN Ai-guo, LI Jia-biao, HAO Tian-yao, WU Qing-ju, XU Yi. Inversion of far-field seismic waves at Shidao Seismographic Station[J]. Haiyang Xuebao, 2006, 28(2): 85-92.

Citation:

RUAN Ai-guo, LI Jia-biao, HAO Tian-yao, WU Qing-ju, XU Yi. Inversion of far-field seismic waves at Shidao Seismographic Station[J]. Haiyang Xuebao, 2006, 28(2): 85-92.

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Inversion of far-field seismic waves at Shidao Seismographic Station

1.
Key Laboratory of Submarine Geosciences of State Oceanic Administration, Hangzhou 310012, China;Second Institute of Oceanography, State Oceanic Administration, Hangzhou 310012, China
2.
Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100101, China
3.
Institute of Geophysics, China Seismological Bureau, Beijing 100081, China

Received Date: 2005-02-02
Rev Recd Date: 2005-03-28

Abstract

Abstract

Far-field seismic waves recorded at the Shidao Seismog raphic Station,located in the South China Sea,are used to inverse earth anisotropy and shear wave velocity vertical distribution under the station respectively.(1) The approach of rotated correction function is applied to five satisfactory ScS wave recordings at distance of 25°~35° to inverse shear wave splitting parameters of lithosphere.The inversion result of the deepest earthquake shows that the polarization of fast shear wave is N94°E and the extensional stress or the moving direction of the mantle mass in the Xisha region is nearly EW.It suggests that the crust in this region is a transitional one and driving force beneath comes from the mass flow whose flowing direction is consistent with the moving of Eurasian plate in the South China Sea.The time delay between fast and slow shear waves is 1 3 s,from which the anisotropy effective thickness is estimated about 100 km.(2) The method of receiver function is used for nine high quality P wave recordings with three components at distance of 20°~60° to inverse vertical distribution of shear wave velocity beneath the station.The result indicates that the crust can be divided into three layers:above 5 km where there is a gradient zone including several small layers,in which shear wave velocity increases from 1.5 to 3.5 km/s gradually;between 5 and 16 km the velocity is about 3.8 km/s in average including several small layers;between 16.0 and 26.5 km the velocity is about 3.6 km/s which is an obvious low velocity layer.The buried depth of Moho discontinuity is 26.5 km and beneath the Moho the velocity is about 4.7 km/s in average,including several small layers,especially an obvious low velocity layer just beneath the Moho.The analysis of the arrival time of transformed waves and the velocity swinging variation around initial model suggest the smaller layers maybe are not reliable,but the velocity layer between 16.0 and 26.5 km may be is real one implying the plasticity of the lower crust.
- South China Sea,
- Swave splitting,
- receiver function,
- Swave velocity structure,
- waveform inversion

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References(25)

References

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