Study of anisotropic velocity structure by splitting analysis of Ps converted waves

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The S-wave polarization anisotropy is investigated in the upper and lower crust and the mantle wedge by shear-wave splitting analysis of Ps converted waves which originate at the Conrad and Moho discontinuities in the crust and at the upper boundary of oceanic plates subducting beneath the Japan Islands. The waveform cross-correlation method and stripping method are employed for the shear-wave splitting analysis. As a result, the upper crustal anisotropy is shown to mask the Ps phase polarization anisotropy in the lower crust and the mantle wedge. In addition, it is found that in Chugoku and Shikoku districts the anisotropic properties of shear wave are different between the upper and lower crust and that in the east coastal region of Tohoku district the fast polarization directions of Ps waves in the mantle wedge show basically N-S direction trend.