Although some small amounts of hydrous minerals (serpentine, antigorite, talc, chlorite, clinoclore, etc.) in the subducting slab are very anisotropic for both P and S waves39, we think that seismic anisotropy is induced mainly by olivine CPOs in the upper mantle considering the resolution scale (~40?km?×?50?km?×?50?km) of our tomographic model. Recent experiments have suggested that the same olivine fabric shows the same seismic anisotropy for S-wave17 and P-wave40.