Time-lapse change in anisotropy in Japan's near surface after the 2011 Tohoku-Oki earthquake

摘要: [1] We apply seismic interferometry to strong-motion records detect the near-surface (i.e., an upper few hundred meters deep) change in anisotropy caused by MW9.0 Tohoku-Oki earthquake on 11 March 2011. We show that increased difference between fast and slow shear-wave velocities arising from splitting most parts of northeastern Japan, but it did not significantly polarization directions near surface. Through monitoring velocity, we find changes velocity partially recover with time; they are, however, still different pre-event values after nine months. The comparison spatial distribution indicates are generally correlated, especially Honshu (the main island Japan). largest principal stress direction weakly correlates anisotropy.