The elevation of the free surface from the undisturbed level by tsunami generation is expressed as the convolution of the Green's function and the vertical velocity of the bottom deformation integrated over the source area. The cross correlation of the waveforms at two observation stations is shown to yield the Green's function between these positions. The trans-ocean tsunami waveforms are computed with the Green's function retrieved by cross correlating tsunami records. The waveforms at the stations near the Japan coast which are estimated with the Green's function between the two observation stations are compared with the observed records. The agreement between the observed and computed waveforms shows fairly good.
