A static dislocation model of the Sanriku earthquake of 1933 is proposed which is consistent with the initial motion of the tsunami. The wave equations of a tsunami were solved numerically on the displacement fields for various fault parameters and the computed time histories of the water surface elevation at the coast were compared with the observed initial motions. The best fit parameters were determined by trial and error. It is a normal fault reaching the earth's surface and having a dip of 30° toward the west, a dimension of 270km (length)×70km (width) and a dislocation of 2-5m. The assumed rigidity of 7×1011 dyne/cmcm2 gives a moment of (3-7)×1028 dyne-cm. The fault of this model has a longer, narrower fault surface and smaller dip angle than that of the seismic model (KANAMORI, 1971a). The dip angle of the present model is in fairly good agreement with that of the deep-focus seismic plane in this region. It is understood that the upper part of the sinking slab slid down with the earthquake and it contributed to make the oceanic plate slide down as a whole under the island arc. Thus it is shown that the tsunami data is useful in making a fault model.
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Kuniaki Abe (1978) studied this question.