Add to ORKGTwo Iturup tsunamis of 1958 and 1963 have offered a good opportunity to investigate the behaviour of edge waves on the continental shelf. Taking into account the results of a model experiment carried out lately, an attempt is made to investigate the problem by techniques of digital filtering and the Fourier transform. The complexity of the shape of the continental shelf along the Pacific coast of northeastern Japan adds difficulty to obtain the fair results such as a model experiment. The results obtained in the present work are that a dispersive wave group with the characteristics of edge waves seems to follow the direct wave but this wave group includes the wave component normal to the coast which is 1 to 3 times the wave amplitudes of ed...