Abstract
The shape of tsunami source deforms ususlly elliptic and the earthquake origin situates on the edge of the tsunami elliptic source. Then, it seems that the tsunami occurrence elongates apparently from one edge of tsunami source to another.
The subject of this report is to study the relationship between such apparently elongated tsunami source and tectonics near occurrence area. Some obtained results are followings.
1) The apparently elongated direction of tsunami source has a close relation with the sea depth of tsunami occurrence area, plate formation and earthquake mechanism.
2) Tsunami sources is parallel to iso-depth lines, however, vertical to them in the Tokachi-oki and the Hyuganada, corresponding to changed point of the Pacific and the Philippine plates.
3) The elongated direction of tsunami source is parallel to the slip direction of earthquake fault in the Tokachi-oki, the Boso-oki and the Hyuganada, and vertical to other areas. This depends with the slip angle of earthquake fault.
4) Tsunami amplitude and earthquake intensity seem to be large at the direction of earthquake fault.
In general, it seems that tsunami occurrence and tectonics at the changed points, are more complicated than other ones.
