Physical model test of hokkaido nansei-odi earthouake tsunami around cape aonae

摘要

On July 12, 1993, a tsunami generated by the Hokkaido Nansei-Oki earthquake caused devastation on Okushiri Island. The inundation heights exceeded over 10 m at various sites of the island, which were Inaho located on the west side of north end, along the southwest coast and Hamatsumae district located on the southeastern part. One of these area with high tsunami runup, Hamatsumae district was of particular interest since it is located in an area sheltered from tsunami source area by Cape Aonae. Moreover, the shape of the coastline around Hamatsumae was convex to the sea, which was not believed to produce large inundation. Numerical simulations were performed to reproduce the propagation and the inundation of the tsunami (for example, Takahashi et al.; 1994). They simulated the distribution of inundation heights to some extent, but failed to reproduce the anomalous inundation height at Hatsumae. Since the tsunami attacked in midnight immediately after the earthquake occurred at 10:17pm, observations were scarce. Physical model tests were therefore performed in the present study to investigate the mechanism of tsunami of tsunami transformation in this area in detail.