Oral

IAPSO

JPM01 - Interdisciplinary Tsunami Science

Penetration of the trans-Pacific tsunamis into the Sea of Japan

The Sea of Japan is a region of high tsunami risk. The major threat is posed by regional events that originate within the basin. However, large transoceanic tsunamis from the Pacific Ocean are observed to penetrate the Sea of Japan through its connecting straits. Thus, such tsunamis can pose an additional risk for coastal communities in the sea. Using numerical modeling, we estimate the ability of the three major connecting straits to allow oceanic tsunami waves to penetrate the Sea of Japan. As the individual straits each have complicated shapes and bathymetric profiles, a simple approach of a flat regular channel cannot be applied. An energy flux analysis shows that the waves enter the sea mostly through Tsugaru Strait and La Perouse Strait, and that the contribution of the wide Korea Strait is surprisingly insignificant. Because of the sharp bathymetric change at the seaward end of Tsugaru Strait, a significant part of the wave energy remains on the Japan Sea shelf adjacent to the strait and does not propagate to other parts of the sea. The transfer functions are specific to each strait. Tsugaru Strait acts like a narrow band-pass filter that passes waves with periods of around 1.5 h, while the transfer function for La Perouse Strait has a longer major period of around 3h and a wider pass band. The transfer functions of the straits are used for analysis of the waves penetrating the sea through the straits during the largest observed historical trans-Pacific events: the 1960 Chilean tsunami, the 1964 Alaska tsunami and the 2011 Tohoku tsunami. The work was carried out with the support of the Russian Science Foundation (Grant no. 24-17-00313).