カムチャッカ～北海道東部間の津波エネルギー分布

抄録

Many tsunamis have been actively generated along the Kurile-Kamchatka trench. Historical tsunamis in the Kamchatka region have been recorded since 1737. The 1952 Kamchatka tsunami, magnitude on the Imamura-Iida scale (m=4), is the largest, and hit North Japan, Hawaii and South America. In recent years, the South Kurile (East Hokkaido) tsunami on Dec. 4, 1994 (m=3) and the Kamchatka tsunami on Dec. 5, 1997 (m=1) were generated near the trench. In the present paper, the distribution of cumulative energy (square value of tsunami heights, H², where H: the mean height in segment unit) for each 150km segment along the Kurile-Kamchatka trench is investigated for the recent 99-year (1900-1998) and historical (1737-1899) periods. The result shows that the cumulative value, ΣH², from South Kamchatka to the North Kurile regions is the largest, and the 2nd highest value in the South Kurile Islands during 1737-1998. For the recent 99-year, the observed value in South Kamchatka reached the expected value which was calculated assuming the mean rate of energy accumlation. On the contrary, the observed value in the North Kamchatka and South Kurile regions are twice larger than the expected value because of the recent high seismic activities.