| Summary: | application/pdf For seven tsunamis which reached the coast of Japan, from Iturup, Kamchatka, Aleutian, Alaska and Chile, the distribution of tsunami energy are shown along the isobathymetric line of 200m. As compared with the distribution, given by R. Takahasi(1951), for tsunamis originated in the sea adjacent to Japan, the patterns of energy distribution are approximately similar to each other. The regions in Sanriku and Kishu receive high percentage of the total energy of the tsunami. The ratio between heights of the initial wave and the maximum wave seems to increase with decreasing seiche period of the bay. Along the Sanriku coast, the tsunami is always high because of particular geographical conditions, concentrated wave energy by refraction, and amplifying by coastal effects. Refraction diagrams in the adjacent sea of Japan are drawn with the aid of arrival times of the wave fronts observed by the tide-gauge stations. 日本に伝播した7個の遠地津波(浪源:Iturup, Kamchatka, Aleutian, AlaskaおよびChile)について,日本太平洋沿岸に沿つた200m等深線上に津波エネルギー分布を求め,高橋(1951)が示した近地津波の総エネルギー分布と比較したとき,かなり傾向が相似し,三陸および紀州地域が受ける津波エネルギーの割合が他地域に比して大きい.湾の周期特性と,湾口と湾奥の波高増幅度との関係について,渡辺(1964)は1933年の三陸津波と1960年のチリ津波との相沢を理論的に説明したが,概して遠地津波の場合,一観測点における最高波と第1波の波高比,すなわち波高の増幅度は,短周期のセイシュを持つ湾程,大きい. departmental bulletin paper
|
|---|