岩手県大船渡市における津波の浸水痕跡の調査,測量の結果を模擬する数値実験を行った.津波は大船渡に最も大きな被害を与えた1960年チリ津波と,また湾口にくらべ湾奥で波高が低い特徴のある1933年三陸津波も対象とした.浅海波方程式を基礎方程式として陸上遡上を含み,leap-frog法で数値計算を行った.市街地の水流抵抗を等価摩擦係数であらわしたが,今回はf=1.0という大きな値で,市街地の浸水高の減衰が近似出来た.1933年津波は短周期であるので,浸水高の分布が局地的に著しく異る特徴をもっている.
A detailed distributions of tsunami inundation heights in Ofunato City in Iwate Prefecture, northeastern Japan, for the 1960 Chile tsunami and the 1933 Sanriku tsunami are available. Thus, a tsunami simulation for these two cases has been carried out numerically by the finite differnce method (leap-frog method) on the basis of shallow water equations. Computational mesh sizes were decreased from the open sea to the innermost part of the bay in several steps. The movement of the water front due to inundation on dry land was taken into consideration only in the innermost part of Ofunato Bay. In the case of the 1960 Chile tsunami the incoming wave patterns at the eastern open sea boundary located about 150 km from the coast of Honshu were inferred from the obsereved tsunami records at Miyagi-Enoshima, a small island just off the main coast of northeastern Japan. A better simulation of the overall inundation height distribution for this tsunami was obtained by using a somewhat higher value of the effective friction coefficient on land area, f=1.0, than the value (f=0.5) previously used in the simulation made in Owase City, Mie Prefecture for the tsunami of 1944. For the 1933 Sanriku tsunami, a seismic fault model already published was used as the tsunami source. Simulated tsunami inundation heights agreed fairly well with the measured data in most parts of the investigated area. In this simulation, the local variation of the maximun water level was remarkable because the prevailing period of this tsunami was rather short (8 to 15 min).
雑誌名
東京大學地震研究所彙報 = Bulletin of the Earthquake Research Institute, University of Tokyo
巻
58
号
1
ページ
175 - 185
発行年
1983-07-28
ISSN
00408972
書誌レコードID
AN00162258
フォーマット
application/pdf
日本十進分類法
453
出版者
東京大学地震研究所
出版者別名
Earthquake Research Institute, University of Tokyo
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6. 大船渡市街に遡上した津波の数値実験
ji0581006.pdf
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