天保14年(1843年)北海道東部津波の波源域

概要

論文の詳細を見る
新史料を加え,天保14年(1843年)北海道東部津波の挙動を検討した.浸水被害状況から,津波の高さは厚岸4～5m,白糠3～3.5m,函館0.5m,八戸2.5～3mと推定され,津波マグニチュードはm=2.5とみなせる.近年の十勝沖・根室沖津波と比べると,震度・波高分布は1952年十勝沖津波のものと同様なパターンを示し,波源域は十勝沖にあった可能性が大きい.With the addition of new data on the East Hokkaido tsunami of Apr. 25, 1843 (Tenpo 14), the inundation heights along the Hokkaido and Sanriku coasts are investigated. According to the old documents, 75 houses were washed away and 45 persons drowned at Akkeshi, East Hokkaido. Several houses were damaged at Hachinohe, and 46 persons drowned at Taro on the Sanriku coast. The estimated inundation heights (above mean sea-level) are 4-5m at Akkeshi, 3-3.5m at Shiranuka, 0.5m at Hakodate, and 2.5-3m at Hachinohe. The tsunami magnitude (Imamura-Iida scale) seems to be m=2.5. Distribution patterns of the seismic intensity and inundation height in the Hokkaido and Tohoku regions are very similar to those of the 1952 Tokachi-oki tsunami (m=2.5). The source area of the 1843 tsunami may be located off the Tokachi coast along the west side of the 1894 Nemuro-oki tsunami (m=2). A segment of about 100km in the Tokachi region should be considered a relatively high tsunami risk area.
1984-12-25