JpGU-AGU Joint Meeting 2017

Presentation information

[JJ] Poster

S (Solid Earth Sciences) » S-VC Volcanology

[S-VC51] [JJ] Reconsiderations on 1986-IzuOhshima eruption, learning new things from the past

Sun. May 21, 2017 1:45 PM - 3:15 PM Poster Hall (International Exhibition Hall HALL7)

convener:Kei Kurita(Earthquake Research Institute,University of Tokyo), Hidefumi Watanabe(Disaster Prevention Division, Tokyo Metropolitan Government)

[SVC51-P09] The tsunami caused by the volcanic eruption of Izu Ooshima Island on September 18th, 1684

*Yoshinobu Tsuji1, Yosuke Kuroyanagi2, Takahiro Kinami3, Yuya Matsuoka4, Mutsumi Odagiri(Shiraishi)5, Masami Sato6, Yayoi Haga6, Fumihiko Imamura6 (1.Fukada Geological Institute, 2.Pacific Consultants Co. Ltd., 3.Kubiki Engineering Co. Ltd., 4.Tohoku Univ., 5.Hanamaki City Museum, 6.IRIDeS, Tohoku Univ.)

Keywords:Tsunami caused by a volcanic eruption, Izu Ooshima, Historical Tsunami, Cauchy-Poisson's waves

Volcano Izu-Ooshima island began to be active on March 31st, 1684, and it became the stage of climax in 9th, August of the same year. The volcanic activity stopped in 1690. Fifty nine years after the finishing of the volcanic activity, “Izu-Ooshima Sashidashi-cho (The geographical and historical report of Izu Ooshima Island)” was published. In this report, there is a description of a tsunami which had hit Niijima Village (Motomachi Town at present) in August, 1684 as the following: “ Niijima Village in Ooshima Island, in August of 1684, more than sixty trading and fishing vessels were carried away by a tsunami, and in addition that four people and more than 60 houses were swept away. ” The date of the tsunami is not mentioned explicitly, but it is recorded by another documents that the volcanic eruption became most active on 8th August, so, the tsunami was probably generated on the same day. The total number of houses in Ooshima village was 253 in 1749, and was 245 in 1793, so it was considerable to be about 250 also in the year of the tsunami, 1684.
The number of tsunami swept away houses was about 60, so about quarter of total houses were swept away in Niijima village. We made ground height measurement in Motomachi town at a point on the contour line which separates about quarter part of the residential area of Motomachi Town, Izu-Ooshima. We found that the ground height at the point was 13.9 meters (above T.P. 0m). We estimated that the tsunami height was in minimum 13.9 meters, and it is possible, sea water rose up to the level of fifteen meters above the mean sea level.
Acknowledgement: This study was achieved as a part of the commissioned research named “Study on the historical tsunamis in the Pacific coast of Japan (2016)” on disaster prevention for nuclear facilities proposed by the Nuclear Regulation Authority, Japan.