著者

樋渡 康子 佐藤 魂夫 今村 文彦

出版者

公益社団法人 日本地震学会

雑誌

地震 第2輯 (ISSN:00371114)

巻号頁・発行日

vol.54, no.4, pp.431-440, 2002-04-25 (Released:2010-03-09)

参考文献数

15

被引用文献数

1

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Three earthquakes and accompanying tsunamis of 1704, 1793 and 1804 hit the coastal area of the Aomori-Akita districts in the northern part of Japan Sea, causing several hundreds of fatalities and serious damages to houses and ships. In this study, we simulate the generation and the propagation of these tsunamis by assuming several fault models, and determine a set of fault parameters for each earthquake that best fits the observed distributions of tsunami heights and crustal uplifts. The fault model previously proposed by Sato (1980) for the 1704 Iwadate earthquake generally explains the observed tsunami heights, but a similar model with the fault length 3km longer towards the north is more consistent with the reported crustal uplift at Henashi peninsula. For the 1793 Ajigasawa earthquake, a fault model lying off the coast of Tsugaru peninsula better explains the observed tsunami heights around Ajigasawa. The tsunami simulation also corroborates the observation that tsunami caused by the event might flush into the Jyusan Lake. Among several fault models tested for the 1804 Kisakata earthquake, a fault model located most offshore shows the best agreement with the observed distribution of tsunami heights. The tsunami simulations for the 1704 Iwadate and 1804 Kisakata earthquakes show that the tsunamis are largely amplified at Oga peninsula. The amplification is ascribed to an energy concentration by the reflection in the 1704 Iwadate tsunami and the edge wave trapped in the shallow sea in the 1804 Kisakata tsunami, respectively. Both are important mechanisms affecting the heights of tsunamis along the Japan Sea coast.

著者

山科 健一郎 中村 一明 福留 高明 佐藤 魂夫 田中 和夫

出版者

公益社団法人 日本地震学会

雑誌

地震 第2輯 (ISSN:00371114)

巻号頁・発行日

vol.38, no.1, pp.81-91, 1985-03-25 (Released:2010-03-11)

参考文献数

18

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Based on a few tens of photographs, height change of Kyuroku-shima Island, which locates very close to the focal region of the Japan Sea earthquake (M=7.7) on May 26th, 1983, is analyzed. 1) The island and adjacent small islets are considered to have subsided by about 30-40cm associated with the 1983 earthquake. The average offset obtained by 13 reliable photographs is 32±9cm. 2) Precursory deformation and secular change of the height were not found during 1964 through 1982. No detectable deformation was caused by largest aftershock (M=7.1) on June 21, 1983, and other aftershock activity. 3) Coseismic tilt and local collapse were not observed in the island. 4) In some cases, a height can be inferred even from snapshots with the error less than several percents. Crustal uplift and subsidence more than 10-20cm may be possible to be detected photographically at the seashore and lakeside.