[S-SS12] Active faults and paleoseismology

[SSS12-P08] Reliability of Tsunami Data from the 1780 Urup Earthquake in Japan

*Yutaka Hayashi¹ (1.Meteorological Research Institute, Japan Meteorological Agency)

Keywords:Kuril Islands, east coast of Hokkaido, voyage logbook of the St. Natalia, historical tele-tsunami, false tsunami

Most of the widely used domestic [e.g., Usami et al. (2013)] and international [e.g., NGDC/WDS Global Historical Tsunami Database (NCEI), TL/ICMMG Global Historical Tsunami Database (NTL)] tsunami catalogs and databases claim that the 1780 Urup earthquake caused a tsunami on the east coast of Hokkaido. The logbook of the Russian ship St. Natalia [Soloviev and Ferchev (1961)], which encountered the earthquake and tsunami on the east coast of Urup Island on June 29, 1780, is the most reliable source of information on this tsunami, as it was recorded by the encounters themselves at that time. However, the logbook does not contain the arrival and traces of the tsunami on Etorofu Island and to the southeast of it. Also, no mention of this tsunami was found in the chronicles and genealogies [e.g. "Fukuyama kyu-ji-ki"] of the Matsumae Domain, which declared control of the territory including Urup Island and Hokkaido until 1780. On the other hand, some tsunami chronicles published after 1950s pointed out that the tsunami caused by the 1780 Urup earthquake had an economic impact on the east coast of the main island of Hokkaido under the isolationist policy, by following the perception by Omori (1919). Apart from the correctness of this historical perception, the explanation can easily be misunderstood as if the target area was directly affected by the tsunami rather than indirectly and economically. The tsunami catalog by Iida (1984), which is frequently referred to in subsequent tsunami catalogs and databases, is one source of English information based on this misunderstanding. Some of the catalogs that were widely used today do not cite the original historical material, but they are based on the literature influenced by Iida's misunderstanding, or may use misunderstood data without showing any bases. Therefore, it is reasonable to conclude that the information that the tsunami caused by the 1780 Urup earthquake reached Japan is unfounded. The only reliable information about the 1780 Urup earthquake and tsunami is from the logbook of the St. Natalia based on direct observations. The false information in the catalog should be deleted to change the current situation in which the false image of the 1780 Urup earthquake and tsunami was formed based on data contaminated by unfounded information.

References
Iida, K., 1984, Catalog of tsunamis in Japan and its neighboring countries, Aichi Institute of Technology, Toyota, Japan, 52p.
National Centers for Environmental Information (NCEI), NGDC/WDS Global Historical Tsunami Database. DOI:10.7289/ V5PN93H7.
Novosibirsk Tsunami Laboratory (NTL), 2005, TL/ICMMG Global Historical Tsunami Database, http://tsun.sscc.ru/gtdb/default.aspx.
Omori, F., 1919, Honpo Dai-jishin Gaihyo - Taiwan Chosen wo nozoku, Report of the Imperial Earthquake Investigation Committee in Japanese Language, no.88-2, 1-61. (in Japanese)
Soloviev, S.L. and M.D. Ferchev, 1961, Summary of data on tsunamis in the USSR, Bull. Counc. Seismol. Acad. Sci. USSR, 9, 23-55. (in Russian)
Usami, T., H. Ishii, T. Imamura, M. Takemura, and R. Matsu’ura, 2013, Nihon Higai Jishin Soran 599–2012 (The Catalogue of Damaged Earthquakes in Japan from 599 to 2012), University of Tokyo Press, Tokyo, Japan, ISBN 4130607596 (in Japanese).