1741 eruption of Oshima–Ōshima and the Kampo tsunami

Volcanic eruption and tsunami off the coast of Hokkaido 1741 eruption of Oshima–Ōshima and the Kampo megatsunami Ganpo tsunami map.png Oshima Oshima 18 August 1741 1 May 1742 Unknown 4Oshima-Oshima 285010 2022-03-20渡島大島 有史以降の火山活動 https://www.data.jma.go.jp/svd/vois/data/sapporo/115_Osimaosima/115_history.html Japan Meteorological Agency 30 March 2021 Sector collapse and regional tsunami 1,467–2,033 dead Off the coast of Hokkaido.Sea of Japan, Japan Japan 300 41.5 139.3 yes Ōshima Mountain sign.svg 300 Estimated tsunami heights in various areas The devastating eruption of Oshima–Ōshima began on 18 August 1741 and ended on 1 May the next year.Significant Volcanic Eruption https://www.ngdc.noaa.gov/hazel/view/hazards/volcano/event-more-info/2673 NGDC NCEI 30 March 2021 Eleven days into the eruption, the Kampo tsunami (Japanese: 寛保津波, Hepburn: Kampo tsunami) with estimated maximum heights of 60–90 m on swept across neighboring islands in Japan and the Korean Peninsula. The eruption and its resulting tsunami killed at least 1,400 people. Damage was extreme along the coast of Japan, while in Korea, the tsunami damaged fishing boats. Background Japan is situated along a zone of convergence between at least four major and minor tectonic plates. The Philippine Sea plate dives beneath the Amurian Plate and Okinawa plate along the Nankai Trough and Ryukyu Trench in southern Japan. In northern Japan, the Pacific plate subducts beneath the Okhotsk microplate, part of the larger North American plate, along the Japan and Kuril trenches. The subduction process is related to the production of volcanoes in Japan as the downgoing oceanic slab undergoes dehydration at depths of roughly 90 to 100 km 5 beneath the overriding plate.Tatsumi, Y. Suenaga, N. Yoshioka, S. Contrasting volcano spacing along SW Japan arc caused by difference in age of subducting lithosphere Scientific Reports 14 September 2020 10 15005 15005 10.1038/s41598-020-72173-6 32929150 7490715 free Water in the structure of hydrated minerals interact with the upper mantle, lowering its melting point. As the mantle begins to melt, its density decreases and rises through the upper crust, forming a volcanic vent. Oshima Island Oshima is the uninhabited island located in the Sea of Japan, approximately 60 km west of the Oshima Peninsula on the larger island Hokkaidō.ja:北海道・渡島大島大噴火の巨大津波 絵図に残った凄まじい風景 建築研究所特別客員研究員・都司嘉宣 https://www.sankei.com/affairs/news/160606/afr1606060015-n1.html 30 March 2021 Sankei Shimbun Sankei Shimbun 6 June 2016 ja The island consists of two basaltic-to-andesitic stratovolcanoes, the highest measuring 737 m us above sea level. No records of eruptions prior to the 1741–42 eruption exists due to the remoteness of the island although some fumaroles were documented. The most recent record of an eruption was in 1790. Activity resurfaced in 1996 with seismic unrest beneath the island but no eruption occurred. Kampo tsunami The initial eruption began on 18 August and was visible from Hokkaido by 23 August. By 25 August, so much ash had been ejected that sunlight was blocked out. Ash fall measured up to over 20 centimeters at places. On August 29 at 05:00, a second and more violent eruption took place on the island and was followed–up by a large tsunami that engulfed many coastal villages and towns along the shores of the Sea of Japan. While the eruption itself did not result in any casualties, the ensuing tsunami drowned over 2,000 people.Sang-Shin Byun Kyeong Ok Kim A study on the effects of the 1741 tsunami recorded in the Annals of the Joseon Dynasty Journal of Korean Society of Coastal and Ocean Engineers 25 February 2021 33 1 30–37 10.9765/KSCOE.2021.33.1.30 233955868 http://jkscoe.or.kr/journal/view.php?number=361 30 March 2021 free In Kaminokuni, the waves reportedly wiped out 50 homes and drowned all but one of its residents. Ishizaki, a city separated from the sea by a ridge 19.4 m above sea level, was also engulfed by the tsunami. Around the Matsumae Peninsula, heavy ash fall from the eruption blocked out the sun and plunged villages into darkness. A tsunami arrived along the shores at some time between 20:00 and 22:00. More than 729 homes were washed away and 33 others were seriously damaged. The tsunami also took with it two warehouses and destroyed 25. Wave heights reportedly exceeded 9 m. One document states that approximately 120 km was inundated, and that at least 1,467 inhabitants lost their lives, a figure that excludes native Ainu inhabitants that left no written records. Estimates of the total casualties including Ainu suggest that over 2,000 people lost their lives.Satake Kenji June 8, 2007 Volcanic origin of the 1741 Oshima-Oshima tsunami in the Japan Sea Earth, Planets and Space 59 5 381–390 10.1186/BF03352698 free 2007EP&S...59..381S https://earth-planets-space.springeropen.com/counter/pdf/10.1186/BF03352698.pdf Some 1,521 fishing boats and ships near the erupting volcanic island were also destroyed by the waves. One hundred and forty people were killed while 53 vessels and 83 houses were lost to the waves in Tsugaru on the island of Honshu.Tsunami Event Information W. Hokkaido Island https://www.ngdc.noaa.gov/hazel/view/hazards/tsunami/event-more-info/419 NGDC NCEI 30 March 2021 Wave heights for Gankakezawa have been estimated at 34 m 0 based on oral histories, while an estimate of 13 m is derived from written records. At Sado Island, over 350 km mi nmi 0 away, a wave height of 2 to 5 m has been estimated based on descriptions of the damage, while oral records suggest a height of 8 m 0. Wave heights have been estimated at 3 to 4 m even as far away as the Korean Peninsula.Satake Kenji Volcanic origin of the 1741 Oshima-Oshima tsunami in the Japan Sea Earth, Planets and Space 2007 59 5 381–390 10.1186/BF03352698 2007EP&S...59..381S https://earth-planets-space.springeropen.com/counter/pdf/10.1186/BF03352698.pdf free A maximum height of 60–90 m was observed on Sado Island, while on Oshima, the tsunami was 6–10 m.Tsunami Event W. Hokkaido Island https://www.ngdc.noaa.gov/hazel/view/hazards/tsunami/related-runups/419 NGDC NCEI 30 March 2021Iida Kumizi Catalog of Tsunamis in Japan and Its Neighboring Countries 1984 Aichi Institute of Technology https://tsunami-dl.jp/document/111 14 July 2026 On the Korean Peninsula, the tsunami slammed into the east coast, flooding nine villages and destroying many fishing vessels.1st article celebrated on July 27, 17, Yeongjo The Annals of King Yeongjo 54 http://sillok.history.go.kr/id/kua_11707027_001 31 March 20211st article in Gyeongjin on July 18, 17, Yeongjo The Annals of Yeongjo 54 http://sillok.history.go.kr/id/kua_11707018_001 31 March 2021 The tsunami was documented five times in the annals of the Joseon dynasty.Min Kyu Kim Hyun-Me Rhee In-Kil Choi The effect analysis of 1741 Oshima-Oshima tsunami in the West Coast of Japan to Korea Transactions of the Korean Nuclear Society Spring Meeting 2013 https://www.kns.org/files/pre_paper/2/13S-05L-6A-%EA%B9%80%EB%AF%BC%EA%B7%9C.pdf 30 March 2021 Estimation of wave heights along the coast range from 3–4 m. Origins The source of the Kampo Tsunami is still debated among scientists, claiming an earthquake, debris avalanche, or some other phenomenon caused the tsunami. There is still no consensus in the debate but much evidence points to a landslide and debris avalanche along the flank of the volcano. Earthquake Off the western coast of Hokkaidō and northern Honshu, at the eastern brink of the Sea of Japan lies a convergent plate boundary between the Amurian and Okhotsk plates, microplates of the Eurasian and North American plates respectively. The convergent boundary is the source for many historically documented tsunamigenic earthquakes in 1833, 1940, 1964, 1983, and most recently, the 1993 southwest off Hokkaido earthquake.Satake Kenji Volcanic origin of the 1741 Oshima-Oshima tsunami in the Japan Sea Earth Planets Space 19 January 2007 59 5 381–390 10.1186/BF03352698 2007EP&S...59..381S https://earth-planets-space.springeropen.com/track/pdf/10.1186/BF03352698.pdf 30 March 2021 free Based on analyzing records of the tsunami heights, a large magnitude 7.5–8.4 earthquake along the eastern margin of the Sea of Japan would have been sufficient to generate the wave heights as observed in 1741.Im Sang Oh Alexander B. Rabinovich Manifestation of Hokkaido Southwest (Okushiri) Tsunami, 12 July, 1993, at the Coast of Korea: Statistsl Characteristics Spectul Analysis, and Energy Decay The International Journal of the Tsunami Society 1994 12 2 93–116 https://library.lanl.gov/tsunami/00394725.pdf 30 March 2021 Seoul National University 0736-5306 24 July 2023 https://web.archive.org/web/20230724075116/https://library.lanl.gov/tsunami/00394725.pdf dead Katsui, Yoshio Yamamoto, Masatsugu The 1741-1742 Activity of Oshima-Ōshima Volcano, North Japan Journal of the Faculty of Science, Geology and Mineralogy 1981 19 4 527–536 https://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/36702/1/19_4_p527-536.pdf 30 March 2021 Hokkaido University Japanja:日本海における大規模地震に関する調査検討会 報告書 https://www.mlit.go.jp/river/shinngikai_blog/daikibojishinchousa/dai08kai/sanko1.pdf Ministry of Land, Infrastructure, Transport and Tourism 30 March 2021 August 2014 jaAbe Katsuyuki Quantification of tsunamigenic earthquakes by the Mt scale Tectonophysics 1989 166 1–3 27–34 10.1016/0040-1951(89)90202-3 1989Tectp.166...27A https://www.sciencedirect.com/science/article/abs/pii/0040195189902023 30 March 2021 0040-1951 subscription The earthquake hypothesis, however, is challenged because no records of shaking from an earthquake exist. A 1995 research article suggested the 1741 tsunami may have been caused by an earthquake that ruptured a present–day seismic gap on the plate boundary between the rupture zones of the 1833 and 1983 earthquakes.Ohtake Masakazu A seismic gap in the eastern margin of the Sea of Japan as inferred from the time-space distribution of past seismicity Island Arc 13 March 1995 4 3 156–165 10.1111/j.1440-1738.1995.tb00140.x 1995IsArc...4..156O Because of the absence of documented shaking caused by a possibly large earthquake (t 7.5–8.4), scientists interpreted the event had characteristics similar to a tsunami earthquake. Initially proposed in 1972 by Hiroo Kanamori, these events release seismic energy in long periods.Hiroo Kanamori Mechanism of tsunami earthquakes Physics of the Earth and Planetary Interiors 1972 6 5 346–359 https://www.sciencedirect.com/science/article/abs/pii/0031920172900581 10.1016/0031-9201(72)90058-1 1972PEPI....6..346K subscription Such events involve a slower-than-usual rupture propagation along the shallow segment of a subduction zone. An event of this sort would go undetected by humans because of the low–frequency ground motions. Tsunami earthquakes rupture the shallowest section of the subduction boundary, which generates large tsunami run-ups. The earthquake theory also did not rule out the possibility of the volcano collapsing because of the extreme tsunami run–ups. However, there has been no attempt to conduct submarine surveys in the Sea of Japan to confirm the claim of seismic activity along the plate boundary.Yukinobu Okamura ja:日本海東縁海域の活構造およびその地震との関係 Geological Survey Monthly Report 1998 49 1 https://warp.da.ndl.go.jp/info:ndljp/pid/8173818/www.gsj.jp/data/bull-gsj/49-01_01.pdf 31 March 2021 Active structure in the eastern margin of the Sea of Japan and its relationship with earthquakes Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology ja Sector collapse A landslide and debris avalanche involving a subaerial and submerged portion of the volcanic island has been the more accepted source mechanism of the large tsunami. With an initial height of 850 m, the event reduced the elevation of Hishi–yama peak to 722 m. An estimated 2.4 km3 section of the volcano came loose and fell into the seafloor and settled towards the north of the island, similar to that during the 1980 eruption of Mount St. Helens, which was 2.3 km3.Kenji Satake Yukihiro Kato The 1741 Oshima-Oshima Eruption: Extent and volume of submarine debris avalanche Geophysical Research Letters 1 February 2001 28 3 427–430 10.1029/2000GL012175 2001GeoRL..28..427S free The slide deposit on the seafloor has a thickness of 36 ± 2 m on average and 182 ± 10 m at maximum. The debris field presently covers an area calculated at 69 ± 4 km2 and extends 16 km away from the island. This would make it the second largest historical volcanic sector failure in history, alongside the 1888 eruption of Ritter Island.Raphaël Paris Kazuhisa Goto James Goff Hideaki Yanagisawa Advances in the study of mega-tsunamis in the geological record Earth-Science Reviews 2020 210 103381 10.1016/j.earscirev.2020.103381 2020ESRv..21003381P 224925006 0012-8252 https://hal.uca.fr/hal-02964184/file/Paris_ESR_2021.pdf A more recent study in 2019, however, stated that the slide volume was 2.2 km3, a significant difference from the 2001 research. The same paper also implied that the maximum thickness of the landslide is 300 m and an area 14 km by 9 km was buried under debris.Yuichiro Tanioka Hideaki Yanagisawa Gentaro Kawakami Numerical Simulation of the Landslide and Tsunami Due to the 1741 Oshima-Oshima Eruption in Hokkaido, Japan Journal of Geophysical Research: Solid Earth 28 January 2019 124 2 1991–2002 10.1029/2018JB016166 2019JGRB..124.1991I 134267212 See also Earth sciences Tsunamis Volcanoes Japan List of deadly volcanic eruptions List of tsunamis References Category:1741 disasters Category:VEI-4 eruptions Category:Tsunamis in Japan Category:Volcanism of Japan Category:Natural disasters in South Korea Category:Floods in South Korea Category:Natural disasters in North Korea Category:Floods in North Korea Category:Tsunami earthquakes Category:Megatsunamis Category:1741 in Japan Category:18th-century volcanic events Category:Earthquakes in Japan Category:Earthquakes of the Edo period Category:Volcanic tsunamis Category:Volcanic eruptions in Japan Category:Landslides in Japan Category:1740s natural disasters Category:18th-century disasters in Japan Category:Sector collapses