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1026 Manju tsunami
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Tsunami affecting Japan
yes June 16, 1026 Japan >1,000 dead 10 m Iwami Province, Japan 34.8 131.8 inline,titleSignificant Earthquake Information 10.7289/V5PN93H7 https://www.ngdc.noaa.gov/hazel/view/hazards/earthquake/event-more-info/5902 National Geophysical Data Center / World Data Service: NCEI/WDS Global Historical Tsunami Database. NOAA National Centers for Environmental Information National Geophysical Data Center j yes 7.8
The 1026 Manju tsunami affected the Sea of Japan coast of the then Iwami Province on June 16. Considered one of the largest tsunamis in the Sea of Japan, it generated a tsunami with waves of 10 m at present-day Masuda, Shimane. Off the coast, an island reportedly sank because of the waves. More than 1,000 people were killed, and 3,000 homes were destroyed.Tsunami Event Information https://www.ngdc.noaa.gov/hazel/view/hazards/tsunami/event-more-info/83 National Geophysical Data Center / World Data Service: NCEI/WDS Global Historical Tsunami Database. NOAA National Centers for Environmental Information 10.7289/V5PN93H7 14 December 2024 National Geophysical Data Center The source of the tsunami has been debated between an earthquake or undersea landslide.
Description
250px|thumb|right|An artist's impression of Kamojima, which allegedly sank into the sea after an earthquake
In historical records, locals claimed that a large stone called Kuroiwa was carried by the tsunami to its present location in Tonda, along Japan National Route 9 about 3.5 km from Masuda Station. The 5 m tall stone was allegedly carried 2 km from the coast at an elevation of 25 m. A subsequent investigation revealed the stone, comprising basalt, originated from the inland mountains, as basalts do not occur at the coast, and was transported downhill by a landslide rather than the reported tsunami.Kanaori Hiroshi ja:活断層と大地震~自然と記録から学ぶ~ Active Faults and Major Earthquakes: Learning from Nature and Records ja Proceedings of the Natural Disaster Research Council 2016 2 1–6 https://yamaharu-nds.jp/ndic_chugoku/wp-content/uploads/sites/3/2016/03/02-01.pdf Chugoku Region Subcommittee
The tsunami reportedly sank the islands of Kamo, Nabeshima, and Kashiwajima, which were then busy settlements. Oral records suggest these features were solid outcrops rather than sandbars. Kamo Island was located 1 km off the coast of Takasu and was 2 km long by 0.3 km wide. When the tsunami struck Takatsu and the Masuda River mouth, its waves were about 2 m. Subsidence occurred at Hamada, and there was no record of a tsunami. The waves destroyed the Hitomaro Shrine on Kamo Island and dumped the resident statue of Kakinomoto no Hitomaro in Masuda.Iida Kumiji Research on Historical Earthquakes (2) : Earthquake and Tsunami Disasters on May 23, 1026 (June 16, 1026) Aichi Institute of Technology Research Report Bulletin 1979 14 http://repository.aitech.ac.jp/dspace/handle/11133/496 Aichi Institute of Technology
In the Toinomawari area of Masuda, the tsunami overwhelmed a sand dune embankment and buried the surrounding land. The waves advanced towards Kamitonoma, flooding Shimotonoma and Nakatonoma along the way. It caused massive devastation to farmland and properties; many people also went missing. Tonomawari Bay became so overwhelmed with debris that it was impassable for ships. At the Oko ward of the city, the waves reached the foot of Mount Eboshi and carried marine life inland. The statue of Kakinomoto no Hitomaro was retrieved and placed in the Matsuzaki Hitomaro Shrine before subsequently relocating to the Kakimoto Shrine in Takatsu. Another temple on Kamo Island, Senpukuji, was reconstructed, while Manpukuji was never rebuilt. Many other relics, such as three statues of Vaiśravaṇa, a Han dynasty mirror, and a pair of cymbals, were recovered. Ruins of an ancient pagoda buried by the tsunami deposit were revealed after a flood in 1729.
Near Gōtsu Station, Gōtsu, the tsunami destroyed 1,000 homes, while more than 500 temples and homes were damaged. Along the Shioda coast, the tsunami washed away three islets. It travelled up the Gōnokawa River and was recorded in Ochi District; the tsunami was also reported as far east as Kuromatsucho.
Tsunami evidence
Paleotsunami
In 1994, Island Arc published the discovery of a sand layer about 1.5 m beneath the Masuda coastal plain, which could only be explained as the result of a tsunami inundation. This layer comprised mud and medium-to-fine-grained sand that originated from the sea. These materials, comprising coarse sediment grains and brackish benthic diatoms, were mixed with the estuary mud under tsunami-like conditions. The absence of bedded grading also suggests these materials had to be quickly transported onto the plain. A piece of wood from the excavated area, above the tsunami layer, was radiocarbon dated to 930±80 years before present, suggesting the layer may be evidence of the June 16, 1026 event.Minoura Koji Nakata Takashi Discovery of an ancient tsunami deposit in coastal sequences of southwest Japan: Verification of a large historic tsunami Island Arc 1994 3 1 66–7 10.1111/j.1440-1738.1994.tb00006.x A water tank experiment suggests the tsunami was triggered by an undersea landslide, and a preserved landslide topography in the Sea of Japan may represent that trigger event. A numerical modelling estimated the mass failure volume at 8.6 km3. The historical record does not document any seismic shaking from an earthquake before the tsunami arrived at the coast;Minoura Koji Sugawara Daisuke Yamanoi Tohru Yamada Tsutomu Aftereffects of Subduction-Zone Earthquakes: Potential Tsunami Hazards along the Japan Sea Coast The Tohoku Journal of Experimental Medicine 2015 237 2 91–102 10.1620/tjem.237.91 26399180 free however, should an earthquake occur, its magnitude would be estimated at j 7.8.
See also
List of earthquakes in Japan
List of tsunamis
References
Category:1026
Category:Tsunamis in Japan
Category:Earthquakes in Japan
Category:History of Shimane Prefecture
Category:Masuda, Shimane
Category:Gōtsu, Shimane
Category:11th-century disasters
Category:1020s in Japan
Category:Landslides in Japan
Category:Medieval tsunamis