1843 Tokachi earthquake

Earthquake in southeast Hokkaido, Japan 1843 Tokachi earthquake yes 1843 04 25 06:00 Japan Hokkaido 8.0 jma y 42.0 146.0 inline,title Japan Yes 91 drowned The southeastern part of Hokkaido and the northern Sanriku coast in Japan were struck by a major earthquake and tsunami on 25 April 1843 at 06:00 local time. It had an estimated magnitude of about 8.0 w yes. The tsunami resulted in more than 90 deaths. Tectonic setting The island of Hokkaido lies at the southern end of the Kuril–Kamchatka Trench, near its junction with the Japan Trench. At this destructive plate boundary, oceanic crust of the Pacific plate is subducting beneath the Okhotsk plate. The section of the megathrust along this plate boundary has been subdivided into three main segments, in terms of its rupture behaviour in historical earthquakes, named from southwest to northeast: Tokachi, Akkeshi and Nemuro. The last two large interplate earthquakes to affect this area were in 1952 and 2003, rupturing the Tokachi and Akkeshi and just the Tokachi segments respectively.Nanayama F. Characterization of Modern and Historical Seismic–Tsunamic Events, and Their Global–Societal Impacts 2021 9781786204783 Dilek Y. Special Publications, Geological Society London 501 131–157 Evidence of giant earthquakes and tsunamis of the seventeenth-century type along the southern Kuril subduction zone, eastern Hokkaido, northern Japan: a review 10.1144/SP501-2019-99 Ogawa Y. Okubo Y. Earthquake Along the Pacific coast of Hokkaido the earthquake was felt with an intensity of 5 on the Japan Meteorological Agency seismic intensity scale (Shindo). Elsewhere, the earthquake was felt in Tsugaru, Aomori, near Hirosaki, and at Hachinohe in northern Honshu with an intensity of Shindo 4, and as far away as Tokyo (then Edo).Sawai Y. Kamataki T. Shishikura M. Nasu H. Okamura Y. Satake K. Thomson K.H. Matsumoto D. Fujii Y. Komatsubara J. Aung T.T. 2009 Aperiodic recurrence of geologically recorded tsunamis during the past 5500 years in eastern Hokkaido, Japan Journal of Geophysical Research: Solid Earth 114 B1 10.1029/2007JB005503 The estimated magnitude for this event varies between jma yes 8.0 and s yes 8.4. The size of the tsunami has also been used to estimated a tsunami magnitude t of 8.0. The earthquake is thought to have ruptured the Akkeshi segment of the plate boundary and possibly the Tokachi segment. Evidence of higher run ups in the Nemuro area than observed in the 1952 event has been used to propose that the Nemuro segment was also ruptured in the 1843 event. Tsunami The tsunami affected the southeastern coast of Hokkaido and the northern part of the Sanriku coast in northern Honshu. Run ups for the tsunami have been estimated from contemporary reports. On Hokkaido, the maximum estimated run up was 5–6 m at Senpoushi Monshizu,Hirata K. Satake K. Tanioka Y. Hasegawa Y. 2009 Variable Tsunami Sources and Seismic Gaps in the Southernmost Kuril Trench: A Review Pure and Applied Geophysics 166 77–96 10.1007/s00024-008-0432-7 or 7.1 m at Hanasaki. On the Sanriku coast the maximum estimated run up was 3.1 m at Akamae, near Miyako.Tsuji Horie T. Hashimoto K. Sasaki T. Mabuchi Y. Okada K. Kuroyanagi Y. Ooie T. Kurimoto M. Kinami T. Imamura F. 2014 Tsunami height distribution of the 1843 Tenpo Nemuro-oki earthquake https://www2.jpgu.org/meeting/2014/session/PDF/H-DS27/HDS27-13_e.pdf 8 June 2025 Japan Geoscience Union Meeting 2014 Tsunami deposits have been identified at the Kiritappu lagoon and the Mochurippu-toh estuary, both near Akkeshi, that have been linked to the 1843 earthquake. Impact Most of the impact from this earthquake was a result of the associated tsunami, although reports from a temple at Akkeshi describe stone lanterns and statues being toppled. Many buildings along the coast were swept away by the tsunami including 75 houses at Akkeshi and a village of 50 houses at Hanasaki. Houses were also damaged at Hachinohe. All of the reported casualties were a result of the tsunami. 45 people were drowned at Akkeshi, while a further 46 people were drowned at Tarō, Iwate on the Sanriku coast.Hatori T. 1984 Source area of the east Hokkaido tsunami generated in April, 1843 https://repository.dl.itc.u-tokyo.ac.jp/record/32917/files/ji0593004.pdf Bulletin Earthquake Research Institute 59 423–431 References Category:Earthquakes in Hokkaido Category:Megathrust earthquakes in Japan Category:April 1843