Jōgan earthquake 869

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Jōgan earthquake 869
Jōgan earthquake 869 (Japan)
Bullseye1.svg
date July 9, 869
Magnitude 8.1-8.4  M W
epicenter 38 ° 0 ′ 0 ″  N , 143 ° 45 ′ 0 ″  E Coordinates: 38 ° 0 ′ 0 ″  N , 143 ° 45 ′ 0 ″  E
country Japan
Tsunami Yes
dead ≈ 1000

The Jōgan earthquake 869 ( Japanese 貞 観 地震 Jōgan jishin ), also called Jōgan-Sanriku earthquake ( 貞 観 三 陸 地震 , Jōgan Sanriku jishin ), was one of the strongest earthquakes with tsunamis in the history of Japan and occurred on July 9th 869 ( traditional date : Jōgan 11/5/26) off the Sanriku coast .

The event is described in the Reich Chronicle Nihon Sandai Jitsuroku (Volume 16) compiled in 901 as follows:

「五月 […] 廿六 日 癸未。 陸 奥 国 地 大 震動。 流光 如 晝 隠 映。 頃 之。 人民 叫 呼。 伏 不能 起。 或 或 屋 仆 壓死。 或 地 裂 埋 殪。 馬 牛 駭奔。 或 相 昇 踏。 城郭 倉庫。 門 櫓 墻壁。 頽 落 顛覆。 不知 其 数。 海嘯 哮吼。 聲 似 似 雷霆。 驚濤 涌潮。 泝 徊 漲 長。 忽 至 城 下。 去 海 数千 百里。 浩 々 不 辧 其 涯 俟 矣。 原野 道路。 惣 為 滄 溟。 乗船 不 湟。 登山 難 及 及。 溺死 者 千 許。 資産 苗稼。 殆 無 孑 遺 焉. 」

"5. Month […] Day 26: A great tremor hit the province of Mutsu . The sky was as bright as day [cf. Earthquake light ]. After a short while, people's screams echoed. When thrown down, one was unable to get up again. Some were crushed by collapsing buildings and died, while others were swallowed up by the ripping open floor and died. Horses and cattle were frightened, ran around and trampled one another. Countless structures such as castle walls, warehouses, gates, towers, fences and walls collapsed. The sea roared like thunder, great waves poured in and moved upriver for a great length. In a very short time they reached the castle town . The sea made a few hundred miles disappear and one did not know where the coast [= the inland] ended. The fields and roads became the ocean. There was no time to get on the boats or flee into the mountains. About a thousand people drowned. Personal possessions and the seeds were almost completely destroyed. "

The castle town described in the report is often identified with the one around Taga Castle (now in the municipality of Tagajō ), which was then the provincial capital ( kokufu ) . In addition, archaeological evidence of their destruction for the 8th / 9th Century found.

Based on the damage described for this location, which suggests a seismic intensity of at least level 5, it is assumed that the earthquake had a magnitude of 8.3. A simulation by Minoura et al. The 2001 earthquake localized between 37 ° and 39 ° N, 143 ° and 144.5 ° E, with the fault about 200 km long, 85 km wide, and 1 km deep. The tsunami then had a height of about 8 m. Satake et al. determined in 2008 the fault with a length of 100 to 200 km and a width of 100 km with a moment magnitude M W 8.1 to 8.4. The earthquake database of the National Geophysical Data Center of the US-American NOAA gives a surface wave magnitude of M S 8.6.

Geological investigations found marine sediment deposits, which can be attributed to this tsunami, in the plain between today's Sendai and Sōma more than 4–4.5 km inland. However, the level was then about half a meter lower than it is today. This confirms the large-scale flooding described and the high number of fatalities (compared to the fact that the area was then far less and only very scatteredly populated). For the 8th century, this second most populous province is assumed to have a population of 186,000.

In addition, indications of two similarly devastating, previous tsunamis with similar effects were found: one between 910 and 670 BC. And one between 140 BC. Based on this, it is assumed that such tsunamis hit this coastal area approximately every 800 to 1100 years, or, with the addition of the Keichō-Sanriku earthquake in 1611, every 450-800 years. Minoura et al. said in 2001 that a similarly strong tsunami, which penetrated about 2.5–3 km into the country, was to be expected. This prediction was often identified with the Tōhoku earthquake and tsunami of March 11, 2011 and this in turn was equated with the Jōgan earthquake.

See also

Notes and individual references

  1. ↑ The 13th of July is also often given, but this is an anachronistic application of the Gregorian calendar .
  2. ↑ Kōji Minoura: 津 波 災害 は 繰 り 返 す . In: University of Tōhoku (ed.): ま な び の 杜 . No. June 16 , 2001 ( full text ). , Translation based on Masatoshi Ishii: Information History: Research .
  3. ↑ a b c d e f K. Minoura, F. Imamura , D. Sugawara, Y. Kono, T. Iwashita: The 869 Jōgan tsunami deposit and recurrence interval of large-scale tsunami on the Pacific coast of northeast Japan . In: Journal of Natural Disaster Science . tape 23 , no. 2 , 2001, p. 83-88 ( PDF ).
  4. ↑ a b Koji Okumura: Interplate megathrust earthquakes and tsunamis along Japan Trench offshore Northeast Japan. (PDF; 233 kB) In: Home of Geography. Retrieved August 17, 2011 .
  5. ↑ Significant Earthquake. National Geophysical Data Center, National Oceanic and Atmospheric Administration, accessed August 17, 2011 .
  6. ^ A b Masatoshi Ishii: Information History: Research. In: ChuoOnline. Yomiuri Shimbun , May 6, 2011, accessed August 17, 2011 .
  7. ↑ Cornelius J. Kiley: Provincial administration and land tenure in Heian Japan . In: Donald H. Shively, William H. McCullough (Eds.): The Cambridge History of Japan . Volume 2: Heian Japan. Cambridge University Press, 1999, ISBN 0-521-22353-9 , pp. 255 ( limited preview in Google Book search).
  8. ↑ a b Kenji Satake: The Giant off Tohoku earthquake of 11 March 2011. (PDF; 9 kB) AGU - Natural Hazards Focus Group, March 16, 2011, archived from the original on March 1, 2012 ; accessed on August 15, 2015 .
  9. ^ Project Study on the Effective Countermeasures against Earthquake and Tsunami Disasters Bulletin (No. 4). (PDF) Japan International Cooperation Agency, May 2011, p. 1 , accessed on August 17, 2011 .