869 Sanriku earthquake
Template: Infobox earthquake / maintenance / time missing template: Infobox earthquake / Maintenance / depth missing template: Infobox earthquake / Maintenance / injured missing template: Infobox earthquake / maintenance / property missing
The Jogan Earthquake 869 (Japanese贞 観 地震, Jogan jishin ), also Jogan - Sanriku earthquake (贞 観 三 陆 地震, Jogan Sanriku jishin ) called, was one of the strongest earthquakes with tsunamis in Japan's history and occurred on 9. July 869 (traditional date: Jogan 05/11/26 ) before the Sanriku coast.
The event is described in the compiled in the year 901 Empire chronicle Nihon Sandai Jitsuroku ( Volume 16 ) 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。溺死者千許。資産苗稼。殆無孑遺焉。」
"5 Month [ ... ] Day 26: A large earthquake hit the province of Mutsu. The sky was crossed by daylit phenomena. After a short time echoed the cries of the people. Prostrate, we were not able to get up again. Some were crushed by collapsing buildings and died, others were swallowed by aufreißenden ground and died. Horses and cattle were frightened, ran about and trampled each other. Countless buildings like castle walls, storehouses, gates, towers, fences and walls collapsed. The sea roared like thunder, big waves streamed approach and moved on a larger length upstream. In a short time they reached the castle town. The sea could disappear a few hundred miles and you did not know where the coast [= domestic ] ceased. The fields and roads were to the ocean. There was no time to board the boats or flee to the mountains. About a thousand people drowned. Personal property and the seeds were almost completely destroyed. "
The castle town described in the report is often identified with that of the castle Taga (now in the church tagajo ), which was then the provincial capital ( Kokufu ). In addition, archaeological evidence of their destruction for the 8/9 were Century found.
Based on the described damage for this place, which suggest 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. 2001 located the earthquakes between 37 ° and 39 ° N, 143 ° and 144.5 ° E, where the fault approximately 200 km long, 85 km wide and was held at 1 km depth. The tsunami had therefore then a height of about 8 m. Satake et al. In 2008, the specific fault with a length of 100-200 km and a width of 100 km at a moment magnitude MW 8.1 to 8.4. The earthquake database of the National Geophysical Data Center of the U.S. NOAA indicates a surface-wave magnitude MS 8.6.
Geological investigations were marine sedimentary deposits that are due to this tsunami, in the plain between the present Sendai and Sōma more than 4-4.5 km inland. However, the level at the time was about two feet lower than today. This confirms the extensive flooding described and the high number of deaths ( in view of the fact that the area was inhabited at that time far less and only very scattered ). Thus a population of 186,000 is assumed for the 8th century for this second most populous province.
In addition, evidence was found with similar effects on two similarly devastating, previous tsunamis: a 910-670 BC and between 140 BC and 150 AD. Based on this, it is assumed that such tsunamis hit this coastal area about every 800 to 1100 years and with the addition of the Keicho - Sanriku earthquake in 1611 all 450-800 years. Minoura et al. argued in 2001 that a similarly strong tsunami that intrude approximately 2.5-3 km into the country, was to be expected. This prediction was often identified with the Tōhoku earthquake and tsunami of 11 March 2011, and this in turn equivalent to the Jogan Earthquake 869.