July 13, 869 Tsunami: Sanriku, Japan

July 13, 869. A tsunami fell on the Sanriku coast (general name for the Pacific coast of the prefectures of Aomori, Iwate and Miyagi) on a stretch of hundreds of kilometers. The earthquake and tsunami were especially strong in the vicinity of Sendai; a wave reached the Takajo fortress here. About 1000 people died; hundreds of villages were destroyed. (reference #414)

July 13, 869. Many structures and houses destroyed. Tsunami attacked Taga Castle near Shiogama, Miyagi Prefecture. About 1,000 persons drowned. (reference #150)

July 13, 869. Great waves on the coast of Sanriku. (reference #1897)

Followning earthquake sea rushed inland along several hundred km of coast. About, 1000 deaths. Hundreds of villages ruined. Considered by Imamura to be, with tsunami of 1611 Dec. 2, largest of Sanriku history. Date given incorrectly as July 9, by Davison (1936), and Heck, and as July 2 in Ofunato-shi publication (Anon 1962). (reference #79)

Regarding the 869 Tohoku-oki (Jogan) earthquake, a Japanese history book, Nihon Sandai Jitsuroku (A chronicle of Japan), records "On the 26th of the 5th month of the Japanese calendar (July 9, 869), a large earthquake occurred in the province of Mutsu (divided since into the five provinces of Iwaki, Iwashiro, Rikuzen, Rikutyu and Mutsu). The sky was illuminated like day-time. A little later, people, panic-stricken by the violent trembling, were lying on the ground; some were buried under fallen houses and others inside wide-opened ground fissures, while horses and cows desperately ran about and trampled each other. A number of castles, towers, and other tall structures collapsed. Then roarings like thunder were heard towards the sea. The sea soon rushed into the villages and towns, over-whelming a few hundred miles of land along the coast. There was scarcely any time for escape, though there were boats and the high ground just before them. In this way about 1000 people were killed. Hundreds of hamlets and villages were left in ruins." (Imamura, 1934). This earthquake is suggested to be one of the predecessors of the 2011 Tohoku-oki earthquake (e.g., Sawai et al., 2015). The magnitude and source region of the 869 earthquake were re-evaluated (e.g., Sugawara et al., 2012; Namegaya and Satake, 2014) using the insights obtained from the 2011 tsunami. (reference #12525)