Ninna earthquake

Ninna earthquake (Japanese: 仁和地震) occurred on 22 August 887 (26 August, third year of Ninna). It is presumed to have been a Nankai Trough megaquake.¹ The earthquake magnitude is M8.0–8.5. In Kyoto, the collapse of private houses and government offices caused many deaths by crushing. Damage in Settsu is said to have been particularly severe. The Shoku Nihon Kōki recorded that an earthquake had struck the Tōnankai region, based on records of massive damage in the Kinai; however, when combined with records that all of the Gokishichidō experienced the earthquake and with geological records, it is estimated that a contemporaneous earthquake also occurred in the Tōkai sea area. In the Ukishimagahara lowland of Fuji, Shizuoka Prefecture, there are records of rising water levels caused by fault activity.² Mount Yatsugatake collapsed, creating a landslide-dammed lake on the Ozu River. The dammed lake is recorded to have collapsed around the following June, producing debris and causing flooding in the Chikuma River basin.³⁴⁵

Footnotes

Footnotes

1. 国立天文台 (2017-11-30（2018年版）). 《理科年表 平成30年》. 理科年表. 丸善. ISBN 978-4-621-30217-0. P.736 ↩

2. 小松原純子; 宍倉正展; 岡村行信 (2007년). “静岡県浮島ヶ原低地の水位上昇履歴と富士川河口断層帯の活動” (PDF). 《活断層・古地震研究報告》 (일본어) 7: 119-128. 2018년 10월 14일에 확인함. ↩

3. “vol.26 縄文時代の女と男のオシャレ” (일본어). 信州発考古学最前線. 2007년 2월 22일에 원본 문서에서 보존된 문서. 2018년 10월 14일에 확인함. ↩

4. 早川 由紀夫 (2009년 5월 26일). “平安時代に起こった八ヶ岳崩壊と千曲川洪水” (PDF). 《Japan Geoscience Union Meeting 2010》 (일본어). 2018년 10월 14일에 확인함. ↩

5. 井上公夫 (2011년). “長野県中・北部で形成された巨大天然ダムの事例紹介” (PDF). 《歴史地震》 (일본어) (26): 106-107. 2012년 11월 19일에 원본 문서 (PDF)에서 보존된 문서. 2018년 10월 14일에 확인함. ↩