Also described is an earthquake in July 869 and a tsunami that flooded the plains of northeast Japan : “ The sea soon rushed into the villages and towns , overwhelming 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 1,000 people were killed . ” These were the same plains that were submerged in the 2011 Tōhoku earthquake and tsunami , according to one account . " Analysis of sediments left by the 869 tsunami led to an estimate that the earthquake had a magnitude of 8.3 . " '' Nihon Sandai Jitsuroku '' is the final text in the '' Six National Histories '' series . In 936 , a national history bureau ( 撰国史所 ) was established to maintain the existing national histories as well as to continue with their compilation . A new text , '' Shinkokushi '' , was begun . However , it remained in draft form and was never completed . The declining power of the Ritsuryō institution is cited as a cause
2011 Tōhoku earthquake and tsunami
2011 Tōhoku earthquake and tsunami
Nihon Sandai Jitsuroku