=========================== FOLLOWING PSMSL DOCUMENTATION ADDED 11-Jun-1991
Kamaisi II          642/017 RLR(1975) is 8.6m below BM Kamaisi
=========================== FOLLOWING PSMSL DOCUMENTATION ADDED 22-Feb-2012
A massive earthquake magnitude 9.0 occurred at 14.46 JST (05.46 UTC) on Friday 11th March 2011 with the epicentre situated approx. 70km east of the Oshika Peninsula of Tohoku. It was the largest earthquake ever to strike Japan and triggered a tsunami with waves of up to 40.5m travelling inland up to 10km. 
=========================== FOLLOWING PSMSL DOCUMENTATION ADDED 05-Apr-2022
Following review of data affected by the Tōhoku earthquake of 2011, all data has been flagged as good as GSI have recommenced levelling at the site. The station flag has been set to indicate the record needs to be treated with care, but the data appears to accurately reflect the earthquake's ongoing effect on local relative sea level.