Gauge re-sited 1/7/77
=========================== FOLLOWING PSMSL DOCUMENTATION ADDED 11-Jun-1991
Onahama             642/041 RLR(1965) is 9.0m below Attached BM
=========================== FOLLOWING PSMSL DOCUMENTATION ADDED 12-Jul-1993
Positive secular trend reverses into a negative one during the 1970s.
=========================== FOLLOWING PSMSL DOCUMENTATION ADDED 21-Feb-2012
A massive earthquake of magnitude 9.0 occurred on Friday 11th March 2011 with the epicentre approx. 70km east of the Oshika Peninsula of Tohoku. It was the most powerful known earthquake to hit Japan and triggered a tsunami with waves up to 40.5m and travelling up to 10km inland. It looks as if the earthquake badly damaged the tide gauge at Onahama as there is a jump and then it stops working in July 2011. Data following the earthquake has been flagged.
=========================== FOLLOWING PSMSL DOCUMENTATION ADDED 04-Feb-2013
There have over the years been a number of different benchmarks because of space restrictions not all are included on the RLR diagram. Where two or more benchmarks have the same name the later are suffixed. Throughout the RLR factor has remained the same.
=========================== 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.