[DONET Expedition 2011 Spring Season]
Two expeditions for DONET observatory construction (KY11-03 & KY11-06) were carried out in March, and in April to May 2011. Thirty three ROV dives and eight burial casing operations (using piston corer) were implemented in this duration. Three new observatories in KY11-03 and six new observatories in KY11-06 were activated in the expeditions and start to generate valuable ground motion and pressure sensing data. In total, seventeen observatories are in operation as of May 10, 2011.
On March 11 when on the expedition KY11-03, a M9 class mega thrust earthquake hit the north-eastern Japan and associated tsunami rising over the seaboard cities. This disaster made us recognize the importance of earthquakes and tsunamis prevention over again. At that time, Ten observatories were operating in the DONET system where the approximately 800km far from hypocenter of the 2011 Tohoku-oki earthquake. Attached figure is observed tsunami event at the Nankai-trough. It can be confirmed that the tsunami of 60cm pp surges several times in this area.