[DONET starts to deploy the seafloor observatory on a massive scale]
Three DONET expeditions were implemented by JAMSTEC research fleet in the first quarter of FY2010.
The first half of KY10-07 (2010/05/1 - 2010/05/09) is an expedition to install the burial casings in the seafloor sediment at the candidate DONET observation sites. The burial casing attached with a penetration rod was lowered down to the seafloor by means of a seafloor sampling system, as seen in photos above. This method makes it possible to take the burial casing vertically into the seafloor to fit the posture requirement of the ground motion sensing system (seismometer).
The seafloor and water column obstacle sweeping on extension cable laying routes was implemented by a deep-tow camera system in expedition KY10-07(second half: 2010/05/9 - 2010/05/18) and KY10-08 (2010/05/25 - 2010/06/16). The condition of the ROV working area along the cable laying route was verified in these operations. This prior safety management is indispensable for conducting long distance cable laying ROV operations without any accidents.
NT10-09 (2010/05/21 - 2010/06/03) is an expedition for DONET seafloor network component installation and construction. The ROV “Hyper Dolphin” deployed three new science nodes (site B, D, and E), and three buried observatories (A-2, A-4 and E-17) in this expedition. On-board scientist missed a chance to connect the extension cable between the observatory and science node to boot-up the observatory during in this expedition period. However, this preparation of the network components will be a great assistance in accelerating the increased use of observatory during the upcoming expedition in October.