On 29 August 2009 we began a series of intensive dives to install instruments at our Ocean Drilling Program (ODP) 1027 (Cascadia Basin) location. This site, in the centre of the Juan de Fuca Plate, is critically important for several NEPTUNE Canada research projects, including Ocean Crustal Hydrogeology , Seismograph Network and West Coast "Tsunami-meter" .
Ocean Crustal Hydrogeology
Ten boreholes were drilled across the Juan de Fuca Plate between 1991 and 2003 by the Ocean and Integrated Ocean Drilling Programs (ODP/IODP) expressly for the installation of "CORK" (Circulation Obviation Retrofit Kit) hydrologic observatories. These CORKs allow geoscientists to observe changes in sub-surface temperatures and pressures caused by earthquakes, hydrothermal convection and regional plate strain. With live connections to the NEPTUNE Canada network, scientists will gain the ability to monitor stresses and fluid movements in real-time, as they occur.
On September 1, ROPOS attached connectors from our instrument platform to the temperature and pressure instruments on CORK 1026B. Eventually we hope to connect additional CORKs and CORK instruments to our network. More on CORKS.
The NEPTUNE Canada Seismograph Network will help seismologists do real-time seismic monitoring and research on the ocean floor. Altogether, we plan to install four broadband seismometers, forming a large footprint spanning our Clayoquot Slope, Barkley Canyon, Cascadia Basin, and Endeavour locations. Three of these broadband seismometers will be installed and connected to our network during the second leg of this summer's installation cruise.
West Coast "Tsunami-meter"
Results of this study will aid in tsunami, storm surge, and earthquake modeling. Highly sensitive bottom pressure recorders (BPRs) with built-in temperature and conductivity sensors will be located at all NEPTUNE Canada node locations. At ODP 1027, the plan calls for a triangular arrangement of 3 bottom pressure recorders, each positioned 12.5km from our instrument platform. Such an arrangement lets scientists make very precise measurements of deep water tsunami wave height, speed and direction of movement.
The 12.5km cables are challenging to lay. When spooled on ROCLS (the ROPOS Remotely Operated Cable Laying System) drums, they weigh over 3.7 metric tons. ROCLS, with spool attached, is lowered to the seafloor using the ship's winch. Then, ROPOS flies to the seafloor, unfastens the cable end from the spool, attaches it to the instrument platform, picks up ROCLS and gradually spools the cable out over the designated path. At the same time, the ship must slowly follow ROPOS, always keeping a careful eye to separation, orientation, track and sea conditions.
ODP 1027 Instrument Platform