August 29 2009 we began a series of intensive dives to install instruments at our Ocean Drilling Program (ODP) 1027 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".
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 ODP 889, Barkley Canyon, ODP 1027 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.
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.
On Friday August 28, the R/V Thompson and ROPOS crews deployed our instrument platform to Folger Deep. Instruments on the platform include:
- conductivity-temperature-depth (CTD) gauge (SeaBird SeaCAT SBE 16plus)
- echosounder (Biosonics DT-Xu)
- acoustic Doppler current profiler (RDI Workhorse Monitor 300KHz)
- oxygen sensor (Aanderaa optode)
Two additional instruments, a Naxys hydrophone and a bottom pressure recorder, were positioned close to the instrument platform.
This platform is connected to the Folger Passage node. We will return later to run a 700m cable from the node to the Folger Pinnacle.
Wally the crawler now sits among hydrate outcrops 867m below sea level. He's tethered to the Barkley Hydrates instrument platform by a 70m extension cable festooned with flotation blocks to keep it off the seafloor and away from Wally's tractor treads.
Wally's equipment includes:
- conductivity-temperature-pressure gauge
- webcam and lights
- methane sensor
After transporting Wally to the seafloor, ROPOS set out markers around a hydrate mound and along a pathway to be followed over the coming months and years. Then ROPOS unwound the extension cable and connected it to the instrument platform. This platform also connects, via a 1430m extension cable, to our Barkley Canyon Axis instrument platform.
We have yet to test Wally in operation, but hope to have an opportunity to power him up and go for a test drive sometime soon!
With crews of R/V Thompson and ROPOS, we have deployed an instrument platform dubbed "Barkley Benthic Pod 1" to a spot in the depths of Barkley Canyon, 984m below the surface. This operation included laying a cable from the instrument platform up-slope to connect with our instrument platform in the Barkley Hydrates study location.
The first task was lowering the Remotely Operated Cable Laying System (ROCLS) with cable spool to the seafloor, using the Thompson's crane and winch. Once positioned, acoustic releases connecting the winch cable to the ROCLS assembly were sent an acoustic signal, commanding them to release ROCLS. Then the winch cable was recovered.
Next, ROPOS was attached to Benthic Pod 1 and deployed. ROPOS carried the instrument platform to the seafloor, placed it, set up measuring poles for the camera, deployed the hydrophone ~10m away from the platform, lifted the rotary sonar into an upright position, and plugged the cable connector into the platform.
After these tasks were finished, ROPOS connected to ROCLS (which was resting on the seafloor), and laid the 1430m-long spool of cable. Finally, they attached the far end of the cable to our Barkley Hydrates platform.
This was indeed a very productive and interesting dive!
Our Vertical Profiler System (VPS) was lowered by crane to the seafloor early this morning. Exact geo-coordinates: -126.174095W; 48.427253; depth: 396m.
ROPOS then dove down to plug the VPS in via an extension cable connected to our nearby instrument platform on Barkley Slope.
In the afternoon and evening, the VPS was powered up and communications established with its instruments. We hope to test deployment of the float during an upcoming ROPOS dive.
Our 5th node was successfully deployed this morning. It is sitting in 2323m of water at 47.57.5021 north latitude and 129.02.1263 west longitude. All four ports were tested from our shore station, and functioned properly. Three short-haul science ports were tested using a junction box strapped onto ROPOS. A fourth long-haul extension port was tested using a test bench aboard the Thompson.
This node will remain alone in its position near Endeavour Ridge until next year, when we return to deploy numerous instruments for studying everything from hot vent ecology to plate tectonics.
R/V Thomas G. Thompson departed Esquimalt Graving Dock 8:00 Saturday morning, fully loaded with instrument platforms, extension cable spools, NEPTUNE Canada staff, students, contractors, and ROPOS equipment and crew.
Once underway, all scientific crew were introduced to safety procedures, including how to properly don personal survival suits. Needless to say, this was the first time for NEPTUNE Canada staff members Murray Leslie and Dwight Owens, who have joined this deployment cruise.
Meanwhile, the C/S Lodbrog has deployed a remotely operated vehicle (ROV) for "PLIB" work in Folger Passage. "PLIB" stands for Post-Lay Inspection and Burial, and is required for all of our shallow-water cables. To do this work, the ROV descends to the seafloor and finds the cable by "listening" for a signal in it generated by the cable station. The ROV then moves along the cable track using water jets to progressively bury the cable.
The ROV aboard the Lodbrog is a "trencher" operated by LD TravOcean.
Our trawl-resistant frame (TRF) and science node for the ODP 889 site were deployed successfully yesterday. The TRF is sitting in 1250m of water at 48° 40.4686'N, 126° 51.1525'W.
This site on the mid-continental slope is rich in shallowly buried gas hydrates. Here, NEPTUNE Canada will help scientists monitor changes in hydrate distribution, depth, structure, properties and venting, particularly related to earthquakes, slope failures and regional plate motions. To learn more, visit the Bullseye Vent Gas Hydrates experiment.
We've just received these photos from the Lodbrog, taken during deployment of the Trawl-Resistant Frame and science node to our ODP 1027 location.
We've received a batch of pictures taken during installation of our two instrument platforms at Barkley Slope. Selected shots are shown below. The Barkley Slope platform (located at the shelf-slope break where the Vertical Profiler System will also be positioned) holds an Acoustic Doppler Current Profiler (ADCP) and a Conductivity-Temperature-Depth (CTD) gauge. Its junction box also provides communications and power to a hydrophone and a bottom pressure recorder, both of which rest on separate small frames positioned a short distance from the platform.
The Barkley Hydrates platform holds a junction box, which will provide power and communications for Wally, our benthic crawler.
Two important instrument platforms have been installed and tested in Barkley Canyon:
- The Barkley hydrates platform holds the junction box that will service Wally the Crawler.
- The Barkley slope platform is positioned in the area where the continental shelf begins to slope downward into the deep sea. Co-located with our Vertical Profiler System, this platform holds a CTD (Conductivity-Temperature-Depth) sensor, an ADCP (Acoustic Doppler Current Profiler), a hydrophone and a bottom pressure recorder.
The installation team connected these platforms to the two extension cables (see their respective locations on this map), and were able to power them up from the shore station, via the Barkley Canyon Node. Data were gathered from several instruments.