September 14-15 we installed and connected a second broadband seismometer to the NEPTUNE Canada network. The first was installed at Barkley Canyon on 8 September. The second was installed at ODP 1027, not far from the ODP 1026B CORK and our instrument platform there.
About the Seismometers
Pacific Geosciences Centre technician Bob Meldrum prepared and oversaw the installation of this delicate instrument. The cast titanium case, designed by Monterey Bay Aquarium Research Institute, holds both a seismometer and a strong motion accelerometer. The seismometer is equally sensitive to movements in three dimensions at periods from 6 minutes all the way down to 1/50th of a second.
In fact, it's so sensitive it can detect subtle tilts in the ground from earth tides caused by the moon's gravitational pull!
While the seismometer is tuned to small movements, such as waves produced by an earthquake on the other side of the earth, it cannot be used to measure intense shaking, such as might be caused by a nearby earthquake. That's where the strong motion accelerometer comes in. This device picks up where the seismometer leaves off, coping with accelerations up to 2G.
Preparations
Pacific Geosciences Centre instrument technician Bob Meldrum prepares a broadband seismometer for deployment to ODP 1027, 13 September 2009.
A peek at the ODP 1027 broadband seismometer within its cast titanium sphere, 12 September 2009. The NEPTUNE Canada broadband seismometers (model CMG-1T) are manufactured by Güralp Systems Limited.
Dalhousie University oceanographer Doug Schillinger and NEPTUNE Canada instrument manager Reece Hasanen admire the ODP broadband seismometer prior to deployment, 12 September 2009.
NEPTUNE Canada contractor Jason Williams and Pacific Geosciences Centre instrument technician Bob Meldrum prepare seismometer-related instrument package for deployment to ODP 1027, 13 September 2009.
(Click images to view slideshow.)
Deployment
The original plan called for the ODP 1027 seismometer to be deployed along with a small frame to hold a battery, differential pressure gauge and an acoustic Doppler current meter. The battery could supply the seismometer for up to a month's time in the event a large power failure (such as might result from a large earthquake) knocks out the NEPTUNE Canada network.
But even best-laid plans do not always work out. When we deployed the instrument frame and tested it through the network, a ground fault was detected. The seismometer itself tested perfectly, so we were able to leave it in position, connected to the ODP 1027 instrument platform by a 70m cable. But the battery and additional instruments could not be deployed, so we recovered them.
The actual process of installation was the same as before. ROPOS pushed a wide-diameter section of heavy plastic pipe (the "caisson") down into the seafloor sediment, then vacuumed the interior out with its zip pump. We poured a shallow layer of glass beads into the base of the caisson and placed the seismometer inside. Finally, we buried the seismometer completely in glass beads.
Seismometer Deployment
ROPOS spills bags of tiny glass beads over the seismometer within its installation caisson, 15 September 2009.
Placement of the ODP 1027 broadband seismometer within its caisson, 15 September 2009.
ODP 1027 seismometer, now buried in glass beads, 15 September 2009.
ROPOS carries the ODP 1027 seismometer to its deployment site, 15 September 2009.
ROPOS gingerly places the seismometer into the caisson, 15 September 2009.
Seismometer and caisson after it was vacuumed out by the ROPOS zip pump, 25 September 2009.
(Click images to view slideshow.)
Animal Encounters
Sea creatures are ever-present during our installation operations, and today was no exception. While descending through the water column, we passed through a dense school of tiny fish. Squid lurked on the perimeter, feeding on the fish. Then, when we reached bottom and began the seismometer installation, several rattail fish came to supervise.
Small Fry and Rattails
Rattail fish observed at 2660m, 14 September 2009.
This rattail fish was very interested in our seismometer installation work at ODP 1027 (2660m). The fish hung around for much of the time we worked, watching, smelling, and even trying to eat bits of nylon rope. 14 September 2009.
During the descent for installation, ROPOS passed through a dense school of small fish swimming downward between 350-650m. Local time was between 5:30-6:00 AM, 14 September 2009.
In rapid succession we deployed the remaining two benthic pods to Barkley Canyon, 10-11 September 2009. Now, the full quartet of Barkley benthic pods has been deployed, including pod 1 in the axis of Barkley Canyon and pod 2 located on the upper continental slope above Barkley Canyon. Together, these four instrument platforms will provide a wide variety of data to scientists studying benthic ecology in the area. Learn more about the Barkley Benthic research project.
The communications pathway from the University of Victoria to these two new benthic pods is as follows:
Power and communications ports on Barkley benthic pod 4.
Instruments affixed to Barkley benthic pod 4 include a CTD, fluorometer and multibeam sonar. Photo taken prior to deployment, 10 September 2009.
The microbial sensors were kept continually wet for many weeks prior to deployment.
Gray microbial sensor plate, 10 September 2009.
White microbial sensor plate, 10 September 2009.
An end view of Barkley benthic pod 4, 10 September 2009.
Deployment
ROPOS Sr. ROV operations manager Keith Tamburri, 10 September 2009.
ROCLS is lowered by ship's winch to the seafloor, 10 September 2009. The drum held an extension cable used to connect Barkley benthic pod 4 to our network via the Barkley hydrates instrument platform.
Dalhousie University oceanographer Doug Schillinger discusses plans with R/V Thompson marine tech Jenny White, 10 September 2009.
ROPOS pilot Ian Murdock monitors deployment of the cable reel, 10 September 2009.
(Click images to view slideshow.)
Pod 4 on the Seafloor
As installation wrapped up, we took two push-core samples of the seafloor sediment. One very large squid came to inspect our work.
ROPOS deploys the first of two microbial sensors connected to Barkley benthic pod 4, 11 September 2009.
ROPOS connects Barkley benthic pod 4 to our network, 11 September 2009.
(Click images to view slideshow.)
Barkley benthic pod 3
Low-light black and white video camera with lights, lasers and pan/tilt mechanism mounted beneath Barkley benthic pod 3, 10 September 2009.
Connector and hose that were plugged into Barkley benthic pod 4 during deployment.
Two views of the plankton pump within its frame, 10 September 2009.
ADCP and sonar affixed to Barkley benthic pod 3, 10 September 2009.
Barkley benthic pod 3 with piggy-back plankton pump. After deployment to the seafloor, the plankton pump was removed from the platform and placed on the "bongo drums", a base platform made from blue plastic pipes.
(Click images to view slideshow.)
Pod 3 on the Seafloor
Final layout of the plankton pump and Barkley benthic pod 3, 11 September 2009.
Barkley benthic pod 3 in position on the seafloor, with rotary sonar lifted into deployment position, 11 September 2009.
The plankton pump in position on the seafloor, 11 September 2009.
(Click images to view slideshow.)
Microcosm on a Sponge
During installation, we encountered this sponge growing at 937m, playing host to a slow-moving crab and numerous tiny shrimp.
Sponge and Friends
Tiny shrimp inhabiting a deepsea sponge, 10 September 2009.
Sponge, crab and shrimp observed at 937m in Barkley Canyon, 11 September 2009.
While working in Barkley Canyon, we encountered this sponge inhabited by a crab and numerous tiny shrimp.
, not far from the ODP 1026B CORK and our instrument platform there.
