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
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.	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.
Pacific Geosciences Centre instrument technician Bob Meldrum prepares a broadband seismometer for deployment to ODP 1027, 13 September 2009.

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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 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.
ODP 1027 seismometer, now buried in glass beads, 15 September 2009.	Placement of the ODP 1027 broadband seismometer within its caisson, 15 September 2009.	ROPOS spills bags of tiny glass beads over the seismometer within its installation caisson, 15 September 2009.

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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.

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