“The OBS deployment cruise was an unqualified success. Our
highly efficient team of sea going professionals was able to maintain a
brisk deployment schedule and completed all 25 ocean bottom seismometer
deployments within 8 days. We averaged 3 deployments a day, including
time for instrument surveys to derive their precise locations. The only
thing that suffered was our sleeping habits, but it was well worth it!
We also wish to express our gratitude to the Captain, crew, and Marine
Tech of the Wecoma for their hard work that allowed our project to be
“All 25 SIO and LDEO instruments were deployed with sites prioritized
prior to the cruise in consultation with the community to focus on
different scientific questions. This prioritized sequence was further
modified prior to the cruise to accommodate recommendations from the
Oregon Fishermen’s Cable Committee (OFCC), The Oregon Trawlers
Association, the Quilete and Quinault tribes, and the Canadian Trawlers
Association, all of which represents the various fishing communities on
the Oregon, Washington and Canadian continental margins. Of the 25
instruments deployed, one SIO Abalone instrument lost its anchor as it
was being deployed. Another Abalone was deployed in its place as a spare
anchor was sent to Newport during the cruise. We returned to port
briefly after deploying the first 24 instruments, and returned to the
site to deploy the lone remaining Abalone. All instruments will remain
on the seafloor until the summer of 2012.”
Following the continental margin, the Wecoma cruised south at about 10 knots for most of the day. The seas picked up slightly, and there were light scattered showers. We deployed another Abalone seismometer at 4:30, and it was on the bottom by 5:30. We will be deploying the last Cascadia seismometer at 1: am.
Wednesday afternoon, October 19th – Off the coast of Washington at the edge of the continental margin
We just deployed another Cascadia seismometer. It will take 65 minutes to reach the ocean floor, 2630 meters below. It will take another hour to conduct the acoustic survey, as the Wecoma cruises in a kilometer and ½ circle overhead.
The weather has deteriorated somewhat, but is still serviceable. We deployed two seismometer last night and another one this morning. Since we are in deeper water, it takes longer for the seismometer to reach the bottom. A acoustic survey is immediately conducted to determine its exact location in three dimensions; latitude, longitude and depth. The Wecoma circles the seismometer location as the acoustic release sends signals to the ship.
We have traveled north to test two Cascadia seismometers that were deployed earlier during the first leg during July. A specific frequency of sound (between 9 and 13 kilohertz) is sent down to check if the instrument package is working. Sometimes a fishing trawl can flip over the seismometer, rending it useless. If the instrument is working, it responds with a series of audio chirps that are picked up here on the Wecoma.
So far we have deployed five Cascadia and four Abalone seismometers. Another five are scheduled for deployment through the night.
Yesterday, we deployed three seismometers, two “Abalones” from Scripps Institute of Oceanography with the trawl resistant design and one from the Lamont-Doherty Earth Observatory (LDEO) called “Cascadian” which also has an absolute pressure gauge and hydrophone. These seismometers are generally deployed deeper along the continental margin.
Sea Grant's Bill Hanshumaker chronicles ocean research missions