Category Archives: Missions

2011 - R/V Wecoma, 2011 Crew, Missions

Last Day at Sea

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We deployed the 24th seismometer at 9: this morning. The atmospheric pressure is dropping and the seas are rising, making the deployments more challenging. The roll of the ship increases the difficulty of both getting the seismometer to the rail and successfully releasing it over the side. We are heading back to Newport to pick up another anchor plate for one that we lost a couple of days ago. We’ll be doing a “touch and go”, without even putting out the gangplank. Fortunately, the last site is close to Newport.

At 9:50, seven of us met in the wheelhouse for a live Skype broadcast to HMSC. Tracy Crews organized “Career Day” for high school students and we responded via two way video to student questions from the Hennings Auditorium. Our virtual presence was projected on its large screen.

Bob Dziak – Chief Scientist – Professor, Marine Geophysics, OSU,  – What are you studying out there? What’s it like working at sea?

Dave Ogorman – Marine Instrumentation Engineer, Wecoma – How did you choose this career?

David Gassier – Ocean Research Engineer, Lamont-Doherty Earth Observatory, Columbia University – What is your background? Is there a specialized degree in Ocean Engineering?

Del Bohenstiehl – Co-chief Scientist – Associate Professor – North Carolina State University – What do you like most about being a scientist?

Matt Fowler – Mooring and Instrumentation Engineer – Research Assistant, OSU – What is your background? What do you enjoy most about your job?

Martin Rapa – Development Engineer, Scripps Institute of Oceanography – What did you have to consider when designing an underwater seismometer?

 

Tag lines are used to stablize the deployment

 

Matt is struggling with a jammed quick release mechanism
2011 - R/V Wecoma, Deployment, Missions, Seismometers

Off the coast of Washington

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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.

Ready to be released

 

Wecoma’s crane is lifting the seismometer over the side

 

It takes at least 5 crew members to deploy a seismometer
2011 - R/V Wecoma, Deployment, Seismometers

Wednesday’s Sunrise

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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.

Wednesday’s Sunrise
2011 - R/V Wecoma, Deployment, LDEO, Seismometers, SIO

A Beautiful Monday at Sea

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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.

 

2011 - R/V Wecoma, 2011 Crew, CTD, Procedures

CTD Cast

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CTD stands for conductivity, temperature and depth. These terms refer to the changing seawater characteristics that the CTD array encounters as it descends. It electrically sends continuous measurements back to the ship.

Conductivity is an electrical measurement of salinity. The salinity varies near the surface, but is a reliable 34 to 35 parts per thousand for most of the descent. The seawater temperature drops to about 3 degrees Celsius, about 37 degrees Fahrenheit.

We dropped the cabled CTD to just above the seafloor depth of 1500 meters (4921 feet). The pressure increases about one atmosphere for every 10 meters (or ~33 feet) of depth. We attached to the CTD array two nylon bags filled with Styrofoam cups, decorated by students from the Lincoln County School District. When subjected to pressure 150 times greater than standard atmospheric, the air is squeezed out from the Styrofoam.