Unspooling seismic streamer


Dan Sousa, LDEO, carrying a 'bird,' which is used
to control streamer depth. The streamer reel
is in the background.
Having finished the deployment of 70 OBS on the seafloor, we spent ~20 hours deploying the other key parts of the seismic gear for our project: a seismic “streamer” and a seismic source.  Seismic streamers are long cables filled with closely spaced hydrophones, which detect small pressure changes associated with passing sound waves.  The streamer for our program is ~10 miles long! It is stored on large reels, which unspool the streamer off the back of the ship and into the water. As we deploy the streamer into the ocean, we attach equipment to it that is used to control the depth of the streamer beneath the sea surface and determine its location behind the ship, which is very important for such a long cable.  The depth controllers have wings that can be pivoted to dive the streamer deeper or bring it shallower, so they are affectionately called 'birds.'

Now that we have 70 OBS on the seafloor and 15 km of seismic streamer behind the ship, it’s time to collect some data!

Donna Shillington, LDEO

Seismic streamer entering the ocean from the back of the ship.




Comments

Post a Comment

Popular posts from this blog

The Emperors among us

Image
The main lab's view of the last seismic reflection data being collected. Overseeing  them are  drawings of Emperor Jimmu and Empress Suiko. Finishing the seismic reflection acquisition part of our experiment, we find ourselves south of Jimmu Guyot and near Suiko Guyot. The term ‘guyot’ refers to a flat top seamount that was first named by Harry Hess, a pioneer in developing our current understanding of plate tectonics. These features have a similar morphology to the plateaus found in the Western United States with both having a flat terrain on top that is raised above with surrounding areas often by steep slopes. The Hawaii-Emperor Seamount Chain is a great example of the formation of guyots along volcanic chains. Active volcanism is found on the youngest in the chain, currently at the Big Island of Hawaii which sits atop the central Hawaiian hotspot, a small spot in the plate that fuels the volcano from great depths. As the Pacific Plate slowly but steadily moves to the no
Read more

Thank you thank you thank you

Image
On June 1, we arrived in port in Kodiak, Alaska, marking the end of our expedition. Kodiak greeted us with spectacular vistas of mountains and lush green hills. It’s not called the Emerald Isle for nothing!   Views of Kodiak on our way into port Despite a late departure and some rough weather, it was an enormously successful trip. We collected a suite of fabulous datasets that will help us understand the formation of this 6000-km-long chain of volcanos that have formed across the Pacific plate over the last 80 million years.   Many mysteries remain about the water-covered parts of our planet, particularly in remote regions like our study area, despite the fact that they host truly gigantic structures. Jimmu Seamount is nearly as tall as Denali, the tallest mountain in North America, and much more massive!     Comparison of bathymetry across Jimmu Seamount and elevation across Denali Collecting data that enables us to unravel Earth’s mysteries r
Read more

Back to sea...

Image
Planned design of seismic study After cooling our heals for ~6 months on land, we are preparing to head out to sea again on the R/V Marcus G. Langseth for the second phase of our project focused on the Hawaii-Emperor Seamount Chain.  The first leg in September-October 2018 focused on the Hawaiian Islands, which are the newest additions to a ~6000-km-long chain of volcanos that continues northwest of Hawaii all the way up to Kamchatka.  These volcanos get progressively older with distance away from Hawaii.  Very little is known about the older Emperor Seamount Chain, particularly the geological structures below the seafloor.  During the next 45 days, we will collect data to image the upper ~20-50 km of the earth beneath a ~60-million-year-old part of the Emperor Chain. Map of depth to seafloor showing the location of the Hawaii-Emperor Seamount Chain One reason we know so little about the Emperor Seamounts is that they are a long way from anywhere, and so not easy to reach! O
Read more