UW scientists record undersea vents' roar, and they're sharing

You've probably seen pictures of the undersea vents called "black smokers" spewing billowing clouds into the water. Now you can hear them as well.

University of Washington scientists have, for the first time, recorded the sound produced as the scalding fluid rushes from the vents faster than water out of a fire hose.

The roar is reminiscent of an avalanche, said Tim Crone, the doctoral student who led the project.

"It was pretty surprising how loud it was and how strange," he said. "It's kind of a rumbling and bubbling and popping kind of sound."

When he analyzed the pattern closely, he also found an array of distinctive tones embedded in the general cacophony. Some sound like the buzzing of giant horseflies, while others are like the deepest notes on a stand-up bass.

The tones are probably created as the chimneys and cavities in the black smokers vibrate like the pipes of a pipe organ, he said.

Crone made his recordings on two vents nicknamed "Sully" and "Puffer," nearly 1.5 miles below the surface and about 300 miles west of Seattle. The vents sit along the Juan de Fuca Ridge, where tectonic plates are spreading apart, creating new sea floor.

Information

Hear the vent: For more information and to hear the vents: http://uwnews.org/article.asp?articleID=30030

Ocean water circulates into the Earth's crust, where it is heated and picks up chemicals and minerals. Smokers form where these hot fluids are ejected back to the ocean. The dark color comes from dissolved minerals that solidify when the 750-degree liquid hits the cold sea water.

"It's so hot, that when they were first discovered, the temperature probes we put into them melted," Crone said.

When he launched his project, Crone was greeted with skepticism. An attempt nearly 20 years ago had failed to detect any noise coming from the vents.

"There was a general consensus that this was crazy," he said.

But working with an engineer, Crone put together what he calls a glorified tape recorder: a digital-recording system in a titanium pressure housing that could stand up to the depth and heat.

Crone dove to the sea floor in the submersible Alvin to position the instrument near the vents, collecting more than 180 hours of sound.

His goal wasn't simply to lay down some cool tracks, though.

Monitoring the sound produced by the vents may be a way to detect changes in their flow rates, he explained. Long-term flow measurements are impossible, because instruments dropped into the plumes are destroyed so quickly. But working on the principle that stronger flows are louder, sound could provide a rough yardstick.

Scientists are interested in the way underwater earthquakes and volcanic eruptions affect the amount and type of fluids flowing from the vents, and what those fluctuations might mean to the tube worms, crustaceans and other creatures living in the harsh environment.

It's also possible fish and other deep-sea dwellers hear the rumbling of the vents and know to avoid the deadly plumes in a world where darkness is complete.

"Sound is the light of the deep sea," Crone said. "It's a way to find out about your environment."

Sandi Doughton: 206-464-2491 or sdoughton@seattletimes.com