Mile-high ‘noodly line’ rising from seafloor off Alaska’s Aleutian Islands leads to discovery of gas seep

A mysterious “noodly line” has been discovered rising from the seafloor off Alaska’s Aleutian Islands, like a giant finger reaching toward the surface, according to NOAA Ocean Exploration.

It’s at least a mile high and about 1,640 feet in diameter, researchers say.

The rope-like column was detected by multibeam sonar and originates from a point at least 1.4 miles deep, along the Aleutian Trench, NOAA says.

What is it?

Gas bubbles. Lots and lots of gas bubbles.

“The noodly line was actually created by our multibeam sonar sound pulses bouncing off bubbles,” a May 15 NOAA field report said.

“Bubbles are indicative of gasses seeping up through the seafloor, and indeed, we had found ourselves a gas seep!”

The leak is large, but NOAA can’t offer an accurate volume estimate “without targeted measurements.”

It was discovered during an expedition that is using advanced technology aboard NOAA’s Okeanos Explorer to map deep-water habitats of the Aleutian Islands and Aleutian Trench. The expedition runs through May 27 and will focus on waters deeper than 656 feet, officials say.

Three gas seeps have been found by the team, but details on the others were not released.

Gas seeps are prized by scientists because they are “potential sources of alternative energy and biopharmaceuticals,” NOAA says.

It’s suspected some gas seeps may have been spewing for thousands of years, experts say.

“Gas seeps occur where hydrocarbon-rich fluid seeps up from cracks or fissures below the seafloor, often as methane or hydrogen sulfide,” NOAA says.

“These hydrocarbons are pushed up through the seafloor when tectonic activity squeezes the sediments below the surface, which releases the chemical compounds into the ocean. ... We don’t know from our mapping data that the gas seep is methane, but we’ve detected methane seeps through multibeam data previously.”