Lava flow from deep-sea volcano captured on video

More than three-quarters of volcanic eruptions happen underwater. But no one has seen molten lava flowing from a deep-ocean seafloor volcano — until now.

A team of scientists set out on an expedition, from Samoa, in early May to study an erupting volcano. Within an hour of reaching the West Mata volcano, the team saw smoke

"And then, wow! There it was. Red lava," said Joe Resing, a University of Washington oceanographer and chief scientist on the expedition. "Everybody. Went. Nuts."

It was 4,000 feet below the surface. The eruptions create new ocean floor.

Video of the eruption, which was recorded earlier this year, was released Thursday during the American Geophysical Union meeting in San Francisco.

The video shows red magma bursting in 35-foot streams from the volcano, turning black as it cooled, and rock fragments being thrown 150 to 300 feet.

Had such an eruption occurred on dry land, without the water pressure to keep it contained, lava and debris would have reached much farther.

The recording was made with a remote-controlled vehicle that could get within eight feet of the eruption site, something that's not possible on land.

"Something seemingly as plain as day, a process you'd expect we would have seen over and over again through the course of history, we've seen for the first time: lava flowing on the ocean floor, lava making new ocean crust," Resing said.

Other scientists, seeing telltale signs of volcanic activity, have chased possible eruptions around the seas. Often, the volcano explodes before they arrive.

Only one other seafloor volcanic eruption has ever been seen; that one sent debris and gases streaming into the ocean, but not lava, according to the University of Washington.

Resing hopes that seeing eruptions under the sea will help scientists understand eruptions that occur on land.

The expedition was funded by the National Oceanic and Atmospheric Administration and the National Science Foundation.

Maureen O'Hagan: 206-464-2562 or mohagan@seattletimes.com