Scientists have recorded the deepest erupting volcano yet discovered--West Mata Volcano--located 4,000 feet below the surface of the Pacific Ocean, in an area bounded by Fiji,Tonga and Samoa.

The imagery includes large molten lava bubbles three feet across bursting into cold seawater, glowing red vents exploding lava into the sea, and the first-observed advance of lava flows across the deep-ocean floor. Sounds of the eruption were recorded by a hydrophone and later matched with the video footage.

Expedition scientists released the video and discussed their observations at a Dec. 17 news conference at the American Geophysical Union (AGU)'s annual fall meeting in San Francisco.

"For the first time we have been able to examine, up close, the way ocean islands and submarine volcanoes are born," said Barbara Ransom, program director in NSF's Division of Ocean Sciences. "The unusual primitive compositions of the West Mata eruption lavas have
much to tell us."

"We found a type of lava never before seen erupting from an active volcano, and for the first time observed molten lava flowing across the deep-ocean seafloor," said the expedition's chief scientist Joseph Resing, a chemical oceanographer at the University of Washington.

The West Mata Volcano is producing boninite lavas, believed to be among the hottest on Earth in modern times, and a type seen before only on extinct volcanoes more than one million years old.

University of Hawaii geochemist Ken Rubin believes that the active boninite eruption provides a unique opportunity to study magma formation at volcanoes, and to learn more about how Earth recycles material where one tectonic plate is subducted under another.

Water from the volcano is very acidic, with some samples collected directly above the eruption, the scientists said, as acidic as battery acid or stomach acid. Tim Shank, a biologist at the Woods Hole Oceanographic Institution (WHOI), found that shrimp were the only animals thriving in
the acidic vent water near the eruption. Shank is analyzing shrimp DNA to determine whether they are the same species as those found at seamounts more than 3,000 miles away.

The scientists believe that 80 percent of eruptive activity on Earth takes place in the ocean, and that most volcanoes are in the deep sea. Further study of active deep-ocean eruptions will provide a better understanding of oceanic cycles of carbon dioxide and sulfur gases, how heat and matter are transferred from the interior of the Earth to its surface, and how life adapts to some of the harshest conditions on Earth.

The science team worked aboard the University of Washington's research vessel Thomas Thompson, and deployed Jason, a remotely-operated vehicle owned by WHOI. Jason collected samples using its manipulator arms, and obtained imagery using a prototype still and HD imaging system developed and operated by the Advanced Imaging and Visualization Lab at WHOI.