Scientists funded by the National Science Foundation (NSF) and National Oceanic and Atmospheric Administration (NOAA) have recorded the deepest erupting volcano yet discovered – West Mata Volcano – describing high-definition video of the undersea eruption as "spectacular".
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."
The volcanic eruption, discovered in May, is nearly 1,2 km below the surface of the Pacific Ocean, in an area bounded by Fiji, Tonga and Samoa.
"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.
"It was an underwater Fourth of July, a spectacular display of fireworks nearly 1,2 km deep," said co-chief scientist Bob Embley, a marine geologist at NOAA's Pacific Marine Environmental Laboratory in Newport, Ore.
"Since the water pressure at that depth suppresses the violence of the volcano's explosions, we could get an underwater robot within feet of the active eruption. On land, or even in shallow water, you could never hope to get that close and see such great detail."
Imagery includes large molten lava bubbles 1 m 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 in December at a news conference at the American Geophysical Union (AGU)'s annual fall meeting in San Francisco.
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.
Julie Huber, a microbiologist at the Marine Biological Laboratory, found diverse microbes even in such extreme conditions.
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 analysing shrimp DNA to determine whether they are the same species as those found at seamounts almost 5 000 km away.
The scientists believe that 80 per cent 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 sulphur 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.
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 Visualisation Lab at WHOI.
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Video: Deepest underwater volcanic eruption captured on film