Pacific eruption captured

NSF and NOA/ AP

PACIFIC ERUPTION: A plume of sulphur and molten lava erupts from the West Mata Volcano nearly 1220m beneath the Pacific Ocean, south of Samoa.

NSF and NOA/ AP

MAJOR DISCOVERY: A robotic arm collects samples at the West Mata Volcano. Scientists have captured on video fiery bubbles of molten lava, calling it a major geological discovery.

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Scientists have witnessed the eruption of a deep-sea volcano for the first time ever, capturing on video the fiery bubbles of molten lava as they exploded 1220m beneath the surface of the Pacific Ocean.

Researchers are callling it a major geological discovery.

A submersible robot witnessed the eruption during an underwater expedition in May near Samoa, and the high-definition videos were presented on Thursday at a geophysics conference in San Francisco.

Scientists hope the images, data and samples obtained during the mission will shed new light on how the ocean's crust was formed and how the earth behaves when tectonic plates ram into each other.

"It was an underwater Fourth of July," said Bob Embley, a marine geologist for the National Oceanic and Atmospheric Administration. "Since the water pressure at that depth suppresses the violence of the volcano's explosions, we could get the underwater robot within feet of the active eruption."

The eruption was a spectacular sight: Bright-red magma bubbles shot up releasing a smoke-like cloud of sulphur, then froze almost instantly as they hit the cold sea water, causing black rock to sink to the sea floor. The submersible hovered near the blasts, it's robotic arm reaching into the lava to collect samples.

Witnessing a deep-sea volcanic eruption was 25 years in the making. Researchers from NOAA and the National Science Foundation had studied deep-sea volcanoes extensively but never witnessed an eruption. Eighty percent of the earth's volcanic activity occurs in the sea, but their underwater locations have complicated scientific efforts to this point.

The mission's chief scientist, Joseph Resing, last year detected volcanic material in the water in the area, and realised it was erupting. In May, the researchers travelled to area and sunk the submersible robot, called Jason, hoping to make scientific history.

"When we got there, we put the sub down and within in an hour and a half we found an eruption there in its full glory," said Resing, who is a chemical oceanographer at the University of Washington. "We haven't seen this before and now for the very first time we see molten lava flowing on the sea floor."

Scientists said the water around the volcano was more acidic than battery acid, but that shrimp and certain microbes were able to thrive in such a harsh environment. Biologists will study these creatures to see if they are unique to this volcanic environment.

Researchers will also continue monitoring the changing West Mata volcano, located about 225km southwest of Samoa.

Earth and ocean scientists also said the eruption allowed them to see the real-time creation of a material called boninite, which had previously been found only in samples a million or more years old.

"The unusual primitive compositions of the West Mata eruption lavas have much to tell us," said Barbara Ransom, programme director in the National Science Foundation's Division of Ocean Sciences.

West Mata is on the western side of the deep Tonga Trench.

On September 29 a magnitude-8 earthquake struck on the other side of the trench.

It generated a tsunami which killed over 180 people in American Samoa, Samoa and Tonga.

- AP