May 26, 2006 — An unmanned probe got within feet of a violent underwater eruption in the Pacific Ocean, returning with the clearest footage ever captured of seismic activity under the sea, a team of Japanese and U.S. researchers have reported.
Most of Earth's volcanic activity happens underwater, and is therefore difficult to observe.
But when the submarine volcano NW Rota-1 erupted 1,800 feet underwater in the Mariana Arc volcanic chain, researchers sent two remotely operated research submarines to watch the show.
The resulting footage, released Thursday by the Japan Agency for Marine-Earth Science and Technology, shows gray ash and rock spewing from the volcano as it erupted in October.
The ash contained thousands of droplets of molten sulphur, which coated the research vehicle's surface as it captured the eruption on film. The water surrounding the volcano's crater -- even when there is no eruption -- is as acidic as lemon juice.
As a result, the environment is relatively inhospitable to life. Only specialized microbes, and a few species of shrimp, are known to thrive there.
Lava streams down the volcano, which is some 60 miles north of the U.S. Pacific territory of Guam.
The Japanese-American research team also collected sediment samples, team leader Yoshihiko Tamura said. The Hyper Dolphin probe went as close as 7-10 feet from the eruption.
"We believe it's the first time anybody has captured quality footage of an underwater eruption from such a close distance," Tamura said.
Analysis of the footage and sediment could help explain how repeated eruptions of underwater volcanos eventually give rise to islands and even continents, Tamura said.
"Further research could shed light on the very fundamentals of how land masses are formed," he said.
Preliminary research findings are reported by Tamura, Robert W. Embley of the U.S. National Oceanic and Atmospheric Administration and other team members in this week's edition of the journal Nature.
