Watch! An underwater volcano creates new island south of Japan

By Los Angeles Times

An exploding underwater volcano is causing a new island to form in the Pacific Ocean about 620 miles south of Tokyo, and you can watch a bit of its dramatic rise in the video above.

The video, showing thick plumes of steam and ash shooting out of the new volcanic island, was captured this week by the Japan Coast Guard. The new island -- really more of an islet -- is just 600 feet in diameter. And it is unclear whether it is here to stay.

"Most of the time islands like this have very short lives because they are built of ash and larger rock particles that get eroded by wave action,"  Bruce Houghton, a professor of volcanology at the University of Hawaii, told the Los Angeles Times.

However, there is a chance that the new island could stick around. Those massive plumes of steam and ash are caused by sea water interacting with magma. But if the island gets large enough, the sea water will be pushed away from the magma, allowing it to pour out more passively over the island, covering it in a potentially more stable skin that is less susceptible to wave action.

This particular volcano is part of the Izu-Bonin-Mariana system, which forms a line of volcanoes in the western Pacific south of Japan. The new island is emerging right off the coast of the uninhabited island Nishino-Shima, which is also made of volcanic rock.

Dave Hilton, a geochemist at the Scripps Institution of Oceanography in La Jolla who has studied subaerial and submarine volcanoes in this part of the world, said he suspects this volcano did not start erupting super-deep below the ocean's surface.

"The water is not going to be particularly deep there," he said. "You have a gently sloping flank down from Nishino-Shima and this eruption probably occurred on the flank, and that is what made this new island."

Volcanoes are notoriously unpredictable and so no one can say with certainty how long this particular one will keep erupting.

"If we look globally at eruptions, some have lasted a few hours and some have lasted for 30 years," Houghton said. "It is such a huge range."