On Thursday, the Japanese coast guard released video of the new island, forged under billowing smoke and steam. The video shows ash and rocks exploding from a crater that erupted from the sea. A coast guard volcanologist, Hiroshi Ito, told FNN news that it's unclear if the island will become permanent or get reclaimed by the sea.
Japan is an archipelago of thousands of islands, though most of the nation's people live on a few of the largest ones. Japan is well known for volcanic activity and earthquakes, and it is perched on the Ring of Fire, a fringe of coastline that surrounds much of the Pacific Ocean. The tectonically active region includes coastal eastern Asia and long stretches of western North and South America. It is the Ring of Fire that fueled last century's big eruptions at Mount St. Helens in Washington State and Mount Pinatubo in the Philippines. The volcanoes that built Japan's newest island last erupted in the mid-1970s, along the Izu-Ogasawara-Mariana Trench.
http://news.nationalgeographic.com/news/2013/11/131121-japan-volcano-new-island-eruption-science/