http://www.newsweek.com/new-island-created-explosive-underwater-volcano-1841427 > A new island has formed following an explosive underwater volcano eruption in Japan. > The freshly formed isle lies off the coast of Iwo Jima, south of Tokyo. When underwater volcanoes, also known as seamounts, erupt, the build of lava occasionally breaks the surface of the water. This causes an island to form.