Explorations east of Japan have revealed a previously unknown type of volcano.
Volcanoes typically emerge in one of three geological settings, explains Stephanie P. Ingle, a geochemist at the University of Hawaii in Honolulu. Some crop up along mid-ocean ridges, where Earth's tectonic plates spread apart. Others, such as those on land along the western coast of North America, form where one plate is being subducted, or forced beneath, another plate. And volcanoes far from plate boundaries, such as those in Hawaii, appear where hotter-than-normal plumes of Earth's mantle well up (SN: 7/9/05, p. 24: Available to subscribers at Volcanic Hot Spots).
Ingle and her colleagues, however, have found inactive volcanic features in a completely new setting under the sea about 600 kilometers from Japan. "Finding these peaks was serendipitous luck," Ingle notes.
Analyses of ocean floor nearer Japan had hinted at the presence of undersea volcanoes. So,