Steam explodes from a glacier-topped Iceland volcano in an aerial picture taken April 14, 2010, by the Icelandic Coast Guard. The new eruption began Tuesday, just as the headline-making lava fountains at a neighboring, ice-free vent were dying down.

Volcanic heat is rapidly melting the 650-foot-thick (200-meter-thick) ice block atop the vent, which is part of Eyjafjallajökull volcano. Fearing floods, officials evacuated about 800 area residents at the first signs of the second eruption, said Páll Einarsson, a geophysicist at the University of Iceland's Institute of Earth Sciences. (Read "Iceland Volcano Erupts Under Glacier, Triggers Flood.")

Initial reports suggest the glacial melt has raised local rivers by as much as ten feet (three meters). A major road has been closed and water continues to gush into the ocean, but as of press time, there are no reports of casualties.

Pictures: Iceland Volcano Erupts, Under Ice This Time

The second new hot spot on Iceland's Eyjafjallajökull volcano is under a glacier, meaning big steam and major flooding.