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.
Spurred by the under-ice eruption at nearby Eyjafjallajökull volcano, glacial meltwater flows through an intentional breach in Iceland's main coastal ring road on Wednesday. Workers had smashed holes in the highway in three spots to give the rushing water a clear route to the coast and prevent bridges from being swept away.
"The volcano is quite steep, so the floodwater comes down rather powerfully in a short time," geophysicist Einarsson said. "We were nervous that we would not be able to evacuate people in time, but this was quite successful."
Glacial meltwater surges seaward across Icelandic plains on Wednesday.
The under-ice volcanic eruption that liquefied a glacier atop Eyjafjallajökull volcano earlier that day was 10 to 20 times more powerful than an eruption last month in an ice-free area of the volcano, scientists say.
Water pours off a glacier near Iceland's Eyjafjallajökull volcano in an aerial picture taken Wednesday, when a new vent began erupting beneath glacial ice.
Eyjafjallajökull first erupted at an ice-free vent on March 20, 2010, in a fiery display that sent fountains of lava shooting high into the air and ribbons of lava flowing down cliff faces. (See pictures of the initial Iceland volcano eruption.)
What it lacked in floods, Eyjafjallajökull volcano's previous eruption made up for with fire. Before dying down Monday, the ice-free vent—shown in a March 24 satellite picture—sparked a steady tourist trade with its photogenic lava fountains. (Iceland Volcano Pictures: Eruption Sparks Tourist Boom.)
Both eruptions might have agitated a neighboring volcano, called Katla, about 12 miles (20 kilometers) away, scientists say.
"Historically," Einarsson said, "the eruption of [Eyjafjallajökull] has triggered the eruption of Katla," which, due to its history of causing catastrophic flooding, is considered one of Iceland's most dangerous volcanoes.