REYKJAVIK, Iceland — Iceland's Bardarbunga volcano burst forth with a small eruption Saturday under the ice of Europe's largest glacier, scientists said, prompting the country to close airspace over the area.
Thousands of small earthquakes have rattled the volcano, located deep beneath the Vatnajokull glacier, in the last week. Icelandic Meteorological Office vulcanologist Melissa Pfeffer said Saturday that seismic data indicated that an eruption had begun, with magma from the volcano melting ice within the glacier's Dyngjujokull icecap,
The remote area, 200 miles (320 kilometers) east of the capital of Reykjavik, is uninhabited.
The Civil Protection Department said scientists flew over the ice cap Saturday afternoon but saw no visible signs of the eruption on the surface. Late Saturday the Met Office said there were "no signs of ongoing volcanic activity."
Still, authorities raised the country's aviation alert to red — the highest level on a five-point scale — indicating the threat of "significant emission of ash into the atmosphere."
Icelandic authorities declared a no-fly zone of 100 nautical miles by 140 nautical miles around the eruption as a precaution, but did not shut down air space over most of the island nation in the North Atlantic.
"All airports are open and flights are on schedule," said spokeswoman Olof Baldursdottir.
A 2010 eruption of Iceland's Eyjafjallajokul volcano produced an ash cloud that caused a week of international aviation chaos, with more than 100,000 flights cancelled.
Pfeffer said it was not clear when, or if, the eruption would melt through the ice — which is between 100 to 400 meters (330 to 1,300 feet) thick — and fling steam and ash into the air. She said it could take up to a day for the ice to melt — or the eruption might remain contained beneath Europe's largest glacier.
Scientists were monitoring a hydrological station downstream from the volcano for flooding, a common result of volcanic eruptions in Iceland.