REYKJAVIK, Iceland (AP) — Iceland’s Meteorological Office says a subglacial eruption is underway at the Bardarbunga volcano, which has been rattled by thousands of earthquakes over the past week.
Vulcanologist Melissa Pfeffer says sesmic data indicates that lava is melting ice beneath the Vatnajokull glacier.
She said it was not clear when, or if, the eruption would melt the ice and send steam and ash into the air.
Iceland raised its aviation alert for the volcano to the highest level of red on Saturday. The red alert is the highest warning on the country’s five-point scale.
Earlier this week authorities had evacuated several hundred people from highlands north of the Vatnajokull glacier as a precaution. The area is uninhabited but popular with hikers.
Scientists had planned to fly over the glacier later Saturday to look for changes on the surface but it was not clear if that would still take place.
A 2010 eruption of the Eyjafjallajokul volcano produced an ash cloud that caused a week of international aviation chaos, with more than 100,000 flights cancelled. Aviation regulators since have reformed policies about flying through ash, so a new eruption would be unlikely to cause that much disruption.
Seismologists say magma is moving under the glacier but so far has traveled horizontally at a depth of 5 to 10 kilometers (3 to 6 miles). The volcano will erupt if the magma rises and melts the ice above.
Pfeffer said the amount of ash produced would depend on the thickness of the ice.
‘‘The thicker the ice, the more water there is, the more explosive it will be and the more ash-rich the eruption will be,’’ she said.
Iceland sits on a volcanic hot spot in the Atlantic’s mid-oceanic ridge and eruptions have occurred frequently, triggered when the Earth’s plates move and when magma from deep underground pushes its way to the surface.