A volcanic eruption in Iceland, which has thrown up a 6-km (3.7 mile) high plume of ash and disrupted air traffic across northern Europe, has grown more intense, an expert said on Thursday.
The eruption under the Eyjafjallajokull glacier continued to spew large amounts of ash and smoke into the air and showed no signs of abating after 40 hours of activity, said Pall Einarsson, a geophysicist at the University of Iceland.
"The seismographs are showing that since this morning the intensity of the eruption seems to be growing," he said.
Hot fumes had melted up to a third of the glacial ice covering the crater, causing a nearby river to burst its banks, and frequent explosions on the floor of the crater sounded like bombs going off, he said.
The floods were abating, however, and some of those living in the sparsely populated area near the volcano had returned to their homes.
Another scientist said the eruption was 10 times more powerful than one which occurred last month on the flank of the volcano, though the two were part of the same event.
To the east of the volcano, thousands of hectares of land are covered by a thick layer of ash while a cloud blotted out the sun in some areas along the southern coast of Iceland, local media reported.
The cloud of ash from the eruption has hit air travel all over northern Europe, with flights grounded or diverted due to the risk of engine damage from sucking in particles of ash from the volcanic cloud.
Scientists picked up the first signs of increased seismic activity at Eyjafjallajokull last summer and had been expecting an eruption at any moment, Einarsson said.
The eruption began in March but subsided earlier this week when a magma conduit became blocked, building up pressure which finally escaped through the volcano's main crater.
Einarsson, who described the eruption as "reasonably powerful," said it was the most significant volcanic event in Iceland since a huge eruption in 1996, when an eruption under the Grimsvotn lakes led to widespread flooding.
He said scientists were still concerned the ongoing eruption could trigger Mt Katla, a more powerful volcano nearby covered by a thicker ice sheet, but had not picked up any clear signs of brewing activity.
The volcano under the Ejfjallajokull glacier, Iceland's fifth largest glacier, has erupted five times since Iceland was settled in the ninth century.
Iceland sits on a volcanic hotspot in the Mid-Atlantic Ridge and has relatively frequent eruptions, although most occur in sparsely populated areas and pose little danger to people or property. Before March, the last eruption took place in 2004.