Iceland glacier flood fears

The disturbance indicates activity under the ice

By Alex Kirby BBC News Online environment correspondent

UK scientists have detected signs of unusual geothermal activity beneath two ice caps in Iceland.

They say this has caused the appearance of two deep depressions, known as cauldrons, in one of the caps.

Beneath the other they have recorded seismic movements which could be the precursor of a big eruption.

The scientists say there is little threat at present, but cannot predict how the activity may develop.

The two ice cauldrons, about 12 km (eight miles) apart, are on the Tungaarjokull glacier, on the western edge of the Vatnajokull ice cap in southern Iceland.

Iceland has glaciers and is the world's most volcanic island - a recipe for dramatic events.

David Hilliard, Earthwatch

One cauldron is 1.5 km wide and 100 metres deep, and the other almost as large. The glacier itself is 200-300 m thick.

One of the scientists involved in the research is Dr Matthew Roberts, of the Icelandic Meteorological Office.

He told BBC News Online: "The larger cauldron has grown deeper and wider in the last 24 hours.

"We think the geothermal activity triggered a rapid release of meltwater from under the glacier."

Volatile ice cap

The team believes this water could eventually burst free of the glacier and this could pose a danger to surrounding areas.

A similar glacier outburst flood, known in Icelandic as a "jokulhlaup", in 1996 washed large quantities of ice and sediment into the Atlantic, causing huge damage to bridges, roads and power lines.

Dr Roberts told BBC News Online he and his colleagues were also concerned about another ice cap, Myrdalsjokull, in south central Iceland.

He said: "We've detected earthquakes there reaching nearly three on the Richter scale.

"The last time there was an eruption there, in 1918, the outflow reached 250,000 tonnes of water per second from the ice cap, and the fallout of the ash cloud spread to the mainland of northern Europe.

"We know that Myrdalsjokull will erupt again, though whether in the next few days or the next decade we can't say."

Waiting to happen

Dr Roberts is working with two colleagues from the UK - Dr Andrew Russell, of Keele University, and Dr Fiona Tweed, of Staffordshire University.

They are part of a project supported by Earthwatch, a conservation charity which undertakes scientific field research.

David Hilliard of Earthwatch told BBC News Online: "It's important for the Icelanders to understand the dynamics of jokulhlaups, because of the potential threat to property and to life.

"Iceland has glaciers and is the world's most volcanic island - a recipe for dramatic events."

The cauldron is growing

Images courtesy of Earthwatch