Experts claim that four more big volcanoes in Iceland could erupt at any time.

They think the erupting volcano in Iceland, causing the ash clouds, could be the first of many. The scientists have worked out that the eruptions in Iceland happen in cycles and a quiet 50 years is coming to an end.

The volcano erupting at the moment is called Eyjafjallajokull. Its ash clouds have meant lots of flights have been cancelled and now it’s thought the volcano could carry on erupting for weeks, months or even years.

There are fears, too, that the volcano could trigger the eruption of other volcanoes nearby – all of which are bigger.

In the past they have been devastating. One of them, Hekla, has erupted about 20 times since AD874. Scientists say that snow is melting on Hekla’s summit right now which is a sign that magma (molten rock under the Earth’s surface) is rising.

A massive volcanic eruption in Iceland in 1783 ejected so much ash that it cooled the whole of the northern hemisphere for three years. The low temperatures meant crops failed and caused famines.

Everyone is wondering how long the eruption happening now will last.

Earth scientist Professor Stephen Sparks, from Bristol University, said: “Every volcano has its own personality. This particular volcano has erupted before in 1612 and 1821. Last time it continued erupting for 15 months so there is no reason why it could not last a similar period of time.”

Watch the video of Eyjafjallajokull spewing more ash below...