Katla

Previous eruptions of Eyjafjallajokull seem to have acted as harbingers of a subsequent Katla eruptions.

Scientists say history has proven that whenever the Eyjafjallajokull volcano erupts, Katla always follows -- the only question is how soon.

The historical record would be the only reason to suspect that, but right now I don't think there are signs of unrest at Katla.

That said, Katla does seem to erupt on a semi-regular basis, with typical periods between eruptions of between 30 and 80 years.

Meanwhile, bookies have slashed the odds on a second Icelandic volcano erupting this year following a flood of bets on active volcano Katla.

Icelandic geologists have long monitored Katla because an eruption might melt the ice and send floodwaters rushing into the valleys below.

A very large eruption, thought to be one of Katla's, left ash all across northern Europe about 10, 300 years ago.

The potential eruption of Iceland's volcano Katla would likely send the world, including the USA, into an extended deep freeze.

There is some evidence that the longer Katla waits before relieving itself, the more spectacular the results are.

A big eruption, thought to be one of Katla's, left ash all across northern Europe about 10, 300 years ago.

Perhaps even more worrying than that is the risk that the neighbouring Katla volcano might erupt too.

The volcano they chose was not Eyjafjallajokull, but its neighbour, Katla;