The Great Debate UK

Why volcanoes are likely to continue to cause chaos in Europe

By Dr Andy Hooper. The opinions expressed are his own.

Within the space of just over a year, aircraft have now been grounded in Europe twice by ash blowing in from Iceland.  This has caused many millions of pounds of disruption.

A key question uppermost in many minds is whether the frequency of eruptions in Iceland is increasing. The short answer here is ‘yes, probably’. But, it is not just the frequency of eruptions that matters.  To impact the airspace of the United Kingdom and continental Europe, the ash has to be ejected high enough, and be fine enough that it can remain airborne for days.  Then the winds have to conspire to push it towards Europe, and the winds blow over Iceland from the north only a small fraction of the time.

Studies by researchers at the University of Iceland have noted that the frequency of eruptions from volcanoes beneath the Vatnajökull ice cap (including Grímsvötn, which erupted in May this year) seems to wax and wane with a cycle of about 140 years.

Prior to the 1980s, there were no such eruptions from these volcanoes for over 40 years and there have now been four within 15 years.  The reason for the apparent cyclicity is not established but, in any case, we appear very likely to have entered a phase of more eruptions.

The volcanoes beneath the Vatnajökull ice cap are not, of course, the only ones in Iceland — Eyjafjallajökull, for instance, which erupted last year, is not covered by the Vatnajökull ice cap — and the same patterns may not apply elsewhere.  However, perhaps more importantly than the number of eruptions, the University of Iceland study also noted that the intensity of eruptions increases in times of high activity, meaning that the height of the ash, and therefore the chances of it reaching Europe, also increases.

Perhaps of even greater concern is that the major fissure eruptions have also occurred during periods of high volcanic activity, although with only two of these within the last 800 years, this could be coincidence.  Here the concern is not so much for air traffic, but for something far worse.