Iceland volcano: and you thought the last eruption was bad.
This month marks the second anniversary of the eruption of Eyjafjallajökull that left millions stranded across Europe, and cost airlines an estimated €150 million a day for six days. But alarmingly, there are signs of high activity beneath the much larger, neighbouring Katla caldera in Iceland – a possible sign of an impending eruption. This should prompt extensive high-level contingency planning across Europe, as Katla has the potential to be much more damaging than Eyjafjallajökull. Since Iceland was settled in the ninth century, Katla has erupted on average every 60 years, but has not had a significant eruption since 1918. Ominously, eruptions of Eyjafjallajökull in 1821-23 and 1612 were followed within months by eruptions of Katla. Judged by the historical calendar, an eruption is overdue. Last July, a flood of water burst from beneath the ice cap on top of Katla, washing away a bridge. This indicates that an extra pulse of heat reached the base of the ice. Since then, there have been erratic movements of the surface of the volcano, measured by precise GPS instruments, and bursts of high earthquake activity beneath Katla’s caldera. These observations imply that magma has risen to shallower depths. Katla’s eruption in 1918 produced five times as much ash as the 2010 Eyjafjallajökull one. A major eruption could result in large parts of Iceland being flooded as snow and ice melted; significant poisoning of Icelandic agriculture; destruction of property; and, of course, the grounding of aircraft across Europe. If enough material is ejected it could even have a cooling effect on the global climate for a few years. A precedent for that would be the 1783-84 eruption from the fissure of Laki, which is part of the same volcanic system, Grímsvötn, that erupted last year. This was a very large eruption of 15 cubic kilometres (3.6 cubic miles), compared to the fraction of a cubic kilometre ejected in 2010, and had a huge impact on the northern hemisphere, reducing temperatures by up to 3 C. This had catastrophic effects far beyond the shores of Iceland (where at least a fifth of the population died), with thousands of recorded deaths in Britain due to poisoning and extreme cold, and record low rainfall in North Africa.
0 comments:
Post a Comment