Eyjafjallajökull erupting on May 11, 2010. Photo: Icelandic Met Office, by Sigurlaug Hjaltadóttir.
Scientists are keeping close watch on Iceland’s Katla volcano, where a series of recent seismic tremors reaching magnitude 3.9 have raised the possibility that an eruption may be imminent.
With memories of last year’s Eyjafjallajokul eruption still fresh, concerns are that Katla’s much larger magma chamber could lead to a much stronger and more damaging event.
A small eruption at Kalia occurred in early July and was confirmed by the Icelandic Meteorological Office in September, but was not sufficient to relieve enough pressure in the volcano to rule out a larger event in the near future.
Located in the East Volcanic Zone near Iceland’s southern shore, Katla is one of the largest volcanoes in the country, with a 6 mile (10 km) caldera covered by 660-2,300 ft (200–700 m) of ice. Reaching a height of 4,961 ft (1,512 m), Katla has historically erupted every 40-80 years. While the volcano has shown signs of unrest since 1999, the last major eruption occurred in 1918 – 93 years ago.
The spring 2010 eruption of Eyjafjallajokul, located only 25 km from Katla, spewed ash up to 11,000 meters into the atmosphere and was most notable for the causing the worst peacetime disruption of air travel in history.
As ash spread across Europe, nearly all major airports were forced to close, stranding millions of passengers for nearly a week as thousands of international flights were cancelled for fear aircraft engines would become clogged with ash.
June 12, 1991 eruption of Mount Pinatubo. Photo: U.S. Geological Survey, by Richard P. Hoblitt.
A full-blown eruption of Katla could dwarf the destructive power of last year’s Eyjafjallajokul.
The strongest of past Katla events were comparable the 1991 Pinatubo eruption, which measured 6 on the Volcanic Explosivity Index (VEI) scale of 0-8. Pinatubo ejected some 10 cubic km of magma and caused global temperatures to drop by 0.5 °C (0.9 °F).
Locally, the greatest threat posed by Katla may due to the fact that it’s buried beneath the Mýrdalsjökull glacer. Major eruptions of subglacial volcanoes often produce massive flooding downslope with little notice.
