Iceland’s Katla volcano is always aquiver with seismic activity and local people and scientists have been waiting for an eruption for years — although they probably experienced them this year and in 1999 without even noticing.
There has been increased activity at Katla since early July, when a sharp flood was released from under the Mýrdalsjökull glacier and down the Múlahvísl river, washing a road bridge away; as was widely reported at the time. Katla’s unrest has, it seems, entered a new stage, a leading geophysicist says.
Katla is a very unusual volcano in that there is seismic activity in and around nearly all the time. That activity usually comes in stages — the latest of which began in July.
“The most likely explanation for this is that Katla is, in actual fact, always on the brink of erupting. This we saw in 1999, when there seems to have been a small eruption of a similar type to this [latest small eruption this July]. That one was accompanied by unrest and changes to seismic activity and increased geothermal heat in the subsequent years,” Páll Einarsson, University of Iceland geophysics professor, told RÚV.
Last year there was significant seismic activity associated with the Eyjafjallajökull eruption, but since this July — when the Múlahvísl flood took place — activity around Katla and the Mýrdalsjökull glacier has increased and changed, Páll says.
He believes that the frequent but irregular small earthquakes are caused by magma intrusions coming from a shallow depth in the crater itself which could lead to an eruption — just as also happened in July and in 1999, he believes. In that regard Katla is just like other volcanoes: “Sometimes it produces big eruptions, sometimes it produces small eruptions, sometimes it produces tiny eruptions; so it is not always a disaster when Katla erupts,” Páll says.
(Photos: Ágúst Rafnsson. Taken at Fimmvörðuháls in 2010, for illustration purposes only.)