Friday, June 22, 2012

Continuous Seismicity in Katla Volcano

Earthquake swarms this time of year are no stranger to Kalta volcano in Iceland, however the current swarm may be cause for at least a minor amount of apprehension. Since late last month, quakes have been occurring regularly within Katla's summit caldera underneath the famed Mýrdalsjökull glacier. Katla regularly has rumblings of this nature, but the latest tremors have also been accompanied by ice melt, which is a cause for concern-- or at least a cause for residents to begin getting their "eruption kits" ready to go.

Katla has not had a major eruption in centuries in recent memory (Jon Frimann pointed out eruptions in 1860 and 1918 int he comments below, however most people were not alive back then) , however in late 2011, it did produce a minor eruption which resulted in a jökullhlaup, or 'glacier outburst flood', in which a significant amount of the glacier covering the caldera was melted, creating a massive sub-glacial lake, that suddenly burst from the outer walls of the glacier to produce a flood laden with liquefied ash, boulders, and chunks of ice that demolished a bridge and damaged roadways and farms on its rampage to the coast.

Katla's 2011 eruption was considered extremely minor for this volcano, which has been responsible in the past for some of the largest eruptions in modern historical time from the Atlantic island. In addition, some scientists claim that the volcano should have erupted shortly after its neighbor, Eyjafjallajökull, did in 2010, but this so far has not occurred.

As the seismicity has been ongoing for over a month now within the caldera, I would certainly say at this point that the volcano is growing restless. Granted, no harmonic tremor has so far been recorded, at least nothing out of the norm... these could be merely crustal adjustments to the volcano due to the shrinking icecap in the summer, and adjustments due to the small discharge of magma to the surface last year compensating for the gap in the magma chamber... one can definitely not be sure as there is currently no employed technology on Katla capable of imaging the magma chamber. 

The volcano, given the fact that thus far there has been no clear signal of magma injection, is by no means in a phase of imminent eruption however. While seismicity remains high, there are still none of the typical signals that the volcano is gearing up for a show. There have been instances when long dormant volcanoes have suddenly blown with little to no warning, and perhaps Katla might be one of them, but it is impossible to tell. As there were no scientific instruments available hundreds of years ago to give us an indication of the behavior of the volcano, we have no record of any precursors from a Katla eruption.


1 comment:

  1. Last major eruption in Katla volcano where in the year 1860 (VEI 4) and in the year 1918 (VEI 4+) the latest.

    So saying that Katla volcano has not had major eruption in centuries is wrong.

    Data source: http://www.volcano.si.edu/world/volcano.cfm?vnum=1702-03=&volpage=erupt

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