Thursday, June 7, 2012

Large Quake Swarm At Katla Volcano

Katla volcano is again showing increased seismicity and unrest, as the Icelandic cold season comes to a close. Today there were over 25 small quakes within the caldera, with most of the quakes in the range of 1.0-2.0 in magnitude. Katla volcano has long been thought to be overdue for an eruption. As the train of thought goes, as goes Eyjafjallajökull, so goes Katla shortly thereafter. This has proven to be somewhat of a guesstimate,  as Katla has refused to blow even after the 2010 eruption of Eyjafjallajökull which caused massive disruption to transportation in Europe.

Katla has been having near continuous quakes under its caldera for decades. While lately it may seem that Katla is preparing to blow, it should be noted that many quake swarms occur in the area regularly. These quakes are probably (almost definitely) related to magma intrusion into the caldera, it remains a phenomena that is unlikely to produce a massive eruption.

Katla volcano is covered in a thick glacier, and as such has somewhat of a natural eruption suppression system in place, given that the ice sheets are so thick. The volcano does frequently have magma intrusion, but most of the time, the ice mitigates this and simply causes glacier outburst floods (jökullhlaups) to occur, typically not resulting in explosions. However when Katla builds enough pressure, the result can be disastrous.

The current activity at Katla volcano is not a surprise, nor unexpected, and probably will not result in a whole lot of action. The media such as the BBC, or the Telegraph, will most likely blow this out of proportion. It is important to note that Katla frequently has quake swarms, dike intrusions, etc, that do not immediately manifest themselves as volcanic activity. However there is always a risk that an eruption could occur as a result of these magmatic intrusions into the volcanic system.

As always, time will tell if this will result in anything. A good 90% of the time, quake swarms are merely a distant precursor to a future eruption and nothing more. Sustained swarms are the ones to watch for, and given the past few weeks, I'm fairly certain that this is simply normal behavior for the volcano. Nonetheless, it is a noteworthy swarm, and you can watch the near real-time activity at http://en.vedur.is.

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