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Katla Volcano In Iceland Alert Raised
Katla volcano in Iceland has been raised to Yellow status, as a near three day quake swarm is rattling the massive volcano. A warning from Icelandic authorities has been issued as follows (translated):
"The National Commissioner of Police and the District Commissioner of Police in South Iceland have declared a Civil Protection Uncertainty phase due to seismic unrest in Katla volcano in Mýrdalsjökull.
The contingency plan for an eruption in Mýrdalsjökull has been activated accordingly. Uncertainty phase means that a course of events has started that may lead to natural hazard in the near future. Monitoring, assessment, research and evaluation of the situation is increased.
Increased seismic activity started on September 29 and is still ongoing. Following a meeting with the Scientific Advisory Board of the Icelandic Civil Protection it is likely that the seismic activity is caused by magma movement within the Katla caldera. Three most likely scenarios have been defined.
1. Seismic activity dies out with no further consequences
2. Glacial outburst flood, jökulhlaup, will emerge from the glacier due to a small eruption
3. Eruption starts in Katla Myrdalsjökull that will force its way through the ice with glacial outburst floods and ash fall Accordingly a warning has been issued for travellers in the vicinity of Mýrdalsjökull especially around glacial rivers."
Katla volcano has not erupted since 1918, according to the Smithsonian GVP. It's smaller neighbor, Eyjafjallajökull erupted in 2010, with an eruption of Grimsvötn (Grimsfjall) following the next year.
In the past few days, there have been hundreds of quakes within the caldera under the glaciar Myrdalsjökull. This follows the events of August when two earthwquakes of mag 4.5 were detected in the caldera. Many of the quakes in the current swarm are 3.0-3.5 in range.
Screenshot from Icelandic Met Office Website
It has been theorized for many years that Katla was 'overdue' to erupt, given that it is typical for Eyja to trigger Katla, or vice versa due to a theory that says the two magma chambers may share a sill that allows their magma chambers to interact.
According to some, Katla may have long been 'primed' for eruption and was awaiting some seismic activity to trigger it, much like Japan's Mt Fuji is theorized to be. It is still of course possible that this earthquake swarm does not end up in an eruption, or has a small subglacial eruption, but time will tell. This is a vigorous and apparently escalating swarm. It is a great time to keep an eye on it. There is a good webcam here.