Tuesday, September 11, 2012

Light Seismicity at Eyjafjallajökull and Katla Volcanoes

2012 has been an extremely kind year volcanically to Iceland. In 2010-2011 there were a couple major eruptions, from Eyjafjallajökull and Grimsvötn (Grimsnes) volcanoes that caused some chaos for travelers, and misery for Icelanders near Eyjafjallajökull due to heavy ashfall. But while there are no volcanoes erupting (yet), Iceland remains ever restless. 

Today there were two very minor and somewhat deep earthquakes between the summit of Eyjafjallajökull, and Katla volcano, very near the vicinity of the initial fissure eruption of Fimmvörduhals. While it is not unusual for the occasional small quake to occur, especially after an eruptive period, there are several things to consider when looking at Katla and its long-winded neighbor. 

Some scientists suggest that Katla and Eyjafjallajökull share a somewhat symbiotic magma chamber (although it is speculation) in which an eruption of one volcano can trigger an eruption in the other. Katla volcano has remained mostly quiet after the Eyjafjallajökull eruption, but not silent by any means. In June of 2011, it is thought that Katla had a very minor sub-glacial eruption that resulted in a jökullhlaup (glacier outburst flood), but since it has been content to rumble away. Currently most seismic and hydrothermal activity is restricted to the Western flank of Katla.

Another notable area of seismicity is occurring on the Reykjanes peninsula on the SW portion of Iceland. The volcanic system of Brennisteinsfjöll, and Krísuvík have been experiencing frequent seismic swarms, and blogger Jon Frímann has reported some fish kill at Kleifarvatn lake between the two volcanic systems. The Askja caldera, and neighboring systems have also been experiencing persistent seismicity.

A year without volcanic activity on Iceland would likely be a welcome respite from the past few years, although several volcanoes, including Katla, are due for an eruption, more specifically, Hekla volcano, which typically erupts nearly every ten years. The last eruption of Helka occurred in 2000, which means it could potentially erupt at a moments notice (although the volcano has given no signs of unrest so far).

Iceland is part of a hotspot/spreading rift that makes it one of the most volcanically active places on the planet except for, perhaps, the big island of Hawaii, where the ongoing eruption of Kilauea volcano has been ongoing since January of 1983, and has shown no sign of slowing down. Iceland is however different in the fact that it rests on the split between the North American, and European plates, a spreading rift, which results in not only a much larger island, but a variety of different eruption types. The eruptions of the Hawaii hotspot are almost exclusively basaltic pahoehoe lavas, whereas Iceland produces a much wider variety of volcanoes, lavas and eruptions.

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