Thursday, July 23, 2015

Iceland May Be gearing Up For Another Round of Eruptions

Iceland may be gearing up for another round of volcanic and tectonic events, and some of them could be spectacular. The world only recently started paying close attention to Iceland's volcanoes after the eruption of Eyjafjallajökull in 2010, Grimsvötn the following year, and the recent eruption of a Bárðarbunga fissure system at Halhuraun. Bárðarbunga's eruption was the largest in recent history, with a massive lava field being issued, and millions of tons of SO2 gas.

The events at Bárðarbunga were part of the heart of what Iceland is, the eruptive center of a massive magma plume, which coincidentally lies on the spreading sealfoor rift of the North American and European plates. These plates are spreading, and recent seismicity shows just how active that spreading is.

Several volcanoes are either overdue for an eruption, or showing signs of awakening. Accoring to Jon Frimann of the Iceland Geology Blog, the island of Surtsey in the Vestmanneyjar volcanic system has shown signs of increased thermal activity. This is one system to watch, as in 1973, Eldfell volcano was born on the Icelandic island of Heimaey, with no warning. The eruption devastated residential homes, and advanced to the island's only port. During this eruption, Icelanders actually fought back the lava flow using massive pumps, piping cold ocean water in vast amounts onto the lava. They saved the harbor.

But this is a volcano, and it will erupt again in the future. The Island of Surtsey was created in a spectacular and never before documented eruption type. The term 'Surtseyan' eruption was born on the day Surtsey arrived. Boiling out of the ocean floor to breach the surface in 1963, the eruption lasted until 1967, building a new Icelandic volcano island. The island remains off-limits to all but the scientific community, who are studying biodiversity on newly created islands. 

This means that the people of Heimaey are living on a still very active volcano, and it has been quite silent for some time... until now. Unlike the recently erupted volcanoes that have been in the news, Vestmanneyjar is off people's radar these days, and unlike those volcanoes, does have population centers in its immediate vicinity. Heimaey after all is a very busy trading port.

Other volcanoes are stirring as well, some in the vicinity of the recently erupted Bárðarbunga system, which seem to have been disturbed by that eruption. Some have been eerily quiet for a long time, but are starting to have small quakes.

Hekla volcano is a dangerous volcano. Not because it is close to any population centers (although close enough for gas and ash to fall in the capitol), but because it is one of those volcanoes, like many in Iceland, which tends to erupt without warning. It has been experiencing sporadic quakes, which worry volcanologists. 

Torfajokull to Hekla's East, and NNW of Katla volcano, is also experiencing some quake activity, although this may be purely tectonic. This is a caldera system, which has not erupted in many centuries, however still has very active fumeroles, hot springs, and geysers.

Katla itself is assumed to be primed for an eruption, and may have had a very minor subglacial episode following the eruption of Ejyafjallajökull. It typically displays spurts of seismic activity, however would still be difficult to predict or monitor given its size, and the glacier mounted on top. This eruption would likely dwarf those of Ejyafjallajökull and Grimsvötn. But it just hasn't popped off as of yet. This would likely be the most dangerous eruption, as it would affect air travel (again) in Europe on a larger scale, create massive glacier outburst floods (jökullhlaups), and could last for a long time.

Tungnafellsjokull, to the East of the Bárðarbunga caldera, has been experiencing very unusual and heavy quake swarms during and after Bárðarbunga's fissure eruption and caldera collapse. I have stated in the past this may be a 'toothpaste tube' like scenario, where one magma chamber has stressed the other, and created a  more dynamic situation under Tungnafellsjokull. I still believe this to be the case. It is unknown whether this means an eruption will happen, or if things are settling down, but this volcano does not have a historical eruption record (in Iceland these date back to Viking times), so it could be unlikely... but nothing is impossible.

And to the North of Bárðarbunga, Askja volcano, which is another record-holding volcano in Iceland, had a catastrophic eruption in 1875, one of Iceland's largest, has been having persistent seismicity after the fissure eruption of Bárðarbunga. One of its much older and unmonitored neighbors, Herðubreið has followed that trend as well.

All of these volcanoes are in the vicinity of the spreading rift, and it does appear that the magma plume under Iceland is getting a little restless. Time will tell, but Iceland is an ever-changing landscape of ice and fire, and it does not appear to want to lose that description any time soon.

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