Update: Late Wednesday evening Iceland time, the nation's meteorological office reported that scientists observed a row of deep "cauldrons" along the Vatna glacier south of the Bardarbunga caldera. The thirty to fifty-foot deep holes form a long line a few miles in length and were created as a result of melting, possibly from a subglacial eruption that went undetected at some point during the current period of heightened activity. The office reports that about 1,300 tremors have been recorded on Wednesday alone, including a 4.5 magnitude quake near the Askja volcanic system. Below is a photo posted to the Twitter feed of the Icelandic Police.
The 10-15 m deep cauldrons, 1 km wide, south of the #Bárðarbunga caldera. Picture by https://t.co/ZiKocZlLJS pic.twitter.com/lSLWDJZnEO
— Almannavarnir (@almannavarnir) August 28, 2014
The Icelandic National Broadcasting Service also posted this map of the location of the meltwater cauldrons.
Kort sem sýnir staðsetningu sigkatlanna. Map showing location of depressions spotted in glacier today. #Bardarbunga pic.twitter.com/8g47CKotHe
— Fréttastofa RÚV (@RUVfrettir) August 28, 2014
It's been more than a week since near constant earthquakes began rumbling beneath and around the largest glacier in Europe, which also serves as an ice cap over Iceland's restless Bardarbunga (Bárðarbunga)
Over the weekend, Iceland's Meteorological office briefly thought that a subglacial eruption was beginning and put the aviation world on red alert before retracting the report of magma making contact with the glacial ice. Since then, scientists have continued to monitor hundreds of earthquakes that help to map out where the magma is moving. (As magma moves underground it melts rock, changing pressure and causing tremors along its path.) The magma seems to be moving in a northeasterly direction away from the Bardarbunga caldera, beyond the edge of the glacier and towards the Askja volcanic system.
Volcanologist Haraldur Sigurðsson told reporters in Iceland that it's possible the magma could reach Askja and ignite a powerful eruption there, but he says it's more likely that the current activity will just peter out and lead to no above ground eruptions. The magma probably still has 10-15 miles to travel to reach Askja, but if it were to continue to travel in the same direction at the same rate, it could reach the neighboring volcanic system in a few days. Askja last erupted in 1875 to disastrous effect, with the ashfall killing crops and livestock and leading to migration away from the area.
Nearly everyone with any knowledge of Iceland's volcanoes that reporters speak to will tell you that there is no real way to predict what will happen next. The magma flow and seismic activity could begin to slow to a stop without any further incident, or an above ground eruption could occur somewhere between the huge Vatna glacier and Askja. This option could be quite dangerous on the ground, but would probably have a lesser impact in air travel. If there were to be an eruption through the glacier, the impact on flights is likely to be the most serious, due to the more onerous types of ash that would be spewed above the island. An eruption through the glacier also increases the risk of damaging floods from glacial melt.
While Iceland's Meteorological Office says that an eruption through the glacier at the Bardarbunga glacier is less likely than the other scenarios, the caldera remains restless, registering a 5.7 magnitude earthquake on Tuesday. Over 900 earthquakes have been registered in the area on Tuesday alone. The good news for now is that almost all of them remain centered miles below the surface, and there have been no reports of the harmonic tremors that often indicate magma is making its way towards the surface and an eruption.
I'll continue to update this post as new information becomes available.
