The Dead Zone
In the area going from Vatnajökull down to Torfajökull and Myrdalsjökull there is normally almost no seismic activity. This has given the area the not so scientific name of the Dead Zone. It contains the fissure swarms of Bárdarbunga, Grimsvötn and Katla. Grimsvötns fissure swarm is called Laki and Katlas is called Éldgja.
Bárdarbungas fissure swarm is called Veidivötn, and has had the largest lava-floods on the planet in the last 10 000 years. The largest of those is called the Thjorsahraun putting out an estimated 20 cubic kilometers of lava.
Rifting Fissure Eruption
When Katla, Bardarbunga or Grimsvötn has a major and sudden influx of magma from the hotspot, and the fissure swarm of the volcano in question suffers a rifting of the Eastern Icelandic Seismic Zone opening it up. Then what happens is a VEI-6 eruption at the central volcano, and a minimum of 10 cubic kilometers of lava erupts down a minimum of 100km fissure. It is the most destructive type of eruption likely to happen in the northern hemisphere.
The reason of them being that problematic is that it at the same time it releases a lot of ash into the atmosphere, about 100 times the amount from Eyjafjallajökull and also the fissure releases a lot of sulphuric gasses. This phenomenon is called dry fog, and was reported in most of northern Europe and the USA during the eruption of Laki in 1783.
The Laki eruption is the most deadly in European modern history due to the famine that followed. 1783 is also known as the year without summer.
Dead Zone activity of today
During the last 12 hours a series of small (1 to 1,8M) earthquakes happened inside the Dead Zone. They trend from Torfajökulls Landmannalaugar up along the Veidivötn fissure towards Skrokkalda.
What is remarkable that this phenomenon has never been recorded before.
At the same time there where harmonic tremoring in the SIL-station of Skrokkalda, Vatnsfell and also Snaebyli, shown here is the activity at Vatnsfell.
There has also been activity at the Dyngjufjöll, the principal SIL-station of the Bárdarbunga volcanic complex.
And here is a webcam of sorts for the Veidivötn area:
Caveat for the press
Please dear all, it is still far from any possible eruption in the area. At most this is a signal of what can come, nothing more.