Let's just hope this once-in-800 year event is not related to increased nucleation of gases in magmas sitting beneath Iceland, Greenland and the Atlantic Ocean as the glaciers are losing weight which issue I raised at Cochabamba-Tiquipaya Climate Summit:
An interesting point. This current eruption is much more rare than a once-in-800 years. The magma is extremely hot and primitive, which apparently means that it comes straight from the mantle. Magmas of this type have not been found in Iceland going back at least 8000 years.
Shortly after the end of the last ice age, a large number of shield vocanoes were formed in Iceland with very primitive magma like the current one. The main theory is that hese shield volcanoes were a result of lessened pressure due to the melt of the massive ice age ice shield.
But the current eroption is very far away from any major ice caps. It is in an area (The Reykjanes peninsula) which is one of the most active in the world, even if it takes periodic 800-1000 year breaks, followed by a few centuries of intense activity. A new eruptive phase was expected to start "any time now" in geological time, i.e. within a century or two. That it starts now is not really surprising, but that this new eruptive phase starts with such primitive magma is totally unexpected.
The hot spot which is the proximate cause of the landmass of Iceland being above sea level, and which makes Iceland as a whole by far the most active volcanic area in the world (as measured in annual average volcanic material productuion) is actually situated under the main ice cap in the south-east, and this icecap is melting fast, with the surrounding areas experiencing significant uplift.
Wich means that the site for the next shield volcano-like eruption should have been somewhere in that area, not where it is currently located. But none-the-less very interesting!
The first of the following images is from
a very interesting report (in Icelandic) on the changes happening in Iceland due to the rapid melting of its glaciers. The picture is nr. 5.18 and shows vertical movement between 1993 and 2004, in mm/year.
I've no idea what SKRO stands for, but the hot spot (and the immensely active Grimsvotn volcano) is placed more or less where the 0500 red spot is shown on the image. I've marked the location of the current eruption.
The second image shows the hotspt (properly named a "mantle plume"), with the yellow bands showing where the Mid-Atlantic spreading zone crosses Iceland (from
Geology and geodynamics of Iceland