Iceland has many active volcanoes; at least 27 of them are counted as active central volcanoes. There is probably more than twice that number that are capable of having an eruption at some time or another. This leads us often on marry chases as one or another of them suffers from a magmatic intrusion into their systems.
What we generally forget are two things. The first is that we generally tend to overstate the risk of a volcano erupting in Iceland. Since the last turn of the century about 75 percent of all eruptions occurred in two volcanoes, Grimsvötn and Hekla. Grimsvötn stood for a staggering 50 percent of all eruptions during this time. If we go back a millennium they will have done 50 percent of all eruptions with Grimsvötn responsible for roughly 40 percent of all eruptions. If we put in Askja, Bardarbunga and Katla into the equation we have about 90 percent of all eruptions during the last 1 000 years coming out of five of the 27 active central volcanoes.
The other thing is that most volcanoes on Iceland have numerous magmatic intrusions before erupting. Some volcanoes seemingly can take 100s of intrusions before they erupt. So what is actually an eruption? It is a magmatic intrusion or intrusions that are large enough to break the surface. Even during an eruption the bulk of the magmatic intrusion will stay below the surface.
And then we have those volcanoes that on occasion suffer from a minor magmatic intrusion that causes a bit of a fuss. For us it is a small point of interest, but rarely do we think it will erupt.
Kistufell is one of those volcanoes that have occasional magmatic indigestion. In reality it is a heavily comatose patient suffering from indigestion. It shows on the monitors, but it does not go any further. In the case of Kistufell it does have an odd twist that I will come back to.
There is geological evidence of Kistufell having had at least 3 eruptions. Two during glaciation (there was probably more) and one at the extreme end of glaciation. The glacial eruptions helped to form the volcano of Kistufell into a classic table top mountain. But at the end of the glacial it suffered its last eruption, this time around the ice was not thick enough to contain the eruption well enough and the thuja shape was partially destroyed.
After that it went dormant, it did not even erupt during the large basalt conflagration after the glaciation. Instead it just slowly slid into coma. And that is a mystery on its own. It shouldn’t have done that for two reasons. The first is that it is sharing the same majestic fissure swarm as the mighty central volcano of Bárdarbunga, a fissure swarm that have produced Iceland’s largest shield volcano, the Odhadhahraun lava field, and the epic Thjorsahraun flood basalt, and numerous large flood basalt eruptions over at Veidivötn and Vatnaöldur.
The second reason is that it is placed slap bang right on top of the center of the Icelandic Hotspot. Those two things taken together really should have made little Kistufell into something much more noteworthy.
I think that if it had not been on top of the Hotspot it would have gone from comatose into dead a long time ago. As it is now the volcano is not a big enough weakness to actually erupt, but it has through numerous magmatic intrusions kept its magmatic system. But, it is a failing central volcano. The patient might be burping in its coma, but as time goes by the organs will fail one after another until death occurs. The latest activity will probably not change more then 10 000 years of coma. One should also remember that this volcano did not even flinch as the before mentioned very large eruptions took place around it.
For those interested in Kistufell I recommend this paper: