During the night of 15-November-2015 a swarm of deep earthquakes took place not far from Trölladyngja. The thing about Trölladyngja is directly connected to Bárðarbunga volcano and its eruption cycles. Trölladyngja it self was formed in a eruption in the year 5000 BCE, according to historical overview from Global Volcanism Program. According to some sources, Trölladyngja is a shield volcano, I don’t know if that is exactly correct. Regardless of what type of volcano Trölladyngja is, there is clearly something going on in it. Since this is not the first time I see earthquake swarm at this depth at this location. I doubt that this are stress related changes in the crust due the collapse of Bárðarbunga volcano caldera.
The earthquake activity in Trölladyngja (red dot). Image is from 05:50 UTC. Copyright of this image belongs to Iceland Met Office.
All of the earthquakes taking place were small, the largest had the magnitude of 1,1 and the depth was from 18 – 15 km.
In the early days of the earthquake swarm that started in Bárðarbunga in August-2014 a dyke intrusion pushed into this direction and than it just stopped as it lost the energy, or hit a obstacle that it was unable to break trough.
Image from August-2014. The earthquake activity close to Trölladyngja is clear on this image. Copyright of this image belongs to Iceland Met Office.
Image from August-2014. The earthquake activity close to Trölladyngja is clear on this image. Copyright of this image belongs to Iceland Met Office.
I don’t know yet what the chances are for an eruption at this location. More earthquake swarm activity is needed until the magma that is clearly down there breaks up. However the rifting that is taking place in this location might speed things up by unknown factor. This rifting might and possibly is allowing more magma entering this area deep underground without any earthquake activity. It is difficult to know what is going on at this location, so a lot of this is a speculation on what might happen. What actually happens in the end is a whole different thing and only time is going to tell us what happens next.