Q&A: What can we learn from the Icelandic eruption?

Thursday, March 25, 2021 

Iceland’s Reykjanes peninsula exploded into the public spotlight after several weeks of seismic activity gave way to a brand new volcano late on March 16, 2021. The eruptive fissure occurred near Fagradalsfjall, an older shield volcano. This is the first such activity on the peninsula for about a millennium.

The eruption, which is now being referred to as Geldingardalsgos, has posed no major threats to people living on the island. However, it has certainly provided a mountain of interesting scientific information.

We spoke with Carnegie volcanologist and geodesist Hélène Le Mével about what we can learn from eruptions like Geldingardalsgos and how this may be the start of a longer period of volcanic activity on the island.

Why is the Geldingardalsgos​ eruption scientifically interesting?

One of the most interesting things is the location of the eruption on the Reykjanes peninsula (SW Iceland). This region has experienced an increase in seismic activity in the past year or so but no eruption in the past ~1000 years. Geologists think that this eruption might thus be the beginning of a more active period of eruptions on the peninsula (as has happened before).

What is very exciting is all the recorded geophysical data sets (in particular deformation and seismicity) that allowed us to follow, day after day, the propagation of the magma under the surface until it eventually reached the surface and formed a new fissure eruption. We have very few data sets that capture the entire sequence from a dike intrusion leading up to an eruption, so this is a great opportunity for volcanologists.

Did scientists expect an eruption?  

It wasn’t a surprise. 

For about 3 weeks there was an increase in both seismicity and deformation recorded which indicated magma was moving at shallow depth and rising towards the surface. However, in many cases, the dikes—magma sheets injected/intruded in the crust—can stall and end up not reaching the surface to form an eruption. Until Friday, there was no certainty that this episode would culminate in an eruption and if it did, where exactly would that be.

However, the location of this activity was a bit surprising since it hasn’t been the site of eruptive activity in the past ~1000 years. So this eruption is not happening on a historically active volcano, instead, a new eruptive fissure opened up, and lava is flowing from there, accumulating, and maybe eventually will form a new edifice.

You lived in Iceland yourself for a time, what did you think when you first heard about the eruption?

I had been following the precursory activity for the past few weeks and I was very excited at the prospect of an eruption in this area, which was not specifically active when I was there as an undergraduate student. When the eruption happened of course I thought: I wish I was still there!

Luckily the eruption does not pose an immediate threat to the population as it happened far enough from towns and so far mostly consists of short lava flows and small lava fountains confined to a valley. 

Instead of being there I regularly check out the live cam (mesmerizing!): https://www.youtube.com/watch?v=BA-9QzIcr3c

How do scientists harness these events to learn more about volcanoes and our planet? 

A lot of interesting data sets will come out from studying this eruption and will help our understanding of magma ascent and eruption. 

The two main geophysical data sets that scientists analyze are the seismic data (i.e., the type of earthquakes, their location) and ground deformation data (i.e., changes in the shape of the Earth’s surface from GPS and radar satellites). These two things tell us where the crust is being stressed while magma is making its way through the crust. 

Since the eruption started, lava samples and volcanic gas are also being collected and will be analyzed to understand the origin and properties of the lavas.

What new information might this particular eruption provide?

 New observations mean we will be able to improve our understanding of the physical processes that drive magma ascent to the surface and how the magma dikes interact with local tectonics and faulting. These data sets can be used to calibrate and improve numerical models. Eventually, these models will help improve future forecasts of the location and timing of eruptive fissures.

Do you think there are more eruptions in Iceland's future?

Yes, of course! 

In the SW region, this eruption might be the start of a long period of eruptive activity. New fissures can open near the current site or elsewhere on the peninsula. Iceland being the on-land portion of the Mid-Atlantic Ridge—the divergent plate boundary between the North American Plate and the Eurasian Plate—has over 30 active volcanoes. There will be many opportunities for eruptions of all types—including more explosive ones.