Why the earth rumbles in Iceland

- EN - DE
Nicole Richter stands in front of lava © OVPF-IPGP
Nicole Richter stands in front of lava © OVPF-IPGP
The earth is rumbling in Iceland - again. This time it is the Bįršarbunga volcano, located in the middle of the island, that is causing concern. Nicole Richter, junior professor at the Neotectonics and Georisks department at RWTH Aachen University, explains what is happening and what effects an eruption could have.

What is currently happening in Iceland?

On January 14, there was an earthquake swarm at the Bįršarbunga volcano in Iceland with at least 140 individual events, which led to the alert level being raised, among other things. According to the Icelandic meteorological authority IMO, it was the strongest earthquake swarm since the end of the last eruption in 2014/2015. This so-called "seismic crisis" occurred at the northwestern caldera rim and was probably caused by a magma intrusion, i.e. the start of magma rising from the near-surface reservoir to the surface. However, this phase of activity has now ended and there was no eruption.

Could there be an eruption of the Bįršarbunga volcano?

Yes, Bįršarbunga is an active volcano and geodetic data since 2015 shows a ground uplift, which indicates that magma is accumulating underground.

What consequences could this have? Is there a threat of another ash cloud that could massively restrict air traffic?

Bįršarbunga is a large volcano that is partly covered by a glacier and is closely monitored by our Icelandic colleagues. In the event of an eruption, the collision of lava and ice could lead to lahars, i.e. avalanches of debris and mud consisting of a mixture of ash and meltwater. Increased ash ejection could also be expected. The extent to which this affects air traffic depends on the height of the ash column and weather conditions such as wind direction. As with the eruption of Eyjafjallajökull in 2010, airspace could be affected.

The volcano is located in the immediate vicinity of a glacier. What interaction can a volcanic eruption have with the ice?

Ice increases the hazard potential of a volcano; it can lead to the lahars described above or to explosive, so-called phreatic or phreatomagmatic eruptions.

Why do such events occur again and again in Iceland?

Iceland sits on a hotspot and on a plate boundary. The island state therefore has almost inexhaustible magma resources.

How can we monitor volcanoes and warn them as precisely and early as possible?

A forecast - predictions are not yet possible - is only possible at volcanoes that are equipped with a dense measuring network of seismometers and GNSS stations in particular. These measure seismicity and ground deformation over the longest possible periods of time, and degassing is also monitored. Through long measurement time series, but also through their eruptions, we then learn from active volcanoes how the internal architecture of the magma, storage and transport system is structured, what structural instabilities the volcanic edifices exhibit and what "behavioral patterns" occur. If we identify similar patterns, the correct interpretation of the data can help us to warn of impending eruptions.