The volcanic activity that has rocked Iceland’s Reykjanes Peninsula recently could be here to stay. An international team of geologists and volcanologists predict that recurring, similar, moderately sized eruptions will continue in the next several years and could last for decades. The findings are described in a study published June 26 in the journal Terra Nova.
“After over 780 years of dormancy, volcanic activity has now led to eight individual eruptions on the Reykjanes peninsula over the last three years, which is associated with frequent earthquakes and plate boundary dislocations,” Valentin Troll, a study co-author and volcanologist at Uppsala University in Sweden, tells Popular Science.
[Related: Volcano erupts in Iceland near an airport, a power plant, and an evacuated town.]
Historically, Iceland sees volcanic eruptions about every three to five years. The most recent eruptions suggest that there is a potentially extended period of activity on the Reykjanes Peninsula, home to roughly 22,000 people, Keflavík International Airport, several geothermal power plants, and popular tourist destinations like the Blue Lagoon spa.
In the study, Troll and a team of researchers from six universities examined eruptions that began in 2021 in the Svartsengi-Fagradalsfjall-Krýsuvík area. The region has seen seven fissure eruptions since 2021. Instead of the eruption coming up from a central vent in a volcano, fissure eruptions occur when underground dikes filled with magma intersect the surface. They can then feed lava flows that can travel for miles, as it has in the area. The nearby fishing town of Grindavik has been completely evacuated several times since late 2023 due to the dangerous conditions.
The team used earthquake data and geochemical analysis of lava and samples of rock fragments ejected by the volcanoes called tephra. Based on previous eruptive behavior, they believe that this pattern is likely to continue. They also found an interconnected magma plumbing system beneath the peninsula. The geochemical and seismic data indicates that there is a magma reservoir about 5.5 to 7.4 miles beneath the Fagradalsfjall volcanic system.
“It seems we are dealing with a main reservoir under the Fagradalsfjall volcanic system that has now also supplied the Svartsengi/Sundhnukur volcanic system via a set of shallower magma pockets,” says Troll.
This shared reservoir system instead of a larger peninsula-wide reservoir is why the team believes the eruptions will continue.
“The latter [Svartsengi/Sundhnukur volcanic system] is also the main heat source for the Svartsengi geothermal power plant that delivers electricity and hot water to Keflavik International Airport, and is a vital element of infrastructure that is now at risk,” says Troll.
A previous study suggested that magma on the Reykjanes peninsula was fed directly from the mantle. This does not appear to be the case, since this new study found a series of smaller magma reservoirs in the Icelandic crust that can store magma before eruptions.
“The good news is, that the probability of many simultaneous eruptions on the peninsula is a little lower than would be the case if they were directly fed from the mantle,” says Troll.
[Related: How the Tonga eruption rang Earth ‘like a bell’.]
The team urges preparedness, largely due to the risk to some of the country’s critical infrastructure. However, scientists are also able to study these forces in real time.
“The current eruption episode is unparalleled in that we had now real opportunity to understand how Icelandic lava fields build up and how they assemble large flood basalt areas,” says Troll. “Now we have the opportunity to witness processes, timescales and supply mechanisms first hand. An amazing opportunity for a volcano researcher.”