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After 800 years of dormancy, volcanoes have awakened on Iceland’s Reykjanes Peninsula, about 56 kilometers south of the capital Reykjavik.
Since 2021, a series of eruptions have disrupted daily life in the densely populated area, leading to evacuations, power outages and damage to infrastructure. It has also raised fears of an event similar to the eruption of Eyjafjallajökull, a large volcano about 50 miles (80.5 kilometers) southwest that caused an international travel crisis in April 2010.
While there is no risk of a global disaster, researchers are now warning that new scientific evidence suggests that eruptions coming from the Reykjanes Peninsula could continue for years or even decades. The prolonged volcanic activity could lead to more disruption and possibly force a long-term evacuation of Grindavík, a fishing village of more than 3,000 that is also the gateway to Iceland’s biggest tourist attraction, the Blue Lagoon geothermal pool.
“I think we should prepare to give up on Grindavík,” said Valentin Troll, a professor at the department of earth sciences at Uppsala University in Sweden and lead author of a study on the eruptions published Wednesday in the journal Terra Nova.
“It can still survive as a fishing port, with people coming in and out. But people staying there, with the possibility of a very rapid onset of volcanic activity, I don’t think that’s advisable. What we think now is that the eruptions are likely to continue as we have seen over the past three years, and our results would support that.”
To predict whether the eruptions would continue and how future volcanic activity would develop, Troll and his fellow researchers took a new approach. Combining two separate branches of science, they discovered that there was a primary underground source of magma, or molten rock, fueling activity on the Reykjanes Peninsula.
Hugh Tuffen, a lecturer in volcanology at Lancaster University in the UK who was not involved in the report, said the research made a solid case for the frequency of eruptions in coming years. “This study provides a useful synthesis of evidence from the history of eruptions on the Reykjanes Peninsula, the chemistry of the erupted lava, and the depth and nature of earthquakes,” he said.
“The evidence all points to the formation of a single magma reservoir beneath (the volcano) Fagradalsfjall, and that this reservoir can then feed eruptions at different positions on the Reykjanes Peninsula, depending on changing stresses in the crust.”
A new era of volcanic eruptions in Iceland
Iceland, which is about the size of Kentucky with a population of nearly 400,000, boasts more than 30 active volcanoes that have become tourist attractions in the country’s breathtaking landscape.
The large number of volcanoes actively erupting or showing signs of unrest is due to the fact that the island sits on the boundary between tectonic plates (giant, slow-moving pieces of the Earth’s crust and upper mantle), Troll explained, causing cracks formed that allow magma to rise to the surface.
“The Reykjanes Peninsula sits right on this plate boundary,” he added, “and it looks like we’re witnessing the earliest part of a major eruptive episode. That’s a recurring phenomenon on the peninsula, with 800 years of hiatus or quiet, followed by 100 or 200 years of intense eruptions, followed by another quiet period. Scientifically, we’re lucky to be able to observe that, but from a societal perspective, we’re not, because it’s happening in a very densely populated part of the country with a lot of infrastructure.”
There is now a huge barrier system around Grindavík to protect the city, with lava pushing against it in many places, Troll said. There is also a power station in the area, and it supplies power to Keflavík International Airport, the country’s main airport located on the tip of the peninsula. “If the power plant is affected, we could face long-term energy shortages at Keflavík airport, which could then impact international travel,” Troll said.
However, he added that the chance of an event like Eyjafjallajökull is quite small because the situation on the Reykjanes Peninsula is different: the lava fields are shallow and the eruptions of the past three years did not come close to the levels of Eyjafjallajökull.
Major magma reservoir revealed
The research team looked at the issue from the standpoint of geochemistry and geophysics.
First, the team used geochemistry to look at the composition of the lava and discovered a similarity between samples taken several kilometers apart. This finding shows that the eruptions are all fed by a shared magma reservoir located 9 to 12 kilometers (5.6 to 7.5 miles) below the surface, rather than different sources.
The scientists then used geophysics to look at the distribution of a series of earthquakes associated with the eruptions, and found a cluster of deep seismicity at exactly the same depth underground. “It’s right under a volcano called Fagradalsfjall, and that appears to be the main magma chamber or macro reservoir, which also supplies water to other volcanoes,” Troll said.
“That’s good news in a way, because it means we’re probably going to continue to see smaller, individual eruptions for a while, but not a lot of simultaneous eruptions across the peninsula,” he explained.
According to Troll, geochemistry and geophysics are not often combined, but it can lead to an informed estimate of the number of eruptions a volcano can produce.
“The strength of this study and what makes it really powerful is that we combine two fundamentally independent methodologies to come to very similar conclusions,” he said.
“Geochemistry says the magma comes from the same source, and seismic tomography says there is only one main reservoir at depth. Putting these two things together gives our prediction quite a bit of power.”
Seismic tomography is a process of monitoring and analyzing patterns of seismic waves generated by earthquakes. In this way, the Earth’s internal features can be detected and characterized as three-dimensional models.
Monitoring seismic activity
The study is interesting and the results are convincing, says volcanologist Einat Lev, associate professor at the Lamont-Doherty Earth Observatory at Columbia University in New York.
“I think it’s great to see geophysics and geochemistry being used in synergy to answer important questions about the Earth,” said Lev, who was not involved in the research. “The volcanology community understands that interdisciplinary collaboration is critical, and it’s definitely a direction we’re working toward.”
She added that the eruptions could indeed threaten Grindavik. “We have already seen that even if magma does not erupt or lava does not flow into the city, ground inflation and deflation, as well as the cracks they cause, threaten the stability and safety of Grindavik’s infrastructure.”
Combining different types of evidence, such as geochemical information about the lava and geophysical data from the earthquakes, is quite new and it’s exciting that they both agree, says Jessica Johnson, associate professor of geophysics at the University of East Anglia in The United Kingdom. , who also did not participate in the work.
Showing that the magma is being supplied from a shared reservoir has implications for the frequency of eruptions and how long they will last, she added.
“It means there is a large reservoir of magma that can easily erupt, which could allow eruptions to continue in the region for a long time,” Johnson explains.
“Unfortunately, because the storage area is quite large, it means that it is more difficult to say exactly where the next eruption will be. Therefore, everyone in the area needs to be prepared for continued eruptions.”
According to Tuffen of Lancaster University, the research highlights the importance of ongoing monitoring efforts. Icelandic geoscientists and international collaborators are tracking the frequency and intensity of seismic activity and ground deformation in real time. The approach allows them to quickly estimate the likelihood of future eruptions as magma builds up in the Earth’s crust and new pathways unfold.
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