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. Fears have also been raised about an event such as 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 eruptions originating from the Reykjanes Peninsula could continue for years or even decades. The prolonged volcanic activity could lead to more disruption and possibly force the prolonged evacuation of Grindavík, a fishing village of more than 3,000 residents 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 going in and out. But people staying there, with the possibility of a very rapid start of volcanic activity, I don't think that's advisable. What we're thinking 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 might develop, Troll and his fellow researchers took a fresh approach by bringing together two separate branches of science that investigate a primary underground source of magma, or molten rock, brought to light. activities on the Reykjanes Peninsula.
Hugh Tuffen, a lecturer in volcanology at Lancaster University in the United Kingdom who was not involved in the report, said the research provided a solid case for the frequency of eruptions in the 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.
"All evidence suggests that a single magma reservoir formed beneath (the volcano) Fagradalsfjall, and that this reservoir could then feed eruptions at different locations on the Reykjanes Peninsula, depending on changing stresses in the Earth's 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 island's location on the boundary between tectonic plates (giant, slow-moving pieces of the Earth's crust and upper mantle), Troll explained, creating cracks that allow magma to rise.
"The Reykjanes Peninsula sits right on this plate boundary," he added, "and it looks like we're witnessing the early part of a major eruption. 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 socially, we're not, because it's happening in a very populated part of the country with a lot of infrastructure."
There is now a huge barrier system around Grindavík to protect the city, which is being pushed against by lava in many places, Troll said. There is also a power plant nearby, which supplies power to Keflavík International Airport, the country's main airport, located at the tip of the peninsula. "If the power plant is affected, we could have long-term power shortages at Keflavík Airport, which could affect international travel," Troll said.
However, he added that the chance of an event like Eyjafjallajökull is quite small, as 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 discovered
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 found a similarity between samples taken several kilometers apart. This finding shows that the eruptions are all fed by a shared magma reservoir 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 linked to the eruptions, and found a cluster of deep seismicity at the exact same depth underground. "It's right underneath 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'll probably see smaller, individual eruptions for a while, but not many simultaneous eruptions across the entire peninsula," he explained.
The combined use of geochemistry and geophysics is not common, but Troll says it can lead to informed estimates of how many 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 of seismic activity
The research is interesting and the results are compelling, said volcanologist Einat Lev, an associate professor at Columbia University's Lamont-Doherty Earth Observatory 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 study. "The volcanology community understands that collaborations between different disciplines are key, and it's definitely a direction we're working toward."
She added that the eruptions could indeed threaten Grindavík. "We have already seen that even if magma does not erupt or lava does not flow into the city, land inflation and deflation, as well as the cracks they cause, threaten the stability and security 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, said Jessica Johnson, associate professor of geophysics at the University of East Anglia in the United Kingdom, which also did not cooperate in the investigation.
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.
"That means there is a large reservoir of magma that can easily erupt, meaning eruptions could continue in the region for a long time to come," Johnson explains.
"Unfortunately, because the storage area is quite large, it means it is harder to say exactly where the next eruption will be. Therefore, everyone in the area must 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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