After 800 years of calm, volcanoes have awakened on the Reykjanes Peninsula, located about 56 kilometers south of Iceland’s capital, Reykjavik.
Since 2021, a series of eruptions have disrupted daily life in the densely populated area, leading to evacuations, power cuts and damage to infrastructure. They also fuel fears of an event like the eruption of Eyjafjallajökull, a large volcano about 50 miles to the southwest that caused an international travel crisis in April 2010.
While there is no risk of a global calamity occurring, researchers are now warning that new scientific evidence suggests that eruptions originating on the Reykjanes Peninsula could continue for years or even decades. Prolonged volcanic activity could lead to more disruptions and potentially force the long-term evacuation of Grindavík, a fishing town with more than 3,000 residents that is also the gateway to Iceland’s biggest tourist attraction: the Blue Lagoon geothermal spa.
“I think we need to prepare to give up on Grindavík,” said Valentin Troll, professor in the Earth Sciences department at Uppsala University in Sweden and lead author of a study of eruptionspublished on Wednesday (26) in Terra Nova magazine.
“It can still survive as a fishing port, with people coming and going. But people staying there, with the possibility of a very rapid onset of volcanic activity, I don’t think that’s recommended. What we think now is that eruptions will likely continue as we have seen over the past three years, and our results support that.”
To be able to predict whether eruptions would continue and how future volcanic activity might unfold, Troll and his fellow researchers took a novel approach by bringing together two separate branches of science that revealed a primary underground source of magma, or molten rock, fueling the activity in the Reykjanes Peninsula.
Hugh Tuffen, reader in volcanology at Lancaster University in the United Kingdom, who was not involved in the report, said the research made a strong case for the frequency of eruptions in the coming years. “This study provides a useful synthesis of evidence on the history of eruptions on the Reykjanes Peninsula, the chemistry of the ejected lavas, and the depth and nature of the earthquakes,” he said.
“Evidence points to the establishment of a single magma reservoir beneath Fagradalsfjall, and that this reservoir can then fuel 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 roughly the size of the state of Pernambuco with a population of nearly 400,000 people, has more than 30 active volcanoes that have become tourist attractions in the country’s stunning landscape.
The large number of volcanoes actively erupting or showing signs of unrest is due to the fact that the island is situated on a boundary between tectonic plates (huge pieces of the Earth’s crust and upper mantle that move slowly), Troll explained, creating fissures that allow magma to rise.
“The Reykjanes peninsula is exactly on that plate boundary,” he added.
“It appears that we are now witnessing the beginning of a major eruption episode. This is a recurring phenomenon on the peninsula, with 800 years of pause or calm, followed by 100 or 200 years of intense eruptions, followed by another period of calm. Scientifically, we are lucky to be able to observe this, but from a social point of view, we are not, because this happens in a very populated part of the country with a lot of infrastructure.”
There is now a vast system of barriers around Grindavík to protect the city, with lava pressing against it in many places, Troll said. A power plant is also in the area. It supplies Keflavík International Airport, the country’s main airfield located at the tip of the peninsula.
“If the power plant is affected, we may experience power shortages at Keflavík Airport in the long term. This could then have an effect on international travel,” said Troll.
However, he added, the probability of an event in the style of what occurred at Eyjafjallajökull is quite low, because the situation on the Reykjanes Peninsula is different. The lava fields are shallow, and eruptions over the past three years have not been remotely close to the levels of Eyjafjallajökull.
Magma reservoir revealed
The research team approached the question from the point of view of geochemistry and geophysics.
First, the team used geochemistry to analyze the composition of the lava and recognized a similarity between samples collected several kilometers apart. This discovery shows that the eruptions are all powered by a shared magma reservoir that lies 9 to 12 kilometers below the surface, rather than from different sources.
Scientists then used geophysics to analyze the distribution of a series of earthquakes connected to the eruptions and found a cluster of deep seismicity at exactly the same depth underground.
“It’s directly under a volcano called Fagradalsfjall, and this appears to be the main magma chamber or macro reservoir, supplying other volcanoes as well,” Troll said.
“That’s good news, in a way, because it means we’ll have smaller individual eruptions probably occurring for some time, but not many simultaneous eruptions across the entire peninsula,” he explained.
The combined use of geochemistry and geophysics is not frequent, but it can lead to educated estimates about how many eruptions can come from a volcano, according to Troll.
“The strength of this study and what makes it really powerful is that we are combining two fundamentally independent methodologies to come to very similar conclusions,” he said.
“Geochemistry says the magma is from the same source, and seismic tomography says there is only one main reservoir at depth. Putting these two things together gives a lot of strength to our prediction.”
Seismic tomography is a process that tracks and analyzes patterns of seismic waves generated by earthquakes to detect and characterize the Earth’s interior features as three-dimensional models.
Monitoring seismic activity
The study is interesting and the results are convincing, said volcanologist Einat Lev, associate research professor at Columbia University’s Lamont-Doherty Earth Observatory in New York.
“I think it’s great to see geophysics and geochemistry being used synergistically to answer important questions about Earth,” said Lev, who was not involved in the study. “The volcanology community understands that interdisciplinary collaborations are critical, and it is definitely a direction we are working towards.”
She added that the eruptions could indeed threaten Grindavík. “We have already seen that even if the magma does not erupt or the lava does not flow towards the city, the inflation and deflation of the ground, as well as the fissures they create, threaten the stability and security of Grindavík’s infrastructure.”
Combining different types of evidence, such as geochemical information about lava and geophysical data from earthquakes, is quite innovative, 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, who also was not involved in the study. work.
Demonstrating that magma is being supplied from a shared reservoir has implications for the frequency of eruptions and how long they will last, she added.
“This means there is a large supply of magma that is easy to erupt, allowing eruptions to occur in the region for a long time,” Johnson explained.
“Unfortunately, because the storage region is quite large, it means it is harder to say exactly where the next eruption will be. Therefore, everyone in the area needs to be prepared for continued eruptions.”
According to Tuffen, from Lancaster University, the study emphasizes 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 assess the likelihood of future eruptions as magma accumulates in the Earth’s crust and new pathways unfold.
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