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After 800 years of dormancy, volcanoes have reawakened in Iceland’s Reykjanes Peninsula – about 56 kilometers (35 miles) south of the nation’s capital, Reykjavík.
Since 2021, a string of eruptions has disrupted daily life in the densely populated area, leading to evacuations, power cuts and infrastructure damage, as well as fears of an event such as the eruption of Eyjafjallajökull, a large volcano about 80.5 kilometers ( 50 miles). ) south-west caused an international travel crisis in April 2010.
Although there is no risk of a global catastrophe, researchers are now warning that new scientific evidence suggests that the eruptions from the Reykjanes Peninsula could continue for years or even decades. Prolonged volcanic activity could lead to more disruption and could affect the long-term evacuation of Grindavík, a fishing town 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 have to be ready to give up Grindavík,” said Valentin Troll, a professor in 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 volcanic activity coming very quickly, I don’t think that’s recommended. What we think at the moment is that the eruptions are likely to continue as we have seen over the last three years, and our results would support that.”
To be able to predict whether the eruptions would continue and what the future impact of volcanic activity would be, Troll and his fellow researchers took a novel approach by bringing together two separate branches of science that a primary source revealed about earth magma, or molten, fueled rock. activity in the Reykjanes Peninsula.
Hugh Tuffen, a reader in Volcanology at Lancaster University in the UK 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 from the history of eruptions on the Reykjanes peninsula, the chemistry of eruptive lavas and the depth and nature of earthquakes,” he said.
“All the evidence points to the formation of a single magma reservoir under (volcano) Fagradalsfjall, and that this reservoir can then feed eruptions at different locations on the Reykjanes peninsula, depending on the stress transfer in the crust.”
A new age of volcanic eruptions in Iceland
Iceland, which is about the size of Kentucky with a population of nearly 400,000, has more than 30 active volcanoes that are now a tourist attraction within the country’s stunning scenery.
The high number of volcanoes that are actively erupting or showing signs of restlessness is due to the fact that the island is located on a boundary between tectonic plates (huge pieces of the Earth’s crust and upper mantle slowly moving), explained Troll, creating cracks that allowed magma to come up.
“The Reykjanes peninsula is directly on this plate boundary,” he said, “and it appears that we are now witnessing the earliest part of a major eruption event. This is a recurring phenomenon on the peninsula, with 800 years of rest or quiescence, followed by 100 or 200 years of intense eruptions, followed by another quiet period. Scientifically, we are lucky to be able to see this, but socially we are not, because it happens in a very densely populated part of the country with a lot of infrastructure.”
A massive barrier system is now in place around Grindavík to protect the town, with lava pushing against it in many places, Troll said. There is also a power plant in the area, and it supplies Keflavík International Airport, the country’s main airfield located at the tip of the peninsula. “If the power station is disrupted, we may have energy shortages at Keflavík airport in the long run. This could have an impact on international travel there,” said Troll.
However, he said the likelihood of an Eyjafjallajökull-style event is quite slim, as the situation in the Reykjanes Peninsula is different – the lava fields are shallow, and the eruptions over the past three years have not been remotely close to the levels of Eyjafjallajökull. .
Key magma reservoir exposed
The research team looked at the question from the point of view of geochemistry and geophysics.
First, the team used geochemistry to look at the composition of the lava and identified similarities between samples taken several miles apart. This result indicates that all the eruptions are being fueled by a shared magma reservoir that sits 9 to 12 kilometers (5.6 to 7.5 miles) below the surface, rather than from different sources.
Next, the scientists used geophysics to look at the distribution of a series of earthquakes associated with the eruptions, and found a cluster of deep seismicity at the same depth underground. “It’s right under a volcano called Fagradalsfjall, and that seems to be the main magma chamber or macro reservoir, which also supplies other volcanoes,” Troll said.
“That’s good news, in a way, because it means we’re going to have smaller, isolated eruptions that are likely to continue for a while, but we’re not going to have a lot of simultaneous eruptions across the entire peninsula,” he explained.
Geochemistry and geophysics aren’t often used together, but it could lead to an educated guess as to how many eruptions might come from a volcano, according to Troll.
“The strength of this study and what makes it really powerful is that we have combined two fundamentally independent methodologies to reach very similar conclusions,” he said.
“The geochemistry says the magma is from the same source, and the seismic tomography says there is only one main reservoir at depth. Putting these two things together gives strength to our predictions.”
Seismic tomography is a process that tracks and analyzes the patterns of seismic waves generated by earthquakes to detect and characterize the Earth’s interior as three-dimensional models.
Monitor seismic activity
The study is interesting and the results are convincing, said volcanologist Einat Lev, associate research 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 Earth,” said Lev, who was not involved in the study. “The volcanology community understands that cross-disciplinary collaboration is critical, and that’s certainly the direction we’re working toward.”
She added that the eruptions could indeed threaten Grindavík. “We’ve already seen that even if magma doesn’t explode or the lava doesn’t flow towards the town, land inflation and deflation as well as the fissures they create 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 novel, 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 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 continue, she said.
“It means there’s a large supply of magma that’s easy to erupt, making the region prone to eruptions for the foreseeable future,” Johnson explained.
“Unfortunately, because the storage area is quite large, it means it’s harder to tell exactly where the next eruption will be. That’s why everyone in the area needs to be prepared for continued eruptions.”
According to Tuffen of Lancaster University, the study 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 assess the likelihood of future eruptions as magma accumulates in the Earth’s crust and new pathways emerge.
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