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On the Reykjanes Peninsula, about 56 kilometers (35 miles) south of Iceland’s capital Reykjavik, volcanoes are active again after 800 years of inactivity.
Since 2021, a series of explosions have disrupted daily life in the densely populated region; led to evacuations, power outages, and infrastructure damage; It also raised fears of an event such as the eruption of Eyjafjallajökull, a large volcano about 80.5 kilometers (50 mi) away. ) to the southwest, which caused an international travel crisis in April 2010.
While there is no risk of a global catastrophe occurring, researchers warn that new scientific evidence now suggests that eruptions from the Reykjanes Peninsula could continue for years or even decades. Prolonged volcanic activity could cause further disruption and potentially force the long-term evacuation of Grindavík, a fishing town of more than 3,000 residents that is also the gateway to the Blue Lagoon geothermal pool, Iceland’s biggest tourist attraction.
“I think we should prepare to give up on 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 could continue to exist as a fishing port, with people coming in and out. But I don’t think it’s advisable for people to stay there because of the potential for volcanic activity to start very quickly. What we think right now is that the eruptions will continue as we’ve seen for the last three years, and our results support that.”
To be able to predict whether eruptions will continue and how future volcanic activity will play out, Troll and his fellow researchers combined two separate branches of science to uncover the primary underground source of magma, or molten rock, known as the fuel for activity on the Reykjanes Peninsula.
Hugh Tuffen, a reader in volcanology at the University of Lancaster 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 erupted lava, and the depth and nature of earthquakes,” he said.
“All of the evidence points to the establishment of a single magma reservoir beneath the Fagradalsfjall volcano, which could then fuel eruptions at different locations on the Reykjanes peninsula depending on changing stresses in the crust.”
A new era of volcanic eruptions in Iceland
Iceland, which has a population of approximately 400 thousand and is the size of Kentucky, is home to more than 30 active volcanoes, which have become a tourist attraction among the country’s breathtaking landscapes.
Troll explained that the large number of volcanoes that are actively erupting or showing signs of unrest are due to the island being located at the boundary between tectonic plates (giant slow-moving pieces of the Earth’s crust and uppermost mantle), creating fissures that allow magma to rise to the surface.
“The Reykjanes peninsula is right on this plate boundary,” he added, “and we seem to be witnessing the earliest part of a major eruptive episode. This is a recurring phenomenon on the peninsula, 800 years of pauses or stagnation, followed by 100 or 200 years of intense eruptions, followed by another quiet period. Scientifically, we’re lucky to be able to observe this, but societally, we’re not lucky because it’s happening in a very populated part of the country with a lot of infrastructure.”
The troll said that there is now a large barrier system around Grindavík to protect the town, and in many places the lava is pressing against it. There is also a power plant in the area, providing energy to Keflavík International Airport, the country’s main airport, located at the tip of the peninsula. “If the power plant is affected, we may experience an energy shortage at Keflavík airport in the long term. This could then have an impact on international travel,” Troll said.
But he added that the likelihood of an Eyjafjallajökull-style event is extremely low because the situation on the Reykjanes Peninsula is different, the lava fields are shallow and the eruptions in the last three years are not remotely similar to Eyjafjallajökull levels.
Significant magma reservoir uncovered
The research team looked at the issue from the perspective of geochemistry and geophysics.
First, the team used geochemistry to look at the composition of the lava and noticed a similarity between samples taken several miles apart, suggesting that the eruptions were all fed by a common 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 linked to the eruptions, and found a deep seismic cluster at exactly the same depth underground. “It’s right under a volcano called Fagradalsfjall, and this appears to be the main magma chamber or macro reservoir that also supplies other volcanoes,” Troll said.
“This is good news in a way, because it means that individual, smaller eruptions will continue for a while, but there won’t be too many eruptions at once across the entire peninsula,” he explained.
According to Troll, although the use of geochemistry and geophysics together is not common, it can lead to predictions about how many eruptions a volcano is capable of.
“The power of this study, and what makes it really impactful, is that we combined two essentially independent methodologies to achieve very similar results,” he said.
“Geochemistry says the magma is coming from the same source, and seismic tomography says there’s just one main reservoir at depth. Putting those two things together gives a lot of power to our estimate.”
Seismic tomography is a process that monitors and analyzes the patterns of seismic waves generated by earthquakes, detecting and characterizing the Earth’s internal structure as three-dimensional models.
Monitoring seismic activity
Volcanologist Einat Lev, an associate research professor at Columbia University’s Lamont-Doherty Earth Observatory in New York, said the study was interesting and the results convincing.
“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 knows that interdisciplinary collaborations are critical, and that’s definitely a direction we’re working on.”
He added that the eruptions could pose a real threat to Grindavik. “Even if magma does not erupt or lava does not flow into the town, we have seen that ground swelling and deflation and the cracks they create threaten the stability and security of Grindavik’s infrastructure.”
Jessica Johnson, an associate professor of geophysics at the University of East Anglia in the United Kingdom, said combining different types of evidence, such as geochemical information about lava and geophysical data from earthquakes, is quite new and exciting that they both agree. , did not participate in the study either.
He added that showing that magma is fed from a common reservoir has implications for the frequency of eruptions and how long they last.
“This means that there is a large source of magma in the region that is easy to erupt, allowing for long periods of eruption,” Johnson said.
“Unfortunately, the size of the storage area means it is difficult to tell exactly where the next explosion will occur. So everyone in the area needs to be prepared for ongoing explosions.”
The study highlights the importance of ongoing monitoring efforts, according to Tuffen of Lancaster University. Icelandic geoscientists and international collaborators are monitoring the frequency and intensity of seismic activity and ground deformation in real time. This 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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