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- Written by Rebecca Morrell and Alison Francis
- BBC News Science
Iceland experienced another fire day this week, with towering lava fountains lighting up the dark morning sky.
This time, the evacuated town of Grindavik was spared, but the lava still wreaked havoc, engulfing pipes providing heating and hot water to thousands of people living in the area and cutting off the road to the tourist attraction Blue Lagoon. .
This is the third short-lived eruption on the Reykjanes Peninsula since December 2023, and the sixth since 2021. But scientists believe this is just the beginning of a period of volcanic activity that could last for decades or even centuries.
Iceland is no stranger to volcanoes and is one of the most volcanically active places in the world.
That’s because the country sits on a geological hotspot, where plumes of hot material deep in the Earth are rising toward the surface.
However, Iceland is also located on the boundary between the Eurasian and North American plates. These plates pull apart from each other very slowly, creating space for hot molten rock (magma) to flow up.
As magma builds up underground, the pressure increases and it bursts through the earth’s surface in an eruption (the hot rock at this point is called lava).
Iceland has more than 100 volcanoes, and more than 30 are currently active.
However, the last time lava flows were seen on the Reykjanes peninsula was several hundred years ago, starting in the 8th or 9th century and lasting until 1240.
Now eruptions are starting again, but why the 800-year gap?
Professor Tamsin Mather, a geoscientist at the University of Oxford, explains: “Over geological time, tectonic plates are pulled apart by a few centimeters a year, about as fast as fingernails grow.”
“But they don’t seem to be leaving smoothly. They’re experiencing pulses of higher activity. And this is probably what we’re seeing in Reykjanes right now.”
Rocks in the area can reveal more about the past, showing a pattern of quiet periods lasting about 1,000 years followed by centuries of eruptions.
“There is evidence that there have been around three episodes of this type in the last 4,000 years in this region,” Professor Mather explains.
“Right now things are going as expected, and what we’re expecting is a series of relatively small, relatively short-lived eruptions over the next few years to decades.”
How to predict when an eruption will occur is currently a major concern for Iceland, especially since the town of Grindavik and its geothermal power plant, an important part of the national infrastructure, are in the danger zone. There is.
Dr Evgenia Ilyinskaya, a volcanologist at the University of Leeds, explains: “Now that we’re seeing repeated eruptions, scientists have a better understanding of what’s going on.”
“So they’ve been tracking how the ground expands as magma comes out from deep underground, and now they can tell better than ever when magma is expected to start breaking through the ground. Now we can know with much more certainty.”
However, it is difficult to pinpoint exactly where eruptions will occur. These are not cone-shaped volcanoes like, for example, Mount Etna in Italy, where the lava erupts from approximately the same location.
On the Reykjanes Peninsula, magma is held loosely beneath a larger area and erupts through cracks and fissures that are many miles long.
Icelandic authorities have built large barriers around the town and power plant, which are good at stopping lava.
But when cracks appear inside the fence, as was the case when a house was destroyed in Grindavik in January, there’s not much that can be done.
A prolonged eruption would have a major impact on Iceland.
“This is the most densely populated region in Iceland, with 70% of the population living within 40 kilometers,” explains Dr. Ilinskaya.
“And all the major infrastructure is there, as well as a major international airport, a large geothermal power plant, and a lot of tourism infrastructure, so that’s a big part of Iceland’s economy.”
Lava flows cutting off major roads and air pollution from eruptions are just some of the risks.
Dr. Ilyinskaya said the capital Reykjavik could also be affected.
“One of the scenarios that would be dangerous for Reykjavik (Iceland’s capital) is if the eruption moved further east along the peninsula.Reykjavik now has lava flows from the last eruption cycle 1,000 years ago. exists, and based on that, it is not impossible that lava flows could flow there in a future eruption.”
So is there a way to predict what will happen in the long run?
Scientists are investigating various volcanic systems across the peninsula.
“In the last cycle, the first eruption started in the eastern system, moved westward, and had a few bouts here and there,” said Dr Dave McGarvey of Lancaster University.
This time, the first eruption that began in 2021 occurred in a system located in the central part of the peninsula.
“That system now appears to be completely turned off. There’s no clear sign of magma gathering underneath it. We don’t know if it’s temporary or permanent. Hmm. It may not erupt again in this cycle.”
The most recent eruption, which began in December, is now in a neighboring system slightly to the west.
Dr McGarvey said scientists could learn how much magma exists underground and whether magma could migrate from Grindavik and the power plant to other nearby volcanic systems. It has said.
“If they see the rate of magma flowing down, that’s probably an indication that it’s starting to stop flowing, and if it does, it may take a few minutes before it completely subsides. It might take a month.
“The question is, is this a temporary lull or is it actually the end of this phase of activity? At that point we’re in uncharted territory.”
Scientists are learning more with each eruption, but great uncertainty remains for Iceland as a new volcanic era begins.
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