What’s Going On With the Volcanic Eruption in Iceland?
Reading Time: 5 minutesA Crack Opened Up in a Small Icelandic Town. A Volcano Scientist Tells Us What’s Next., A scientist tells us how likely it is to blow—and what could happen if it does., Iceland volcano: A scientist on how they know an eruption is coming, and what’s next.
Last Friday, a crack in the earth began to spread through a small Icelandic town called Grindavik. Roads broke in half and grassy hills split apart, causing a great deal of damage. But the real concern is what might come next.
The town sits within the Reykjanes Peninsula, a hot spot of volcanic activity that has experienced three eruptions in the past two years. But those were in remote areas (and were huge tourist attractions). This one threatens people and infrastructure, including homes, a geothermal plant, and a popular lagoon.
The town’s 3,500 residents were required to evacuate over the weekend amidst warnings that a volcanic eruption was due within days. As of this morning, it hasn’t happened yet, but the likelihood remains high, according to scientists at the Icelandic Meteorological Office.
To learn the latest, we checked in with Vincent Drouin, a scientist at the IMO who has been helping to monitor the fissure. Our conversation has been edited and condensed for clarity.
Anna Gibbs: I imagine things are crazy busy for you right now!
Vincent Drouin: It was extremely busy for me this past weekend. Now it’s getting a bit more quiet because the dike stopped propagating. But we still need to analyze a lot of data on a daily basis to see what’s happening.
Wait, what’s a dike? Is that what caused this big crack in the ground?
Yup, the cracking was caused by the dike. A dike is a vertical sheet of magma within the crust. Magma can move horizontally or vertically. When sheets of magma are horizontal, they won’t reach the surface. But when they’re vertical, they can move horizontally along the crust, or they can decide to go up, and then they will reach the surface and cause an eruption.
In videos of the crack, it looks like it’s literally steaming. Is that the magma simmering below the surface?
No, the magma would have to be extremely shallow to start to see something like that, probably within a few meters. Sometimes steam can happen because the crack is near a geothermal area and geothermal fluid finds a way to the surface. But what you see in the town, as far as I know, is just caused by broken water pipes.
So how far down is the magma now?
It’s sitting about 1 kilometer below the surface.
How long would it take for the magma to get to the surface?
When it started, the dike was very big, and the magma was moving fast. It was traveling, I think, more than 2 kilometers per hour horizontally in the crust. And if it’s at a 1-kilometer depth and it started to move vertically, then it would have taken only half an hour to reach the surface.
OK, that explains why reports this past weekend said that the eruption could occur within hours. But then why hasn’t it erupted yet?
If the pressure in the dike stayed as high as it was at the beginning, the magma would have erupted very quickly. But now it seems that the pressure and the momentum have stopped. So it might actually take a few days or even a couple of weeks. For the eruption we had in 2021, a dike formed, and it wasn’t until four weeks later that we had the eruption. So it’s probably going to take a while.
So the magma is literally moving through the ground? Is that what’s causing the hundreds of constant small earthquakes that are happening every day?
Yeah, the magma is cracking its way through the crust. It creates earthquakes as it’s advancing. So at the front of the dike, you have seismicity there.
Did you have any idea that this crack in the earth was coming? Or was it a total surprise?
It wasn’t a total surprise. For the last two weeks, we had noticed increased deformation in the area. Then, on Friday morning, one of our seismologists noticed a cluster of seismic activity in a very repeated pattern. If you have an earthquake due to normal stresses in the crust, you have a big one followed by smaller ones. But in this case it was small, constant earthquakes. Usually that means that the magma is trying to crack the crust in this area.
And that’s what happened. It finally managed to push out of the crust to start cracking.
So you had been keeping a close eye on things. How does monitoring for volcanoes work in Iceland?
We have constant monitoring around Iceland. One technique we use is the Global Navigation Satellite System. Instruments are placed on the ground. They measure location very precisely, down to centimeters or millimeters, so they can capture deformation over time.
In this case, we had two GPS stations, one on each side of the dike. We noticed that they were being pulled apart very fast because the magma was making its way into the crust and pushing the stations apart. Within a few hours, they moved about 1 meter.
Another technique, which I’m the expert on in the Iceland Met Office, is called synthetic aperture radar interferometry. The satellite takes pictures of the ground with a radar instrument, and by comparing images, you can see how much the area has moved between two images.
So what’s happening now with the dike?
There’s still constant earthquakes happening all the time. Not very big ones, but it’s still active. If you look at a seismic activity graph, you can see it’s slower than it was on Friday evening. But the concern has not gone down for the risk of eruption. We still think it’s very likely. On Tuesday afternoon, some gases were detected near the dike, which could indicate that the magma is shallow. But nothing since then [as of 12 p.m. EST Wednesday].
Iceland is pretty well known for its volcanoes. How common of an occurrence is an issue like this?
In this area, we’ve had three eruptions, one every year, since 2021. Maybe now we will experience this kind of event once or twice every year. We can’t know for sure. But what we’ve seen from history in the Reykjanes Peninsula is that it seems to have a pattern of 700 to 800 years of nothing happening, and then you have one or two centuries of volcanic activity all around this peninsula, and then it stops for 800 years. And it’s been a long time—I think it was 700 years since the last eruption. So maybe we are now at the start of this phase where there will be a lot of volcanic activity for the next decade or centuries. Only the future will tell.
This all sounds very scary. How alarming is this to Icelandic folks, who have more experience with volcanoes?
In general, eruptions aren’t too much of a concern. We normally average an eruption every five years, so it’s not like a daily occurrence. In the past three years, this area has been very active, as I mentioned. But those three eruptions, we weren’t overly concerned. They were in the middle of nowhere, no one lives there, and it was a tourist attraction for people from abroad. So it was overall a plus.
But this one is much more of a concern. People in Reykjavik are safe, but for the people that live in this town, it’s a big concern. Half of the town is 1 meter lower compared to the other half. There is a lot of damage, and many houses will probably be destroyed. So even if the event stops here, it’s already a big problem. And like I said, if it starts to be more active in this particular area, it might be that it happens again in a year, and this town is in the path.
Reference: https://slate.com/technology/2023/11/volcano-iceland-eruption-when-science-dike.html
Ref: slate
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