Looking Back at Iceland's Last Eruption—and Ahead to the Next One

[00:00:01]Hey there team, geology professor Shawn Willsey here. We're going to take a look at what's going on in Iceland. It's been a few weeks since we've done an update on Iceland. I want to provide the latest data to you and also take a look back.

[00:00:13]We just had the 1-year anniversary a few days ago on July 16th of the last eruption we had on the Reykjanes Peninsula. So, this was July 16th, 2025.

[00:00:24]Want to take a look back at that eruption. There were some interesting things that happened. It was fun for me to kind of look back and just refresh my memory on just what took place on that day. So, let's go ahead and take a look at what's going on in Iceland now. You can see with the live webcam view there that uh it's a little bit foggy, kind of cloudy. If we kind of scroll back a little bit here with the webcam, though, we might get a good view. There we go, a little bit better view of the crater road there at Sýslingakór. You can see some of these craters. They're still steaming and outgassing um from the eruption a year ago or even more, depending on which part of the crater field you're looking at there.

[00:01:01]So, let's take a look at what's going on in Iceland. Um it's kind of fallen off the radar for some folks. I know many of you still follow it quite closely. I think the most important thing here is that we have signals uh from the GPS stations there that the area is still uplifting. And so, we do expect um there to be another eruption sometime soon, at least possibly. It's possible that there is no eruption, but the GPS data still shows continued insteady inflation. We can kind of take a look at that here.

[00:01:34]Uh looking at the Sarts- Sartsengi station, kind of zooming in on the bottom plot here, which shows the up and down movement. And you can see the last uh I guess this is the last year or so of movement at this station. So, since the last eruption last July uh 2025, it looks like we've had about 30 8 cm, 380 mm of upward movement of this station. And remember, that signal then is interpreted as uh magma accumulation and magma influx into the system. Uh there's no uh Met Office updates to talk about. The last one they did was July 3rd. I don't know why they they they've been doing them pretty regularly every 2 weeks on a Tuesday. Not sure why they missed this past Tuesday, but uh nonetheless, the last couple updates from the Met Office have been uh pretty typical just is telling you the same thing that the uplift is still happening. It's still steady. Um and I think we're right now somewhere near about almost maybe 30 million cubic meters of magma. So, we're at the highest uh projected and modeled volume of magma stored in the subsurface of any other time we've seen during the last few years there. So, uh you can see that the steady uplift here, but you can see that that that slope has changed over the last year. So, the accumulation, the rate of uplift has decreased over time, but it's still going on. So, the long-term trend is still uplift. Magma is still moving into the system. And the big question there is exactly well, what what's going to happen there? I think the big question we all have uh that I certainly have is what's the nature of this magma at this point? Is this magma that is um if we have a lot of fresh magma coming in with a lot of with gases in it, then it's going to be more buoyant. Is the subsurface still hot and fluid enough that the magma can move pretty freely?

[00:03:24]Um if it's not that way, if it's more sticky, if it's cooled off quite a bit, and maybe there's just fresh magma coming in slowly to one little area, then that's going to make it more difficult for that magma to erupt. But, uh you know, it could still just depending on uh the pressures reached and such. So, there's lots of variables, lots of unknown about the state of that magma as it sits in the subsurface right now. Uh so, that's what we have for um the GPS data, it's also fun to look at kind of where we've been. And so, again going to the Svart Sengi station, this is going back a good um like 8 years plus, I suppose. So, the main thing to look at here is when things started to uh rise here in late 2023.

[00:04:09]Um and then you can see the big drop here. So, that was the formation of that dike in early November, November 10th of 2023. Uh then we had more uplift uh or just you know, recovery, I suppose. That led to the eruption at the end of 2023 in December. Uh and then you can see each one of these lines um then sort of the top of each line represents how high the state that station rose before we had an eruption. And you can see how steep these lines are. I think that's the important point. And then you can see as we got into 2025, they started to become a little less steep. And then the most pronounced one, of course, then is this last trend here over the last year, where, you know, the initial recovery was similar to what we'd seen the last few eruptions, but now it's actually changed. There's a little change in slope there. Um and you can see where that's gone there. But, it is still impressive that, you know, looking at this thresholds here and the previous threshold of of the ground surface, you know, back in I guess late 2023, you're looking at, you know, um almost a meter of movement there of this of the surface due to the magma being injected. Uh rocks though, remember rocks, especially once they get kind of warm and hot, they they're somewhat pliable. We know the rocks at depth are somewhat warm because we have the power plant and the the hot springs in that area there. Um so, they do have some kind of elastic properties, if you will. Um looking at the earthquakes in the area over the past week, uh pretty quiet. And of course, earthquakes are going to be the GPS is probably our best long-term signal that magma's continuing to accumulate. Our best signal right now for an eruption happening, you know, in the short term would be earthquake activity.

[00:05:55]And we just don't see anything happening around the crater row there and above the magma system to indicate that we've got anything the rock's basically not being broken. The magma's not pushing on rock, widening fractures, doing anything that causes earthquakes. And so until that happens, we're not going to see an eruption. If we look at the past, what have we got here? The past 30 days month, again, just not a whole lot going on, just a few tiny earthquakes, just kind of background noise, if you will.

[00:06:26]This is sort of typical, even if we were to look at this area, you know, 10 plus years ago before this whole thing happened. Just not a lot happening here.

[00:06:34]The ones we see out here on the offshore area, the ones over here around Lake Kleifarvatn are all pretty typical as well.

[00:06:42]So, not a lot going on with the monitoring data. So, let's take a look back at this earthquake. So, there was a news article that came out this past week, you know, sort of commemorating this 1-year anniversary since the last eruption. And then they talk about that the scientists in Iceland still expect more volcanic activity. That, you know, I think that's the consensus. It's doesn't mean that it's a certainty, but the odds are still greater that we're going to see, as long as that accumulation continues and the uplift goes on, we're likely to see an eruption at some point. But when, where, how much those are all the uncertainties. I think the the danger though, of course, is as we get more magma into the system, how big will that eruption be? And how much magma will come to the surface as lava? And how widespread will that be?

[00:07:31]Those are some of the the factors there that we're not sure about. So, let's look at this eruption that took place a year about a year ago. So, July 16th, so you can see uh location here, kind of zooming back out. Here's the town of Grindavik. Of course, you can see all the black here from these previous eruptions. This image is as of uh August of 2025. So, this includes the lava that poured out from this July 16th eruption. You can see the deflection around the berms. We can throw the berms on there for fun if you want. Uh so, the green lines there are the protective berms around the town and the power plant and the Blue Lagoon.

[00:08:05]But, this was an eruption that was a little bit further to the north um than what we'd seen in the past, which was good for the town of Grindavik.

[00:08:14]And uh it was fun for me to look back at what what I was doing um in terms of reporting what was going on a year ago.

[00:08:22]We actually did a drone flight with Jóhann and Nature Eye over this area, over, you know, just the whole this air region um about 4 hours before the eruption took place. Of course, we had no idea the eruption was going to happen, um but we did a live stream, we did a drone flight, you know, we'd had months of not much happening, so you know, it was interesting that that's just the way it worked out timing-wise.

[00:08:45]So, we did that drone flight, um you know, then went went about my day, and then then 4 hours later, which would have been a was about 4:00 a.m. uh Iceland time is when the eruption began.

[00:08:57]This eruption on July 16th of last year was unexpected in that it was quite early. Um we were still recovering from the April 1st eruption that had taken place, and the magma had only accumulated about 2/3 of the volume that it needed for that April 1st eruption.

[00:09:17]So, it was unexpected in the sense that it came earlier than most people would have thought or predicted. We We We assumed that we needed to get back to or close to that April 1st volume threshold for the next eruption to occur, and we didn't think that would happen till probably the fall of 2025. Below and behold, it was actually uh right there on July 16th. So, it was a bit earlier.

[00:09:41]And I think it was something it was less than 22 million cubic meters of magma.

[00:09:45]Remember, now we're close to 30 million cubic meters of magma. So, we're quite a ways beyond what it took to break through the surface there on July 16th.

[00:09:56]So, you can see where it erupted here.

[00:09:58]It was just southeast of Litli-Hrutur here.

[00:10:02]Of course, it started as a fissure. So, even though I've got the little volcano symbol there, that's not you know, it came out of a big linear fissure in the area.

[00:10:11]And we can look at maybe extent of the lava field here. We can also maybe take a look at um just some of the the what what that looked like. So, just going back to my um my live stream when the eruption took place just to show you a couple visuals here. Here's a look at when that actually began. So, here's like the initiation of the eruption. And then let's get you some nice eye candy here with a good look at the extent of the fissure once this thing was kind of going. So, you know, that as the way these things go, we're trying to get the best data we can. Here's some nice images here. These might be from the the Coast Guard helicopter view there over the area. I know this is a drone shot here. Sorry.

[00:11:01]Um So, that's the way the fissure looked again on July 16th. So, it started out pretty typical like we'd seen with a lot of eruptions there.

[00:11:11]The fissure length into about 2.4 km or about a mile and a half within a few hours.

[00:11:18]And this whole thing was preceded by some shallow earthquakes. So, again, that's the signal we tend to see right before these things occur. So, there's a little view of that there. And then also want to show you what the um What did the earthquakes look like? So, here's the earthquakes from July 16th of last year. And then, you can see that that dike there. So, more magma moved from that subsurface system over to the east um forming this northeast-southwest oriented dike. And then, the eruption that took place was right here. You can see a greater concentration of earthquakes in this area. And that's where the fissure opened up was in this area right here. So, even though we see quakes down here, didn't actually break the surface here at the south end, which was really good for uh Grindavik. So, let's see if there's anything else in this uh Oh, here's some really great uh footage here of the the fissure in action. So, if it's been you know, it's been a year since you've seen the red stuff in Iceland. So, here Here you go. You can uh scratch that itch by maybe looking back at this this video and live stream. And I'll link this specific um live stream into this video here so you can look back at this if you if you choose to.

[00:12:33]Um but, great little uh footage there of the eruption that took place. Uh they did evacuate the Blue Lagoon and Grindavik. There wasn't a lot of people in Grindavik, but the the few couple hundred people that were there, they did evacuate them um probably once they saw the earthquake and such. Not sure where that that fissure was going to open. So, they did uh do that as a precaution. Um and let's see get this thing moving here.

[00:13:01]Yeah, different views of the fissure system here.

[00:13:04]Um and then, this thing lasted until August 5th. So, what What is that? Like 2 and 1/2 weeks? Maybe 3 weeks or so.

[00:13:11]Um it did consolidate from being a fissure with multiple vents down to a few vents and then, ultimately one uh specific vent. And then, the other thing to kind of wrap this up with the other thing I found particularly interesting about this eruption was that on that day, July 16th, maybe a few hours after, you know, once the sun had come up and um a few hours after the whole thing began, we had um oops, let's see here. We had a really interesting phenomena associated with this eruption. We had part of the fissure system become phreatomagmatic.

[00:13:52]Let me get the right clip here.

[00:13:56]And show this to you.

[00:13:59]um And so these were some drone shots that uh Johan sent me from Nature Eye.

[00:14:06]And there's no sound with these, but these just show you what was happening later that day. So what we can see here, I'll just let these run and just maybe narrate these again. Um but you can see some of the lava erupting here on the right. Um but it's a little bit more vigorous. It's actually shooting out a little bit. And then we have this really energetic plume here on the left. So that's a clear sign that the magma's interacting with water, ground water. Uh so we have a a phreatomagmatic sort of jetting vent there. I think the drone's going to kind of swing around here and kind of show this.

[00:14:38]Um so it's interesting contrast here cuz you have these two somewhat different types of behavior. Here we have mostly lava with a minor amount of of water.

[00:14:47]And so you can see it's mostly a lava eruption. And here we have a considerable amount of water mixing with the lava, uh turning that water into steam by the heat of the lava. And you can see some of the rocks being tossed out here. Actually, an interesting contrast with the colors here. You can see the white plume is where it's mostly steam. Uh and the gray is actually ripped up rock. You can see more hopefully if you zoom in there, you can see some little chunks of well, probably large chunks of rock, but they look small on the screen. They're actually being thrown out of the vent there. So an interesting um comparison there in terms of the amount, the ratio of water to lava, which will dictate to some degree the colors you get and also sort of how energetic the plumes are. And you can see that even though there's quite a bit of steam coming out of this white vent over here, it's really um much more vigorous over here with these darker plumes here where it's just it's flashing to steam and it's uh there's kind of a nozzle effect through those small cracks in the lava field there. So, it's really coming out with quite a bit of power. And then you move over here to the right and it's your typical fissure eruption where there doesn't seem to be any ground water mixing with the lava. And that could be because the the lava's kind of walled off the ground water or it could be just the actual conduits and and the the the architecture of the permeability in the subsurface where the ground water is actually kind of moving there. Uh so, we might skip through this one a little bit there. Uh really cool video though.

[00:16:13]I'm glad uh he was able to get this and send this to me. I've used this in classes a few times to show students just different ways in which uh eruptions can take place.

[00:16:25]Here's a nice view here. Now he zoomed in to and this really shows just how energetic these are in terms of those steam uh powered eruptions. Almost looks like it's on fast forward, right? It almost looks like I've altered the speed, but this is in just normal uh time here.

[00:16:39]You can see the lava being ripped up here by the the the steam being blasted out. Um but the more and then some of it's draining back it looks back down and so it's sort of this cycle. Uh but the real impressive thing here is is this these bigger energetic vents and you can see some of that stuff getting ripped out.

[00:16:58]So, I have this little clip here and let me show you one more clip um from the same day and the same flight that nicely shows this type of behavior as well.

[00:17:12]I think this one's zoomed in a little bit more. Yeah, so this is maybe be a continuation of that, but um We can see some of those dark chunks being thrown out there.

[00:17:23]Yeah, and we did see this with one previous eruption, too. I can't remember which one it was. It might have been May 20 2024. Uh we did also had a a a a portion of that eruption become phreatomagnetic.

[00:17:37]You can see the vents there, uh but they all line up with the fissure, right? So, this is all in line with that dike that and the magma's coming up vertically through that conduit. Over here, though, you either have higher uh lava supply versus groundwater, or more likely, you just don't have much groundwater interaction at all. The lava just sort of overwhelms the groundwater.

[00:18:00]Here, you have enough groundwater that it's significantly changing uh the way that the the eruption's taking place. You can see some of these rocks coming out, and they have little tails of of white behind them. You can see some of the sizes of these here. Uh pretty incredible. Just really cool footage there of this phreatomagnetic eruption.

[00:18:20]Um there's the whole length of the fissure. I believe we're looking to the south there. So, this is at the northern end.

[00:18:27]Um And I think it behaved this way for uh I don't know, may- maybe an hour or so. It wasn't long, and it definitely wasn't like a a prolonged period of time. Remember, too, that as the the eruption went on, this, you know, these vents or fissures along the length here, they eventually consolidated in just a a couple places. And so, this area probably just didn't get the lava supply after a little while.

[00:18:53]Uh you can see the the winds there moving everything to the left, which is to the east. So, some west-directed winds.

[00:19:00]Now, they're kind of looking down the length of the fissures. And again, you can see these sort of consolidated spots. Um the the whole thing kind of coming up like think of like fingers, you you like your hand coming up and there's individual vents, vertical vents that are feeding those those surface flows.

[00:19:19]Uh looks like yeah, we're looking it's kind of turning to the that might be the power plant over there. Not sure. Oh no, that's looking to the east. That's looking towards the edge of the lava field over there and probably burning some of the moss.

[00:19:33]Um so this might be the south end now that I'm looking at it. I might have my uh orientation and direction a little bit mixed up.

[00:19:43]Yeah, just incredibly powerful there this uh phreatomagmatic eruption.

[00:19:50]And great that they could capture this uh with the drone. Doesn't look like it was particularly windy so they were able to keep the drone pretty stable uh during the flight.

[00:20:00]Um maybe bounce around a little bit here.

[00:20:07]More of the same but still really impressive so.

[00:20:11]Anyway, good stuff. Um yeah, so hopefully you enjoyed that. Just kind of a look at where we are with the current situation in Iceland. Also look back at the July 16th event of 2025 um and hopefully, you know, we'll see something soon but you never know this could go on for months um weeks potentially. We could see an eruption.

[00:20:32]Don't know how large that'll be. There is a chance too that, you know, the the inflow of magma slows to the point where it's just not uh providing enough pressure to overcome the overlying rocks and stuff and we just don't see an eruption. So lots of different options and scenarios on the table but I'll keep you posted as best I can. Thanks for your support of the channel and we'll see you next time, friends. Stay care.