Iceland's Fagradalsfjall Fires

[bjdeming]

No overall changes. Pall Einarsson, who seems not to be given to overstatement or wasted words, told Morning Paper (autotranslated) that it is a situation never before seen in Iceland or anywhere else.

The national weather service, IMO, did its best to make a forecast in today's update:

Landris in Svartsengi continues at the same rate as models predict that the amount of magma added to the magma chamber in Svartsengi since the eruption began on March 16 is now approaching 10 million m 3 as the graph below shows. In previous events, magma has flowed from Svartsengi when between 8 and 13 million m3 have been added to the magma chamber since the last magma flow.




The graph shows the estimated amount of magma that has been added under Svartsengi between the eruptions or magma flows that have occurred since November 2023.

If magma accumulation continues at a similar rate, there is a greater chance that the power of the eruption on the Sundhnúks crater series will increase significantly.

• New fissures open in the area between Stóra-Skógfell and Hagafell and/or the existing fissure expands due to a sudden increase in lava flow that could be comparable to the initial phase of the last volcanic eruption in the area. It could happen with very little or no notice.
• It is also possible that magma flow from the magma chamber under Svartsengi to the Sundhnúks crater series will gradually increase until there is a balance between the inflow of magma into the magma chamber and the outflow from there to the surface.

It is also possible that there will be a magma run that ends with new fissures opening elsewhere than in the area between Stóra-Skógfell and Hagafell. This scenario is considered less likely than the others and would be accompanied by considerable seismic activity and deformation with more advance notice than previous eruptions...

This layperson's guess is that the unusual features are due to Iceland being part of the Mid-Atlantic Ridge system, since that's one of two unique things here.

Something down there also has produced a lot of lava as well as uplift that has raised the Ridge as much as a mile above sea level, but after doing some reading I'm not as certain as I used to be that those who call it a mantle plume are completely right -- those who disagree have very convincing arguments, too (mainly Martinez et al. and Foulger et al. in the sources used for my blog post series, with Allen et al. being the most convincing "pro-plume" advocates I've read so far).

Anyway, the other unique thing is interaction between the Ridge and this mantle anomaly -- as you might expect, with so little known about either, that is debatable, too.

It would all be so arcane and academic if it hadn't already essentially destroyed a major Icelandic town and if it wasn't occurring underneath the country's most populous region.

 

[bjdeming]

This was uploaded ten days ago but I just found it -- someone drives across that road they made over fresh lava in between the eruption and the power plant, also some detail of the power plant barrier.

Pretty amazing!

 

[bjdeming]

This satellite view nicely highlights what IMO says in their update about lava active along Grindavik's east wall -- it's flowing through tubes.

 

[bjdeming]

They say (autotranslated) north of Grindavik, but L12 looks to perhaps be part of that eastern line where the lava flow has been growing.

Hrauntunga stretches over a rampart​

Lava from the eruption at Sundhnjúksgíga has begun to stretch over a dike north of Grindavík and a short distance into a gravel road below. There is little danger from it.​

Ingibjörg Sara Guðmundsdóttir
April 27, 2024 at 13:00 GMT,updated at 18:27

In the picture, you can see, in the middle of the picture, where a tongue of lava stretches over the defense wall L12 and descends towards a gravel road below.
RÚV – Webcam in Þorbirn​

A small tongue of lava from the volcanic eruption at Sundhnúksgíga has stretched right over a dike north of Grindavík. It flows quite slowly and so far there is no danger.

Lovísa Mjöll Guðmundsdóttir, a natural hazard expert at the Icelandic Meteorological Office, says the lava tongue reaches right up to the defense wall. She is not traveling fast and there is no danger from her so far. However, the development will continue to be closely monitored.

The lava tongue extends over the rampart L12 which is marked in green on this map.

 

[bjdeming]

Magnus Tumi had a lot to say (autotranslated) to Morning Paper.

Read the whole thing, but this is especially interesting:

It is important to keep in mind that the behavior of the Reykjanes Peninsula does not indicate continuous eruptions for years and decades. "That's not what the peninsula has been doing, but there can be a break and eruptions come back, which then ends in the affected area. So maybe a hundred years will pass until the next eruption, we can't know anything about that," the professor explains to the best of his ability.


The Reykjanesskagag eruptions are a long run that can go on for a considerable time with breaks, and it is well worth trying to protect Grindavík as much as possible and use the town when the eruptions subside.


"There's a lot of activity going on there that's important to minimize the damage from these forces, it's the short-term situation that's full of caveats, but the long-term situation suggests that we're going to see this trend continue for quite some time and under that we have to to be finished," concludes geophysicist Magnús Tumi Guðmundsson.

 

[bjdeming]

Earlier they said just an old piece of lava had been pushed over the berm but this picture from Visir (autotranslated) shows a small flow (also -- lava cop Seriously, I read somewhere that they are turning 50-100 people a day away even though volcanologists are saying over and over again that this could open up with an initial burst):

...

Here you can see how the lava tongue flows down the rampart.Pointer/Steingrím Doo​

Reporter Berghildur Erla Bernhardsdóttir was on the Reykjaness Peninsula today in the area where the lava tongue began to flow over the defense wall. She talked to Atla Gunnarsson, head guard at the police in Suðurnes, about the situation.


"We have increased response and surveillance in Grindavík and are paying closer attention to the places we think we need to be at." Here and where the people are going up to the eruption, mainly to prevent it," says Atli.

Atli Gunnarsson is a warden at the police in Suðurnes.Pointer/Steingrím Doo

​

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The crater was sluggish earlier today (Pacific time) but now it is quite lively. Even if it doesn't get intense again, this will be a challenge for the downstream defenses.

BTW, Iceland is quite beautiful at night just now because there is sunlight almost all the time.

 

[bjdeming]

New update (autotranslated) from IMO. It touches on a number of point so here's the whole with highlights of points I thought especially interesting. In sum, they don't think the eruption is going to end soon; I'm glad the lava stopped overtopping L12 but what's going to happen there and elsewhere at Grindavik and Hraun with a fast flow to the south?

Updated April 30 at 14:55

• Landris still measures up to Svartsengi, but there are indications that it has slowed down in the last few days.
• Despite the land subsidence, model calculations show that magma accumulation under Svartsengi continues at a similar rate as before. It indicates that pressure is increasing in the magma chamber.
• The total volume of magma under Svartsengi since March 16 is estimated at over 10 million cubic meters.
• In the last two weeks, the average flow of lava from the crater, which is still erupting, is about a third of the average flow in the first half of the month.
• Measurements and model calculations indicate that there is considerable uncertainty about the future, but it is likely that it will soon lead to news and the power of the eruption on the Sundhnúks crater series could increase.
• Risk assessment updated. The risk of lava flow has been increased, but the risk of eruption has decreased.

The eruption at Sundhnúk continues and lava flows to the south from the crater, just like recently. The southern part of the lava bed continues to thicken where lava flows in closed channels. On Saturday, April 27, a small lava tongue crossed a dike east of Grindavík. No more lava has crossed the dike since then.


The image measurement team of the National Institute of Natural Sciences (NÍ) and Landmæringi Íslands (LMÍ) has been processing satellite images and data since April 25. The area of the lava bed that has formed in the eruption is now 6.16 km 2 and is almost unchanged between measurements. However, the volume and thickness of the lava bed continues to increase and the volume is now 34 ± 1.9 million m 3 and the average thickness of the lava bed is 5.5 ± 0.3 m.





Based on these results, the estimated average lava flow in the eruption between April 15 and 25 is 0.9 ± 0.4 m 3 /s. In previous measurements of the average lava flow for the period from April 3 to 15, it was estimated at 3 to 4 m 3 /s.

Caption: The attached map shows changes in the thickness of the lava bed between April 15 and 25.​

Landris still measures up to Svartsengi, but there are indications that it has slowed down in the last few days. At the same time, eruptive turbulence has shown a slight increase and microseismic activity has temporarily increased in the Sundhnúks crater series, although there are indications that the land giant is slowing down, model calculations show that magma accumulation under Svartsengi continues at a similar rate as before. The total volume of magma that has accumulated under Svartsengi since the eruption began is estimated at over 10 million cubic meters. The fact that the land giant is slowing but that magma continues to flow into the magma chamber indicates that pressure is building there.


Measurements and model calculations indicate that there is considerable uncertainty about the future, but it is likely that it will soon make headlines. If magma accumulation continues, it is more likely that the power of the Sundhnúks crater series will increase significantly rather than that it will subside. Based on the latest measurements, however, it is difficult to say which of the scenarios below is more likely

• New fissures open in the area between Stóra-Skógfell and Hagafell and/or an existing fissure expands due to a sudden increase in lava flow that could be comparable to the initial phase of the last volcanic eruption in the area. It could happen with very little or no notice.
• It is also possible that magma flow from the magma chamber under Svartsengi to the active crater on the Sundhnúks crater series will gradually increase until there is a balance between the inflow of magma into the magma chamber and the outflow from there to the surface.

The graph shows the estimated amount of magma that has been added to sub-Svartsengi between the eruptions or magma flows that have occurred since November 2023. ​

Gas diffusion prediction​

Today's weather forecast is for a northerly direction (Tuesday) and gas pollution is moving to the south and there could be pollution in and near Grindavík. Lows tonight and then pollution could accumulate near the eruption sites. Turns to the west tomorrow (Wednesday) and southwest in the afternoon. Gas pollution travels to the east at first and could occur at the South coast, but later to the north and northeast and pollution could occur in the Höfúðborg area, Vogur and the Vatnsleysu coast. You can follow the gas distribution forecast here .

Risk assessment updated​

At the Norwegian Meteorological Agency's scientific meeting this morning, the risk assessment was reviewed. The changes are in the risk assessment that the risk due to pyroclastics has been reduced from a considerable risk to low in areas 1 and 6. This change is made because there has not been much pyroclastic release into the atmosphere. The risk in area 4 (Grindavík) has been increased from moderate to high due to lava flow, as the lava tongue has been expanding, albeit slowly, within the area in recent days. This means that the overall risk in zone 4 goes from considerable (orange) to high (red). In addition, there is an increased probability that it will soon lead to news in the area around Sundhnúki, and it is estimated that it is more likely than before that lava can flow quickly to the south.








(Click here to see the map larger)

 

[bjdeming]

Terrible forecast uncertainties for IMO. On the one hand, it's great that they're following this so closely and can see so much -- AFAIK this in-depth near-real-time understanding is rare at an active volcano due to geology, with Iceland being a special case. On the other hand, it's such an unusual situation and so much depends on it. (Note: Links in the quote below might take you to an Icelandic language page; the text is via machine translator.)

• Landris still measures up to Svartsengi. Pressure therefore continues to build up in the magma chamber.
• Lava flow from the erupting crater has been decreasing in recent days.
• Measurements and model calculations indicate that there is considerable uncertainty about the future. There is still an increased chance of a new magma run and that the power of the eruption on the Sundhnúks crater series will increase.
• There is a risk that the lava will cover defenses east of Grindavík if the force of the eruption increases again.
• Risk assessment is unchanged

Landris continues to measure at Svartsengi and the speed has remained unchanged for the last few weeks (see picture below). It was reported in the news earlier this week that there were indications that it had slowed down in the previous days. Measurements since then show that the speed has remained the same if you look at the last few weeks. Pressure continues to build up in the magma chamber and there is a possibility of a new magma flow from the magma chamber under Svartsengi to the Sundhnúks crater series.

The graph shows the vertical displacement of the GPS station SKSH in Svartsengi. The measurements show that the rate of land erosion has remained fairly constant since the beginning of April. The blue line represents the timing of the non-eruptive magma intrusion, while the red represents the start of the current eruption.​

Seismic activity has increased in the Sundhnúks crater series in the last few days. These are small earthquakes that are probably a sign of tension release in and around the magma passage on the Sundhnúks crater series due to increased magma pressure in the magma chamber under Svartsengi.

Lava flow from the crater is significantly less than it was three weeks ago. The lava flow as it is today is estimated to be very small, but it must be expected that the eruption will continue for some time despite this small lava flow.

The attached map shows the changes in the thickness of the lava bed between April 15, 25 and April 30.​

In recent weeks, lava from the crater has piled up at the defense walls east of Grindavík. (L12 in the picture above). If the power of the eruption increases or new fissures open south of the current vent, the advance of the lava margin at the defense walls east of Grindavík must be assumed. On Saturday, April 27, a small lava tongue crossed a dike east of Grindavík. There is a risk that such cases will increase if the power of the eruption increases again.

These two scenarios remain the most likely for the continuation of activity in the Sundhnúks crater series:

• New fissures open in the area between Stóra-Skógfell and Hagafell and/or an existing fissure expands due to a sudden increase in lava flow that could be comparable to the initial phase of the last eruption in the area. It could happen with very little or no notice.
• It is also possible that magma flow from the magma chamber under Svartsengi to the active crater on the Sundhnúks crater series will gradually increase until there is a balance between the inflow of magma into the magma chamber and the outflow from there to the surface.

Signs of a new magma run would be, as before, extremely sudden and intense small earthquakes in and around the magma tunnel and subsidence in Svartsengi.

The Norwegian Meteorological Agency's risk assessment remains unchanged and is valid until May 7, all things being equal.

Here you can see the weather watch's gas pollution forecast.

 

[bjdeming]

At the moment, there is an intense microswarm going on under Svartsengi itself, which is odd -- it usually occurs around the eruption site.

To see it, go here, zoom in to the peninsula, and keep hitting the + until you see Grindavik on the map. This is extremely time dependent, but the swarm I'm talking about is NW of Grindavik. The eruption is NE of town.

It seems to extend all the way down to just west of Grindavik, which probably is not good at all, though these things often do come and go without seeming rhyme or reason. Fingers crossed

 

[bjdeming]

That came and went without problem. I haven't been checking consistently but right now there is a swarm of microquakes in the "proper" place -- NE of Grindavik.

Most of it is north of the current vent, which is sluggish but still with occasional vital signs on the cam. The southernmost quake along the line is underneath central Grindavik, about 4 km down. The shallowest listed currently, up with the other ones, is a little over 1.5 km down.

Time out to say that this is just a layperson reading a very simplified graphic FWIW.

Now, the reason I mention depth is because at the moment that graphic also shows an intense swarm in the Brennisteinfjoll fissure group, but deep ones in the 4 to 5 km range. This is the general area where those big quakes recently occurred near Reykjavik.

I know. Another Icelandic word. There's no need to memorize it, apart from the seismic hazard to the capital, since boffins reportedly have said in the past that there is no sign of magma movement in those cracks (as there still is in nearby Fagradalsfjall, though quite deep, too).

It's just that the peninsula is alive in so many ways. Eldey, on the tip, is another system -- or Reykjanes subsystem, depending on who you ask -- partly offshore, and it's acting up, too.

Do not be fooled by that seemingly burning out crater east of Sundhnukur. Something is going on, for sure. Just what, though?

I was impressed that IMO spelled out "crustal magma chamber" in their update, because my reading tells me that:

• Most Icelandic volcanic systems involve a central caldera set amid a connected system of fissures. It has to do with how the ridge and the plume/mantle anomaly interact. Of course that gets confusing real fast -- for example, the infamous Laki eruption that began in 1783 is part of Grimsvotn Caldera's system. More helpfully, an eruption that the current fires have been compared to -- Krafla, 1975-84 -- occurred on a typical caldera/fissure system in northern Iceland.
• There are no crustal magma chambers on the Reykjanes Peninsula. There are only fissures, in volcanic systems that to this layperson seem to have as many different names as a leopard has spots.

Per De Freitas from the source list, the peninsula does have geothermal areas -- I think, at areas where different tectonic stress features meet -- and an excellent and large one more than 800 m below Svartsengi and the Eldvorp craters 6 km SW of Svartsengi (site of the last Reykjanes eruption in the 1100s or 1200s).

They've used that for geothermal energy since 1976.

If you're still with me here, [layperson speculation] some experts think calderas develop out of geothermal areas. It is not impossible that, with this ongoing intrusion under Svartsengi from at least 2020 on, we might be seeing the initiation of another typical Icelandic caldera/fissure system -- unfortunately, centered under the power plant, Blue Lagoon, and Mount Thorbjorn -- over the next couple centuries.

The birth of one has not been observed in Iceland before. It could explain the broad-scale tectonic stress changes and might be a reason for the unexpected geochemical findings of lavas since 2021.

And it would certainly make volcanologists say that this is new ground for them. It's probably not something they they have ruled out although the timing is way too early for them to confirm it.

It doesn't change current emergency management and other measures for Iceland, if this is what"s happening. "Caldera" has a scary feel, but we're not talking Pinatubo 1991 here or even Kilauea 2018 -- a caldera collapse that most of us didn't even notice.

It's of academic interest. As well, it's a heads-up that Iceland needs to rearrange, or at least look at rearranging, its power sources. That involves politics, economic interests, and who knows what else -- there must be some very interesting background conversations going on right now in that country's decision-making centers.

All because of a volcano.

[/layperson speculation]

 

[bjdeming]

As someone once wrote at Volcano Cafe, Icelanders fight their volcanoes.