Iceland's Fagradalsfjall Fires

[bjdeming]

In layperson Jón Frimann's update today, he addresses something I had been wondering about but had not seen covered, since everyone understandably is focused on Grindavik and the dike there: what about the intrusion under Svartsengi that everyone was focused on until the dike formation began last Friday?

Jón's take:

It took me a week. But it seems that this dyke intrusion under Grindavík town is because of the magma sill (dyke) under Svartsengi. That area has inflated around 110mm in a week. That is a inflation of 15mm/day based on my best calculations. That is a lot of inflation, since before 10. November the inflow of magma into Svartsengi was at most 8m3/sec according to measurements of Icelandic Met Office.

The sill in Svartsengi created a lateral dyke in Sundhnúkar and nearby areas. When the pressure in the sill is high enough again it is going to push the magma into the dyke at Sundhnúkar again with the same force as it did before. How long that takes I don’t know. Last time this was from 25. October to 10. November. That’s seventeen days, but there was a lot of deeper sills in Svartsengi and its impossible to know much, if anything flowed form them into the dyke. This is my personal view, it might be wrong. But this is what I am reading from the data.

There is other good information at that link; check it out.

Just another lay opinion (mine), phrased as a question: What if that inflow into the Svartsengi area built up enough force to break open that old fault on November 10th and 11th, but only relieved a little pressure? Could it break through somewhere else, perhaps along one of the old fissures Massimo mentions here (Italian: Twitter can translate it)?

This is where that recent article by Magnus Tumi comes in so handy, along with the graphic that shows the full extent of the area of concern:

 

[bjdeming]

Just another video on dikes and sills (and a couple of other intrusive features, including veins that, when they've concentrated economic minerals and are found, millions of years later, are called "lodes").



This fits in with today's question on the Iceland Web of Science about whether a dike/rift ("sickle valley," per Google Translate) can form under a nearby town -- Reykjanesbær.

Páll Einarsson answered it (autotranslated). In brief:

A sickle valley usually forms directly above the corridor. On the Reykjaness Peninsula there are several of these and they can with some certainty be used as a sign of where corridors have passed through and where they have not. Grindavík lies within such a fissure swarm, and the fissure swarm of Krýsuvík's volcano system lies around the easternmost suburbs of Reykjavík, Kópavog and Garðabær, as can be seen on the map above obtained from the article by Pál Einarsson et al. fl. (2017). The town of Reykjanesbær, on the other hand, lies outside the cracks.

This layperson assumes that, while old cracks are weak crustal points and more likely to reopen, there is also the less likely possibility that a new crack can open.

 

[bjdeming]

Icelanders know volcanism better than most of us ever will, and they are looking at the bigger picture over the long term and, reportedly (autotranslated), taking appropriate protective steps, including this at Míla:

Daði says that last week, among other things, staff connected electronic communications in a different way than before in order to ensure that the systems can withstand a heavy load, in the event of a major disaster on the Reykjanes Peninsula.

 

[bjdeming]

From the blog.

These images released today answer my question about whether magma will break out somewhere else (images: Nov. 11 on left and Nov. 18 (first tweet?/Nov. 17 (second tweet, different scale):



The Earth flexed all that muscle (shown left) to break open the seemingly innocuous dike.

Seemingly.

Per a geoscientist at today’s Civil Defense meeting, as reported by mbl.is (autotranslated):

...

"The magma tunnel still continues to widen and deepen, but widens and deepens less in the last 24 hours than in the previous 24 hours."

The magma has reached a very high level​

This decreasing activity indicates that the magma has reached very high up in the earth's crust, where it has already become very fractured, and does not need much fighting to reach the surface.

While model calculations still indicate that magma is flowing into the vent, it must be considered likely that it will erupt and that this increased probability will last for at least the next few days.

The data also indicates that the greatest widening of the corridor is around its middle, in the area west of Hagafell. Therefore, scientists believe that this area is the most likely source of eruptions.

"The consequences of such an eruption depend on its size and it is difficult to predict," said Kristín...

I understand better what Jón Frimann was getting at yesterday: the sill, centered at the original point of concern northwest of Thorbjorn and near the Blue Lagoon/Svartsengi power plant, isn’t reinflating — at the moment.

It probably will start up again — in days, weeks, months, or years.

The question: Is that what it will take to squeeze out an eruption here, or is it more a matter of a packet of superficial magma that is not quite pressurized enough — yet, anyway — to burst out of the ground?

Come to think of it, the Litli Hrutur eruption this summer was surprisingly brief, compared to the earlier two.

So what?

Well, this layperson doesn’t know. But at Litli Hrutur, reportedly, magma is sitting ~10 km down in that dike after a brief surface episode. Now, a lot of magma (in the present sill) is sitting ~5 km down after a brief surface episode.

There could be a little hope dawning that maybe, if there is an eruption during this magmatic rifting event, it won’t be as big as previously expected.

As each day comes and goes without an eruption, the hope grows that perhaps there won’t be an eruption any time soon.

But there are so many variables. And over the long term there will be other rifting events — Icelanders are wise to prepare for a volcanic disaster on the peninsula. One, at least, is likely to come over the next century.

 

[bjdeming]

Someone who can analyze such images notes:



Twitter translation: "New satellite analysis: Reykjanes Peninsula continues to deform in complex ways. The Blue Lagoon area has started to rise again, while the #Grindavík area continues to sink, albeit more slowly. The dike is still fed, but we are at a standstill."

Sigh.

 

[bjdeming]

Per mbl.is at around 10 p.m. on the 18th noted (autotranslated):

...Einar Hjörleifsson, a natural disaster expert at the Icelandic Meteorological Office, says that it is now a waiting game.

"We see small changes from day to day and there is no sign that the activity is decreasing," says Einar in an interview with mbl.is.

The largest earthquake of the day measured 2.8 and occurred at 15.02.

Einar says the earthquakes are at the same average depth as before, about 5 kilometers deep, but that from time to time earthquakes are measured shallower than that...

A paper just came out (jargon alert) that has a nice diagram to put those depth reports into perspective (although they're looking at another Reykjanes segment):

The diagram shows their model of peninsula plumbing hundreds of years ago when the system they're interested in was active.

Update, Nov. 19th: The lead author of that paper did a brief Twitter thread on it:

 

[bjdeming]

I don't know whether this M3.7 in the Krysuvik system near Fagradalsfjall is significant, but it's kind of close for a triggered quake (like the one in Reykjavik on the 18th):

Note: These quakes aren't reviewed by a seismologist before posting, but they are reviewed and amended when necessary.

Update: It was probably just a triggered quake -- the 0549 geoscientist note puts it only 3 km west of Kleifarvatn lake, where there have been other triggered quakes.

 

[bjdeming]

From RUV (autotranslated) about half an hour ago (Icelandic has always seemed a little challenging for Google Translate, and it shows here) -- link and emphasis added:

Increased land at Svartsengi​

In a new post by the Southern Volcanoes and Natural Hazards Group on Facebook, a wave cross image from the Icelandic Meteorological Office is published that shows an increased speed of land mass in the area around Svartsengi.

The post says that the images show landfall of up to 30 mm in one day on the 18th-19th. November. This landris can also be seen on GPS meters in the area.

For comparison, the rainfall in a similar area was about 50 mm in a 12-day period from 19-31. October.

Looks like "here we go again" -- this is quick for a geological process, but it does make weather systems look as though they move like The Flash as they cross the west coast, travel cross-country, and exit over the water again.

 

[bjdeming]

Microswarm in the expected vent area (Twitter will translate). This particular one is apparently over now, but read the whole thread, begun within the hour:



Last post, per Twitter translation: "Micro-earthquake activity has increased at the vent. Einar Hjörleifsson, a natural hazard expert at the Icelandic Meteorological Office, says between 50-70 earthquakes have been recorded every hour today. He says this is certainly an increase compared to the last few days and that developments will be closely monitored."

 

[bjdeming]

Per RUV, the microswarm ended in a M2.6, and geoscientists are monitoring the situation.

The beach-ball for that 0328 UTC quake shown here (time dependent) shows, if I understand things (a big "if,") sideways vertical movement, not vertical sideways (told you it was a big "if"! )

This came out mid-afternoon Sunday, local time:

This is what volcanologist Þorvaldur Þórðarson says in an interview with mbl.is.

"The flow of magma into this storage chamber, which is 4.5 kilometers deep, is 8 to 10 times more than what people were talking about before November 10. Back then it was between 5 and 7 cubic meters per second, but now it's around 50 cubic meters per second," says Þorvaldur.

...

Svartsengi regains its former position​

If this pace continues, Þorvaldur believes that Svartsengi will have reached its previous position in 5 to 15 days.

"What will happen then, it is difficult to say. We can have a soda, we can have a repeat of November 10 or just something completely new."

Is the chance of an eruption in this area increasing?

"I think the chances are always getting bigger and bigger of an eruption on the northern side of the Sundhnúka series or then in Illahrauni. I think the probability of an eruption there is increasing because of the land giant that is there."

Place name graphic:

 

[bjdeming]

The reply tweet shows the 2021 barrier attempt at Geldingadalir:



This new project is ambitious, but the lava, if and when it comes, will have much more room to spread out across the land, meaning that it isn't likely to pile up as high and with as much force against the barrier as in that narrow valley.

BUT, the Icelanders must build a much longer barrier.

At stake is the plant supplying 31,000 people with heat (geothermal) and electricity. Near the Arctic Circle. In late November/early December.

Pretty high stakes.

Otherwise quiet thus far into Iceland's November 20th, with the geoscientist reporting 800 small quakes in the dike since midnight.

 

[bjdeming]

Still no eruption, but they have considerably widened the hazard zone, this layperson suspects as a result of that speedy rise in the Svartsengi area.

This is the IMO update from about five hours ago, autotranslated (the one earlier today goes into great detail about the thinking behind the expansion of this hazard zone):

The Icelandic Meteorological Office has updated the hazard assessment map for the area around Grindavík and Svartsengi. Based on new satellite images of Svartsengi and the magma tunnel, together with data that was discussed this morning with civil protection, experts from the Meteorological Office and the University of Iceland, the danger zone has been expanded since before.

There are three danger zones as you can see on the map. The Public Safety and the Police Commissioner in Suðurnesj have the map as a consideration in the planning for the area.

What a nightmare this must be for local residents!

This interview with a U of I geophysicist (autotranslated), from yesterday (published before today's civil defense meeting) is helpful, too.

This morning, Magnus Tumi reportedly said, among other things "What happened is that the pressure was greatly reduced by these events on November 10. It is common to see flow coming back in after such an event.

"That influx does not mean we should expect it to erupt in a new location. There are no tremors associated with this land giant because there is no tension and it is still being filled in.”

Further:

Magnús says there is still a possibility of an eruption, but if it did, it would flow up through the weakness in Sundhnúkasprungun.

"While the weakness is in the Sundhnúka crack, that's the most likely place, it's just like if there's a hole in your roof, the rain finds its way in there.

It is by far the most likely place if it were to erupt, although it cannot be ruled out."

He says there is no data to suggest that it will erupt in other places, such as in fissures in the west, and if it were to happen, it would be visible in the seismic activity with some warning.

Meanwhile, this hard-working rescuer describes his experiences as being unprecedented and like a movie. (Nice Nordic touch: of course he sleeps eight hours a day, and then gets up for that 16-hour activity period. Earth has messed with a tough people!)

But there is such a thing as economics (autotranslated: given this context, the "useless" probably means that this expenditure cannot be matched through income; it cannot be fiscally replaced. Iceland is thriving, hard-working, but small compared to, say, us, and its geographic setting imposes limits on how much they have been able to diversify, limits that they constantly challenge and sometimes surpass -- but this, even before any eruption, is a national disaster in the short term.).

 

[bjdeming]

There is a livestream now of what movements the seismometers are picking up along that crack:



They are showing RSAM in the blue-colored line.

Clarification: The equipment is close to Hagafell, but this is the same 15-km crack, filled with moving magma (as shown on the seismogram) that's under Grindavik.

As the Cambridge volcanologists note, the equipment is very sensitive and we're going to see many small quakes (and, I suppose, wind artifact, etc.)

Since the Hagafell area might be where magma surfaces, this will pick up the earliest indications of an impending eruption.

Scientists from around the world are on this.

 

[bjdeming]

In barrier news, per Twitter translation (I think "landslides" might be a mistranslation for "inflation" -- "landriss": Icelandic is rough on machine translators):



"RUV 21:28:

- The lines to 60% of the defenses have been laid.
- The first defense line is 2-3 meters high and will later be raised to an average height of eight meters.
- Due to landslides in Svartsengi, work started today on the park west of the power plant and the Blue Lagoon."

This account has some interesting posts on the 2021 effort roday, too.

 

[bjdeming]

No changes, per IMO, but it's interesting to note that weather briefly stopped work on the lava barriers -- but not the way most people would expect:



IMO mentions the weather and how it (and coastal waves) affect seismic monitoring equipment here:

As mentioned before, the Icelandic Meteorological Office has increased surveillance in and around Grindavík and the area around Hagafell, while residents approach their properties and contractors work on protective measures. The effectiveness of this surveillance depends on the high sensitivity of earthquake and real-time GPS measurements, which are highly dependent on weather conditions. Given the weather forecast for the next two days, which indicates precipitation and significant wind, it can be expected that both the sensitivity of earthquake detection and real-time GPS monitoring by the IMO will be affected. Waves affects the low-frequency signals in the seismometers where waves appear as noise. Fog and dark hail also affect the visual confirmation of the eruption with cameras.

Not sure what "dark hail" is -- graupel, perhaps?

 

[bjdeming]

IMO is taking it day by day as the magma sill under Svartsengi/Blue Lagoon/Thornbjorn continues to inflate.

Although there might be a flood of awful images after they let journalists into town tomorrow, there is a little good news for Grindvikings -- while magma in the dike is still moving, it possibly has started to harden under Grindavik; thus, per RUV article (autotranslated):

Residents are advised to bring food and water​

The Civil Defense has decided to extend the rights of the residents of Grindavík to look after their property. Earlier this evening, the civil defense level was changed from an emergency level to a dangerous level.

In the Facebook post of the civil defense, it is stated that because of this, the Grindvíkings will be given more permission to enter the town. However, that does not mean that the public is allowed to go there, but only residents. Access to the media is permitted.

This wider access means that Grindvíking will be allowed to enter the town in the coming days to collect valuables and look after their belongings. Residents of damaged houses have been given permission to relocate.

As long as nothing changes for the worse, the town will be open to residents from nine in the morning until four in the morning. Tomorrow, November 23, the town will not be opened until eleven o'clock, when the danger level comes into effect. Residents are still requested to register on island.is and be authorized to enter.

Civil defense also draws attention to the fact that you cannot use toilets in any houses, where there is neither an active drainage system nor running water. It is also recommended that residents bring water and food because it is not possible to get such things in the town.

It is recommended that people come in their own cars, a maximum of one car per household. It is not recommended that children be brought along.

3 hours ago

Bringing heat and electricity to a house in Grindavík is going well​

It has been successful in the last few days to bring heat and electricity to houses that were left without electricity and hot water during the earthworks at Grindavík, according to an announcement from HS Veit.

The systems in Grindavík are damaged in many places after the earthworks, but according to information from HS Veit, three houses out of 1200 homes are without hot water due to damage to the distribution system. It seems that 54 houses get hot water but are not using it. There can be various reasons for this related to the real estate itself.

A plumbing team run by the civil defense will investigate the conditions in these houses in the coming days in consultation with the house owners.

Five houses are without electricity due to damage to the distribution system. It seems that 31 houses get electricity but are not using it. There can be various reasons for that. The electrical team under the auspices of the civil defense is investigating the conditions in these houses in the coming days.

The announcement states that in light of the circumstances, it is not possible to guarantee complete certainty about the status of individual houses or a full picture of the situation in Grindavík. It is impossible to say what the future will be in light of the fact that subsidence and subsidence will continue.

HS Veitur warns especially about the danger created by hot water on the surface or in ditches and due to damaged electricity structures and cables.

Again, when they mention "hot water" somewhere, they're referring to the geothermal home heating system, not the stuff coming out of the tap.

If magma is hardening there, maybe it's also cooling down under the seabed, and without eruption there, Grindavik might get to keep its all-important harbor.

Hope so!

 

[bjdeming]

Happy Thanksgiving, all!

There is no particular news, other than that the big sill under Svartsengi continues to inflate. Eventually something will have to give, and the last paragraph in this IMO update addresses that:

 

[bjdeming]

People stuff.

Per RUV (autotranslated):

The construction of fortifications on the Reykjanes Peninsula is one of the largest defense operations on land in the history of Iceland. Work is being done around the clock with powerful machines fighting against magma movements in the hope of being able to protect the most important infrastructure of Suðurnes...

Good article, and I haven't seen much good English-language media coverage of this "mankind under the volcano" fight yet (okay, so they're sitting on top of the volcano... ). It will come with time -- something they're rather short of in Iceland right now between the Fires and the weather.

 

[bjdeming]

Good news: the dike under Grindavik is probably hardened enough so an eruption in town can't happen.

Farther north, maybe, but seismicity is slowing down.

That's per Magnus Tumi, who also told mbl.is (autotranslated):

He says that only the land giant at Svartsengi has slowed down and he thinks it unlikely that the land giant will reach the same height before the end of the month as it had reached on November 10.

"There are several scenarios. One is that landris will continue under Svartsengi at a significant speed and in a few weeks a similar situation will occur as it was before this scenario," he says and continues:

"However, the other thing is quite clear, the same pressure as before cannot build up. There is a weakness there. Now there's a weakness where the passage is, and although it's largely solidified, there's still probably a connection [where the magma flows up]."

Magnús says it is unlikely that a lot of pressure will build up again under Svartsengi. "The roof has broken and it will take months or years before it reaches its previous strength. Although it is solidified, it is weak.”

Still, here is an interferogram from November 12-24 (wrapped, left, and unwrapped, right -- please don't ask me what that means ):



In some other news articles I've seen, regarding increased seismicity and expansion of a geothermal area in the Hengill system near Fagradalsfjall, IMO staffers have pointed out that the whole region was distorted just before the November 10-11 dike formation and that the land is still readjusting.

That's probably what is shown in the most recent InSAR images, along with the 4.5 to 5-foot deformation in Svartsengi.

Things that I'm keeping in mind as time passes:

1. The growth of that geothermal area near but not in the Fagradalsfjall system. Earthquakes there have been attributed to a geothermal plant, but no one I've seen interviews with has yet addressed the reported change in the underground heat source. This is followed by mbl.is.
2. What Pall Einarsson reportedly said about a possible new dike. I haven't seen interviews with him recently.

 

[bjdeming]

About three hours ago, per this IMO geoscientist note from 0157 Iceland/UTC time, a swarm started in the magma tunnel near Grindavik:

Comments of a geoscientist​

Seismic activity near Grindavík
Just before midnight, an earthquake began that lasted for over an hour. Since midnight, almost 175 earthquakes have been recorded at the magma tunnel, the largest being 3 in size at Sundhnjúk. A total of 700 earthquakes were recorded at the corridor on 26 November.

The swarming isn't unusual, per coverage on mbl.is, but [layperson speculation] M3 is a bit strong for this lessened stress area [/layperson speculation], so it's worth a heads-up for anyone following the situation. We'll have to wait and see what develops

RUV summarizes things nicely (all these links should autotranslate).