Grindavik dropping into the sea

Mount Thorbjorn


Like minds and all, both me and Albert set out to write an update article unbeknownst to each other. I guess that Albert has not yet fully come to grips with me returning back to “life”. But, this is a good thing for you as a reader, you get twice the fun from two different minds as a nice weekend surprise.

Albert is the top part of the article, and I will be down far into the bottom.


Thorbjörn Update by Albert

Credit: Astrograph. Click here to see a high resolution 360 degree panorama in Google Maps of Grindavik, taken on 4th July 2021, with the first Fagra eruption in the background

O what a night.. At the last count, there were 252 earthquake of magnitude 3 or more, the largest at M5.2. That is 252 stars on the map, scattered all over the place as the automatic locator cannot cope with this amount of shaking. It is Christmas come early, with 252 stars of Grindavik. The evacuation of Grindavik adds another semblance of that first Christmas story. But so far, it is a lot of noise but no action. The magma has (so far) remained underground.

To recall, this all started with inflation over an area centred roughly on Thorbjorn, ‘child of Thor’. Thor, according to wikipedia, is a “hammer-wielding god associated with lightning, thunder, storms, sacred groves and trees, strength, the protection of humankind, hallowing, and fertility”. We get our name for Thursday from it. There is certainly a lot of thunder and hallowing going on at the moment – but the protection of humankind has been deferred to the lesser gods of the Icelandic authorities. They are rather good at it and overnight they evacuated both Grindavik and the power plant. Work to protect both against future lava flows has been started, by building embankments of several meters high. It worked for the flows two years ago, although in one case only because the lava did not actually reach the wall. The sign ‘lava – no access’ appeared to be sufficient. The risk, of course, is that a wall may deflect lava onto some other property, raising questions of liability. But not knowing where lava will surface makes planning more difficult.

The following map was uncovered by one of our commenters. It shows how far lava needs to travel to get to Grindavik from various locations. At the moment there is no ‘most likely’ location along the rift. The further north, the better, obviously.

It started mid October when inflation took off. A sill formed with an inflow of 5 m3/s. Over three weeks, that amounts to 10 million m3, or 0.01 km3. It added to previous intrusions which had been happening since 2020.

Why a sill? A sill is a horizontal magma layer, which pushes up the layers above it. This is what is causing the earthquakes and the inflation. The earthquakes happened at 5-6 km depth, suggesting the sill was just below this. How does it form? Magma in rock has to find a weakness, a crack where it can insert itself. This can happen at a place where two different layers connect, for instance where the lava pile which has build Reykjanes lies on top of the oceanic crust below. The two are already a bit separate and magma can prise them apart. This happened over an area of up to a few square kilometer: the sill would have been 10-20 meters thick, in my estimation. There is minor magma around than is in the sill: it has a feeder system below although we don’t seem to know where this feeder is.

Yesterday the sill found another weakness. To move up, it has top break rock and that is not easy in such an old, cold lava pile. So it looks for another connection which goes up. This can be a fault, but in this case it found something else: an old fissure system. The fissure sits on top of an ancient dike, and this dike means there is a vertical discontinuity between the rock and the dike. The first earthquakes along the fissure were several days ago, but yesterday it took off. The magma began to build a new dike along the side of the old one.

The magma moved up by 1-2 km but mostly moved sideways. The dikes here run along the direction of the rift, which in Iceland is SSW-NNE. Because of the spreading, it is easier for magma to insert itself in this direction. And now it went fast. As of this morning, the dike extended over 18 km, from a few kilometer off short to far in-land. That does not mean the magma has traveled all this distance. It means that the old fissure dike is breaking away from the surrounding rock.

So where is the magma? The GPS shows an indications. As this morning, Thorbjorn has sunk by 40 cm. This happened because the dike is forcing the rock apart. That the sinking is so much indicates the magma has shallowed. How shallow? My guess is 2 km but it is only a guess. Both Grindavik and Thorbjorn are moving northwest, but that is harder to interpret. Where would an eruption be? Impossible to tell. It can be anywhere along the line. The highest probability is in the original location which is east of the Blue Lagoon. There is a bit of a gap in the earthquakes and that can be a sign – or not. The second probability is indicated by the deflation – that would put the eruption in the harbour of Grindavik!

RUV put out the following (again taken from a comment)

The signs of magma movement include significant subsidence in the Sundhnúkur craters, indicating that the magma might be shallow below the surface.

The southern end of the crater row is about 1 km from the nearest buildings in Grindavík and approximately 1500 meters from the Svartsengi power plant.

The Icelandic Meteorological Office notes a substantial change in seismic activity, moving south towards the town of Grindavík. According to the Icelandic Meteorological Office, there is a likelihood that magma movement has extended beneath the town of Grindavík.

The volume of magma involved is considerably larger than seen in the major magma intrusions related to the eruptions at Fagradalsfjall.”

Here is the onset of activity, with M2+ magnitudes twice per minute at one point.

An interferogram (thanks Gaz!)

And here is a list of cameras mentioned by our contributors






View of power plant from Thorbjorn

A Thorbjorn view

A multiview

Live from Iceland has views all over iceland, including:

Fagradalsfjall and

Albert, 11 Nov 2023


Grindavik update by Carl

Grindavik, photograph taken by VC FB regular Roman Zacharij and used under Wikimedia Commons.

I promised everyone an update today, so here is an update about why I and every other volcanologist should go and drink some tea and ponder why we underestimated a volcanic risk. I will get back to this below.

This will mainly just be an update that I will edit as things unfurl, and I will throw in a little prognosis of what will happen, and where it will happen, based upon the situation at 11.00 Icelandic Time on Saturday.


Short Recap

Roughly two weeks ago Thorbjörn started to show signs of an eruption being possible as a secondary intrusion started, and a sill formed where magma accumulated.

On Sunday evening I felt confident that the prerequisites for an eruption was there based on GPS-data, spectrography over seismic data, earthquake locationing, etcetera.

And based on that data I pointed at a possible location for the eruption to break out, if activity had continued like that I would probably not have been far off, nor would IMO either, we are after all talking about as little as 800 meters between assumed centroids from our individual models.

IMO weighted GPS-data higher than I did, I tend to weight Earthquake-locationing higher. Both methodologies are solidly based on science, and give similar results most often, well similar enough to give an 800-meter difference. Something that in the greater scheme of things is not a lot.

Earthquake map by the Icelandic Met Office. Note that there are loads of “ghost-earthquakes” that never happened, this is caused by over-saturation of the system by signal reflections.

Yesterday at around 12.00 Icelandic time, Iceland decided to kick those models in the proverbial nuts and a dyke started to form that was NNE/SSW trending, putting the most likely location of breakout at Sundhnukagigar, East of Bláa Lonid (Blue Lagoon) and the Svartsengi Powerplant.

This later led to the powerplant evacuating the workers and going into remote controlled operations after some sort of minor accident that was probably caused by strong earthquake activity.

That part of the formative dyke rapidly stalled out, and the bulk of the activity switched down the other dyke leg towards Grindavik.

This forced the evacuation of Grindavik Town itself, a decision that was proven to be a very good idea, but perhaps not for the reason it was based on.

Right now, the dyke is hammering away South of Grindavik in under the sea.


What We Forgot

Let us leave aside the risk for an eruption, and the earthquakes, and even the dyke, and instead look at another side-effect of the earthquakes and the propagating and dilating dyke.

Iceland is truly spectacularly good at moving about, it is extending itself in all sorts of interesting tectonic ways. Faults spread and drift apart, micro-plates dance about and rotate… it is a mess of simultaneous movement.

One of those movements have a scientific name, and that is Graben-formation. It is when due to spreading-movement a lineament of land is dropping down into the void created by the spreading land.

Some Graben like the Eldgjá-Graben form sharp sides, and if you have your house on the exact spot where that side form your house will start to lean, or even fall on its side. But if your house is in the middle of the forming graben you might end up with your house remaining perfectly straight if you are lucky.

This happens in large caldera volcanoes; I saw a house topple over in Amatítlan in Guatemala in a single night from this phenomenon. So, obviously it is well known thing among volcanologists, and something we take into our risk-calculations.

This time though it had an effect that I am pretty certain that nobody had considered, but that we will do in the future when applicable.

Let us phrase it as a question. What happens if a Graben form under a town adjacent to the ocean, and the Graben continues extensionally into said ocean?

Let us begin with numbers as of 11.00 Icelandic time, the Graben has dilated 120cm and the Graben floor has dropped a whopping 96cm (I will edit this as often as I can).

This means that conversely the ocean level has risen permanently 96cm in Grindavik. Obviously, it is not the water level that has risen, it is the town that has dropped.

Grindavik is built so that 96cm is not drowning houses, there is a margin to account for storm surges etcetera, but that margin has shrunk with said 96cm, meaning that storms are more likely to cause flooding along the shoreline and in the port.

Obviously, this is now. If the Graben continue to widen and drop it will get worse.

My favourite Graben in Iceland is Eldgjá, it is 8.5km long, 600 meters wide and 150 meters deep. Obviously the Grindavik-Graben will not become nearly that wide and deep, but a meter or two more depth is obviously not out of the question.

So, there is an idea to look at those Volcanic Hazard Maps and see if another town is at risk of Grabening itself into The Big Fishtank in the Ocean.



Station GRIC 4-hour solution. Image from Sigún Hreinsdottir’s page.

Remember that this is based on data at 11.00 on Saturday, so take into account that conditions could change with time, it is a snapshot of “now”, and based on future trends that are realistic and congruent with previous eruptions of similar nature in Iceland.

I am writing the above paragraph so that even Charles Gregory can understand, hopefully, that a prognosis changes over time and with shifting data. I do though not have great hope of that.

Eruptions are statistical games based on data, and the length of a dyke is indicative of where it will erupt. Thorbjörns dyke has two dyke-legs based on the breakout point (feeder), the shorter leg is the one running East of Bláa Lonid, and the longer leg is running out into the ocean south of Grindavik.

On a purely statistical standpoint it is more likely that a longer dyke-leg will encounter a weakness that the magma can use to pop up to the surface.

What we know so far is that the Northern leg up to now remains dry (uneruptive), but there are faults that way that may in turn end turn up to be the weakest spot along the dyke.

There are also faults and weaknesses on the longer Grindavik leg of the dilating dyke, but they are a bit more spaced out. There is though one thing that is probably going to affect things more than everything else.

It is that the ground level is constantly dropping as the Grindavik dyke-leg extends and dip its Grabening foot into the water. This means that the distance a breakout needs to travel to the surface is decreasing since the overburden become increasingly thin.

Let us assume that the top of the sheet-dyke is 2km deep at the breakout point from the sill near Bláa Lonid, as the dyke goes south in Grindavik the height of the overburden drops around the point it hits the water and it slowly get deeper until it hits the continental shelf, and it drops below the top of the dyke. But the continental shelf margin is quite some ways out.

On top of that the Graben itself is fertile ground for an eruption to pop up, and on Graben margins you often get a formation of a crater row, see Eldgjá and Lakí just as a couple of examples.

In other words, based on current data a breakout is most likely from about a kilometre north of Grindavik down to a couple of kilometres out into the ocean.

As magma rushed into the dyke, overall systemic pressure has dropped, so for the moment the pressure is probably somewhat to low for continued lengthwise progress, and to form an upwards directed conduit, but the last is depending on how firm the overburden is and how much resistance it can put up.

Eldgjá Graben, photograph by Andreas Tille, Wikimedia Commons.

The diminishing systemic pressure is why we are seeing a drop in the amount and strength of the earthquakes (11.00), it is though still quite impressive.

As magma continue to enter the system from the bottom feeder conduit from the mantle pressure will though go up, and we will get increased activity again, and probably the expected breakout. This can happen anytime from a few hours, up to a few days.

But, at this point it is pretty much a sure thing that something will pop up.

Here I would like to make a point, normally the initial breakout is 10-20 percent from the furthest point of dyke propagation, it is not clearly understood why really, it might have to do with some sort of fluid-dynamic hammer-effect, but why and how is not well understood as I said.

If that will turn out to be true here, we will see the eruption start outside of the port. It would be a tad ashy as it breaks the surface and “rooster-tails” form, but as soon as it is above the surface ashfall will rapidly decrease.

In other words, do not expect the end of the world, well perhaps the fishermen of Grindavik have a different opinion, for them it might end up as the end of the world.

I have seen people “biggying up” the upcoming eruption to proportions it just can’t take. No, it will not be even remotely near the size of Holuhraun. That being said, judging from magma-influx and previous eruptions a likely figure would be a peak average discharge rate doubling that of Fagradal eruptions.

If memory serves that was 40 cubic meters per second during the fountaining phase of Fagradal II eruption, so perhaps as high as 80 cubic meters per second during the peak hour, and then slowly falling to 10 to 20 cubic meters per second.

If we assume the length of the eruptive episode to be somewhat equal of Fagradal eruptions, we end up with an eruption at around 0.1km3, and that is not a bad figure as sizes go. In other words, it will most likely be a fairly impressive tourist eruption, but nothing more.

If the influx is steady and continue, we could end up with a longer eruption and the amount of magma would slowly climb upwards. At the extreme end of probability, we get a small shield formation that lasts for up to a century, but that is a very low probability indeed.

As a final thing I would mention that I seriously hope that Grindavik will be affected as little as possible, and that the lives of the inhabitants soon can return to normal.


P.S. Charles Gregory, “Told you so”. It is now the third time you have been rude and wrong and gotten “I told you so’d”. I suggest pulling in your attitude and stop trying to bully people. I am definitely unbullyable if nothing else.

1,132 thoughts on “Grindavik dropping into the sea

  1. People who were inside the town on Saturday say they did not see those big cracks and holes, so these are not from the large earthquakes, these came later.

    • I’d question the receding comment? Something being lost in translation maybe or by the character limits on twitter.

      The whole system is under pressure so nothing will recede as such until that pressure is released, presumably by an eruption. If the rift widens/increases in size, it will simply be filled under pressure with even more magma from the root supply. If the supply is cut off before an eruption, it will cool in situ.

  2. The clip of the RUV presenter talking into the massive hole with steam coming out of it was quite entertaining, I tried to imagine what she was saying…

    “Yes, yes, it does look very deep, and dark… oh look, there’s a bit of an orange glow … lovely, lovely, and if you stand just over here a bit closer, you get this lovely draught of warm air… and that beautifully soft bubbling noise… just what you want on a winter’s day.”

    I hope she has good life insurance!

  3. Volcano Watch 2023: Going Back To Grindavík

    The Reykjavík Grapevin

  4. I can’t fathom what’s happening. After the severity and quickness of change on Friday I was expecting Grindavik to have been buried in lava by now. Magma apparently only 800m down. And now there are people wandering about picking up their cats…

    • It did the same with all 3 of the previous eruptions. everyone thought “It must start soon…. well tomorrow….. well maybe it wont happen. Even the experts thought it may not happen. Then off it kicked. I see no reason for this time to be different, most especially because this one has caused so much damage without even sticking it’s head out of the ground. If this didn’t end in an eruption I shall eat pasta the next time my husband makes it. A wild thing to say as I do not like pasta. That is why he makes dinner that day and I have my own meal.

      • How can you not like pasta?
        Think of meatballs like Hekla’s volcanic boulders, marinara as lava and the spaghetti as fissures, and I’m sure you’ll come round.

        • No, I think Swedish meatballs with mash potato (and sorry Carl but I just cannot get used to lingonberry jam with meatballs.) is delicious but pasta not for me thanks. I hate macaroni cheese and I hate lasagna. sorry to all Italians, I love your country, your people and even pizza I adore but no Pasta has always made me feel nauseous even to think of. I know I am totally the odd one out and apologise for my foibles.

          • Hello long lost sister! Greetings from another odd one out – no pasta for me, thank you very much! Especially not with tomato sauce, that’s the mother of all meals not meant for eating.

          • Hello Velvakandi are you my long lost twin?

            I am so happy I am not alone in this world of food fads.

            I take comfort that the late Queen of England said that Spaghetti was not to be served to her at state banquets. Of course that could be that spaghetti is not the most elegant thing to eat in public rather than a distaste for pasta in general. Imagine getting up from a banquet with spaghetti sauce all down your front. 🙂

    • What happened on Friday was that the sill that had been inflating, and accumulated a lot of magma, force fed that magma into the crust in the form of a vertical dyke. The flow rate from the sill to the dyke seems to have been a whopping 1000m3/s, which is why everything happened so fast. Had this reached the surface immediately, we would have gotten some extremely intense fountains. The risk of that happening, and in the middle of town at that, was considerable during Friday, which is why the evacuation was ordered.

      After a while, the sill had lost most, if not all, of its magma to the dyke and things slowed down to a crawl. This has reduced the immediate risk considerably, so people are allowed a very brief visit to pick up their stuff and animals.

      Magma is still entering the dyke, but at the more modest rate of somewhere around 7m3/s or whatever number in that ballpark that is what the deep feeder provides. This puts it basically in the same mode of operation as the previous intrusions under Fagradalsfjall. It will probably still erupt, but that will take a few days. Well, it has been a few days now, so it’s probably getting close – it got a very quick start after all. I wouldn’t linger too long inside Grindavik, but at the same time I wouldn’t hesitate to go in there to pick up a loved pet or some important valuables.

      • Your post prompted a thought. How many times past have high fountains occurring in fissure eruptions been actually due to sill deflation? (at least at the first) I also keep thinking about the geysering of cone #4 in the first eruption, as it became clear that the release of gas from melt was the main driver. I am just curious as to how release of gas from the melt might (or might not) be affecting the dike at Grindavik right now?

        • Probably a good number. The thing is sills can get you incredible hydraulic pressure. Like just think the sill here, it was being pressured under *dozens* of km^3 of rock. No wonder it deflated at 1000m^3/s when an escape opened!

        • Probably in every case that a magma chamber wasnt involved. You cant get continuous high fountains from deep supply, nowhere can produce magma fast enough. So it has to accumulate somewhere first and burst out all at once. A magma chamber is basically just the permanent version of a sill.

          • Is there a remote possibility that the entire ‘line’ as drawn on the maps might ‘rip’ open and be active?

    • Too much space underground for the magma to fill. The feeder reservoir emptied into the rift and ran out of magma. It can still erupt but it will be much more subdued if it manages to do so now. And it’s well possible it won’t erupt. If Krafla is a good example then only half the dikes erupt onto the surface, and the big ones are less likely to do so.

      • Apologies in advance for what is probably a dumb question, but I know next to nothing about this field, (even though I have loved reading this blog for many years now), but what you say seems plausible – which begs the question: if no eruption occurs from this latest episode, when would the people of Grindavik be able to go home? What signals would the civil authorities/scientists be looking for to be assured that the magma underneath Grindavik and its immediate environs had cooled or shifted sufficiently to allow people to return home and carry on with their lives? And what sort of timescale would that usually be?

        I’m assuming that the authorities/citizens of Grindavik would definitely need some kind of reassurance that the magma pool was not being fed anymore by a deep feeder, but even if that was the case, how long could it take for the system to re-pressurise and pose a danger due to fresh magma influx? Any appropriate safety/evacuation measures would surely have to encompass a worst case scenario… Obviously there are many towns/cities/populations living cheek-by-jowl with volcanoes, but are there many communities who actually ‘know’ they are living directly above a magma pool? And if so, what precautions are in place?

        Sorry for such a long post!

        • My guess is that if nothing has happened in a month, it will be very hard to keep the locals away from home any longer. That would be really an uncertain situation. Even a small eruption is much better from this point of view than no eruption

          • Yes, that was what I was beginning to think… That a small eruption might relieve pressure twofold: both in terms of magma buildup, but also socially, because a prolonged ‘limbo’ could rapidly become unsustainable and contentious.

            Thanks for your reply, Albert.

    • So, steam Heating pipes burst? Or groundwater heating? That’s the question!

  5. Does anyone remember how long it took between “quieting down” and the eruption of the past 3 in Fagradalsfjall?

    • The first one took 4/5 days. But I feel like I’ve been catfished by a volcano here.
      Not that inanimate earth processes give a toss what a puny human thinks

    • Wasn’t eruption #3 about 5-6 days or so? I do remember people complaining.

      • Yeah, I’d like to speak to the manager about this delay.

    • Just wait for it, magma influx takes a time to move in so much that the pressure goes up enough.

      Over at Fagra there was 3 lull, 3 quakeswarm/dyking episodes, and then a final lull before going. Took weeks.
      Adjust expectations accordingly.

      • But I thought it had already taken weeks Carl. IF I remember rightly it all started quaking around 26 Oct. So nearly 3 weeks. Well a little less it just FEELS like it has been months.

      • I’m still hoping this is a nothing burger. Still not a great thing to have a massive lump of eruptible magma sitting under a town.

  6. So, steam Heating pipes burst? Or groundwater heating? That’s the question!

  7. The worst volcano in the world. Lots of earthquakes, (With all due respect to the evacuees), lots of noise but in the end I think I’ll move to Io.

  8. Did anyone see what happened to the ship that has been standing off the harbour for the last few days? It was there earlier this morning but I haven’t been watching so much today (day-to-day life intervened) so I don’t know if it sailed away or went into the harbour or is standing further off. I believe it was a Coastguard ship.

    • Sailed off (out of shot) about an hour or so ago. Maybe for a crew change?

    • The captain was in the news this morning. The were going to empty the harbour and the coast guard would escort the smaller boats over the sea.

      • Thank you. I missed it going, it’s a good idea to get the boats away.

          • Yes, I just checked on the marine tracking app and it went for a cruise up and down for a while. It is the Thor – the coastguard boat. There are still a few fishing boats showing as being in the harbour there. Maybe the crews were unable to get back to town to sail them out.

  9. Strong quake, est. between 5.7 and 6.1 according to different stations in Papua New Guinea, 137 northwest of Rabaul in the middle of Bismarck-Sea, depth 10km, 5.43 local time.

  10. My favourite videos
    Aerial view of fissure

    Fireman interviewed right by the fissure

    To those that say it’s not going to happen:

    Well it’s possible
    Magma can remain as an intrusion, without erupting, even if just 100-200 meters deep.

    I suspect the steam is due to proximity to magma, but then certain types of gas would be detected at the crack.

    I think with the widening graben, pressure decreased, so less quakes, magma just filled spaces. But activity might restart again.

    • These people have already worked three eruptions, I’m pretty sure they know what they are doing.

  11. It’s got to be broken district heating pipes causing the steam smoke. If it was volcanic the smell would be noticed and talked about.

    • The broken pipes are in itself a bad damage. Many houses relied on the hot water system. All of this has to be fixed one day … Probably the current damages on Iceland are already larger than Grimsvötn’s VEI4 2011.

      For Grindavik this might get worse if it gets the outcome of Pompeii or Goma …

      • When you see that Grindavik lies at the end of Sundhnujkar fissure it maybe wasn’t the best place to build a town. That said, with free geothermal energy, a thriving fishing industry and most likely arable land for farming it’s easy to see why it was built. It’s one of those places with an expiry date, like Managua or Pozzuoli.

        • It is a safe place during the 800-1000 years of non-volcanism. Maybe they founded the village after the Middle Age eruptions. Now it may be time for a temporary “New Grindavik” on a safer place outside the Reykjanes peninsula. After the 30 years of Reykjanes Fires, they may find a place for a return of Grindavik. But it will look very different in a very different landscape.

  12. This map shows the vertical movement:

    The most negative deformation was in the inland from Grindavik to Blue Lagoon. The map both shows the graben of Grindavik and the horst on Fagradalsfjall’s territory. It is a dwarf version of the Upper Rhine Valley and the Black Forest.

      • Thank-you Squonk! The link didn’t work as I wanted.

        The word “Lodrett” (vertical) sounds similar to German “lotrecht” which applies to a “Lot” (Plumb bob that’s historically used to get a vertical line.

        The most vertical movement is between Grindavik and Thorbjörn. If lava erupts there, it would likely flood half of Grindavik and do an ocean entry quickly. It would be the first ocean entry in the Atlantic Ocean since La Palma 2021. When did Iceland do the last ocean entry? Surtsey and Heimaey clearly were the most recent events. Otherwise Bardarbunga occasionally did prehistorically an ocean entry on Iceland’s south coast.

        • Bardarbunga’s last ocean entry was “8600 year old Þjórsá (Thjórsá) lava, flowed 130 km to the south coast of Iceland.” It’s interesting that Bardarbunga nearly did ocean entries on both sides of Iceland. Thorsa did an ocean entry in the south, while to the north lava stopped 15km before the ocean.

        • Iceland has many “recent” (Holocene) lava fields by the sea

          Plenty of ocean entries in previous Reykjaned, Krisuvik,
          Hengill volcanoes, some with impressive lava flows!

          Laki and Eldgja reached the sea, due to large extent of lava flow

          Bardarbunga did a 250km lava flow 9000 years ago and reached the sea

          Hekla nearly did it too

          There are lava flows that might have reached the ocean in north Iceland thousands of years ago.

          Snaefellsjokull reached the ocean several times.

          • Really impressive what Bardarbunga can do, if it goes big. 2014-15 was moderate compared to big fissure eruptions.

            Also Katla is able to do big fissure eruptions like Eldgjá. There the way to the coast is not as long as for Bardarbunga, but effusive eruptions are more rare.

        • Could be. Rift propagation. Doesn’t mean there won’t be volcanism though.

      • This is a really cool image. It shows how Torbjörn and essentially the entire old fissure system (sudu-something?) has been displaced vertically.

    • Nice. You can see the Thorbjorn sill deflating, clearly involved in supplying the dike, but seems a bit too small maybe there was a more substantial source.

      Fagradalsfjall is more of a tuya than a horst.

      • I wanted to apply to “Fagradalfjall’s territory” that includes the plain between Grindaivk and the tuya. All the red part on the map. The graben pushes the land to the east and causes a uplift. The whole South Coast road east of Grindavik sits on Fagradalsfjall’s and later Krysuvik’s system. It is outside the current intrusion of Reykjans-Svartsengi system.

        • The magma will decide. The composition used to differ between the two systems. Of course, Krysuvik and Svartsengi may no longer exist and the new kids on the block are taking over, with their own magma.

          • Svartsengi seems likely to be at least comatose, this is why I stubbornly call this a Thorbjörn eruption, after it had the initial intrusion and not Svartsengi.

            Krysuvik on the other hand is alive and kicking and unlike everything to the west seem to have even a diminutive little magma chamber that was mapped on during the last intrusive episode. Probably a complex sill system and not a reservoir in the typical sense, but it is permanent and happily accepts new magma from time to time.
            I would call it a tourist central volcano since it is so small and gosh darn cute. 🙂

          • Krysuvik unlike Fagradalsfjall is able to do maar eruptions. There is more water around. Krysuvik can be more (phreato-) explosive in some cases.

          • To be honest Thorbjorn looks like just another fissure in the Svartsengi system, only it was formed subglacially. Calling it a separate volcano seems a stretch too far especially when fissures on both sides of it are attributed to Svartsengi, which itself is not always considered separate from Reykjanes to the west.

    • That is svartvengi The geothermal plant. Maybe steam got more noticable as the day cools down.

  13. There’s something smoking / steaming on the top of the hill in the Langihryggur cam. I’m sure that wasn’t there before?!

  14. Nothing to add…. just wanted to say: i’ve missed all of You and have really enjoyed everyone’s comments. Little like a reunion. Thanks! Best!motsfo

    • Hi Mots! [Waves hand enthusiastically] Almost like the old times.

    • Hey Mots
      Just like old times!
      I wonder how many of our friends are back now?!

      • Great to see you Carl!
        ´Kilgharrah’ and I both send a huge thank to you and Albert … Volcano Cafe never disappoints!

        • It is now mainly Albert pulling the weight with me being the “guest lecturer”.
          Life has sort of sidetracked me for a while, but Thorbjörn brought me back.

    • Hello once again Mots! I do hope you are well. Very nice to hear from you!

  15. What’s the steam-like substance coming out of that crack in the video “Why Nesvegur is closed”?

    I have heard that in Iceland many municipalities deliver hot water in pipes to the apartments (presumably from Svartsengi geothermal power plant in this case). Is that steam just what is escaping from those broken pipes?

    See also the interview of Gregory de Pascale (one up from the previous video, “Grindavík damage reminiscent of Christchurch”), where he replies very diplomatically to the interviewer’s question: “Do you think it’s wise thing to let all these people in here, today?”

  16. Question to the scientific community.

    Right now is the most critical period of a fissure eruption when things apparently go silent and all we can do is wait. Surely cannot some type of scientiic instrument be invented to deal with this situation so as to give us some idea of what the magma in the dike is really doing. Why has this part of the fissure eruption become the least scientifically understood? I keep thinking of an acoustical instrument, but perhaps the noise is way too high masking out the subtle signals from magma travel in the dike??

    • I sometimes wish that the history of physics (and science in general) was taught so that, as laypeople, we at least had an understanding of the how and why. Certainly it would be more than useful to know what the magma is ‘doing’ however, there are serious problems with getting meaningful data through many 100 of metres of rock, indeed it is more than amazing the useful information that is gleaned with the instrumentation available. Maybe it would be useful to study some basic principles of seismology to appreciate what can and what cannot be gathered from the technology available.

    • Distributed acoustic sensing could have some potential in that it can detect extremely weak seismic signals. But most obviously, Ground-based radar interferometry could be able to capture the intrusion in real time and great detail. So there are certainly ways, I think. Whether they are cost-effective is a different matter.

      • It is the cost part which might be the hang up. See

        Electromagnetic Monitoring of Miyake-jima Volcano, Izu-Bonn Arc, Japan: A Preliminary Report
        Y Sasai, J Zlotnicki, Y Nishida, P Yvetot, P Morat, H Murakami, Y Tanaka, Y Ishikawa…
        Journal of geomagnetism and geoelectricity, 1997•
        Miyake-jima Island, about 150 km south of Tokyo in Izu-Bonin Arc, is one of the most active basalt volcanoes in Japan. Big eruptions took place in 1940, 1962 and 1983. In this volcano, magma ascends towards a depth of a few km below the summit without any significant earthquakes or deformation, then gives rise to flank fissure eruptions because of the blockaded vent just beneath the summit crater. Hence eruption forecasts are very difficult to make with mechanical methods (ie, seismic and deformation measurements) alone. We have developed an electromagnetic monitoring system of the volcano that combines magnetic, resistivity and electric field (SP) measurements.

        I am trying to find similar papers now.

      • See this one too –
        Changes in the electrical resistivity of the central cone, Mihara-yama, of Oshima volcano observed by a direct current method
        T Yukutake, T Yoshino, H Utada, H Watanabe, Y Hamano, T Shimomura
        Journal of geomagnetism and geoelectricity, 1990•
        We have repeatedly measured the electrical resistivity of Oshima Volcano using bipole-bipole electrode arrangements across the central cone, Mihara-yama. Apparent resistivities obtained by three different pairs of electrodes varied according to the vicissitudes of the volcanic activity. Changes associated with the eruption on November 15, 1986, were particularly remarkable. The increase of the apparent resistivity obtained by the electrode pairs the nearest to the central crater vent became noticeable about one and half years before the eruption, and one day after the breakout of the eruption the apparent resistivity reached a value 17% higher than its original resistivity value. The increase of the apparent resistivity observed with these electrode pairs has been interpreted as a topographical effect caused by the ascent of magma through the volcanic vent.

        Can’t you just see Icelanders trudging long wires across the area? Something like this has been done at Piton De La Fournaise, btw

        • From what I remember of my days in mining exploration geophysics ,
          I would only expect this to work well within 0.5 km depth … Magneto tellurics might be a better way to go for deeper penetration but needs acquisition and processing time …

          • Robert, I suspect that this is what NASA used out west in the USA a couple of years ago, when I watched their U2 and 747 flights from CA. They made big long loops over the volcanic areas in the west, it was obvious that they were checking for underground activity or possible activation. One night in particular they made a very careful run over Craters of the Moon in Idaho it was very obvious watching from FlightRadar24 what they were doing.

          • Pole dipole array with 200 meter dipoles, to n=15 or so would do it, resistivity data to 800 m or so would be no problem, with fullwave acquisition and possibly remote noise filter might even get decent chargeabilities. Might be tricky getting good contacts with no soil to speak of though, and that would apply for MT as well. Basalt resistivity should be high enough to maintain signal levels but close to harbour not so good though as the saltwater saturated groundwater will absorb the signal. With MT you can get as deep as you need, but yeah its a pita to process. I can imagine the shaking wont help either the coils are sensitive enough to pick up nearby trees swaying.

          • Forgot to mention that culture also really messes things up for both methods pipelines/powerlines etc.

          • Also, magnetotellurics aren’t overly impressed with powerlines…
            Which is a bitch when you need to do it in a city…

          • Welcome to my dayjob…
            Doing magnetotellurics, resistivity gravimetric anomaly & magnetic anomaly, data gathering near ginormous powerplants…

  17. This quake around midday. O depth. Would I be correct in assuming that would be a good sized rock fall?
    13.11.2023 12:52:04 63.856 -22.430 0.0 km 1.1 99.0 2.0 km NNE of Grindavík

    • I saw that earlier. The actual depth from IMO is 0.007 km or 7 metres!

      TIME 12:52:04 2023-11-13
      MAGNITUDE 1.14 mlw
      DEPTH 0.007 km
      AREA: Suður­land – Reykja­nes­skagi – Svartsengi

      53 STRIKE
      81 DIP
      -171 SLIP/RAKE
      Seismic moment: 1.38e+11

  18. Hmm.

    “There are no signs that magma is moving closer to the surface on seismic measurements, says Benedikt Ófeigsson, professional director at the Norwegian Meteorological Agency. The magma is still collapsing according to the latest data. The biggest slide at Sundhnúk. As it stands now, there is only a similar probability of an eruption.

    He asks people who are allowed to go to Grindavík to be careful, as new cracks could form.”

    • This current situation is bringing out the different opinions of the experts, definitely.

  19. It’s just a *little* bit annoying that the BBC is still claiming this is going to be Fagra 4 and not Svart 1, and of course they can’t resist trying to suggest we could get Eyjafjallajökull 2.0. 🙄😡

    • The BBC used to be a very good news source. Recently not so good. In fact I seldom watch it and feel deeply injured that I still have to pay a huge licence fee for a channel I extremely rarely watch. They are not alone in being useless. the commercial channels are as bad or worse but I dont have to pay them for not watching the rubbish they churn out.

      • I think most people feel the same these days, me included, I don’t watch anything mainstream anymore.

    • and google keeps mislabeling things at Norweigan, when clearly they’re not

    • Hmmmm…the BBC….eh?? …….and one contributor to a FB group was laying ‘the sky is falling’ dis-information rap on the heads of FOX news.

      • “the sky is falling” is Daily Fail.
        If there is a disaster to be biggied up or misunderstood, then the Daily Fail is your goto choice.

        They are probably calling this little upcoming eruption the Deathmageddon Disaster Eruption that will cause the new iceage, or some such.

        • If it’s in the Daily Mail, I would begin to doubt the existence of Iceland and volcanoes.

    • They all finally figured out how to spell Fagradalsfjall by memory and now dont want to learn another volcano. Silly really, Svartsengi is a lot easier to say than most Icelandic volcanoes are, but Sundhnjukargigarhrod is a different matter… Especially as writing it that way isnt even going to help you say half of it 🙂

      • I’m still having great hopes for either Úpptyppingar or Geirvörtur having an eruption.
        I so look forward to hearing US news presenters saying those names, but for a slightly different reason.
        I am most likely a bad person 🙂

  20. Here are today’s quakes, the australian way (top is bottom, bottom is top). If you drag the gif to your desktop or you save it somewhere, you can see the animation as an infinite loop. Like your thaughts…

  21. Could it not be really simple?

    Magma drained into dike
    Dike is very big, the existing magma from the sill did not fully fill it
    Magma will continue to fill it up slowly
    When full, magma will come to the surface

    How about that? I think it would explain falling seismicity fairly well.

    • I’m with you on this although I have absolutely no qualifications in this field, just a bit of an interest. The original feed location – probably the site of greatest uplift – was just west of the Blue Lagoon but the EQs were happening under Thorbjorn (more or less) and then migrated east. This seems to me like the magma feed broke through to the east as it was prevented from going upwards by a really thick and solid crust of old lava. As it broke through to the existing old dike, we saw the events which lead to the evacuation of Grindavik. Supposing that the original feed is still feeding (so to speak), any/all new magma would surely be moving east, following the earlier migration as the pathways though are now open. Whether the magma breaks the surface will be entirely down to the lifespan of the feed e.g. whether that upwelling has finished or if there is more to come. Where the various conduits are open and magma is not being held back under pressure as it did before the Grindavik situation took place, there would be fewer quakes and hence very few EQ pointers to show whether new magma is still entering the system, just a few quakes at the 4-6 km level as before (which is what we’re seeing a few of still). However, a smaller number of EQs might be because this event is slowing and there might never be an eruption, just a fatter dike than before.
      Happy to be shown just how limited my understanding is by people more edjumacated than I 🙂

      • Wow! I havent heard that word…edjumacated… for so many years I had forgotten about it. Part of my mispent childhood.
        What makes me think that a potential eruption will continue was what a geologist (who was also in the town when people were going for ‘valuables’) said to a reporter. That was that he had been monitoring these ‘cracks’ in the ground since Grindavik was evacuated. He then went on to say that these cracks were deepening and widening with some going upwards and some down. If movement is continuing in these fissures then things are far from becoming stable in that area. Multiply that along the length of the faulting area and that appears to me that magma is still moving however deep or shallow it may be. Again, as others, this is not based on specialist knowledge but just seems to be basic commonsense to me,

        • I think that makes sense: ongoing surface changes show that magma is still moving around below decks and that implies that the feed mechanism is still going. If it goes on for long enough then the magma could reach the surface as there’s only so much the old fissure/fault/dike can contain before the magma goes elsewhere, probably upwards. We know that magma got to the surface about 2,300 years ago, so it would seem pretty plausible for it to do the same again. It just depends on the lifespan of the feed and how much magma is yet to be introduced into the system

      • Monday
        13.11.2023 21:09:50 63.910 -21.930 4.9 km 3.6 50.5 7.1 km ENE of Krýsuvík
        13.11.2023 21:09:23 63.926 -21.926 5.9 km 3.4 90.13 8.1 km ENE of Krýsuvík
        Two more +3 qukes ENE of Krysuvik Is this just stress from further west?

    • I’ve had a similar thought: pressure has been building in the sill, both from the inflow of magma and the strata above it, for some time. Like a hot water bottle under a stack of bricks, when part of the sill “failed” – i.e., when it spread out enough to break the rocks separating it from the crack of a deep pre-existing fault – the pressurized magma shot into that fault, forcing it open to form a dike until the pressure matched what remained in the sill.

      Any thoughts on that mechanism?

    • If I might make a suggestion here, draining usually means things going down to the center of the earth, we actually have magma exiting upwards from the sill pond into the dike, except this time it seems to have pushed much more than the current volume can fill, hence the lag. But I agree with you, that we’re all waiting on magma to fill the space.. which begs the question, just exactly what fills the dike before the magma can reach it? gas? vacuum (facitious 😉 but I keep hearing geologists say that dikes can crack open faster than magma flows, so do they get filled with gas? or vapor or what?

      • Gas mostly, nature abhors a vacuum.
        But the gas is compactible, and hence we get a Graben sinking slowly down on the leakey gas suspension.

        • which would lead to the blowholes and sandy debris by some of the drop-downs, if you noticed.

          • Quakes alone can do that. That big pair of Midwest quakes a century ago caused huge sand geysers, without any magma dyke being involved. I’m not sure of the mechanism, though. It might involve thick, aerated soil and liquefaction so the air can rise as bubbles, in which case the Midwest has that sort of soil but Iceland most definitely does not … Now, blowouts above breaks in the steam pipes from the power plant might also provide a non-magmatic explanation inside the city limits and between it and the plant.

    • I often wonder about the sanity of someone who would walk up to a hole in the ground and start to stamp around it! I wouldn’t walk within 4 metres of it.

      • Indeed, I would be terrified to end up in the earth too early. A thousand years of looking into abysses made these Thule men supernaturally brave. … Or he just didn’t think about it …

        • well, he was already in the cemetery, so what’s the harm? 🙂

      • I did this once while climbing the South Sister in Oregon USA.. because there was a hole in the snow. Turned out that we were very lucky NOT to fall in a 30 ft deep crevasse of ice which would have surely ripped off our coats, etc, had we fallen, and we would have been lodged into the crevice tightly unable to ask for help, up on the 9500 ft level of a volcano. This is why you take mountain poles and poke the surface carefully.

      • Actually, I find that scary.

        On the earthquake chart, if you extend the time, you see four relatively local, circular places where quake activity centers around over time. Which to me means the magma is rising there, straight up, eating through the rock slowly but surely because that’s where it has to go, physically speaking.

        And the largest of those spots (its circumference) coincides rather precisely with the area in western Grindavik that’s been dropping. And it’s dropping because the magma rises (just applying an observation I find logical here). It may seem illogical at first but makes sense: changing the below from solid to fluid allows the above to drop because a fluid is more pressurizable than solid rock, thus the weight of the above pushes the fluid down, increasing the pressure. This in turn however means, due to the increase in pressure, the heat will eat through the remaining rock above it faster and faster until the equilibrium changes in favor of pressure, and the above gives in, and the pressure releases. It will be a spectacle, albeit an unfortunate once-in-a-century one.

        I’m just glad they got BOTH the humans AND the animals out there by now. The fact that they let people back in to get the most important stuff means they understand pretty darn well what’s going on. The sooner they did that, the safer they still were, thus the hurry.

        I bet my horse (that I would have to buy first) that we’ll see an active fissure right in town. 🙁

        • That was also my question. Maybe there are cracks and the golf club cracks belong to the eastern border of the graben.

        • I don’t entirely agree with the liquid hot magma eating away solid rock. I watched both the Iceland eruption lava channels and the La Palma eruption lave channels, and the hot lava really had a rather hard time of it, reliquidfying the solid lave blocks. I will agree that hot fluid lava will eat away solid rock, but quite slowly.

      • The deepest part of the graben seems to be about 250 m wide. The offset on the east side is not mapped as having surface fracture. Why would that be ?

        • Let me try again (and forget the answer above). Perhaps there are indeed cracks to the WEST of the city, but not yet available on images. And maybe the golf course cracks belong to that WESTERN edge of the graben?

          • I think that I misread the map….it is the reddish coloured areas that are higher and the brighter yellow that subsided the most. If so it looks like the west edge of the graben is off the map, and the graben is much wider than 250 m.

          • I saw a figure of 500 meters wide from the golf course to the city crack, if true this one might drop quite a bit more.

        • @Glenn: springboard 😉

          You have one side that’s sliding down (more) than the other which means where the sliding downwards motion occurs you see a sharp drop in height. The opposite side is only bent downwards, at least up to a certain point, so there is not a single crack. It’s stretching out the stress of the downward bend over a larger distance. It is kind of swinging like a springboard on the other side.

    • Luis, on that very nice map, can we locate the GRIC GPS station or is it too far north? This might give us some more insight. The station is right on highway 43, a bit north of the last looping road on the upper left which comes to the highway.

    • Luis, I was comparing the new map with the GPS readings from GRIC and THOB. One thing I cannot figure out, is where all the Northward movement is coming from. Normally we’d expect movement away from the centerline of the fissure, perpendicularly, but the northward movement is not too far off from the fissure direction. Any ideas why things went north on the west side of this graben? I am resisting the idea that something just south or at Grindavik shoved things north.

      • I would stop resisting that notion…

        Come join the Graben side, we have cookies.

      • Something north of the graben could pull it northwards.

        There is an alternative scenario for the cause of the graben …. a lithospheric tear caused to accommodate nearby magma ascent. That does not preclude magma from coming out of the tear but it means there is a lot somewhere nearby. I hope I am wrong.

      • OOPS.Not a good place to have built. Understandable to a degree when the last time eruptions in the area was in the 1300’s, or did I get that wrong.

        On a far more minor scale it reminds me of something that happened to someone my husband knew. This couple had bought a house with a walled garden but two bricks from the lowest course of the wall were missing with a lintel over the top. They thought it looked unsightly and replaced the bricks. 7 years later after a particularly wet winter their garden flooded. Those bricks were missing for a reason, as a spring had come up in the garden and almost flooded the house.

        Sometimes warnings are there if you look for them.

        • It was probably OK when Grindavík was a small fishing port.

        • There is no good place on earth to build a city before climate change … there are million ways to get disasters by that.

          • And even if you find a spot that is reasonably safe from natural disaster you will find that something comes slaming down from the regions of Albert’s day job.
            Tunguska was theoretically about as safe as a place can be… that did not help.

          • That’s true. However, I prefer any threats of nature to threats by human waste (f.e. the present plastic garbage disaster around the world). Nature is somewhat innocent, it does what it does as it did millions of years with reliable laws. Sometimes it helps, sometimes it kills.
            Disasters by human civilization are different, there is always a level of guilty and responsibility in them. Also they often are ugly.

          • If you overlay all the USGS Hazard maps, earthquake, hurricane, tornado, flood, etc., the place in the US least likely to suffer a natural disaster is Pueblo, Colorado.
            The greatest cause of death there? Probably boredom.

          • I agree with preferring natural disaster to human ones, although I far prefer the kind that give you enough warning to get out. Natural tend to be one-and-done; man-made tend to be continuous. I live too close to Weld County, Colorado, the land of “Unconventional Drilling Planned Right Into Your New Neighborhood!” Move into your new house just in time to worry that it might collapse beneath you! SERIOUSLY. I KID YOU NOT. (Curious? Parkdale planned community, Erie Colorado — on the Boulder County side no less.)
            I’ve also learned, though, that natural disasters, after obliterating neighborhoods, leave behind stuff that makes the land not OK to build on.
            I probably should have moved to Pueblo in the 1st place.

        • It also happened to the Romans, and they were excellent builders:

          “The city overlooked the Rhine, was backed by the Jura mountains and had two small rivers on the west and east side. It was a very well devised defensive location. It was also a crucial location for traffic, as the main route through the Rhine graben ended here. Augusta Raurica became much more than a fort. It quickly grew to become a wealthy trading centre with a population of 20,000. The amphitheatre could seat 8,000!
          But although it was well defended against enemy armies, it was not as secure against mother nature. Nature went on the attack when a powerful earthquake hit the city.”

          They couldn’t know that they built a fort in a graben. That graben has a width of 30 to 40 km though. So sometimes you only know after a place was built (and shaken) up.

          I have a very stupid – maybe – question. How can it be known that there is magma under the area at all? Temperature measurements?
          I was wondering whether it could just be an earthquake. If yes it would be the rare case of an earthquake without major damage.
          The question popped up in my head first when I read “graben”.
          Sorry for the q in case it’s stupid.

          • That interferogram is very hard to explain without a dike; as is the spatio-temporal pattern of Friday’s earthquakes in the region. And a dike is pretty much impossible to explain without magma.

            No apologies needed, though. Nobody is born knowing all this stuff. 🙂

          • Well, in the wee hours in 2011 me and Lurking developed the definite alternative theory that explains everything we see.

            There is not a single thing in volcanology that can’t be explained by inserting Graboids as an explanation.
            So, either an infestion of Graboids burrowed through at depth, or we have a Graben.
            We had way to much fun with that alternate reality theory.

          • Depends how deep it is. Magma has lower density than rock, so if there is magma underneath the land tends to rise. You are looking for a bulge in the landscape. Grabens do not normally have magma – they are tectonic – but where they do, again a dome builds in the graben. Earthquakes can trace magma chambers through seismology: the velocity of the wave changes and transverse waves don’t pass through liquid. Magma a few km deep can lead to CO2 emissions, and a few hundred meters deep can give SO2. Geysers do not indicate magma, but show circulating hot water. Geyser fields occur in very stable systems and indicate that a caldera is unlikely to erupt.

        • I dont think the vikings considered the threat of volcanoes when thet settled in Grindavik around year 900 ad.

  22. For those who like their data served raw, with instant gratification:

    To the North, near Vogar:

    To the East, on the Eastern side of the Krýsuvík-Trölladyngja system:

    Map of the location of the two Raspberry Pi streams (yes, there’s plenty more around Iceland and beyond):

    The frequency spectrogram is the one to watch. With magma on the move, those low frequencies (generated by resonance in the conduit walls) will thicken and become saturated in colour. There are other signals to look out for as well – Carl can explain them better than I can! Beware of noise and random artefacts though, it is raw data after all…

    (It may have been linked before, but there have been quite a few comments of late and things get lost quickly. I’ve spent more time un-spamming new commenters and deleting the actual spam than commenting in these past few days. If I get a chance this week I’ll stick as many links in a ‘current event’ page on the top menu bar so they don’t get lost in the comment flood)

    This dragon needs some sleep now…

    • Beardy, I did install both the ShakeNet App and the EQInfo app on my Iphone 14 but I found to my surprise that the Raspberry Shake Net was limiting my earthquakes to mag 3.5 or above. I suspect that this is due to the fact that the app will be overloaded if we drop the quake magnitude. EQInfo wasn’t that helpful, I could not get it simultaneously filter by both area (geophysical boundaries) and by magnitude of the earthquake event. But your post is almost exactly what I would suggest to the readers, so thank you for your post.

  23. How much can you learn about what is below from what is on the surface? Like here we have a graben close to 1.5m deep and probably 2.5km wide judging from where the crack in town versus the golf course crack. Like in theory I assume, though might take unrealistic knowledge of underlying rock, a sufficiently mathy person could calculate a rough cross-section of the dike based on the volume and width of the displacement zone.

    • That would not give the correct size of the dyke, the Graben caries a much larger net volume than the Dyke does.

    • I’d assume that the volume of the dyke isn’t mediated 1:1 until the surface. Also we have to consider that the volume is under a lot of pressure. 1kg magma at 1km depth has fewer volume than 1kg lava without pressure on the surface.

      The crack in Grindavik is the border between the “Graben” (subsidence) and the “Horst” (uplift). A photo of the cracked road clearly shows how one side is significantly higher than the other part. So the border is in parts very abrupt and vertical. The Golf Course looks like it sits on the western border of the Graben.

      The current east-west movement increases tectonic stress on other parts of the peninsula. Kleifarvatn has got a 3.8 earthquake. Also Fagradalsfjall may get tectonic quakes.

      • No. The crack is between greater and less subsidence. There will be not any eruption in Grindavik. Subsidence means that magma pressure is falling here. Maybe in Fagradalsfjall again.

      • Taking a number of 2.5 km wide for the graben would mean the dike is about 1 km deep maybe a little deeper. That is of course assuming magma isnt slowly pushing up without really rifting, but that likewise is also not hoing to make a big eruption either.

        The thing that is always concerning with this scenario is that if the source is still going then an eruption is inevitable, a dike exists now and if magma keeps flowing in then the rock wont offer enough resistance. The big caveat is if magma is flowing all the way to the dike or is pinched off and will refill the sills. If the former is the case then something us going to show up eventually, but ut will be probably like the padt few eruptions we have seen. If the former is the case then everything will be quiet for a few years, but then the sills will burst into the rift once more, and this time will find that it is filled with magma… the only way then is going to be up… at 1000 m3/s…

        The big thing really is that no matter what, unless the magma source moves somewhere else one of these things is going to happen in the next few years. And the longer it takes potentially the worse the outcome 🙁

    • Don’t they mean that pressure waves in the water hit the ship and converted to sound waves?

        • Agreed, but was there any transmission via water? I would think that both water and air were involved, agreed?

        • Yes, but the pressure waves behave a tad different in a non-compresible fluid and in air, so the transition is somewhat interesting as it goes through a steel hull.

  24. A fun fact.

    They evacuated Grindavík Friday night during all those intense earthquakes, only to discover the next day that two people had been left behind.

    Two people had simply slept through the whole thing and had no idea they were the only people left in town!

    I’m just curious to know what sleeping meds they are using.

    • Trust me, I can do that au naturel without pills.
      Once I slept on a broken loading ramp on a Herculas troop transport, the gate was partially open, so I just tied myself down and slept well for 4 hours.

  25. Read the following in an NPR article:The Icelandic Meteorological Office said Sunday there is a significant chance that fire will soon break its way to the surface. It is also likely that mercury will appear on the bottom of the ocean.

    I am wondering about the reference to mercury. Is that correct? Or is that a typo?

    • Mercury is magma, it is because magma in Iceland is ‘kviksilfur’ and that gets translated as quicksilver, which is another name for mercury. Not sure if it is actually a cognate but it is interesting.

      So mercury = magma. Soda = gas and eruption, which is probably not so hard to connect.

    • I think someone earlier said mercury is probably a mistranslation of magma?

      • Thanks. I went to the artlcle on the NPR website and I see that paragraph has been rewritten and no longer mentions mercury.

        • Maybe someone at the NPR actually reads Volcano Cafe? (just a hope 😉

          • It’s a Google translate error, it still hasn’t figured some things out

  26. Another idea outside the box – can we put CO2 sensors in the graben? They are affordable. We could add SO2 sensors too. Wouldn’t the volcanic gas emissions be a reliable guide to let us know the nearness of the magma in the fissure?

    And yes, I know that there are thermal hot spots all over Iceland, but still, wouldn’t this be a viable idea on tracking down magma nearness to the surface in this waiting period we are in now?

    See as a very recent paper on this.

    • In the past we used this to track nearness of magma and possible activation of volcanic centers.

      Leak Detection with Helium – The Portable Helium Detector PHD4

      The PHD4 is an easy-to-use and versatile solution to detect leakages by sniffing Helium as a tracer gas.
      It’s both, very dependable and truly portable. Therefore it can be used in a large variety of environments, such as underground storages or at large biopharmaceutical vessels, to trace even the smallest leakages.

      This is why I am asking if gas sensors might be a way to get a handle on this situation?

    • Gas sensors are most likely deployed there, problem is that IMO is not sharing the data with us.

    • We ain’t no fair weather weather volcano friends. We got your back, young dragon. You rest up all you need. Just do a few 3+ EQs every now and then and we’ll see you opening night.

      • That would have been to the general thread if I had done it right. Def pilot error.

  27. Wow! I just watched the video of that crack. Reminded me of the start of the otherwise silly movie 2012. Good thing they got everyone out of there. Those buildings straddling the crack are badly compromised.

    • 2012 was truly ridiculous. The earth split apart and there was lava between great cliffs of land in California. There was a 20,000 metre high tsunami that somehow travelled inland thousands of miles and hit Everest. The earth’s tectonic plates magically shifted about like they were on roller skates. All because of neutrinos.

  28. I have a question for our Icelandic readers.
    Are the powerlines in Grindavik on electricity poles, or on dug down electric cables?

    The reason I am asking is that if it is on poles it would be far more vulnerable to storms, and if it is dug down then it is more at risk for things like huge honking Grabens forming, pulling on said cables in the ground.

    Regardless, the power Grid in Grindavik must be very sturdy to not have broken down completely by now.
    I was expecting lights to start flicker and die 2 days ago.

    • I’m an American who has lived in Iceland for 7 years. All electricity is transmitted from dams and geothermal power plants by high-tension wires above ground. They are ugly, but strong and much, much cheaper than trying to dig trenches through solid lava. The electricity goes to a sub station, then is transferred through buried tunnels to the houses. In Grindivík there has been some power loss due to cut underground lines. In small communities hot water is generally pumped up locally, but electricity comes long distance from a dam. The capital region gets its hot water and electricity from a geothermal plant in the Hengill area (can we just pause and think what would happen to the economy of Iceland if Hengill erupts…). All of Reykjanes gets its hot water and electricity from Svartsengi. Cold water comes from completely different locations – except for Reykjavík it is usually a closer source. Most every building in Iceland has three different inputs – electricity, how water and cold water. The hot water is separately piped from the cold water. Hot runs to the taps, but also through the radiators before it flows out through exit pipes. To complicate things even more, the impact of lava will be very location specific because of geography – they like to run the wires and pipes side by side to make repair access easier, but it is often not set up that way. The power lines from Svartsengi are above ground and go out in several directions in straight lines. The hot water pipes are also above ground and follow the contours of the land because they are impacted by gravity. One pipe heads south towards Grindivík. The main pipe heads northwest towards Keflavík. If there is an impact on the electrical system they have the ability to work around as the whole country’s grid is interconnected. The hot water is the most serious concern. If Keflavík loses hot water there will be no heating available all winter for 30,000+ people and the main airport. No one has electric heaters or boilers. This will be a long-term crisis and is why they are prepared to go to heroic lengths to save the power plant. Icelanders are expecting that these eruptions will continue for the rest of our lives. The long-term infrastructure issues are at the forefront of their minds.

  29. Tuesday
    14.11.2023 07:35:14 63.820 -22.460 2.1 km 3.7 50.5 2.3 km SSW of Grindavík


    Sucks .. the Gulf Stream have broken down again and Northen Europe is in a deep freeze, going to get quite chilly the comming days in forecast models and I guess Carl wont like it that escaped the Arctic Lapland years ago for milder weather in the south, and now Malmö will be deeply frozen

    But I guess that Chad likes it when its crisp and cold and refreshing and I guess Tasmania never gets like this either 😉

    But I myself does prefer a white crisp winter rather than rain and muck and stink, Iceland is mucky too in winter but that only makes its landscapes more scenic with the gloom

      • Where is Carl now? In Iceland? well an eruption may not arrive in days or weeks even

  31. Not volcanoes but fun physics, Expert answer
    ”On Jupiter at a point in the atmosphere where the pressure is 1 bar – the same as the surface on Earth, the temperature is -70 degrees C. The density of the atmosphere on Jupiter, which consists of 9% helium and 91% hydrogen by volume, is 0.2 kilograms per cubic meter. The density of pure hydrogen at 1 bar pressure and -70 degrees is 0.11 kilograms. So the lifting capacity of a hydrogen balloon would be 0.01 kilograms mass per cubic meter – a hundred times less than the lifting capacity of the helium balloon on Earth.

    Because of the increased gravity, the load with a mass of 500 kilogram would weigh 1250 kilograms in the Jupiter atmosphere at 1 bar pressure – but the lifting capacity of the gas would increase correspondingly.

    The 500 kilogram mass load would require a gas volume of 50,000 cubic meters. Because of the huge increase in size, the mass of the balloon structure would be greatly increased – drastically reducing or eliminating the possibility of carrying a payload.

    Balloons on Earth can also work using heated air. The air is usually heated by a natural gas flame. The products of the combustion are 67% water vapor and 33% carbon dioxide. Water vapor is lighter than air and so assists the lift.

    On Jupiter the obvious heat source would be oxygen, which would burn in the hydrogen atmosphere. But the product of combustion would again be water vapor, which is about eight times denser than the Jupiter atmosphere, seriously reducing lift.”

    Well that also means its very difficult to fly an aircraft probe on Jupiter, at least in the upper troposhere due to the high gravity and that hydrogen thats so light have so little mass, so generate very little force on the wings, you have to fly incredibley incredibley fast at the 1 bar level to get any lift at all, and airliner with oxygen fuel tank woud probaly have to go up to 3300 km an hour to stay aloft at the 1 bar level.

    But deeper down the pressure and density gets much higher so flying and hot hydrogen ballooning become much easier with increased air density, but you needs to get down to 12 to 15 bars before the hydrogen mix becomes as dense as Earths atmosphere at 1 bar. To get the lift of 2 bars nitrogen on Earth you needs to go down to 22 bars on Jupiter I think and there the temperatures starts to get hot

    • And this is why there is a difference between physicists and engineers.

      There is also the fun effect that the deeper into the atmosphere you go the less gravity will affect you.
      Now ponder at what depth you can actually fly by flapping your own arms as gravity goes down and the air will give you sufficient lift for your armflaps.

    • And beacuse of the low weight of hydrogen I wonder what a wind woud feel like on the skinn on the 1 bar level and you only needs an oxygen mask and thick clothes If you sit in a hot hydrogen balloon there, everything woud be high pitched defentivly

      To fly with arms you needs to go one to two Earth diameters down or more and there its 5000 to 10 000 degrees c

      • And go deep enough and the hydrogen enviroment gets so hellish its like swimming in liquid titanium, its an enviroment much hotter than the surface of the sun.. and where nothing we can build woud widstand it for more than a fraction of a second

        Gas Giants are hell pits 🙂

      • At least they are warm.
        Would though be fun to dump in 1000cbm/s of LOX into Jupiter and watch it burn into a waterworld.

    • The upper atmosphere woud be a magnificent sight .. with orange sunsets and huge thunderstorm anvils trailing cirrus Ice crystals in dark blue dayskies for 1000 s of km, the sky color woud depends on the depth and woud range from dark blue to turqouse in deeper layers where skies are not shrouded in clouds, and Cumulunimbus towers whos tops are still lit pink by the sun after it set. It woud be incredibley earthlike in apparence the atmosphere… yet totaly alien and knowing there is no surface below.

      And jovian tropospause at 0,1 bars hydrogen I see little chance of getting any lift unless you go hypersonic in a ramjet, yet the hydrogen atmosphere goes up a further 400 km. Comet Shoemaker Levy 9 was destroyed well above the tropospause but it was going insane speeds through the teneious layers

  32. I don’t understand why the evacuation was ordered the way it was, since they left so many pets behind. Yesterday (or 2 days ago) when they were able to get back for five minutes to get some of their belongings and animal welfare organisations rescued some pets.

    49 cats, 4 hamsters, 90 carrier pigeons,sheep, frogs, hamsters and shrimp were evacuated today

    22 #pets / #animals remain in the evacuated area / are reported missing:
    11 cats
    1 rabbit
    10 chickens

    I just don’t get why people wouldn’t take their pet with them if they evacuate.

    • The main reason was probably that people was out of town when it was ordered and got stuck outside of the cordon.

      • Which might be right as there are no dogs among the pets. When people go out they take their dogs along, but not cats, chicken 🙂 (chicks yes), pigs, sheep or hamsters. Very plausible. Also, when you evacuate swiftly you might not find your cat, esp. at night, but your dog would be right by your side.

        • And let us not forget that most cats will try to murder their owner as soon as they see the travelling cage…
          I guess many people just said sod it and let the cat out to fend for itself instead of going through the bloodfest of caging a cat.

          • Wondering whether there were horses. First thing to do for every horse owner in case of emergency (like fire) is to open the stable doors.

          • I saw an interview yesterday with a police chief there who said the dogs and horses had all been evacuated with the people. In yesterday’s evacuation they brought out an entire chicken farm (50,000 birds) as well as the other animals.

        • I just hope for the inhabitants that they can go back and collect everything. They might have to rebuilt the town elsewhere. It is not a task that can’t be solved.

          Derwent Reservoir:

          Reschensee, Lago di Resia, Italy:

    • I think the evacuation may have started after most of the cats went a wandering in the evening, probably no chance of rounding them up at the time

    • Carl have had both cats and pythons… : )… and the wonderful Carl VS Henrik facebook debate over IF pythons are good pets years ago, it was almost pure comical, the two sides arguing, I loved it it was so fun. But his most beloved fire hydrant jässica is no longer alive I think

      My own father finds snakes… malificious and gross

      • So, if he had needed to evacuate in a hurry the python would have done away with the cat. I prefer dogs plus parrots.

  33. The volume of the new dike is apparently about 70 million m3. At the stated rate of magma flow into the area of 7 m3/s, the dike is made of about 10 million seconds worth of magma. 10 million seconds is 115 days, so it seems like this dike probably did drain out all of the magma intruded in the past few years under the þorbjorn area.

    However, there is a great deal of uncertainty in all of this. One of those is possibly how connected the area is to Fagradalsfjall, which has been continuously inflating for the past few years and by now would contain a considerable store of magma should it join in. And there have been prior episodes of volcanic unrest at Svartsengi in recent decades that didnt result in a dike. So it seems unlikely to me that all of the magma went into the dike and has killed it off. If anything, now that the sill has been decompressed magma flow into it could increase and that has inevitable consequences.

    • The article doesn’t say how he came to the conclusion. The Met office’s last updated specifically mentions there is no evidence to the contrary:

      “In the event of an eruption, the most likely location is at the magma tunnel. There is no evidence of otherwise in the data.”

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