The ballad of Ballareldar: the boom and the bust

The eruption continues. There is so much hiding behind such an easy sentence. It continues – but always changes. It is not life as we know or understand it is the second most memorable phrase (at least in the paraphrased version) from Star Trek. This eruption is like that. You forget that this is actually a very small eruption, because you never know what to expect; it never does ‘more of the same’. You’ll love it, you’ll hate it, but you’ll never get bored.

At first there was the fissure which became the twin cone, slowly eradicating the valley of Geldingadalir. The fissure followed (approximately) the line of what I believe is a small pressure ridge, and ran along its peak. Just when we thought the lava would manage to escape the valley, it erupted a fissure in a much better location and the lava went straight into the valley of Meradalir, the next target on the list. The lava river was spectacular. But it turns out this was just a diversion. The fissure build a series of cones, but eventually the one closest to the original valley won the competition and exterminated the others. Now the lava was undecided, flowing in random directions, but soon found its way into the original valley – and now our favourite camera was the first real casualty of the eruption, sneakily destroyed from behind. The lava sneaked behind the original cones and continued (out of our sight) the onslaught on the escape route. This time it succeeded, and it entered a flattish area with a swampy pond, a rocky outcrop, and two exits – one north into Meradalir, and one south towards Nátthagi. It was a close call. The swamp became a lake of liquid rock, the rocky outcrop became swamped, and (perhaps hours before escaping south) a lava river developed into the Meradalir – absolutely spectacular but out of sight for all of our public cameras. We did wonder where all the Icelandic antics had gone, where were all the people who had been making a fool out of themselves in front of the lava and camera, but it turned out they were at the action we could not see, and no longer had any need to be the action themselves. And so we thought the action would repeat itself, with a new valley to fill and hopefully a new fissure to form. And so we became the fools.

What happened instead was that the victorious cone shape-shifted into a mini-Pinatubo. The change happened just after midnight on May 2nd. The tremor suddenly went through the roof, and the eruption went out – and then boomed. And went out – and again went boom. It became a ‘boom and bust’ volcano exploding into action five times or more per hour. The booms were very impressive and our Reykjavik commentators saw one particular lava geyser from their apartments and gardens. What a view it was. The boom and bust culminated two days ago when after a particular vicious boom the geyser reached 400 meters. We were quite concerned for the people watching from a nearby hill who on camera seemed to be overtaken by the flaming cloud. In reality they were well away, in front of the eruption, but they looked very small compared to the spectacle they were watching! The falling debris set fires in many places. Iceland has had a very dry spring, and the moss was defenceless against the heat of the bombs that were raining down. I am amazed that no one was hurt. After this, the eruption went back to stable effusion, though with some huge lava boats blocking the outflow channel, the lava flooded the lava flood plain and almost found its way back south. After half a day, the cone went dark again and soon the boom and bust cycle restarted.

The evolution is beautifully captured in the time lapses made by Virtual.

The big fountaining is seen here.

The lava field in Meradalir is captured by a webcam accessible at Note that it is fairly slow to load and requires a 4k screen to do it justice. On the right is a menu where you can look through the most recent set of frames. It is the kind of view that makes you want to take the next flight to Iceland.

While the volcano boomed, the lava flow seemed to remain fairly constant. There were spurts following a boom, and there were moments when the river ran a bit dry, but it did not seem that the new behaviour affected the overall lava output very much. That remains true. The lava still reached Meradalir and the edges of the flow are still expanding, but there are no major new developments down there. It suggests that te lava flow rate is still in the range 5 to 7 m3/s. It is a small but remarkably stable eruption. The effusion rate is the only thing that is stable about it.

What caused the recent change in behaviour to boom and bust? There are two clues. One is that this is in fact normal behaviour for eruptions, just normally on a time scale of months to years (or longer) rather than hours. You do have to understand this volcano. It has been bottled up for the past 800 years, and now it is like a hyperactive child in the morning wanting to pack in all the playtime it has been missing into this one eruption, and needing to get rid of a lot of energy. This is the Calvin eruption. The second clue is that change in activity was picked up in the tremor plots. They became very noisy just before the boom started, and in the day when it went back to normal behaviour, the tremor charts also calmed down, before resuming its noisy trend.

What makes a tremor chart noisy? There are two main reasons. (Actually four, but I will ignore the third one, windy weather, and the fourth, human activity.) The first is a swarm of small earthquakes, as happens when magma breaks through rock. Such tremor can precede an eruption. The second one is turbulence. Magma flowing through a conduit is actually remarkably silent. The flow is laminar (like honey) and it flows fast in the middle but very slow at the edges. So there is not much friction with the rock, and it is that friction which can generate noise. Just before an eruption, tremor charts can go quiet. This happens when the conduit is ready and fully filled, and all that remains is cracking open the surface. It is the silence before the lava storm. A full conduit is silent.

But what if the conduit is only partly filled? In that cases it is interacting not with rock but with gas, and that can be noisy. Think intestines after a good lunch, with lots of gurgling showing the gas-rich passage of the much appreciated food. Lava is in effect digested rock (life – but not as we know it), and it too produces gas. Magma can become frothy, filled with small gas bubbles. As the magma rises and the pressure decreases, more gas comes out of the liquid and the bubbles can multiply. Tremor charts pick this up as a continuous background.

In most eruptions, the lava is exposed to the open air, and this allows the gas to escape. This is the sulfur smell of volcanoes. If nothing else convinces you, the smell is the final warning of a volcano that says ‘danger – stay away’. (Current evidence suggest this doesn’t work on Icelandic people who seem to be attracted to the heat of lava as moths are to light.)

But sometimes the gas can’t get out. In that case, the pressure on the gas can rise and rise until finally not even thick rock can contain it. Once the lid breaks, the gas comes out and the pressure inside drops instantly, This forces the remaining volatiles in the magma to turn to gas, they expand their volume 1000 times and what started as a break-out attempt turns into a full-blown explosion. The mountain goes boom, and a Pinatubo is born. From Vesuvius to Tambora, this is one of the main ways volcanoes explode (the second way is flank collapse).

Eruptions can enter a late phase where this kind of behaviour becomes repetitive. Agung did this a few years ago. It erupted explosively, then the lava began to flow but only in the crater. A lava lake developed. As the eruption tapered down, the lava lake developed a crust and this became eventually too thick for the magma below to break through. Kilauea’s lava lake should soon enter this phase. But there is still gas below, and it can no longer get out. So it builds up underneath the crust. Eventually it breaks the crust and blows, and the volcano has a late eruption, which may be months (or more) after the main event had ended. Agung did this after its recent activity, and it had done the same (but more powerfully) after the 1963 eruption. It is also a risk at Kilauea, when the current eruption ends. Even though an explosion down its 200 meter deep hole may be well contained, rocks can fly far. You have been warned.

Let’s go back to the Reykjanes eruption. For now we can make a guess on why it went boom and bust, and why it temporarily went back to steady growth.

The tremor shows that there was gas underground which could not get out. At the same time, the lava glow in the cone had gone dark. Where had it gone?

It seems that the lava had retreated below a lid. A crust had solidified, and the magma was suddenly caught below it. Iceland had tried to put the Reykjanes genie back in the bottle. Calvin did not take kindly to this. The internal pressure build up, as gas collected below the lid. After a while (10 minutes or so) it overcame the lid and the kid exploded back on the scene. The exploding gas took the lava with it, in a tall red geyser. After the geyser, the remaining gas bubbled out causing a phase of turbulent lava flow in the cone. But the lava itself lacked sufficient pressure to make this permanent, and once all the gas had gone the lava retreated, waiting for the next cycle.

Why did it change after the massive explosion? That explosion happened after a collapse of the walls of the cone. Two things may have happened. First, the rubble may have blocked the exit even more than it already was, and in consequence the gas pressure build up higher before it could overcome the weight. Second, the collapse cracked the lid and provided a hole which triggered the eruption, but the hole it made was very narrow. In either case, it made quite an entrance. The geyser went hundreds of meters tall, aided by the narrow nozzle (we know the opening was narrow for this eruption because the lava geyser was well focussed: the width of a jet is closely related to the size of the exit hole).

But this explosion was big enough to do real damage to the plumbing of the volcano. The back pressure wave moved through the magma conduit, and was big enough to even force out a bit of magma from the original cone – which had been dead for weeks. The zombie apocalypse produced a small lava flow. The fact that one cone could damage another shows that the fissure is fed by a single conduit, by the way. If each cone had its own conduits to the dike, then the pressure wave could not easily find its way to the other cones.

Now two things may have happened which changed the shape of the eruption to strong and stable. (The UK does not like stability, by the way. The last prime minister going to the polls on a record of ‘strong and stable’ lost her job. The current incumbent is about as unstable as they come, and has two clear election victories as reward. Life in the UK is an adventure. But back to Iceland.) The pressure wave may have pushed open the feeder channel and increased the magma flow to the cone: the flow rate increased enough for the magma to stay above the obstructing lid in the cone. Or perhaps somewhere, perhaps through the zombie cone or through the side of the active cone, a crack was formed in the rock which allowed the gas to escape.

The phase of stable eruption did not last long. Either the crack closed again (a 5-cm wide crack filled with lava could solidify in half a day), or the feeder conduit narrowed again and the magma flow went back to the old level. Gas began to collect again below the lid, and boom and bust restarted. Volcanoes will not be denied.

So this is my guess on what happened. It is speculation!

What will happen next? I can safely predict that something will happen. The tremor charts show that the tremor has steadily (linear, in fact) increased since May 2nd. The current phase of instability is itself unstable. It is heading for another change. The only uncertainty is what change it will go for.

Perhaps the cone will collapse (it is looking pretty unstable already). Perhaps a new fissure will open. Perhaps the eruption will end. Perhaps it will pretend to end while in fact preparing for bigger boom. Or perhaps it will fool me and the current phase will last weeks, with fountains visible from Reykjavik. Or perhaps Hekla will blow. Predictions are best made in hindsight.

But this volcano has become much more dangerous to sight seeers. The warning signs are clear.

Albert, May 2021

357 thoughts on “The ballad of Ballareldar: the boom and the bust

    • & stopped just after I commented! lol. Have to wait to the next jet …

        • I had noticed this effect before. Two causes. One is the sound wave from the explosion which takes a few second to arrive at the camera. The second is the wind that the blow-out causes. By the way, there are people again on the hill overlooking the cone, and in my opinion they are a bit close.

          • Yes was thinking the same about the people om the hill.. If that big junk of crater wall collapse it can create a odd out burst that can be direction agains that hill. And thank you for the article Albert.

  1. Thanks Albert for the great summary. With so many events happening, it’s good to regain a sense of scope to fully appreciate what a unique event this is.

  2. Up for surprize. “Predictions are best made in hindsight.” I like that.

  3. Interesting and fun to read. Thank you for the article Albert!

  4. Mt. Watterson erupted for ten full years before going dormant.

  5. Has anyone else noticed that the active vent seems to be emitting more steam lately? This morning I noticed that the bursts seem more steamy than I can remember, just now the 16:35 pm burst seemed to carry a fair amount of steam.

    • This is not so easy to answer. The plume is mostly normal air carried upward. It may contain some extra water vapour from the volcano but that won’t be very much. The air rises because of the heat from the volcano. it makes the temperature change with altitude large, and this triggers convection – the same that causes thunderstorm. The air is stable otherwise today, so convection must come from the extra heat. Rising air cools and this brings the temperature down to the dew point. From the look of the cloud, that is at 400-500 meters. IMO says that the temperature was 5C and humidity 50% today. That puts the dew point at 500 meters or so. There is a bit more moisture at ground level than at altitude, so the rising is more moist than the surronding air – hence the cloud.

      There is a second effect: the dust in the ejecta acts as condensation nuclei. Water condenses much more easily in the presence of dust. Smoke does the same.

  6. Some of the highpass drumplots seem to show a slight increase in microtremor the past 24 hours during the active bursts from the cone. They include ASH, FAF, GRV, LAG, LFE.

    KRI, MER seems steady while ISS shows the opposite trend.

    We do know that the overall tremor seems to be increasing (blue shading) as Albert shows by the tremor graph from mer and iss, and we know that it is the impending signal for a change to occur soon.

    Increased steam content in volcanic gas release is causing the slight increase in volcanic tremor

    Is this reasonable? I am fairly certain that the bursts lately seem to contain more steam.

  7. Looking at the live feed it seems wise they (tried) to shut down viewing of the action. The hill is smoking with moss/peat fires. It looks like a few people still on top of the hill……😬

  8. Ejecta landing on the ground right in front of the ruv Langahyrgg camera just now.

    • It really shows the size of this cone. It dwarfs the others now.

    • Why does it have that weird 90 degree straight sided area of lava near the skateboarding kaiju’s tail? Is there some odd faulting there?

    • Wow, Meradalir is filling up faster then I though! Curious to seen if the flow will go to Natthangi before or after Meradalir ovrrflows… anyone?

      • Not just that but all the other valleys on Fagradalsfjall too, eventually. This is going to be a big eruption just not a fast one. It seems at least for the mean time though it is not going to be a shield but an episodic fountaining eruption, which is good as these are way more visually spectacular 🙂

  9. Thanks much for the summary Albert.

    The dark cone after a pulse is intrigueing. The magma must drain in some way back into the conduit.
    I saw a drone vid (Steinbeck?) made of the (what looked rather smallish) conduit some days ago in the minutes between the pulses. The lava surface very smooth, nothing happening, but red so likely hot.

    I was thinking of a sifon like part in the dyke as explaination of the pulsing.
    In the part of the dyke that turns 90 degrees to (about) horizontal, erosion may have taken place, creating a siphon. It could explain why the pulsing started after a period of normal effusion. Upwelling degassing magma stagnates, building up pressure in the siphon, and enters the last part to the conduit in a rush causing the fountaining. Once pressure is released, it has to be build up before another pulse is starting. The rest period.
    This could also explain the longer rest periods between pulses. At the start of the pulsing 1th may, the rest periods were about 2 to 3,5 minutes long. In time the rest periods became longer slowly, to about 5 – 6 minutes today. The siphon may have grown larger gradually by erosion.
    Perhaps the increasing tremor is a result of such larger growing siphon. It contains more magma, so pulses are larger and more explosive than in the first days of may.

    • Love these…. and a lovely bonus of dancing clouds…. wonderful viewing in a grey wet cold spring day. Thanks! Best!mots

    • I was thinking, as I watched those dancing clouds, that Iceland has had an incredible run of mostly fine weather during this eruption sequence. It’s hardly surprising that the moss is catching fire so readly from all the wind-blown tephra, It must be unusually dry anyway, without all the heat from teh eruption als driving moisture away.

      These last few timelapses you’ve produced, Virtual, are my favouritest yet. The three picked out in the article are truly magnificent; I’d love to see them in one long continuous video.

  10. I’ve been monitoring this webcam regularly for signs of the lava hoving into view. There seems to be quite a bit of activity at the northern col earlier today. You may need to zoom in to see it.

    I have been wondering if a small smackerel of dark in the lowest corner is lava, or if it is a trick of the (everchanging) light.

  11. Not sure I would compare the lava at Agung to a lava lake, technically there isnt a real difference but the behavior is pretty different, the andesite at Agung behaves like a semisolid on short timescales and shatters when erupted fast, where a real lava lake is a proper liquid.

  12. Anyone think that’s a party on the long shot Mbls cam down near the blue lights and orange glow near the foot of the mountain near the lava ??? Anyone? Anyone?

  13. 1:19ish, decent sized slab calved off west northwest wall!

  14. Tuff flakes from the eruption at Fagradalsfjall have reached all the way to Grindavík. The flakes are gaseous and therefore extremely light and can travel a long way.

    Teresa Bangsa, a resident of Grindavík, is one of those who has found the grains as they rained on her car earlier today. Teresa says that the flakes are sticky to the touch and nothing more than picking them from the car bad feasible, since if you try to rinse them off, the flakes would leaves scratches.

    Many locals have drawn attention to the grains on social media, but in addition to them, so-called witch hair has also been noticed in the town.

      • Yes, same thing 🙂

        Given probably a lot more people are familiar with the Hawaiian terms for lava formations maybe a good post would be a list of such terms with the Icelandic word for the same thing if it exists.

      • Errm.. yeah I am more used to the Icelandic term so I forgot to correct that part

  15. Can someone post the latest flow outline and the crater map. Thanks! 🙂

    • If this thing keeps doing this for years it could bury the entire fissure line, Pu’u O’o was 1 km wide and 255 meters tall in 1986. If it gets to that point though it will probably bury the entire mountain and send flows to the ocean, then it will have to be called Ragnarfjall 🙂

      Forever will this part of Iceland be changed, it will have a new mountain by decades end.

    • Most of Jesper’s links click to “wp-content/uploads/2015/01/Starry-Sky-01.jpg”

      • Odd, as soon as I posted that and tried again, it worked.
        Maybe the links needs time somehow.

    • Wish those 3D maps had a compass rose embedded so one could
      see the orientation

      • If it helps, the fissure line goes SSW-NNE, veering to NE and the ridge line goes from SW to NE. There was a picture on Twitter showing a representation of a dragon/lizard on a scooter, so if you position the most rounded part of the lavafield to the east, so that the whole model is shaped more like a diamond than a square, then it is pretty close to having north at the top. If you orientate it in that position, there shuld be a series of grey bands on the left, which are the moss fires.

    • It’s visible in the 02:37 image, but disappears later. I wonder whether there was another brief eruption from the first vents, but the live feeds no longer go back far enough to check. There are acouple of later images which show a large fountain from the active vent, then in the next image smoke/gas further to the right.

  16. Given I have been comparing this stage of the eruption to Pu’u O’o, I decided to overlay a graph of Pu’u O’o at various stages of growth with the growing Ragnar cone.

    It is growing very fast, its as big as Pu’u O’o was in August 1984, or just over a year old at that point. Granted Pu’u O’o was sending all of its lava flowing long distances away from the vent but its really incredible how quickly we are watching a mountain form.
    I suspect though if this geysering behavior persists the intervals between fountains will get longer and the volume and duration of fountaining episodes will increase.

    • Ragnars lava looks also just as fluid
      Been flowing like liquid aluminium torrents today .. as the cone fills up
      Very Impressive today as the lava torrents crashed against obstacles and splashing into sheets of lava!
      Looks like this is the most fluid lava ever seen in Iceland by camera? Silvery smooth lava glass draped channel surfaces.. just like infant Puu Oo. Ragnar much lower viscosity than even Holuhraun?

    • Viscosity at Ragnar vent is very low indeed! Probaly just as low as Halema’uma’u vent.. and perhaps Nyiragongo

      Viscosity seems to have gone down alot the recent days of this eruption vent ..

      Whats Chads opinion? Its still getting hotter?

      • Probably this lava is erupting right out of the mantle, as in it doesnt stop at all anywhere on the way up like the earlier stuff could have ( early stuff was maybe sitting in the dike for a few weeks).

        With this in mind I think a temperature of 1300 C is not out of the question 🙂

      • Assuming it will go that way if Nar continues erupting at the current pace ..
        Is the lava hot enough, fluid enough, with a sufficiently high flow rate to make it to the ocean ??

        • Lava tubes and the crust of lava flows insulate the lava inside so that it can flow long distances without cooling too much. Lava tubes are best at insulating, the lava can flow tens to hundreds of kilometres, keeping basically the same temperature, even if they erupt at low rates.

        • As Héctor say.. we needs slower eruptive rates to form lava tubes…
          Lava tubes are incredible insulators… some tube feed flows on Jupiters moon IO are
          400 kilometers long! One tube feed Pahoehoe Rhajamundry flow of Deccan Traps is 1500 kilometers long. The slivery crusts on slow ponded channels are good insulators too.. it allowed the 16 km long Fissure 8 channels to stay smooth… almost down to the ocean

          But lava tubes are best insulators and specialy deeply buried ones. Lava tubes are so good at insulating… that after being active for months their floors start to melt and can be scarped away by the moving flow, resulting in deep tubes, the walls of tubes can be insanely glass smooth and full of decliate flow structures that can only form in that hot furnace like enviroment


      Liquid aluminium is also an insanely scary substance.. because its much denser and conduct more heat than flames do to the body. Getting that stuff on the skinn is terrifying.

      Lava is just as bad too.. But it low thermal conductivity and and outer lava skinn chills against objects for small spatter chunks

      Still both are terrible to be burned in
      Aluminium spatter perhaps worst because of its density and High thermal conductivity

      • Copper is the same, but it is as hot as lava. It is also over twice as dense as lava.

        I think probably the scariest liquid metal though would be titanium, 1700 C and it ignites itself in the atmosphere. I read somewhere it burns in air, normal air, at 4000 C… I assume it is only hotter still in pure oxygen. I can only imagine how hot it is if you burn it in a really energetic oxidant like ozone or nitrous oxide, or fluorine…

        • Titanium aside from this issue is beautiful for screws, also in medicine.
          I read recently that the so called DR of Kongo is having problems near Goma because of groups wanting to get a grip on resources there. Easy to figure when you read a volcano site.

          • Yes it is very unreactive under 400 C, forms a thin oxide layer that is insoluble in pretty much everything, same with aluminium. I think only aqueous HF can attack it because it forms H2TiF6 which is water soluble, but anhydrous HF or any other acid does nothing.

            It does burn in chlorine quite easily though, that probably is its real achilles heal, at least concerning things that are widely available in a household setting. TiCl4 is pretty dangerous too, it turns into TiO2 dust and HCl when it reacts with water, including in your eyes and lungs… yet another example of the marvels of chemistry, turning harmless things into dangerous things.

          • Titanium dioxide is in many sunscreen products. It is good at absorbing UV and safe. Might want to avoid it in sprays though.

          • More that it is created within the tissue of your eye, if you get TiCl4 vapor in them… The exact same thing happens with SiCl4, forms nanoparticles of SiO2 in your eyes and causes rapid permanent blindness.

            Also they fume intensely in air, not a good idea to breath fine insoluble dust.

      • IIRC, the US aerospace ‘black project’ people serendipitously discovered you could either use exotic cutting techniques on titanium sheet, risking distortion & stresses, or draw template with ‘wax’ marker, as that destroyed the protective oxide surface layer and steadily ate its way through…

        Akin to reason why mercury and mercury salts are banned from aircraft etc containing aluminium alloys.

        Back when I was a lab-chemist, I was startled to find an aluminium weighing scoop visibly growing an oxide ‘tree’. Yes, some-one had very recently used it for weighing a mercury salt (or perhaps copper ?) and not cleaned up. ‘Things were said…’

    • I think Fagradalshraun will turn into a Puu Oo like lava shield

      Its been 900 years of collecting magma so it coud have built up a sizable melt pool under Sourthenmost Reykjanes. The supply rate is low ..But its a hot enviroment and it have keept it relatively fresh.

      But Chads decompression machine is also a work wastley increasing the local supply. The current local magma supply must be almost 0,6 km3 a year? As result of eruptions own decompression melting of the mantle

      But the overall background supply of Reykjanes Penninsula is very low
      But its still Thoelitic magmas

      • Its probably not that low, this area is a lot more productive than it looks just activity is very episodic. I would though not be surprised if more lava erupts at Reykjanes this century than erupts at Vatnajokull, that does depend on whether there is a rift at Veidivotn, but that is not a certainty.

        I think it will take quite a lot to break the fountain cycle, Pu’u O’o lasted 3 years and only broke because its foundation rifted, and even at that the only reason high fountains didnt resume in 1992 is because the Pu’u O’o vent had collapsed and lost its narrow conduit, otherwise it would have kept going.
        The new rift at Fagradalsfjall is way less defined than Kilaueas ERZ and seems now to be mostly filled and inactive, the vent cluster could probably elevate itself hundreds of meters without a deep failure. Really its more a standard cinder cone eruption that is in a not so standard location.

      • 0.6 km3 per year is not far from the total iceland magma production rate. And most of that happens in the other side of Iceland. Divide by 10 to get a more plausible number. About 10% of that may be eruptible. Still, over 800 years a few km3 of eruptible magma may have collected (under all of Reykjanes). There are four separate volcanic zones, so there may be 1 km3 eruptible magma deep under Fagradalsfjall.

        • But this spot has also skipped the last 6 cycles, so 6 km3 🙂

          I also would expect the deeper origin to have some consequence in this, most magma storage is in the lower crust but this is in the mantle, melt generation could be locally very exaggerated.

          • The magma is about 15-20 km deep. The distance between the volcanic zones is 10 km or so. I think that is how far magma can travel here horizontally on the way to the surface. And it puts the current location as connected to both of the neighbouring volcanic zones which have had eruptions in the past cycle. So I expect any magma underneath this spot has been used to feed the neighbours. For some reason, the crust is here difficult to get through, and the path through the weak spots on either sides are preferable. Until something happened..

          • I guess we will see. I think it will probably exceed 1 km3 though, if the magma has erupted from depth here then it might not matter that usually it goes elsewhere, because that isnt what it is doing now. It could in the extreme case mean all the magma for this cycle is going to erupt at Fagradalsfjall, though I dont expect that.

  17. The last outflow was massive. Huge overspill at the channel at 07:59

    • The one at 7:51 was even bigger, wow…….

      Hundrets of cubikmeter gushing out

  18. I have a question for Albert or other specialists: It’s beautiful, no doubt, but if it stays like this for say ten years or even gets larger, would that have consequences for Reykjavik at all?

    • The main consequence would be increase in volcano-tourism.
      The emerging Fagradalshraun is not close enough to the metropolitan area of Reykjavík to pose physical threat to it. Might contribute to low air-quality days if the winds are in the right/wrong direction but that would be it..
      The only infrastructure at risk is Suðurstrandarvegur (South Coastal Road) but the lava needs to creep quite a ways for that to happen.

    • Reykjavik is 40 km away .. lava will not reach it .. too far away and the slope Probaly does not allow it either to creep to Reykjavik. If you wants Reykjavik to be invaded .. then Northen Brennsteinsfjöll needs to do a multiple km3 Aa fountain eruption and that simply wont happen : )

    • If Brennsteinsfjöll- Northen Krysuvik does a long lived tube eruption .. then chances are at least some that tube feed lavas coud get into Reykjavik
      Some pahoehoe from Bláfjöll have gotten into Sourthen Hafnarfjördur

      A fast VEI 3 Aa fountain feed lava flow from Bláfjöll woud be a mess for the local arera

    • Looks like thinner .. darker lava is creeping around the ligther thick Aa lava

      This eruption is Probaly generating alot of decompression melting for itself

      • The dark lava seem to have come out through the aa lava front, it is probably an expanding field of rubbly pahoehoe fed from inside the aa.

  19. Only vog, and unlike in Hawaii the wind at Fagradalsfjall goes in every direction so even this wont be a big problem. Reykjavik will have to worry about when Krysuvik wakes up, much more intense eruption and high levels of SO2, just like during Holuhraun, or at Kilauea.

    Grindavik is a lot more sketchy, if the lava field builds up and can flow over to the southwest then its quite likely Grindavik will be buried, especially if it goes to more widely separated fountains that can feed really fast flows, or becomes a pahoehoe shield. It also sits within the fissure swarm of Svartsengi, which is prone to lava floods like Krysuvik, a fissure even goes through it…

  20. A new value for the effusion rate has been published. The latest week it’s up to 12.9m^3/s.

    • So it has basically doubled from before, and tripled what it was back in March. The hell machine is at work 🙂

    • Wow. That is a big jump. So the fountaining increased the eruption rate. That was not obvious from just looking at the cone

      • Maybe an increase in the supply rate from depth excited some sort of resonance phenomenon that drives the on/off behavior and high fountains.

        • The report suggests that the conduit through the lower crust may have widened. I have the impression the size of the jump surprised them too. The funny thing is that you would expect more visible lava if the rate increases, and instead we have seen the lava retreat a bit – and then explode.

          • I was thinking something like a hydraulic ram pump that needs a certain minimum flow to close the waste valve and generate a water hammer effect that drives the outlet flow, but on a much bigger scale.

            The widening of the conduit gives a larger flow rate and the larger flow rate becomes large enough to trigger the pumping effect. Just thinking out loud here.

          • When watching the mbl close-up cam I could more clearly see a huge surge in the outflow just before the pre-explosion “boiling” starts. I generally watch the other cams and that surge is not evident (or possibly visible at that angle) on those cams

          • Nice, Tomas.
            I was also thinking “Ram pump”.
            I’m not claiming that’s right though.But it’s good to know I’m not alone in my foolishness !

          • Ram pumps are fun things, but I cannot see how this can be arranged in this case and since its basically a way for a large low head water supply to deliver a small flow high head supply it doesn’t really make sense.
            If there is flow from other vents under the lava cap then Albert’s original scenario makes sense. The column if fed from a deep gaseous (dissolved) source fills the conduit until enough gets close enough to turn to gas, reducing the hydrostatic pressure and a wave of degassing propagates down the column until its degassed. The degassed lava that remains flows out until the column is primed with gaseous lava.
            I am along with Albert in never seeing remotely the flow from the vent that it appears to power the lava river a little away from the vent.

  21. RUV has some numbers, the cone is 50 meters tall so a bit less than I thought, but still big. They do say the flow rste though is probably higher, closer to 10 m3/s, with an official number on that soon.

  22. Lapilli is visible falling in front of the MBL camera at 13:29. The wind is directly from the cone to the cam.

  23. Looks like the eruption conduit is largening… signs with denser thicker fountains… and lava flows that seem more fluid now as well as fountains not getting supertall, as Chad says… its over 1200 C and perhaps melting the dyke walls around it. 12,9 m3 second is the latest flow rate data from Jarðvísindastofnun. Perhaps it will melt itself a big lava lake hole in the crust and shield

  24. Here is a comparison of Sentinel images from May 4 and May 9, showing the expansion of the lava flow.

    • At the bottom, the flow field is widening and presumably thickening but not moving forward. Today, the liquid lava underneath came out and the front moved quite a bit forward. There was no heat signal on the flow field, so the new growth was fed from within. If this continues at the same rate, we can expect that a flow will begin to go into natthagi within a week.

  25. I’ve been drawing maps of the extent of the lava-covered area for four weeks now. Mostly based on the fan map at that time, with slight updating/modifications based on cams. The increase in flow can be seen in that the new area covered each week is larger than in the previous week. Will have to find another base map soon as flow is starting to expand off-map in several directions.

  26. As Stars Die mentioned above, the time-lapse cam in Nátthagi shows some glow peaking over the edge (in the dark). Now I am not sure if this is from the Nameless Dale or the Wetherdales extension, but the edges of the lava-field in both areas have been creeping towards the lip into Nátthagi (according to 3D model posted yesterday)

    • Here are the clouds from the regular lava spouts. This was on May 4.

  27. There has been published another bulletin update by IMO.
    Google translated.

    Uppfært 11.05.

    “”The activity of the eruption in Geldingadalur has been divided into chapters in recent days. During the weekend, high jets from crater 5 could be seen every 10 minutes, but there is talk of magma jets when an explosion occurs when gas escapes from the magma. The magma jets have reached up to 500 m above sea level and wildfires have ignited a few hundred meters away from the craters due to volcanic eruptions.

    “The most likely explanation for this is changes just below the craters where the magma accumulates. That area is changing. As that area increases or decreases, the gas can accumulate in bubbles and cause magma jet activity “, said Kristín Jónsdóttir, group manager of nature conservation at the Meteorological Office in a conversation with RÚV.

    The production of the lava is even and there are no signs that the eruption will end. The magma rises from a depth of 15-20 kilometers and flows up in a straight channel up, but at a depth of about 100 meters a magma collection site has now been created in some kind of chamber. “”

    • “The production of lava is even …” That is in contradiction what Icelands university has published today.
      The numbers didn’t reach IMO yet I suppose.

      • Why isn’t Steam on the gas release chart? It accounts for 70% to 95% of volcanic gas output. I hope this oversight gets corrected.

        • Think CO2 and SO2 tell you more about how the magma is behaving, but could be wrong.

        • But how do you measure? It is swamped by the water in the atmosphere. Same with CO2: it is present in the release but difficult to separate from the atmospheric CO2. SO2 is much easier, and often CO2 is just scaled from SO2.

    • To complete the table above, a google translation of the text that belongs to it.

      “”Summary of lava flow (written 11 May)
      The more than 50 days that have passed since the beginning of the eruption can be roughly divided into three.

      The first period lasted for about two weeks and was characterized by a fairly steady but slightly decreasing lava flow. The flow decreased from 7-8 m3 / s to 4-5 m3 / s in two weeks.

      The second period, which also lasted two weeks, was characterized by the opening of new eruptions north of the original craters. Lava flow was quite variable, in the range of 5-8 m3 / s.

      In the third season, the last three weeks, one crater has dominated and almost all the lava comes out of it. Lava flow has increased somewhat during this time. The increase has been large in the last week and now the eruption is much larger than it has been so far. However, the intensity of the eruption is still relatively small compared to other eruptions.

      The eruption in Fagradalsfjall is in many ways different from the eruptions we have witnessed in recent decades. Most eruptions have originated in magma chambers under main volcanoes, where the pressure in the chamber and its size seem to largely determine the size and length of the eruption.

      In Fagradalsfjall, this seems to be protected somewhat differently. It can be seen that the inflow veins and their properties have a great influence on the magma flow. The channel opened was relatively narrow and long (reaching a depth of ~ 17 km) and the carrying capacity was limited. An increase with time indicates that the channel is widening, probably due to erosion in its walls. It can not be seen that the pressure in the source has decreased to a certain extent and therefore the flow increases over time as the channel expands. There is currently no way to predict how long the eruption will last or whether lava flows will continue to increase.

      The best way to estimate the size of the eruption in Fagradalsfjall is to map the lava and calculate its volume at any given time. This gives an average lava flow between measurements. The volume of the lava at any given time and the lava flow are shown in the accompanying graphs, in addition to which the results of chemical analysis of the magma and calculated gas emissions from the eruption are shown.””

    • So to be short.
      IMO: magma chamber at 100m. below surface.
      Uni.: dyke is growing larger by magma erosion.

      Thats great! 😁

    • This sounds exactly like a Shield in the making …! and it must be that
      Chads ”Hell Machine” is at work here
      Decompression melting

      With a shallow chamber created and dyke pathway enlarged into a conduit we coud get perhaps a lava lake soon

      For now the vent act exactly like a water geyser but with Magmatic gases that builds up Into the shallow chamber

      • The effusion rate is too high to form a pahoehoe shield, it will form an a’a flow field and a tall cone. Depending on perception this is still a shield but a different sort of structure to a pahoehoe shield.

        I would not be surprised if this gets quite a lot bigger, the standard rules of Reykjanes eruptions likely dont apply here, and if Lanzarote or Mayotte are an indication this will be something for the history books. It is not enturely unlikely the entire cycle will erupt here if this eruption is tapping the deep source of both Krysuvik and Svartsengi, so no rifting lava floods perhaps but a years long episodic lava geyser, like Pu’u O’o in the 1980s, or Etnas SEC.

        • That effusion rate might decrease, we don’t know. I think we will be forced to watch and see what type of cone is created.

          • For one, I will be very happy to watch! No forcing for me! 🙂

          • It could but it isnt likely to, if the conduit is bigger yet still just as pressurised then the equilibrium has not been reached yet. I think we are not even close actually.

        • Not a pahoehoe shield yet… but an Aa shield perhaps feed by higher rates
          But if rates goes up even more and constantly we just get a Holuhraunish looking Aa field
          Your Hell Machine is well at work now… this eruption is the first of its kind in many 100 s of years in Iceland I think. The previous ones in my life been tapped from established chambers

  28. Interesting earthquake swarm south of Carlsbad, near the Texas-New Mexico border

    • Swarms seem to pop up there every once in a while. Old faults being reactivated by fracking? Or could this be an eastern extension of Basin and Range faulting?

      I’d love it if it was volcanism, but I don’t think the folks in El Paso would be so happy…

    • It’s peeking over the edge. Once it starts, there might be some “suction” and it might take off.

      • I don’t believe it.

        Over a month’s nightly monitoring of this webcam, and my first early night (exhaustion of dealing with several family problems over the past few weeks), and I bloody missed the golden opportunity…

        Oh well, in for a penny…

        “What’s that coming over the hill? Is it a monster?”

      • Looking at the other Langihryggur cameras, it’s yesterday’s morning breakout glowing in the dark that’s now visible close the edge. Yes, it’s still got a little way to go to establish a path south down by the river.

        Perhaps another couple of large lavabergs, blocking the Meradalir route for a time, may be enough to push it over the ridgeline.

  29. Interview with Dr. Þorvaldur Þórðarson at Iceland Uni.

    Although more than a week has passed since the eruption in Geldingadalur began to erupt with short breaks, the lava flow has not stopped, the lava river itself has increased. Þorvaldur Þórðarson, professor of volcanology, says that up until now the flow has been between 5-10 cubic meters per second but is now between 10-15 cubic meters. He says that the lava flows and volcanic activity in the crater are in fact behaving independently.

    “There must be a channel that we do not see and comes up from the crater and goes straight into the lava river. It maintains the lava flow in the lava river despite all this variability and the overflow that comes in connection with the magma jets, “says Þorvaldur.

    How does he explain this dual or separate behavior of the eruption?
    “It can be imagined that the degassing that drives the explosive activity starts at a depth of 70-80 meters. These are both large and small bubbles that expand and expand on the way up. But they do not cover the entire eruption channel. They are only in part of the eruption channel, probably central. Then there is a continuous lava flow that flows up the sides and then goes straight into this channel or channel that we do not see. On the other hand, the balloons behave independently and drive up the explosive activity, lifting the lava surface only when they expand. Then they explode and blow out the magma patches.

    But what is the explanation for their formation now?
    Thorvaldur says that they have actually been forming all along. A probable explanation for the changes that took place during the eruption on Monday last week is changes to the top layers of the eruption channel.

    “So there’s a pretty big tank down there that’s more or less full of magma. The outflow and inflow from it through erupting vents that are smaller than the diameter of the tank. When fresh magma enters below, it begins to degas and form the large balloons, which then flow up very quickly. When they are released from the system into the atmosphere, the gas pressure in the system drops. Then the surface of the magma in the crater sinks a little and then you have to pump a little more magma below to get enough balloons to create the next phase. That is why this is such a regular activity, “says Þorvaldur.

    The lava around the eruption grows day by day. Þorvaldur says it is interesting how it is distributed. “The eruption is actually sending lava in quite a number of directions. Lava flows on either side of Nafnlausadalur. It goes down to Meradali and even into Geldingadali. So it’s really starting to spread in all directions from the crater. These are perhaps the first signs that this lava could begin to form a shield. They build up where you have one crater. And the lava spreads in all directions from that crater. Not necessarily all of a sudden, but gradually over time. This is how this shield we know as Dyngja is built. “ Þorvaldur says that if this eruption turns into a shield eruption, it will be a small shield. Its diameter could be three to five kilometers. “So this would be a rather small lava shield or Dyngja. This would not be anything like Skjaldbreið, which is about 30 kilometers in diameter, and for that we need much higher productivity and also a much longer eruption, “he says. The eruption actually needs to be alive for quite some time to form a shield. “We are not talking about months, but years. It is possible that it will happen. There are no signs that the eruption will stop. “

    • That’s the best article I’ve come across on the current Icelandic eruption-thanks Urour.

    • What/where is Nafnlausadalur? No results with an internet search for that word.

    • 5:33am two or three faint puffs of steam from the very most north crater which is old fissure cone set two

    • 5:40 am definitely steaming now at northmost crater and 3 faint white spots to right where the old flow is
      Something which caught my attention

      • looks like an entrance to a lava tube on the geld… side

      • I’ve been wondering where all the overspill lava has been going. I’d thought maybe there was less splashing than it looked, but this is proof that more is being sent over the southwestern collapsed side than is immediately visible.

        • There must be a flow below the surface. That is true both near the cone and in towards the natthagi valley. It is deep enough that nothing shows up in the heat maps

    • I have seen that the lava looks more whitish/bluish when it is viewed through fumes, mainly due to how the fume scatters light.

      Not sure if this is the same as you saw or not, as I wasn’t paying close attention at the time. Any chance you could share a screenshot of it so we can see if it can be identified?

  30. Albert! I think Juno Probe will pass IO soon.. are you thrilled? we will see how much new lava flow resurfacing
    IO haves the largest lava lakes and active surface lava flows in the entire solar system! some compund lava flows on IO are many 100 s of kilometers long, and some lava lakes are as wide as 50 km and 80 km long… perhaps windows into the moons molten magma ocean interior. Their largest lava flow from 1999 galileo is the Amirani Lava flow 400 kilometers long. IO probaly erupt 600 km3 of lava and pyroclastic materials every year.

  31. Today the lava at fagradalshraun… does not look as fluid as yesterday… I wonder why that may be

    • Higher eruption rate maybe promoting the transition to a’a quicker.

      • Chad…. the lava torrents crust close to the vent… does not look as smooth as fissure 8 s
        When its really insanely fluid…fast lava torrents have an almost paintlike crust on them…
        These torents haves a flexible but often broken up crust in tiny pieces perhaps.. suggesting higher viscosity than Hawaii… but Yesterday… it looked superfluid

        • Probably because it was flowing over the edge of the channel so you could see its consistency.

        • On the Geldingadalir camera the flow is stopping almost immediately outside the crater. I think that is because it is not overflowing lava from the crater, but a mass of spatter. It has cooled during the seconds in the air. On the Langi camera the flow is much more fluid.

      • Look at Fissure 8 and Mauna Loa 1984 close to the vents lava channel crust is like alumimium paint
        But Ragnar vent have displayed that too yesterday… so it coud be todays higher fountains thats behind the rougher looking channels

        When Puu Oo did supertall fountains in 1984 you got alot of air cooling and the flows turned into viscous almost Etna like channels

        Impressive video of Ragnar showing higher viscosity of recent days… Big Aa like fast torrents crashing down… but still very fluid

    • And if you are wondering, “mountain king” is the local person who leads the yearly gathering of sheep in the area.

      • That is an interesting attempt. It has been tried before but it works better in deflecting the flow than in stopping it. In this case, the flow has no other way to go, and the pressure is likely to push the barrier out of the way. Still, worth a try

    • I think if the civil defense are going to do this, they will have to start today. The lava front seems to be accelerating.

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