Bárðarbunga loves Grimsvötn = True

Photograph by Eggert Norðdahl. All rights reserved and used under permission.

Photograph by Eggert Norðdahl. All rights reserved and used under permission.

I once again reiterate that it is Icelandic Met Office and Almannavarnadeild ríkislögreglustjóra that has the authority to issue warnings for Iceland in regards of eruptions and jökulhlaups.

For airborne ash advisories it is in the following order London VAAC and IMO that issues advisories. That being said here follows a brief update upon what is happening in Bárðarbunga and Grimsvötns fissure swarms.

Volcanic love in the ground

Who would have thought that the two largest volcanoes of their type on earth could make love to each other? Well, let me expound a bit on how they do it physically. For anyone who is a bit sensitive, this is where you should stop reading. It will get very graphical.

Since the seismic swarm started there has been quite a lot of confusion about what is going on, and where it is going on. Thanks to the Icelandic Met Office (IMO) we now have answers to our questions, and what glorious answers those are.

The reason the picture has been so muddy is that IMO has been swamped by earthquakes. So they have not had the time to manually correct every single one. Instead they have concentrated on the larger ones since they have a much higher importance. Remember that one M2 earthquake carries the energy of 31.6 M1 earthquakes. This means that IMO has only corrected the large ones and the smaller has been left hanging around.

Now, small earthquakes gives less clear signals compared to larger earthquakes, so the smaller the earthquake, the larger the errors. So, many of the uncorrected earthquakes are several kilometers off in all directions. Think of this as a blurry picture. In this case so blurry and out of focus that what actually was going on drowned completely.

Now thanks to IMO we have maps only containing manually recalculated earthquakes, and due to that we can see what is going on and where it is going on. And out of the mist a scene of unadulterated volcanic lovemaking emerged.

Volcanic fissure swarms

The large Icelandic volcanoes are situated on something called fissure swarms; those are permanent thin areas of the crust that are permanently weakened as the continental plates pull apart. They are in a sense of it the actual rifts where the Mid Atlantic Rift (MAR) pulls apart.

Under Vatnajökull there are at least 3 fissure swarms, Bárðarbunga fissure swarm (Veidivötn to the South and Dyngjuháls to the North) Grimsvötn fissure swarm (Lakí to the South and Grimsvötn to the North) and Lángisjör. The last one we can leave for now.

On the fissure swarms you have central volcanoes. 3 are known for the Bárðarbunga fissure swarm, namely from North to South Kistufell, Bárðarbunga and Hamarinn. For Grimsvötn you have Grimsvötn, Háabunga, Thordarhyrna, Geirvörtur, Háagöngur and Éldgigur.

The central volcanoes interact with their fissure swarms in many intriguing ways. But it has been the general opinion that each fissure swarm is a system on their own. There are a couple of hypothetical places where it is suspected that some sort of mechanical interaction could exist, but there has never been any clear cut proof of it. And there has never been any proof or even a causal chain proving movement of magma in between them.

Untill now. First I need to explain one last detail before we get to our lovemaking fissure swarms.

Radial fissures

Radial fissures are fissures that extend outwards from a central point, in this case a central volcano. Think of it like the spokes on a bike wheel. Several are known for Bárðarbunga, the most well known is the Gjálp fissure that erupted in 1996 that extends from Bárðarbunga towards Grimsvötn.

Love is in the ground

Image by Icelandic Met Office. Note how the magma moved out from Bárdarbunga down the radial fissure, and then make a sharp righthand turn as it meets the Grimsvötn fissure swarm.

Image by Icelandic Met Office. Note how the magma moved out from Bárdarbunga down the radial fissure, and then make a sharp lefthand turn as it meets the Grimsvötn fissure swarm.

In the beginning there were two earthquake swarms. One happened at the Kistufell central volcano. We can leave that one be today. At the same time a small swarm happened inside the central volcano of Bárðarbunga that quickly moved into and along a radial fissure.

As the magma followed this radial fissure it went so far out that it encountered a new feature, the Grimsvötn fissure swarm. At that point the magma was injected into a more fertile ground and for pressure dynamic reasons it could not go towards Grimsvötn, instead it started to move further down stream of this new fissure swarm.

Now I just hope that Bárður and Grims baby will not take 9 months of birthpangs until being born.

I can’t stress strongly enough how surprised I am about this. It is the single biggest surprise in my volcanic days. It is surprises like this that makes life truly worth living.



753 thoughts on “Bárðarbunga loves Grimsvötn = True

  1. Just listening on Radio 4’s Front Row to a segment with Ilan Volkov and Hilary Finch about the Iceland Symphony Orchestra playing two Icelandic pieces at the Proms tomorrow night at 7.30 pm: ‘Geysir’ and ‘Magma’. Lots of volcano talk in the piece:


    Will be up on iPlayer soon. Piece starts about 5 minutes into the programme.

    • Details of the pieces they are playing:


      ‘Ilan Volkov directs the Iceland Symphony Orchestra (of which he is Music Director) in the ensemble’s Proms debut. Together they bring works from two major Icelandic composers, both inspired by the power and drama of their native country’s geology. There’s a slow-growing, primal force to Leifs’s Geysir that balances the shifting tectonics of Tómasson’s Magma.’

      • I also heard Front Row and was going to mention it. Magma sounded expecially interesting – I shall try to remember to listen tomorrow evening.

  2. I would really LOVE to see some 3D plots from IMO showing the dyke or perhaps the Bardarbunga magma chamber, using the tomography from all the quakes. They should have quite the wave data from this swarm.

    • Anyone with connections at IMO that could suggest this to them? Or at least to make them public in case they made them already (they probably have, to know the dyke dimensions)?

  3. When you are talking about harmonic tremors freq., here is a link where you can hear how fre. rises before an eruption.

    Freq. pitch goes up to 30Hz and before eruption start there is a short period of silence. One thing i want to know, does anyone knows where i can find freq. records that goes up then 4-5Hz?
    I am new in this field so lot of things i’v learned from your recent posts and i am still learnig 🙂
    Best regards from Croatia

    • Let’s see if I can space that out a little better….

      21.08.2014……17:44:03……64.677…-17.468……4.5 km……3.4…… 99.0 4.9 km NE of Bárðarbunga

      That has to be another star but it isn’t indistinguishable from those already there.

      • Latest on the table is 2.5 for that quake. So been a downgrade and no star. 😦
        21.08.2014 17:44:03 64.677 -17.468 4.5 km 2.5 99.0 4.9 km NE of Bárðarbunga

        • How very odd! Now they have it back up at a 3.5 !!! Both were marked as checked 99%. Seems like someone is checking the checkers. 😀
          21.08.2014 17:44:03 64.677 -17.468 4.5 km 3.4 99.0 4.9 km NE of Bárðarbunga

        • That’s weird… my table is still showing it as 3.4 and I’ve refreshed it twice. I’m guessing the version I’m getting is much slower to update.

            • Oh Frances, I’ve never been so happy for someone to press the wrong number! 😀 And it was such as teeny tiny error with such a happy outcome. 🙂 So where’s our star? (I’m claiming this star for you and me, Frances :D) so where’s our ★ IMO?

            • Hi Mopshell! Welcome to the crazy world of volcanocafe! I should warn you that we party on Friday night – everything goes crazy. We normally have riddles, but that’s just to keep us occupied between eruptions. Also we have a thing about sheep! 😉 😀

            • Hi Mopshell, I think Old Cowboy has the answer to that. Here is what he wrote below.

              For those of you that understand latitude/longitude;
              the 3,4 quake at 17:44:03, lat/long = 64.677/17.468 was at 4,5km.
              the 3,4 quake at 13:02:08, lat/long = 64.678/17.470 was at 4,9km.
              Are they so close that they only show as one star?

            • Hi there, Talla! I like crazy and this is a wonderful place! I fear though that I will drive Carl nuts with my uninformed (but very enthusiastic) speculations. ¯\(°_o)/¯

              I’m not very good at riddles but I’m very fond of sheep. (◕‿◕)

  4. Its really good to know the EU overlords in Brussels have decided how best we can deal with any ash that falls on europe:

      • One of my abiding memories of the Montserrat eruption was some of David Lea’s footage showing a Plymouth resident sweeping a few inches of ash from his roof with a broom. A roof that would now be under several feet of solidified ash.

        • I was in Guadeloupe on 2010 when the dome collapsed. The island was covered by ash up to one inch or 2 in places. The island nearly ran out of water in the Grande Terre (the non volcanic part) where the water is more scarce because everyone on the island used water to clean off the ash from houses, roofs, cars…. Spica made some electronic microscope pictures – see in the menu, but I think you may have already seen them.

    • Oh! Come on Now! Think of all the plastic and energy used by machinery to make that inefficient sweeper…..What they should do is go totally natural and organic . They can test drive mine for efficient & eco-friendly cleaning 😀 Just think a clean home, would Clean up volcanic ash easily and the added bonus of energy efficient shopping trips, not to mention fly- overs of volcanoes 🙂
      Here’ s a taster lesson very similar to those I had back in school in the 1950’s 😀

      Now where was I?……Double, double toil and trouble;
      Fire burn, and caldera bubble……….OOOps! I think I got that wrong……..Oh Dear! what have I done?

  5. My goodness there are a lot of new faces in the Cafe. Carl, have you stocked the cooler and brought out more tables and chairs for the Sheepy Dalek Bar? Seems they all really like the place. Maybe some competition for the Friday riddles? Maybe a short introduction on the Friday happenings for the newbies are in order.

  6. Probably off topic, but this crack appeared in Mexico a few days ago, [Sorry, link removed because of suspected malicious code on that page. See yt video below for reference. chryphia], no volcanism involved it seems… (not the best internet page I guess, but good quality of the movie). If such a crack would start in Barba…..

  7. Some strange thing.
    We went outside and it smells sulphur…

    Wind is mostly from the north (moderate intensity, and weather is pretty sunny), so I am not clear where is the source of the sulphur.

    Can’t stop thinking it could be from Vatnajokull but obviously my rational mind says it is not at all likely.

    I think it is the first time I smell sulphur in the windy air here where I live in Grimsnes. Of course 30km to the west is Hengill and that one releases sulphur gas which can smelled on its surroundings, depending on the wind. But never I had it felt it here.

    Once I also felt sulphur smell near Eyrabakki and that was my only other unexpected sulphur smell experience.

    North of me what is it? Geysir, Langjokull, Kerlingarfjoll, but those are far. Well, this is still an active volcanic region, named Grimsnes

    • Could the wind be coming from the north-east then swinging around to the south just before it sweeps over Grimsnes? If so, then it could be picking up sulphur from Vatnajökull though it would have to be really strong to travel that far… very strange…

  8. Caldera deflation my butt.
    GPS data does not substantiate that. Directly after the first large Eq at Bárdarbunga the deflation trend reversed and we now have full on inflation, also the northward motion of DYNC restarted.

    What I find most intriguing is what is going on at Grimsvötn, the southmotion has stoped and might actually show signs of reversing. But that might just be delays from the previous deflation.


  9. For those of you that understand latitude/longitude;
    the 3,4 quake at 17:44:03, lat/long = 64.677/17.468 was at 4,5km.
    the 3,4 quake at 13:02:08, lat/long = 64.678/17.470 was at 4,9km.
    Are they so close that they only show as one star?

  10. Good evening,

    I have been stuck in a meeting miles from home from early to late and no chance to keep abreast the discussion, any kind soul can give a quick two line summary?

  11. Does Kverkfjoll always steam as much as this? I know it was mentioned on the previous page but that cloud on the left seems bigger than earlier this afternoon.

  12. This run is interesting – start from the earliest at the bottom of the list and work up:

    21.08.2014 . . . .19:38:03 . . . .64.705 . . -17.008 . . . .10.3 km . . . .2.2 . . . .99.0 . . . .12.7 km SE of Kistufell

    21.08.2014 . . . .19:35:00 . . . .64.702 . . -17.005 . . . .10.5 km . . . .2.7 . . . .99.0 . . . .13.0 km SE of Kistufell

    21.08.2014 . . . .19:17:55 . . . .64.687 . . -17.030 . . . .11.7 km . . . .2.1 . . . .99.0 . . . .13.5 km SE of Kistufell

    21.08.2014 . . . .19:07:19 . . . .64.703 . . -16.996 . . . . .8.5 km . . . .2.1 . . . .99.0 . . . .13.3 km SE of Kistufell

    21.08.2014 . . . .18:15:14 . . . .64.699 . . -17.009 . . . .10.0 km . . . .2.1 . . . .99.0 . . . .13.1 km SE of Kistufell

    21.08.2014 . . . .18:10:42 . . . .64.694 . . -17.006 . . . .10.0 km . . . .2.4 . . . .99.0 . . . .13.6 km SE of Kistufell

    21.08.2014 . . . .17:59:38 . . . .64.716 . . -16.941 . . . .11.6 km . . . .2.7 . . . .99.0 . . . .14.6 km ESE of Kistufell

    21.08.2014 . . . .17:56:19 . . . .64.710 . . -16.946 . . . .11.6 km . . . .2.4 . . . .99.0 . . . .14.7 km ESE of Kistufell

    21.08.2014 . . . .17:55:27 . . . .64.723 . . -16.948 . . . . .9.7 km . . . .2.4 . . . .99.0 . . . .13.9 km ESE of Kistufell

    21.08.2014 . . . .17:53:42 . . . .64.712 . . -16.960 . . . .10.6 km . . . .2.6 . . . .99.0 . . . .14.0 km ESE of Kistufell

    21.08.2014 . . . .17:50:37 . . . .64.682 . . -16.979 . . . .10.3 km . . . .2.5 . . . .99.0 . . . .15.5 km SE of Kistufell

    What I found interesting was that this run is moving steadily towards Kistufell, starting from 15.5km away to 12.7km away, and all are around 10km deep. It probably doesn’t mean much but the pattern from the IMO table did jump out at me.

  13. Seems to be a really long earthquake. Lasted about a minute!
    Maybe significant more activity is going to occur this night.

    I start to think that either this will erupt within a few days, or it will keep like this for weeks, until we see a large eruption.

  14. Is there, AGAIN, ring faulting happening around the caldera of Bardarbunga, like we saw in the first day?

    Like Geolurking said a few days ago, this would mean that the entire lid of the caldera is getting under strain all around its edges. Either the caldera seeks to go upwards or sink downwards. Not sure.

    • I agree that if it continues for weeks it could get rather nasty… So, I would prefer it to start soon.

      GPS favours new inflation, not caldera faulting as RUV reported. I trust the GPS…

      • Actually I just thought this: what if, independent of tectonics, that magma from the caldera just massively moved towards the dikes, and partially emptied the caldera. The inflation between DYNC and Grims relates to the dike formation, while Hamarin and Vonarskard push towards Bardarbunga as the magma exited it. Just a theory.

        • I think that is pretty near to what happened. As good a theory as any I have heard so far.
          Problem is that I think that new magma is now injecting into the system again. That explains the new motion pattern for today.

          • In RÚV news, a geologist said also, that the eastern dike is widening at its tip.
            Your theory about a new magma injection would explain that. New magma streaming into Bárdarbunga reservoir, pushing more older magma out into the open dike which is perhaps at its tip encountering a hindrance and breaking through brittle rocks at the sides.

        • Maybe I am getting too fixated on the one thing but what I found initially really strange in this whole episode were the three parallel lines of faults running from west to east, two that ran across north of the caldera and one south of it. There was not the slightest sign of radial faulting or even any obvious juxtaposition to Bardarbunga at all. Possibly these tectonic movements (as I presume they were) triggered such magma movements or were some kind of precursor to it but I can’t help thinking this whole thing is primarily a tectonic shift with resulting magmatic response and not the other way around. And yeah, I’ll shut up now because I’ve really been harping on too much about this. Tomorrow the All Blacks play Australia. I’ll try to concentrate on that.

      • I was wondering about that RUV article too. Accoording to it it was a statement from Gunnar B. Gudmundsson from IMO. I can’t interpret the gps data and i was very surprised by the proposed dropping of the caldera anyway. I’m thinking pressure built up, so inflation. But i did think of a possible mechanism.
        First a wad of magma from below increases pressure on bardabunga’s magma chamber.
        Rock in the current dyke area is under great tension from the yearly build up.
        Rock under tension is rather weak and the magma finds it’s way there through the radial crack.
        Once in the area the magma opens the dyke and the build up tension causes it to crack further because the tension gets a facaul point, like paper or plastic is much more easily teared when you make a tiny cut in it before start pulling it appart like mad.
        The build up tension cause the dyke to pull open and more or less sucking the bardabunga magma in. causing the chamber under bardabunga to deflated somewhat.

        Just a wild thought…

          • Yep, but we are talking about a radial dike that is 20 km deep. Given that radial dikes form from magma pressure in the central system you are talking SERIOUS pressure if you want to invoke the radial dike hypothesis. If the pressure were seriously that high, I’d expect to see upwards inflation… Sorry I was going to shut up wasn’t I.. oh well… I remain with the tectonic explanation and decompression melt scenario.. time for bed.

          • Thanks ! I first like to see prove of the deflation before i believe my proposed mechanism. But it does show i start to understand how things work.. Great learning place this is 🙂
            Would be interesting to see the faucal resolutions of the bardabunga caldera quakes that happened today while tremor kept dropping. No peak today…

            • I must admit those large caldera quakes have thrown a ginormous spanner in the works of all my pet theories. Maybe the simplest answer is best. A simple rifting episode with associated decompression melt creating a) a dike intrusion and b) reactivation of the Bardabunga system. All the other symptoms (Kistufell and the three parallel EW quakes) are just artifacts or noise.

    • Problem is that we are in uncharted territory here.
      I am going to say it like this, anyone who says they can predict what will happen that accurately is someone who does not know a thing…

      I do think it will erupt, problem is that when, where and how could be pretty much anything. At best we will now better right before the start of the eruption. I wish I could help out.

  15. Sorry if thats already been said. I did check the comments but might have missed some. ( I was checking out La Plama instead 🙂 🙂 😎
    Did you notice they no longer talk of Bardabunga alone but the Title for the news is now Bárðarbunga and Dyngjujökull

  16. carl’s image with the ‘nice’ arrows
    and the quakes overlayed (had to rescale teh images roughly until the outline of the glacier lined up)

  17. Hmmmm A 2.2, a 2.9 and a 2.8 all very close in time.

    21.08.2014 20:41:17 64.620 -17.455 9.5 km 2.8 99.0 4.1 km ESE of Bárðarbunga
    21.08.2014 20:37:55 64.616 -17.421 3.4 km 2.9 99.0 5.8 km ESE of Bárðarbunga
    21.08.2014 20:36:17 64.642 -17.064 9.2 km 2.2 30.63 16.9 km SSE of Kistufell

    • “Newbie”…. thanks.

      Its still accurate though, having never encountered a full on critter getter popping up through the ice, though it will be remote sensors for me. I do however, fully understand the scale of things. Jökulhlaups can easily exceed the flow rate of the Mississippi river.

  18. It shall be very interesting to see what new information we learn tomorrow if not more today. I’m thinking that adding Hekla and Kverkfjöll should be added to the possible eruption site list. When was the last time Kverkfjöll had a major eruption?

    • I think that the longer the event prior to eruption the more the risk increases for a larger event. But as Mike Ross has pointed out; “We are not in Kansas anymore”.
      I think we will just have to sit and wait for what will come and look at the GPS.

      • Well we KNOW Laki – which is about the definition of a ‘large eruption’ – was preceded by a month or so of felt seismicity.

        What do we know about the precursors to Askja going caldera?

        I do find it interesting that this started in two fissures swarms, one – the one most directly connected to Bárðarbunga – went dead after a couple of days of strong activity, then only after a couple more days, Bárðarbunga caldera started to get into the action.

        Fissures first, THEN caldera. That’s telling us something about what’s driving this process, and where it’s likely to go, IF there’s enough impetus behind it to get it to that point…

        • I may be fantastically wrong but I wondered if the wave pattern on the tremor readings was being caused by a pumping/pulsing action (rather like long, strong heart beats) that’s ‘pumping’ magma from the mantle into the Barðárbunga chamber. Before the chamber can fill (or because the chamber can’t fill), the magma is flowing into a radial dike which intersects with a radial dike from Grimsvötn and turned sharp left (either because it sloped slightly downwards or the right turn was at least partially blocked). Some 4-5 days ago, there was a wave of earthquakes along the radial dike from Barðárbunga and the first 10 km or so of the transverse dike. The earthquakes have now shifted to the next 10-15km of the transverse dike – the first 10km being silent because it’s been scoured clean and the magma is flowing smoothly through there now.

          Meanwhile, magma is still pulsing into Barðárbunga, putting pressure on the chamber there and further up the transverse dike which is either too narrow or too littered with debris to allow all the magma to pass through smoothly, hence the stronger and more frequent quakes at both Barðárbunga and further along the transverse dike. Considering how little headway it’s made through the transverse dike in the last 24 hours or so, I’m thinking it may have come to a dead end and all those earthquakes are an indication that it is broadening the dike while forcing the rocks ahead to fracture so it can move forward again. With luck it may find its way into a radial dike that leads to Kistufell. If it does, I imagine things will happen fairly quickly.

          Of course, I might be completely wrong! 🙂

          • Mopshell, welcome.

            From what I’ve read you may be misunderstanding… the consensus, including the IMO one, is that the current Barðárbunga caldera quakes are believed to be due to magma in that area *draining* into the fissures swarm, not to the caldera magma reservoir filling and pressurising?

            • Only problem is that Mopshell is in accordance with the orbit change of DYNC and GFUM. The GPS values favour renewed inflation. I have the feeling IMO jumped the gun on that one because the GPS data came after their prediction of deflation.

              I am definitely not consensusing with IMO this time.

            • And I find draining an interesting scenario when you are talking about a fissure 20 km or more in depth. If ALL of that volume came from Bardabunga, you would be seeing some serious deflation there. Possibly, these new caldera quakes are precisely a symptom of this, a sinking of the caldera floor like at Reunion. (in which case we should see a depression in the ice cap due to subsidence). What’s wrong with a bit of decompression melt? It’s how these fissure function most of the time!

          • I can see you’re addicted already. This periodicity was first really focused on by Peter Cobbold during the Eyjaf eruption. Peter is an eminent scientist in his own right and I remember him saying something to the effect of “people, I see a pattern there. It must mean something”.. The pattern at Eyjaf was by no means as clearly expressed as it is in the tremor charts at Bardarbunga today. Rather we had pulses of quakes occurring over an 18 hour interval. We came up with all sorts of theories for this. Here again, we see a similar periodicity over a long interval (24 or more hours). I have thought about it long and hard and resigned. I just don’t know enough. Something makes me think a certain resonance kicks in, kind of like a water hammer in bad plumbing, you know, when an initial pressure wave makes to the end of the system, hits resistance and comes back the other way or something like that.. Peter favors the idea of boluses of new melt entering the system from below. I vaguely remember a scientific paper on it but I’m embarrassed to say I can’t remember their conclusion.

            • “that should change the resonant frequency, yes?”


              And, water hammer is not relegated to bad pipes. Just a coincidence of a resonant frequency being triggered by an appropriate stimulus. I’m sure all those people who had their water heaters implode didn’t think they had a bad piping issue. It was caused by a fire apparatus going into suction mode trying to get enough water to put the nearby warehouse out.

      • PS on one hand, Laki was a fair bit closer to populated areas than Bárðarbunga – so perhaps felt more strongly.

        On the other hand, only a couple of the Bárðarbunga quakes have been strong enough to be felt other than very locally.

        On the gripping hand, with instruments we can obviously see a lot that the folks in early 1783 couldn’t see…

  19. Evening all! Great to see so many new faces – welcome 🙂 interesting following your discussions this evening … And the sheep!! I have a long drive ahead of me tomorrow and I’m hoping I can convince my other half to read all your comments, hoping 😉 I’ve recently discovered the pleasure of audio books – it would be great if there was an audio version of Volcano Cafe! Any volunteers to have their voice recorded? 😉

  20. In the words of the Bard, “To bed, perchance to sleep”. In my words, ‘To bed, perchance to dream’, of Volcanoes! Wouldn’t be the first volcanic dream I have had and I have survived them all so far. 😀
    Night all.

  21. As we are getting more people here by the day (The concern about Bardarbunga has hit the UK news broadcasts again) Can I suggest anyone wanting a daily update by the Iceland Meteorological Office can find it here in English

    My thoughts and thanks go out to all those people in Iceland who work so hard to keep everyone safe . The IMO and University have installed more monitoring equipment in the area. The resultant findings will give vital information for all Vulcanologists/Geologists in the world to use . Predicting volcanic activity will save so many lives , Accurate prediction is still in the future but the experts are making discoveries all the time.
    The Icelandic Police and Everyone in Civil protection organisations are working so hard at the moment. It is so kind of the IMO to make their site and data so accessible to us would be vulcanologists. Again a big “Thank you”.

    • I agree, Diana. It’s amazing to be sitting in my living room looking at all this data, available to anyone. A few years back and we’d just be reading about this in the paper or hearing about it on the radio/tv news. As an Icelander, I’m extremely thankful for and proud of all the people who are involved in keeping us safe and informed.

    • Thanks, Diana! That site will get a star from me…. It’s wonderful seeing all the oldsters around… All the Best!motsfo who is older and tireder than ever.

  22. A flock of sheep came to our gate today, eyeing our very green grass and this evening 15 of our hamburg hens insisted on roosting in the trees. Could these be an eruption precursors?

  23. It has been six intense days of watching Bardarbunga. A few things can be summarized by now. Bardarbunga was behaving restless for years and in the last few weeks even more. We know that every 150 years or so, there is a peak in Icelandic eruptions, and this is just around the corner, so a large rifting episode is more likely.

    In 16th August, this intense swarm started at Bardarbunga, at the caldera but rapidly moved NE and divided into two swarms (clearly magma from deep rose within the caldera and then moved laterally over the Dyngjuháls fissure swarm but it also extended over a radial fissure and then along the Grimsvotn fissure swarm almost reaching Kverfjoll and in the direction of Herdubreid. Every day the magma was travelling about 1km northeastwards. The dikes so far have been around 25km long, between 5 and 10km deep. So far, most magma movements are not yet near surface.

    GPS showed sudden, sustained and dramatic movements. Dyngjuháls moved quickly NW, while Grimsvotn moved southwards and has been inflating (started shortly before this event). Hamarinn and Vonarskard reversed their trend to the NW and moved eastwards, as if either the emptying of magma from Bardarbunga caldera (towards the dikes) pushed those stations in its direction, or tectonics from Hreppar microplate were at play, and Hreppar was doing a clockwise jerk adjustment, contrary to its anticlockwise general trend.

    It is very tempting to favour a tectonic-rifting scenario, because no inflation has been observed in most stations, only lateral movement. Also deflation has not been observed, although some people have pointed to strain earthquakes around the edges of Bardarbunga caldera (and possibly ring faulting). This is probably due to magma exiting the caldera, and then new magma coming in later.

    The rifting scenario suggested is that tectonics in last 6 days reflect movements typical of 5 or 6 years, and as the rift opens, magma rushes to fill the gap and travel along the fissure swarm.

    Recently, the NE dike intrusion seems to be widening at its tip, and almost dividing into two directions again, one along Grimsvotn fissure swarm towards Herdubreid, and another further east, crossing the Kverfjoll fissure swarm.

    The intrusion is supposed to be in the order of 0.1 km3, but those are not my numbers and that is argueable, depending on the width of the dikes.

    If there is an eruption, it will be probably part in ice (explosive and ashy) and part in ice-free (large volumes of lava coming from a fissure). My estimate is that a fissure would be around 10 to 15km long, quite larger than Krafla and Gjálp but smaller than Laki. Any flood is calculated to be around 5000 to 20000 cu meters per second, so about 6 to 10 smaller than the glacial flood of 1996. It would destroy the bridge in Jokulsá à fjollum in the ring road. It would affect Dettifoss, Asbyrgi and Godafoss. There is a minor change that a flood might also go along Tungá river to the southwest. For this reason, authorities are taking this situation very seriously and evacuated the areas in possible danger. They are closely monitoring the situation and they are the ones responsibel for any official statements and warning, not us at this blog.

    It’s difficult to estimate the size of an explosive eruption, but likely something in the order VEI3 to VEI4+, so possibly not worse than Eyjafjallajokull (but this is just my speculation). If a large fissure develops, the problem would be the large amounts of gas released; possibly with problems for the local farmers.

    An eruption can occur within a few days, and then it would be medium size. But if this activity keeps for a month or more, then changes are that it could means a larger rifting episode. I calculated that at this rate that would be achieved by mid September, with a total cumulative seismic energy equivalent to a large M5.5-M6 earthquake. Usually large rifting episodes start with intrusions that first occur in the caldera but quickly migrate along the fissure swarm until its end. There is a period of weeks to months of earthquakes up to M5 or M6 before an eruption starts. Then a rifting episode lasts around an average of 1 year but sometimes it lasts a couple of years. Examples include rifting in Laki in 1783, towards the SW of Bardarbunga in 1862, in Askja in 1875, and Krafla in 1975.

    This swarm of earthquakes show no signs of ending or changing that much. It could go on for a long time,as I said. Usually there are about 1000 earthquakes per day, with a few up to M3.5 or M4.

    Finally on Bardarbunga. It is 2100m high caldera volcano, under thick ice cap with thickness of 700meters (its a deep caldera). The fissure swarm runs along 190km, a part to the SW, another to the NE, where the current magmatic intrusion is happening. It is the largest volcanic system in Iceland, and perhaps the largest caldera. It also has the largest lava fields, largest lava eruptions of all Icelandic volcanoes, and also the only VEI6 since settlement of Iceland.

    I hope this summary has covered most matters. I haven’t covered links but I am tired now!

    • I think you got the most pertinant things…

      I just missed one thing. Bárdarbunga is the largest and most potent mantleplume volcano on the planet.

      • Is not Mauna Loa the largest mantleplume volcano – seen from the bottom of the sea, it is even much higher than Mt. Everest.

    • As to the peak in eruption numbers in Iceland, I remember Icelandic geologists (Magnús Tumi?) having talked about a low at the moment, eruption numbers are just now just slightly going up again.
      And to talk about an 150 or so year rhythm … This would be the same as to say volcanoes are “overdue”, which is scientifically not correct. Also there were about 600 years between Vatnaöldur and Veidivötn eruption series….

  24. Thank you Irpsit. A really handy summary of things so far. I’m off to bed so night all. One quick drink in the Sheepy bar then that’s me done.

  25. the swiss seismologial service registered it as two quakes, both above M4

    2014/08/21 23:51:10 62.58 -10.08 7.3 mb 4.2 SED_NTeT automatic Iceland Region
    2014/08/21 23:50:24 64.53 -17.45 10.0 M 4.6 GFZ automatic Iceland

  26. While you all sleep, I’ll be monitoring the action for you. 🙂

    For my first mini-report, there are two interesting happenings in the IMO table. Please note that I have filtered out all earthquakes less than 2 magnitude because these aren’t reviewed and are therefore not reliable. Firstly this stand-alone earthquake because it’s another magnitude 3.0:

    21.08.2014____22:44:58____64.681–16.998____12.3 km____3.0____99.0____14.9 km SE of Kistufell

    That would place it just south of the green star at the lower end of the incursion activity. It was immediately followed by this pattern:

    21.08.2014____22:59:11____64.692–17.004____2.8 km____2.0____90.05____13.8 km SE of Kistufell

    21.08.2014____22:54:38____64.679–17.041____9.5 km____2.3____99.0_____13.8 km SE of Kistufell

    21.08.2014____22:53:02____64.680–17.038____4.4 km____2.9____99.0_____13.8 km SE of Kistufell

    These three are interesting because they literally occurred one on top of the other, 13.8km SE of Kistufell; one at 9.5km depth, one at 4.4km depth and the shallowest at 2.8km depth. At this point in time (12.02 local time) the latest of these three has not been reviewed. When it has, I’ll include any changes to this event in a forthcoming report.

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