Bárðarbunga reader question

/ August 27, 2014
Image by Tom. Upper part shows a closed propagating dyke. The lower shows a rift open down to the mantle. The upper version draws its magma from a central volcano, the lower from the mantle. Upper alternative would give a smaller eruption than the lower.

Image by Margaret E. Hartley/Thor Thordarson. Upper part shows a closed propagating dyke. The lower shows a rift open down to the mantle. The upper version draws its magma from a central volcano, the lower from the mantle. Upper alternative would give a smaller eruption than the lower.

Richie, one of our readers emailed in a good question that is a good starting point for a brief update on Bárðarbunga.

“Could you do an article comparing this intrusion to others? Looking at the post it appears that it is almost 40 Km long but how wide is it and in terms of volume. I am not sure if any diagrams are available to give an indication of the size underground. ”

It is hard to compare this intrusion to any other that we have instrumental data on. The main reason is that we have not seen one like this from a mantleplume volcano, nor have we seen something like this from a rift volcano.

It has a little bit of semblance from the Krafla Fires rifting episode. But I think that comparison is just too simple. First of all that was a much thinner intrusion that never reached this deep, so it was never even close to get down to the mantle. And the most obvious thing is that it kept to its own fissure swarm.

This intrusion has now been inside 3 different fissure swarms, and has the potential for more magma output when it breaks to the surface. In a way it is much closer to how the Skaftár Fires (Lakí) looked, but that eruption also seems to have stayed within its own fissure swarm.

Image by the Icelandic Met Office.

Image by the Icelandic Met Office.

I would now say that it is a unique intrusion and that makes it all the harder to understand and potentially more dangerous.

I am not aware of any exact diagrams or plots of the intrusion, but Tom made a couple that is interesting where he compares two possible solutions for the shape. One is a bottom closed intrusion with no mantle contact, and the second is a full Skaftár Fires version with a wedge shaped obloid intrusion open down to the mantle.

I currently think we have the first option, but that it is really close to the mantle and that it sooner or later will turn into option two. If I am right this will most likely lead to an increased risk for a flood basalt event.

The rift is now 45 km long and roughly 17.5 km high. Calculating the width is though a bit more interesting. If we take the east and west dilation between the Dyngjuháls (DYNC) and Kverkfjöll (Gengissig, GSIG) is by now 44.5cm. To get the correct values we have to take to recognize that the GPS-station are a bit far from the rift so the value is larger. Now, if we compare with the apparent dilation on further out stations we can roughly calculate that the true value is around 135cm. That would make the current volume of intruded magma into 1.05km3.

Update on Bárðarbunga

Image by the Icelandic Met Office. Note the curious pulsing of the magma reservoir visible in the up component.

Image by the Icelandic Met Office. Note the curious pulsing of the magma reservoir visible in the up component.

At the going rate the intrusion will slam into the eastern side of Askja’s magmatic system in 2 to 3 days. The effects of that could become slightly troublesome.

The large earthquakes are continuing at the caldera of Bárðarbunga and it seems like at least a partial ring faulting might take place there as magma rushes out from the magma reservoir. On the other hand the lowering of the caldera floor seems to be fairly small so the influx of magma is barely smaller than the amount going out into the opening rift.

Earlier tonight I noticed something interesting in the next volcano over. And that is that according to the Grimsvötn GPS it seems like the volcano is pulsing. That is a bit odd for a volcano that is not erupting and looks like it is not doing an intrusion of itself. And it becomes even more quirky since it seems to happen at the same time as the Bárðarbunga intrusion hits roadblocks.

One intriguing possibility is that the Bárðarbunga intrusion hit an old intrusion in Grimsvötns containing molten material and that it due to higher pressure in the Grimsvötn system took that infamous left-hand turn down Grimsvötns fissure swarm. It would certainly explain the marked pulsing on the GPS plot. Having Iceland’s two largest volcanoes force feed a rifting dyke could become slightly interesting in the future if it is correct.

CARL
Update:
Using Down Under ( Andrew)´s comments:August 27, 2014 at 05:04

Everybody, please welcome the dike into the Askja domain.

Credit IMO 27.8.2014

Credit IMO 27.8.2014

bvservlet-1

He also did some trajectories starting August 28th

Down Under (Andrew) August 27, 2014 at 05:04

and August 29th:Down Under (Andrew) August 27, 2014 at 05:08

www.midhus.is webcam pointing at Bardarbunga Up in the sidebar of VC

http://www.midhus.is webcam pointing at Bardarbunga
Up in the sidebar of VC

Spica

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1,502 thoughts on “Bárðarbunga reader question”

  1. Number of 3+ Vatna quakes per 48 hrs seems to have dropped dramatically – 32 as of now on the IMO site. Pretty sure that figure was up around 70 two days ago. Total quakes / 48 hrs has dropped slightly, but nothing like that – from 2500 to 2300.

    Reply

    • First of all that number will increase as IMO does their large daily revision. And secondly this goes in waves. I fully expect an uptick later on.

      Reply

      • I agree that some 3+ seem to be added late, but it’s 12 noon GMT and the 3+ count is now 27. When does the daily revision take place ?

        Reply

    • You’ll also find six of those are above magnitude 4 (four of them above magnitude 5 including the 5.7) so even though the quantity is less, the energy output is much greater. Perhaps that is having an effect on the total number…?

      Reply

  5. Not had time to read all the comments on here as I have only just finished reading the last page of the previous post. Before I go out I just wanted to mention that it appears to me that the dyke has once again started to progress forward compared to yesterdays apparent stall.

    Reply

  7. Words fail me.

    Dr. Erik Klemetti runs a wonderful blog about the wonderful world of magma.

    A blog where both ‘dike’ and ‘dyke’ are forbidden to be used, and any attempted post which uses them is blocked as – presumably – foul language(!)(?)

    As much bloody use as an ashtray on a motorbike.

    Reply

    • Oh now i get it. ((I rarely check the comments on Eruptions anymore. xxx windows popping open, videos start to play, a nuisance of the worst case.)

      But thats not Erik ( as you very well know) thats the more than stupid commenting system called Disqus. Which made many many here leave Eruptions and join this site instead. We are not as scientifically educated but at least you may use the d word …..dike or dyke as often as you like.
      I still do not understand why Erik stick with that. he gets payed for blogging, so many comments are good for him. We would have made a fortune the last days if we would be paid bloggers, which we are not.
      i thought to point that out, all dragons including Carl work in their free time and do not get paid. Thats also why this blog is add free ( if you signed in).

      Reply

    • I think I can clearly state that the moon has a similar effect to quakes and éruptions as Nibiru has.
      Hail Nibiru. Long life to our new lizard masters from Planet X. Please use vaseline when you insert your examination instrumentation deep into my arse. May our ant defenders win the fight for power over the earth. Will Ebola kill us even before the climate change? I’m gonna buy a Prius, because I want to be part of the solution, and not of the problem. SUV’s, heated homes and big sreen TVs are evil. Zeuss and Odin were fake, Allah is real.
      Just meant to say.

      Reply

      • ease off on the troll killing geoloco

        I think someone was indirectly asking if earthtides had any significant impact on the strain fluctuations and whether that had any impact on pattern of large vs small quakes during this event

        I think the answer is ‘no’ probably not – and statistically shown to be insignificant in the grand scheme of things – but in this smaller scale I can see why you might think there might be a statistical correlation if we were looking at a ‘push’ model magma emplacement mixed with a small impact from a ‘pull’ on the plates to open the fissures model.

        (not an expert)

        Reply

          • 🙂 🙂 you are wrong btw Odin is real too – and so is the midgaard serpent – we are seeing the quakes as magma when it’s really just the serpent wriggling a little

            Reply

            • 🙂

              Give me a last litte bit of venting before I leave for lunch.
              Yes, of course. Respect asks for us to state all the gods ever invented are real, the recent ones even more than the old ones. There’s evidence for that, of course. Those who can’t see it are blinded by the obscure.
              My goddess is the holy vagina. We believe genitals live on after the rest of our bodies died. We’re buried ass in the air so we can serve as parking lot for nuclear bikes and help saving the planet. Please everyone respect my beliefs and every behaviour that is related to it.

          • At least Thor is a proven fact.
            He promised to abollish the Ice Trolls. Seen any Ice Trolls lately? So, he is real allright 😉

            Reply

        • No worries, in about ten minutes someone will hand in an application to build a Chalet on the top of a mountain top glacier. And the rest of the day GeoLoco will have to explain why that is not a good idea…

          After that day GeoLoco will be so depressed that he imbibes to heavilly on cheese fondue, that will cause a gassy stomach and the urge to buy a Goldwing. Late in the evening whilst surfing the net on his brand new Goldwing he will come in here and write about why Harpies are a good sign over Paris.
          And this is why we love our GeoLoco :mrgreen:

          Reply

            • Our planes only fly from 8 am to 5 pm. We plan to extend that time range, but for that we need them to have big headlights, and I think the Gripen didn’t have them, at least not halogen (how do you say that in english?) and today that seems to be standard.

        • It depends on the mass involved and the internal dynamics, orientation, location and stability of the system. So no correlation is found for Oldoinyo Lengai in Tanzania but for Kilauea, Hawaii roughly twice as many eruptions have occurred at tidal maximums. Fuego is another that seems tidally influenced – at a tidal minimum from memory but that is possibly due to it being part of the lager La Horqueta complex. So the answer seems to be yes and no – or depends on the system.

          There are actually a lot of papers out there on the topic.

          Reply

          • It’s different if you have a lava lake or not I think. The level of lava lakes seems influences as I remember to have read.
            But that is soooo secondary that my interest for it is quite minimal, I have to admit.

            Reply

          • Kilauea is leaking water through all those faults. Ol’Doinyo Llengai is rather far from an ocean.
            Now over to Fuego, it is one of the side venting volcanoes of the Amatitlan Caldera. And the only irrefutable trend I have found for that volcano is that it never erupts when I am visiting (we have a house on the caldera wall of Amatitlan).

            Reply

        • I would more be the guy on a bobber with a chopped ass…
          Or no, let me say something seriously: if I was to buy a bike right now, it would be the BMW nineT. No joke.

          Reply

          • @geoloco @carl

            🙂 has to be a 90s bmw rs1100 flat4 ! 🙂

            Just a morning browse lol a few things jump to mind

            @geoloco ref convo yesterday email me your address I ll send some tablets lol 🙂 you need a holiday 🙂

            @carl ref comments last night ie ” ***** media” 🙂 appologies NOT TO SCUM SUCKING…………MEDIA ! but yes also fully understand geolurking point just felt some community peops where needing to talk and get support as opposed to be “gagged” because of some scum sucking ****** ………. ok ok where s my tabs !!!

            AND “rant” worst of all I read that after 30 odd thousand years of human evolution (hoping thats not too controversial) and development in order we can see potentially see the smallest tiniest caldera + fissure eruption in 30 000 years nature is going to cover it with a hurricane when it happens ! ********* great!!!!!!

            Ps dont like media:-)

            Reply

      • ” I’m gonna buy a Prius, because I want to be part of the solution”
        I have a prius and not to be part of a “solution” I got it to get even with Exxon and having a 50 mpg average for the 9 years driving it it has done rather well with no problems at all with it

        Reply

        • 50 mgp. Astonishing. And that completely compensates for it’s extraordinary uglyness and complexity (2 engines for 1 vehicle) and the dramatic conditions under which the elements for the batteries are extracted from mother earth (please, I’m kidding).
          Your reaction leads me to think you like your car a lot. You might be a little car nerd. Try a V8 with ridiculous amounts of power (like a brainless Mustang Shelby) and feel the vibration climb up your spine to tickle your brain. You’re gonna love it and forget about Exxon or whatever… 🙂

          Reply

          • Fast cars are for idiots.
            I was an idiot for a few weeks.
            After a few weeks with a sports car my member had shrunk and I decided to sell the car. After that my member grew back into its normal size.

            Reply

  10. If I look at the tremor plots and see there rising and falling frequencies. Are they directly related to Magma entering the dyke? If yes, and given the assumption that the dyke is solely fed by Bardarbunga (which I don’t think it is). Wouldn’t the tremor show up in ASK quite a bit after it shows in DYNC?

    Probably a naive question but I just wonder.

    Reply

  11. @AndrewDownUnder – any chance of a plot (starting any time you like) for a point source for the ash at 10km – but with fresh ash added at 10km every hour(?) for 4 days – and then to see where ash is to be found on 6hr intervals ?

    I don’t know if that is easy/tricky but it is the kind of thing I’d expect to actually be wanted by ‘ash forecasters’

    I’m still trying to get my head around the problems they would face

    Reply

      • The thinking was that, if IMO are now tracking the earthquakes associated with the intrusion dyke using Dreki and Trölladyngja as reference points rather than Kistufell, then graphing these earthquakes according to latitude and one other data field (I chose magnitude because I knew there was already a 4.5 data point and it was close to Askja) should create a graph that would show the movement of the intrusion dyke over the coming days. The real test will be comparing this graph with tomorrow’s!

        Reply

        • Hmm if dreki, trolladynga and kistufell are not on the same micro plate you might get a slightly different set of relative distances, but I think they are all done by latitude and longitude – so would show up correctly on one of dfm’s rotating plots (right?)

          Reply

        • You need to do this in real 3D. That is why Excel is not my choice. It’s not meant to do scientific plots.
          If you look at the plots I do, the magnitude is already shown. Size of the dots is proportional. I’m not sure this could produce something as magnitude is a log scale. Time will tell.

          Reply

          • I know, Excel has many limitations but does give an overview. Of course not as detailed and exact as your plots but I guess ok for a first impression 🙂

            Reply

            • there are plenty of way to do graphs. I went to work with Octave as a free laternative to Matlab. NOw I would probably move on to Python or R, but you need to learn the new language each time, so after a while you capitalize on what you have. A big drawback of matlab or octave is that the scatter function (where you can affect a size to a dot, plus color) is really very slow when you begin to have a lot of dots. There are faster function (like plot) but it will give you only a dot with color and no difference in size. Very fast, but you loose a lot information.
              For instance it takes about 30 s to make one plot at the moment. I will need something around 1000 plots to do the next video….so you’ll get the next one this evening.

            • I love the 3D models – they look spectacular! – but, for me, I prefer a simpler illustration. I’ve become somewhat frustrated with all the different maps showing the earthquake swarm moving north-east; on some it looks like the intrusion is 20 km away while others give the impression that the intrusion is already at Askja! I just wanted to devise a simple graphic illustration for myself that will automatically plot as I add new figures each day. 🙂

  13. Here’s something worth considering….

    Hurricane Cristobal is currently gaining strength and is bearing down on the Bahamas. Should – and I stress SHOULD – it move up the Eastern Seaboard of the United States then track across the Atlantic, striking Iceland at precisely the same time as a volcanic eruption, we could have an unprecedented disaster.

    Hurricane + Volcanic Eruption = “Hurricuption” – and this would mean that the Sci-Fi Channel would be duty bound to create a film that would be far, far worse than “Sharknado”.

    Pray it never happens.

    Reply

    • Cristobal is set to pass over Iceland in a few days according to NOAA. But that may change too. I’m not sure it would add up, I think the rain would take care of a part of the would be ash, depending on the height of the plume of course.

      Reply

      • It is a bit early to be forecasting path of Cristobal with any centainty 4 to 5 days in advance. ATM it looks more headed toward N. Spain and France.

        When it encounters land it will likely be a big depression with moderate amounts of rain. Hurricane Bertha took a similar path and produced and amazingly deep depression over GB and N. of France.

        Reply

        • Yes thank you we got some F1 tornadoes in the north of France and Belgium with the remnants of Bertha. I agree with you, NOAA gives a 5 days track, so the chance is remote.

          Reply

    • hmmm.. .actually I think a hurricane might be a bit of disaster mitigation in this case. All that rain will wash the ash out of the sky tout de suite. The region around Pinatubo was struck by massive lahars when it got hit.. it’s a totally different scenario here as there aren’t going to be a lot of locals in the way of any lahars.. maybe its better to ask Andrew DU on this. He knows a lot more about the weather.

      Anyone got full access to this paper? It looks like a goody:
      http://www.sciencedirect.com/science/article/pii/S0377027309001565

      Reply

    • This has already happened. After the Pinatubo had erupted, there was a typhoon. The combination led to lahars in the Philippines.

      Outside Iceland advantage of a hurricane may be that gases and ash particles spread more quickly and no reach no high density?

      Reply

      • If Christobal is affecting Iceland, it will most certainly have been transformed to or absorbed by a nontropical cyclone and will not be a huricane anymore. It can bring a lot of rain though, washing a lot af ash out of the sky.

        Reply

    • The ‘unprecedented disaster’ I was inferring is the glut of hurricane/volcanic eruption films that would surely follow. However, I am delighted that there could be serious scientific considerations relating to my flippant post.

      Reply

    • Oh you’ve done it now Eddie – you’ve put hurricuption or hurricano or erpticane out there in the universe where some Sci-Fi Channel person is going to pick up the idea and run with it… 😀

      Reply

  15. c. 10:45 another largish quake showing up on Hekla’s strain. (For newbies this does not mean anything is happening at Hekla.)

    Reply

    • They brought it down – not so big after all. (I’ve not seen that happen before – someone must be tending Hekla’s machines). 🙂

      Reply

  16. góðan daginn, ever increasing moods seem to get so irritated

    -… .- .-. -.. .- .-. -… ..- -. –. .- .- -. -.. .- … -.- .— .- -… — — —

    Reply

  17. Edward gave me a few good questions, so I will try to answer all at once, and I will post this new comment since someone else wonders the same thing:

    The questions are here:
    https://volcanocafe.wordpress.com/2014/08/27/bardarbunga-reader-question/#comment-136786

    Well, ash is carried by wind if its light enough and depending on the wind speed. And the ash would follow that red line that would be in that starting point at that time or that day. Weather patterns change constantly (even on a minor scale), so the conditions would change and over time the wind would take the ash perhaps in a slightly different road, with it ending on a different location and being effect by the conditions there. So its pretty much almost like a chaos theory, where small changes in the starting point can severely alter the progression down the line. That is why real ash dispersion models account for that and constantly adjust the flow to the entire column and every 3h, depending on the configured time step in the model itself. And that is why you have to constantly re-plot and update the trajectories. These trajectories are only for one day and one location. So lets say hypothetically, that there would be an eruption at that day of the plot, the ash that would go up to 10km, and if it would be really fine enough, it would follow the red line, and the ash from the first day of the eruption would hypothetically end up somewhere down that line, BUT, as the ash eventually ascents down (you cant escape gravity, especially if you hit moisture as a perfect condensation nucleus :D), or it gets washed down, it gets carried by the winds on that specific altitude it is at. So yea, you see how complicated it really is, and these flow trajectories give you a general idea of the flow and where the ash would go, given it would reach that height on that specific day and time and would it be fine enough to be carried by the wind. A lot really depends on the ash characteristics. The Eyja vs. Grimsvotn was a great example of that.

    And for your second question, the winds on this altitude are not really directly affected by the mountains in general. So what you see there is just natural progression of the pattern, or the trough phasing onwards. The terrain can have some secondary effect on it, but its mainly just through succession by affecting the weather patterns in their own specific way.

    And the last question:
    @AndrewDownUnder – any chance of a plot (starting any time you like) for a point source for the ash at 10km – but with fresh ash added at 10km every hour(?) for 4 days – and then to see where ash is to be found on 6hr intervals ?

    The plot would be one big mess, with such a short interval, and the general flow conditions do not change that fast. So what I can make for example, is a plot with a new trajectory starting every 12 hours, and lasting for 3 days. The bottom plot shows moisture. The flow altitude is 10.000m.

    Basically you can see how tricky it gets with the conditions at the starting point changing. Pretty much a small “chaos theory” in its own way.

    if anyone else has a question, I would be glad to at least try and answer.

    Reply

  18. Fantastic Article once again – loving the scientific aspect of this rather than fluff news articles –

    I have a few follow up questions that i hope people can answer

    If the rift has not yet reached the Mantel Plume what would the change of behavior from current activity if this occurs?

    With the very complex volcanic systems in the area (2-3 different volcanoes, Dyke intrusions and faulting) what is the out come of the mixing of magmas with different properties?

    Regards

    Richie

    Reply

  20. I would like to praise the effort of all the people that are actively contributing to
    this extremely interesting discussion. What could be the influence of solid Earth
    tides on the ongoing activity? I have used the free software available here

    http://home.comcast.net/~dmilbert/softs/solid.htm

    to model the local components of the solid earth tide (East, North, Up) for the
    72 hours starting on 00:00:00 27/8/2014. A summary graph is shown below. It
    is interesting to observe that the last 3 magnitude > 5 event of last night cluster
    around the up-tide maximum (and the North tide minimum).
    Now the next local maximum of the up component (minimum of the North component)
    is forecasted for 14.00 UTC today. Shall we expect any firework?

    Reply

    • Good observation.
      I have noticed that in 3 or 4 days all earthquakes M5 seem to cluster around midnight or shortly after it.

      As much as we think that tides are not supposed to have such an effect, I think it has been something like 7 or 8 of those large earthquakes always around or after midnight, so it’s becoming a trend rather than a simple coincidence.

      Reply

      • I agree that tides should not have a significant effect, but we are probably dealing with an overall “system” that is highly unstable and any little nudge may indeed have an effect. Of course it is guesswork; let’s wait one hour and see what happens 😉

        Reply

      • Here are rough timetables for the current tides.
        The tideshifing moves foreward little over half an hour each day.

        Low tide in Hornafjörður (south-east of Bárðarbunga) is roughly about 10.30 today – moving 30-40 minutes foreward each day.
        Low tide in Húsavík (north of Bárðarbunga) is roughly about 5.50 today – moving about 30-40 minutes forwward each day.
        High tide is roughly 6 hrs 15 minutes behind low tide.

        Reply

      • Not all of them have clustered around midnight or shortly after as you can see from the list:

        27.08.2014 _ _ _ _ 02:50:36 _ _ _ _ 5.2 _ _ _ _ 7.5 km E of Bárðarbunga

        27.08.2014 _ _ _ _ 00:16:28 _ _ _ _ 5.4 _ _ _ _ 3.2 km SE of Bárðarbunga

        26.08.2014 _ _ _ _ 01:26:06 _ _ _ _ 5.7 _ _ _ _ 4.8 km NNE of Bárðarbunga

        25.08.2014 _ _ _ _ 16:19:03 _ _ _ _ 5.1 _ _ _ _ 4.1 km SE of Bárðarbunga

        24.08.2014 _ _ _ _ 20:39:11 _ _ _ _ 5.3 _ _ _ _ 8.1 km E of Bárðarbunga

        24.08.2014 _ _ _ _ 05:33:41 _ _ _ _ 5.1 _ _ _ _ 4.6 km SE of Bárðarbunga

        24.08.2014 _ _ _ _ 00:09:50 _ _ _ _ 5.3 _ _ _ _ 1.9 km NNE of Bárðarbunga

        I wouldn’t say 5:33am, 4:19pm or 8:39pm fit into that category; even 2:50am is stretching it.

        Reply

      • Simple answer, Irpsit, that’s when the pixies come out to play. It is the witching hour after all 😉

        Reply

    • Giggle Translation, (well – sort of…)

      “” Earthquake eruption in Vatnajökull and the march dyke of the glacier northwest side is one of the most significant earth science intrauterine event that scientists and the public in Iceland have witnessed. Never before has anything similar been recorded by modern technology.

      This is a vision Agust Gudmundsson, Professor of Earth Sciences, University of London, Royal Holloway, the scenario last days of the icecap, which has for decades including studied separately and dyke formation of the older rocks in Iceland.

      “This is a very big event and will shed light on the forces behind it when the country is that splits apart in this area. The glacier is considered to be mantle streaks, and nowhere in Iceland is more of a dynamic, “says August, indicating that the eruptions are all ToRs within the territory where the largest volcanic eruption in Iceland’s history have occurred. He said a major eruption possible, although a small eruption or earthquake eruption extinction is much more likely.

      At the foot of the center of the earth
      August says that the dyke is very large; Finally a side corridor that forms outside the volcanic defense. Some have roots going back to the magma chamber below the eruption, but it is not a dyke which now has an average crawl out about four miles a day last ten days. “This is coming from a much more in depth, or the magma chamber beneath which lies between 15 and 20 kilometers, as the most volcanic systems in Iceland. Such filaments are much larger than the magma chamber. Dyke is so large that it controls the whole voltage range, or forces, in this area. There is so much pressure in there it affects the volcano defense around, “says August, adding to it the remarkable situation at the moment is a clear progression dyke towards the volcanic caldera Centre / Dyngjufjöll.

      “If progress continues for several miles in the same direction, we do not know if he does, will attend voltage range dyke voltage range caldera, the volcano itself and magma chamber beneath, affecting a few miles out of them. Then the question is whether the intrusions take the cardboard itself, “says August who thinks too much of magma already in the rock hall for him to come from Bárðarbunga volcanic interior. It argued that it comes from magma chamber depths where much greater and hotter magma accumulate. He does, however, that the vast majority of intrusions, wherever they may be found in the world, never reach the surface.

      “But the key issue is that when the sting of the dyke’s about eight miles from the box itself, which is the equivalent of the width of it, then goes dyke feel the excitement stage where that can lead him to run into the magma chamber under the caldera,” says August acknowledges that this might trigger an eruption of this volcano Holy.
      Nothing like Krafla
      Resemblance to the events occurring at the beginning of the Krafla fires in 1975 have been called in the last days. August, however, is convinced that the other is here the case.

      “I do not see anything similar to what is happening, and consider this a completely different event. In the claim interpretation was that there have been dynamic in a small chamber, and then continues in a small walk from the Krafla chamber to the north and south. That, I believe walking is the dominant ones, not dynamic chamber, which could be the main difference between the two, “says August.

      Data scientists from yesterday show that skjálftavirknin is still high. Most activity is at the end of the corridor north of Dyngjujökli, now it’s about ten miles north of the glacier snout.

      Dyke under Dyngjujökli is now estimated to be 40 miles long. Model calculations based on GPS measurements indicate that the volume increase is just the last hour is about 50 million cubic meters. The amount is slightly lower than 500 cubic meters per second, or almost 1.5 times meðalársrennsli Library, so sizes may be placed in context.

      August believes that more is actually of magma intrusions than 350 million cubic meters, as calculations show right here at home. Even triple, representing all the magma that came up during the Surtsey eruption in the years 1963 to 1967 Hekla eruption 1947 total. Finally, it should be emphasized that the August recalls, as scientists here at home, the various scenarios drawn up but no degrees of plausibility are not Loan loss “”

      Note: ‘miles’ should be km
      50 million cubic metres in 24 hours not one hour

      Reply

      • Peter, further to your theory. One of the things you wanted to explain was why the magma was not freezing over such a long distance when the dike is only 40 cm, max 1m wide and then went looking for a mechanism to explain its molten nature.

        I think this article gives us another couple of clues: the source magma is from a deep region and therefore much hotter than assumed and, two, the dike might only be 1 m wide but the dike is extremely deep, given you a fairly large volume at the face. Couple that with rock being a very effective insulator, the high temperature of the country rock (i.e. only a small temperature differential) and maybe you have enough factors to explain why it remains mobile???

        I still like the cavitation idea though, or at least explosive blasts of magma into opening voids. This might explain the background tremor we are seeing, which should normally only occur when the magma rises high enough to start degassing.

        Reply

        • Dike could be now 0.8 km3.
          Small amount of magma would lead to a small size eruption, probably around 0.1-0.2 km3 at most, unless it either 1) mantle decompression, or 2) reaches the rhyolite magma of Askja, or 3) unless dike continues to grow and increases volume or drains the caldera past a point of collapse

          I repeat the scenarios most likely are either stalling and no eruption, or small eruption.

          Reply

        • Bruce, If we are watching a reprise of the Holuhraun lavas then the intrusion needs to be charactersitic if Barda. I dont know if mantle derived material would have that petrology – maybe not if magma evolves within Barda’s complicated paired magma chambers.
          But I agree if the intrusion is largely from mantle then the tip will be hotter, there’s only maybe 15km , at maximum, for it to rise.
          Chryphia’s animation of the eqs shows eqs ‘shhooting out’ towards Herdubreid, 10km or so ahead of the ‘tip’. But the tip then steers clear of that zone and moves into virgin territory. I do wonder if the tip needs tectoncillay strained terrain to progress! Someoene must have considered thsi before..

          Peter

          Reply

          • Not strain, it is TENSION.

            Tension is the opposite of strain. Strain compresses things together. If you are pressing them together, how the heck to you expect to get dike in there?

            Tension does the opposite, it pulls the rocks apart, FOR the magma, not BECAUSE of the magma.

            The crust on the CGPS stations are screaming out that the crust is tensional.

            The magma doesn’t have to do squat, but rise and wait for the tension to crack the obstacle for it.

            But if it rises enough it can add pressure to the tension as well – then you get the break through.

            It has nothing to do with ‘tips’ or added heat if it’s tensional and decompression melting.

            Reply

            • Stress & strain are tensors. You are thinking in terms of a linear model which is not how the science of stress and strain work. In this case the pulling apart of the upper crust is depressurizing the magma below the rift, allowing it to rise.

            • No.
              A strain is expressed as deformation of a material to an imposed stress. The deformation can be an extension, compression, expansion, twist …etc
              The Barda , Askja area is in an extensional tectonic (stress) field. So yes the crust is being stretched.
              But the term ‘strain’ is not as limited as you claim.

          • In his blog Haraldur also gives image showing measurements of little less than 500 dikes/swarms in Snæfellsnes peninsula – most of them 1 meter, many 3-5 meters but up to 20 meters thick dikes/swarms exist although rare.

            Reply

            • This means the paper where they measured the size of the dike of Laki must be somewhat inaccurate. They give the sizes of 1.5m for 1862 event, 4.5m for Laki, 10m for Veidivotn.

              Must be more.

              Krafla displacement varied between 1 to 8 meters (close to the caldera).

            • Just to point out that post eruption, any closed-over fissure can still form a dike. In other words, it seems most people just assume a dike represents a solidified non-erupted melt. But that ignores the fact that half the dikes formed can be the end-phase melts of a closed over spent major fissure eruption. But yes, many dikes don’t erupt. The bigger they are though, the more likely they did, mantle xenoliths and xenocrysts speak of decompression flow entrainments, and it’s difficult to see how a closed dike can manage that.

            • @Irpsit – I wonder how it would be possible to get exact measurements of the size of Laki’s dike except by excavating quite deep in number of places as there has been little or no errosion removing the surroundings of the dike.

            • @ ohr August 27, 2014 at 13:24

              Go down 50 meters and it will be plenty hot ‘n steamy. I’d try seismic imaging, as the discontinuity may give some clues as to the opening, via the backwash materials as it closed-over for the next few decades. Perhaps gravity as well.

            • @ Unmentionable
              Thank you – As you say, measurements with instruments give clues, not exact width.
              Only way to measure the width exactly would be to get your hands dirty and dig – which, by the way, is of course hardly possible 🙂
              Measurements of underground dikes / swarms are therefore probably more like clues to make estimates of the size instead of discovering the exact size.

            • Newbie question here: Why can’t you create standard underground imaging as it is done all over Europe? I understand they use several Trucks with vibrating blocks and also several reception stations. Does this not work because of the highly fractured ground near a fissure?

            • The dike of laki was on average 40 meters at the surface, several hundred meters at depth. The Graben that formed is between 50 and 500 meters…
              Haraldur is correct, that is the dyke width I have been using all along. The GPS does NOT give the correct answer.

          • ohr
            August 27, 2014 at 14:17
            @ Unmentionable
            —

            Haha, yeah, the blind lead the blind and they both fall in the Laki ditch. 😀

            If you want physical you need drill core – $$$

            Hence no data.

            Reply

        • I found a paper discussing this, by Rubin. He finds that a unmoving 1-m dyke will freeze in 7 days if the surrounding rock is cold. It is not far of the 10% heat loss per day which we estimated. It can take longer if the rock is warm (for instance, if tit was still hot from a previous eruption many years ago). If the magma is moving, viscous heating (friction) will keep the magma temperature constant but something much keep pumping magma into the dyke. From the numbers he gives it is not clear that a 1 metre thick dyke can become as long as is seen here. Could it be a bit wider?

          Reply

        • I must say, I find this all very confusing. Why does it only move in one direction? If it is being fed directly from the mantle below, why are we not seeing deep earthquakes at this point or points and the magma dispersing in both directions? When it hits a “road block’, why does it not flow back the way it came?

          Reply

          • Hi try thinking of it another way, forget this is about magma fissures and the tech stuff.

            First off you havent really got all these voids underground what its more about is pressure differences. This is why you are Not getting “liquid flowing one place to another”

            But visualise the fissure as a closed underground tunnel (the barbarbunga feed appears to be having less and less influence) full of expanding foam. The whole area is effectively being pushed up and pulled apart , this is causing the ground around the tunnel to fracture and create voids which the foam expands into. (Ie the magma)

            Hope this helps

            Reply

          • Haraldur Sigurdsson explains the theory of Göran Ekström and puts it into relation to the newest quakes.
            He tells they are too deep for indicating a lowering of the magma chamber, as Icelandic magma chambers tend to be shallow.
            http://www.mbl.is/frettir/innlent/2014/08/27/tappi_undir_kvikuthronni/

            Águst Gudmundsson, professor at Royal Holloway University, London, thinks that the magma is indeed coming from a deeper magma reservoir and the dyke influencing tectonically all the bigger area around it, also eg. Askja volcano. He thinks the magma is 3x the indicated quantity
            http://www.visir.is/lengist-um-fjora-kilometra-a-dag/article/2014140829176

            Magnús Tumi Gudmundsson, professor with University of Iceland, is now also talking about the rifting. The intrusion is now about 1-3 m wide and this is also the rifting. He thinks, what we are looking at, is something really special re. the geology , something which has not taken place within the last 100 or perhaps 200 years.
            http://www.ruv.is/frett/yfir-700-jardskjalftar-sidan-a-midnaetti

            Reply

      • As Carl has pointed out, at this point the magma estimate may be wishful-thinking, plus we won’t know until we already know, so who cares what the estimate is.

        So what we really need is a better measure of proportions of deformation, and the only thing really providing that measure is CGPS. Thus we need more of the mobile stations to see where the terrain is motioning to, in the north east, to see if it’s going to tensionally hinge-open in a SW direction, as well. Wouldn’t that be ‘fun’.

        At the moment the quakes are struggling because the further the tension gets from the hinge-point, which is SW of Bardarbunga (as shown by CGPS) then the less intense (rarefied) becomes the tensional-opening effect, and propagating to the NE slows and spreads over a larger area.

        Hence the earth quakes are becoming more dispersed in that direction the further you get from the hinge-point locus.

        So the propagation slows down, and as it slows and waits, before it breaks through again, the magma has more time to catch up and rise within the volume increase, and get up to the ‘lip’.

        Note: I’m deliberately ignoring Askja, as I simply have no idea what will happen there if a successful break through for 10 km occurs, say this afternoon. But what I do know is if this is tension-driven, then a ‘pressure-relief’ eruptions wont do anything to stop the dilation, because its not caused by pressure. An eruption will modify events some, but not stop it.

        Askja would just be so-much collateral damage, on the way to the main event, and the same would go for Bardarbunga, if the required crustal tension adjustment is large.

        Reply

        • Yes, Ding.

          This is why I have pointed out that we can see extensive rifting occuring over a wide area, even between Veidivotn or Edlgjá and up to Myvatn, that wouldn’t be a first time. It happened in 1862-1875.

          The caldera event of Askja in 1875 was a collateral event, so it might be any other eruption of a central volcano it might happen, or nearby earthquakes. The focus in on the rifting itself. The tectonics are doing per day what is on average occurs per year. Think about it.

          The rifting is creating much tension and magma just fills the space. What happens next is still rather unpredictable. But a long long dike in being formed. With the potencial for one or several big long rifting fissures. This is just Icelandic history again and again and again.

          Reply

          • The interesting thing is that the Laki system was parallel fissures, suggesting the tensional strain rate was very high, or else two fissures would not have been able to open. So look out for that too. 😉

            Reply

    • Peter,
      *without Dragons Hat* 😎
      I thought we had long time ago agreed not do complete translantions on stories or articles, instead do abstract and then link to article, it can be done via translator.
      This in not falling under important news, like IMO stone tables.
      And at first glance it contains only info already out and posted here.

      Reply

  22. Has it ever happened in recorded history that the rifting episode and the mantle plume coincides as it does now? I think I read it here on the blog a few articles ago.

    Reply

    • what do you mean by recorded history? Since we’ve had seismic instruments or since we first started painting on cave walls?

      Reply

      • Of course I meant since we have had seismic instruments. 🙂

        However maybe there are some records from before that even since the time between these different cycles are known.

        So when was the last time these two events coincided? And are there some eye witness records of volcanic activity during this period? Or maybe it was so long ago that no one knows?

        Reply

        • The Afar Triple Junction (Ethiopia), East African Rift is the textbook example – but you are getting into cutting edge research with plume/ridge interactions, in this case also complicated by the Tanzania Craton.

          That is happening “now”.

          Reply

          • Interesting, I have missed that there are two different cycles in the Afar Triple Junction. What are the time for the African plume “pulsing” and the rifting cycle?

            Reply

        • I am not even sure about these two cycles. Carl was the only source I heard about referring to two cycles. I papers I heard about a trend towards a 100-160 year cycle, with increased volcanic activity in Iceland, and especially in Vatnajokull, with often including large rifting episodes, and one paper suggesting also a link with increased large quakes in SISZ.

          As far as it looks clear, I found out this: about a third of large quakes in south Iceland are within 1 year of an Hekla eruption, and in the cases they are not they are sometimes within 1 year of a Katla eruption. That doesn’t looks to be a mere coincidence.

          Example of the activity starting in 1783. First a large eruption in Reykjanes, a few months later, eruption starts in Laki, then a few months later a sequence of the largest historical quakes in south Iceland, then a large rifting dike episode in Hengill but not erupting in 1789. Coincidence? No, just the sort of events that confirm the author hypothesis of the papers I read.

          But there are more examples. In 1720-1732, there was a fabulous sequence of large eruptions and large earthquakes in Iceland. Even one year with 3 eruptions! Similar situation in 1862-1875. Much rifting took place at Veidivotn, Dyngjujokull, Askja and all the way up to Myvatn, and Grimsvotn included of course.

          If you look back in history, these patterns repeat across Iceland. The cycle itself seems to be only semi-regular. That’s why it is controversial.

          Reply

          • Irpsit has somehow missed the rift cycle in Iceland. The average there is 270 year with 230 – 310 years as outer span. In that cycle span you find all Icelandic large riftings.

            Reply

          • From this recent paper excerpt:-

            Ice-covered central part of system, including Bárðarbunga: On average 2 eruptions per century during the last 1000 years, but most of the eruptions occurred in the interval 1200-1500 CE and in the 18th century. The duration of these explosive eruption ranges from days to months.
            Ice-free southwestern fissure swarm: Eruption frequency has varied from 1 to 10 eruptions per millennium, being highest >7000 years ago. The last three eruptions took place in 1862-64 CE, ~1477 CE and ~870 CE. Duration is months to years. Eruption frequency on the ice free northern fissure swarm is not known.

            Click to access Bardarbunga_kafli20140825.pdf

            Reply

            • Funny, IMO has the wrong info…
              In the last millenium you have 2 real rifting eruptions and a Krafla style. The real rifting eruptions are Veidivötn 1477 and Skaftár Fires (Laki) 1783. Then you have the Krafla type (Vatnaöldur).

              The average time between eruptions in Vatnajökull is one every 7 years for the last millenium.

          • Irpsit, look at the macro tectonics of this dike/fissure swarm’s context. Now look at the mapped grain in all the old repeated fissures and dykes running up the east side of Askja, now look at the macro tectonic structure again.

            It’s so clear why this system is doing what it’s doing, and where it’s doing it. It’s the very reason Bardarbunga is situated where it is. And also why it started there. It’s a zone that keeps on hinging open once or twice, maybe three times per millennia.

            Same for Katla and other correspondences you note. the interpretation of motion is the mantle, the crust is an open book in and tensional eruption.

            It’s the little barely tensional events/eruptions which are far more tricky to diagnose. This one is easy, just look at the landscape, the basement, and the mantle.

            I’m sure you and a few others are get it about right at this point, because its what the terrain the basement and the geodetics and mantle divergence are showing.

            Reply

  23. Hey Bruce,

    very good article http://www.wired.com/2014/08/icelandic-earthquake-swarm-heads-towards-askja-what-could-happen/

    I think the article poses well the different scenarios of what would happen in the possibility of this dike reaching Askja. I also think it’s way more likely for the dike to stall than to reach Askja, but both options have a significant risk.Also a third possibility is the dike missing Askja altogether and going further east.

    I think the least likely scenario now is an eruption starting under the ice cap. I think if it starts it most likely starts where it is located now (and any previous eruptions started at this spot, 1797, 1862..). Then of course it can unzip backwards into under the ica cap. But I don’t think it would start there now.

    Also very likely is the scenario of the dike just stalling for at least months. I think this happened in many cases in Iceland, and I read a paper with evidence that this was the case with Laki (can’t remember the name).

    But, just to make clear, this is all my SPECULATION. The order of my most likely scenarios is this:

    1) dike stalls and stays there a few days to a few weeks, then erupts a middle sized fissure
    2) dike stalls and stays there a few months to even many years and then a larger eruption eventually happens 2) dike eventually reaches Askja and triggers a small explosive eruption there
    3) medium size explosive eruption starts within Bardarbubga caldera (I think that’s a likely scenario, after all, in 1996 there was only a M5 quake and Bardarbunga caldera erupted a minor VEI2 – please let us remember that
    4) the fissure develops into a larger fissure but not as large as Laki, with a significant explosive component because it unzips open backwards
    5) dike continues northwards past Askja and eventually does not erupt
    6) Kverfjoll or Grimsvotn surprise everybody and erupt first (or Hekla, lol)

    Reply

    • I forgot to add scenario 7) Bardarbunga caldera collapses after a large amount of magma is drained and after enduring many M5 to M6 earthquakes. Please remember that I add this as least likely scenario, but still possible.

      And I forgot to add that in scenario 1) or 2) there is a minor change that the fissure stays erupting for a long time and develops into a shield volcano.
      This would actually be the best case scenario for Iceland, as it would be very touristic sight to see, and impressive for volcanologists. Remember the area there is quite abundant in shields. So we must consider that possibility too.

      Reply

    • “I think the least likely scenario now is an eruption starting under the ice cap. I think if it starts it most likely starts where it is located now (and any previous eruptions started at this spot, 1797, 1862..). Then of course it can unzip backwards into under the ica cap. But I don’t think it would start there now.”

      Ignoring Askja (for it will be what it will be), I wouldn’t be even a little sure of low prob under the ice. It’s the locus of the hinge-point back there, it started there from there for a reason. The biggest quakes are happening there for a reason.

      But the best argument goes to a combination of air photos, contour map, and structure map, which shows under that ices is a very popular place for a big exhalations in a bi- or tri-millennial tensional-mode volcanism.

      All depends how big the adjustment is. Ice it’s a big one, you are going to see some serious melt water,

      Reply

    • From IMO page today – that I’ll not link in here:
      “Conclusions of the Scientific Advisory Board:

      Intense seismicity continues. Over 700 earthquakes have been recorded since midnight. Earthquakes are occurring mostly beyond the edge of the Dyngjujökull glacier and the intrusion itself has migrated about 1 km northwards since yesterday.
      At 00:16 UTC today, a magnitude 5.3 earthquake occurred in the caldera of Bárðarbunga. At 02:50 UTC, another similar-sized earthquake (magnitude 5.2) took place in the same region.
      At 01:52 UTC, a magnitude 4.5 earthquake was detected on the eastern side of the Askja volcano. This was followed by a few micro-earthquakes in the same area.
      The dyke intrusion beneath Dyngjujökull is thought to be about 40 km in length.
      Modelling of GPS data indicates that about 20 million cubic metres of magma have been added to the volume of the intrusion in the last 24 hours.
      Modelling results suggest that the dyke intrusion is causing stress changes over a large area, including the region to the north of the dyke’s extent; this could account for the increased seismicity at Askja volcano.
      There are no indications that the intensity of the activity declining.
      From today, the afternoon status report will no longer be produced. However, if the situation escalates (i.e. imminent signs of an eruption), daily status reports will be reintroduced. The results of the scientific advisory board will continue to be distributed daily at around midday.
      …”

      Reply

  25. Please excuse the Grade 3 level artwork but instead of the configuration shown in the original post maybe it looks more like this which would account for the large volume intrusion and draining of the magma chamber

    Also the deep M5+ quakes

    Reply

    • This may be what Agust Gudmundsson, Professor of Earth Sciences was describing in the “giggle” translate article above.
      Could this please be discussed? Thank you.

      Reply

      • But it isn’t what he’s saying. What he’s saying is approximately the same as what I’ve been saying, he i also describing the very obvious from the data to hand, sans models, that the magma rising from below into a tensional crust. In that model of how it happens there’s no rising from below through the whole crust.

        Even Jon’s latest is saying the magma seems to be going deeper. He also is not yet quite accepting that the tension means the magma is coming up from 16 km down, but it’s becoming inescapable.

        The pumping is clearly extension followed by intrusion, cycle after cycle.

        All Bardarbunga is doing is deforming. Hey, its hot, it’s plastic, if you hit it with a 5.7, what do you think it’s going to do, sit there like a cold submarine’s hull, and not move an inch?

        NO! The thing has the consistency of a molasses, it’s going to bend and move as much as it can.

        Now look at the CGPS – it is.

        Reply

    • Oh no, this would put sheepdog and herdsmen out of work, and herdsmen. But for all the wrong reasons and it would not work this way.
      It seems they looked at Border Collies, which have their own way of working that sets them apart from most other ancient and traditional European herding dogs. Indeed, they know these four commands, and these are useful if you need to round up sheep into a pen or a truck, or when you do herding as a sport.
      But if you take a flock out into the mountains or open field or need to keep them off a road while heading for the next pasture, or when you need to keep them out of a corn field while grazing, Borders won’t do. Border Collies have more difficulties to learn to ‘walk a line’. Also not included in the study, a sheepdog must know when to let a flock graze and masticate, while laying or sitting down and wait before move the flock on.

      Reply

    • 7+ quakes are continental drift related. Most do happen outside hotspot area, as most of Iceland basically lies outside cenral rifting areas (where hotspot magma uplift happens.)

      Reply

      • Thanks, Islander. I assumed it was almost impossible for regular magma chambers produce such major earthquakes.

        Reply

      • Hot spot means higher isotherms so higher a-seismic ductile creep, higher water content as well so lower viscosity melt, and also partial-melt ‘mush’ is soft, Plus lower silica in fresh melt, as well as a more dessicated crust, so more avenues for stress and strain relief do exist in the crust, hence a mag 7 quake is going to be very rare. Only the highest vertical movement rates or tensional slips adjustment would be able to generate one in such a crust or sub crust, so only in truly epic strain tectonics.

        Reply

  29. Greetings to all oldies, Carl, Sissel, Renato, GeoLoco, Diana, Spica and others, I’m also back (I’ve been lurking for a while, but not talking so much…)

    Here’s a little bit of trivia for you: as some of you know, I work in a geo department of a university and I can tell you that this event is generating a sizable interest among my geology colleagues to the point that several are rushing to Iceland this week. Some are even considering postponing classes, which start in 2 weeks’ time, something that normally never happens.

    Reply

  30. Hi all, just a flying visit, can’t do without even when I have (actually) no time for volcanoes 🙂 Here is something to read from IMO, you might find some interesting bits and pieces:
    From today’s IMO short update:
    “Because of the current seismic activity in nortwestern Vatnajökull, IMO has been allowed to publish the chapter Bárðarbunga System, an extract from a much larger work in progress.”

    Click to access Bardarbunga_kafli20140825.pdf

    “Note to readers: The text on Bárðarbunga is a pre-publication extract from the Catalogue of Icelandic Volcanoes. The full Catalogue [“The Catalogue of Icelandic Volcanoes”] will be made publically available in the coming months.”

    Reply

  31. Yesterday, I predicted the “up” portion of the VONC plot would rise back over 0. Not a bold guess, but I was right! This is interesting since it’s showing a trend of the Bardarbunga caldera “breathing” or as I would like to think, “pumping” magma in and out of the chamber.

    Reply

    • Nice one cbus, it’s quite predictable … all except for the eruption and quake size … gahh! 😀

      But good to see it’s finally stopped mucking around to the SE (rotation) and has taken up the tensional mode-trend SW trend as well. So that’s removed the ambiguity further at that station.

      Now just waiting for HAFS to clarify as well, but by then we may already be off to the races elsewhere, so to speak.

      Reply

    • If that is the case then the “breathing” got deeper over time which of course will with the next downtrend raise the risk for Caldera collapse. This might also be the reason we have not seen any big EQ’s at Bardarbunga today.

      I don’t think I need to write that I’m no expert. I think that much is clear 😉

      Reply

      • Keep in mind Tom that more energy from the same source takes proportionately more time to build up to a bigger quake. If it is deforming faster, leading to structural lowering, then it may take longer again.

        The fly in the ointment is the more you stretch the crust the more melts (more buoyant and higher pressure) want to rise opportunistically and inflate any cavity that’s opened. So it keeps pumping due to this rise reflex.

        Reply

      • There was this one today:

        Wednesday
        27.8.14 _ _ _ 02:50:36 _ _ _ 6.2 km _ _ _ 5.2 _ _ _ 99.0 _ _ _ 7.5 km E of Bárðarbunga

        I reckon 5.2 is pretty big…. 😕

        Reply

  32. Dave McGarvie @subglacial · 36 min
    #Bárðarbunga. Unlikely that there is any magma beneath the old subglacial massif E of 1875 Askja caldera. Potentially good news – for now.
    ResponderResponderam 0 vezes RetweetarRetweetado 3 vezes3 CurtirCurtiram 2 vezes2
    Mais
    Dave McGarvie @subglacial · 38 min
    #Bárðarbunga. The old subglacial basalt massif at #Askja E of the 1875 caldera has not erupted anything for at least 35,000 years.
    ResponderResponderam 0 vezes RetweetarRetweetado 3 vezes3 CurtirCurtiram 2 vezes2
    Mais
    Dave McGarvie @subglacial · 41 min
    #Bárðarbunga. Swift tweet time. 4.5 quake SW of #Askja appears to be within subglacial basalt massif and not directly on main 1875 faults.

    Reply

    • Because any volcano would accept to erupt just cause a bunch of layman voted so. This does not make any sense at all.

      Reply

    • I’m busy for next several hours, could someone take it on and repost link every hour or so, so others don’t miss it.
      Will review results Thursday morning.

      Reply

  35. One thing to note that I’m fairly confident in that relates to a lot of previous discussions of volume as well as Peter’s discussion of magma cooling in a narrow conduit.

    The approximate 1 meter measurement of spreading is only on the surface level. Take a look at where all the earthquakes have been occurring in the dike swarm – they’re all at depth. Now, take a look at models for rift formation.

    The takeaway here, is that the width of this intrusion is likely to be much wider the deeper you get than the manifestation that is being shown at surface level. Assuming that this rift is a perfect 1 meter wide the entire way across the 15+ kilometer depth is beyond silly. We clearly can see that the spreading is starting at deeper levels, with only the very tip of the spreading reaching towards the surface (hence the lack of shallow quakes).

    Can I prove this? No, but it seems fairly obvious and logical.

    Reply

    • I realize there’s a ding culture at this site so I’ll make like a fish and flock.

      DING!

      Or put another way, if the mantle is divergent below (which it is), which part of the crust is going to thin and distend first?

      (1) The bit closest to the mantle and connected to it, directly?

      (2) Or the bit furthest from it and only indirectly connected to it?

      —

      So if we begin to pick up accelerated divergence in the indirect part, what’s already occurred below?

      There’s a certain mechanical inevitability implied in the CGPS data which Askja and Bardarbunga are the blunt instruments of, not the adjudicators of.

      Reply

  36. Coming back to VolcanoCafe after a few hours away, the thing that strikes me most is the lack of high magnitude EQs today. The Vatnajokull seismology plot on the IMO site is busy but not eyebrow raising at the mo. It feels like we are due a couple of big ones soon.

    On the other hand, the breather has created space for some interesting discussions – some more on topic than others….

    Reply

  39. Carl. Let’s talk about the rift versus hotspot cycle. I am not sure, perhaps they are just the same cycle.
    Ok, you talk about a rift cycle of 270 year average with 230 – 310 years as outer span (is that your hypothesis, or does it come from a peer reviewed study?)
    In one study, authors talk about Vatnajokull cycle (and they include rifting and hotspot activity), 140 years average with 100 to 160 year span (about half of your MAR cycle)

    Let’s see:
    1862-1910: clearly there was not only rifting (Veidivotn, Askja) but also increased Vatnajokull hotspot activity
    1783-1789: clearly a large rifting episode in Laki, Hengill. No evidence of anything else
    1720-1730: clearly evidence of both rifting and hotspot increased activity (examples: Kverjfoll, Oraefajokull, Krafla fires, a rifting episode, a possible smaller size fissure eruption in Bardarbunga too)
    ~1600-1620: some small increase in eruptions but not a clear peak in activity
    ~1480: Veidivotn episode, and not so much as far as we know
    ~1362: a large eruption in Oraefajokull, and not much as far as we know
    ~1220: considerable rifting episodes in Reykjanes peninsula
    ~1104: a large eruption of Hekla, large quakes in south Iceland, but not much as far as we know
    870-934: clear increase in rifting episodes: Vatnaoldur; Katla and Edlgjá
    Of course as we move past centuries, data is more and more absent.

    What are we really confident of seeing from this data?
    A somewhat semi-regular cycle in 140 years in volcanic activity in Iceland, with focus in Vatnajokull, sometimes 120 years, sometimes 170 years.

    Rifting cycle? Hmm, I can see your 270 year cycle of LARGE rifting events, but only 3 peaks out of 4 possible. That would be 934, 1204 no event, 1477, 1783, and then somewhere between 2013-2093.No event circa year 1204. As far as we know. Maybe some small rifting eruption possible but currently unknown. Any more data points? Otherwise I am seeing your trend but not 100% convinced.
    Maybe pre-settlement data point?

    Of course this rifting cycle only apples for large rift events, it does not include Krafla fires 1720s, or the somewhat extensive rifting events circa 1862.

    Reply

    • It’s moved about 1km in the last day or so. Not super fast, but seems to have picked up pace recently after being completely stalled for 2-3 days.

      Reply

      • It’s ‘softening up’ the ground ahead, as I see it that’s just distension that’s already occurred and it’s now sensing the tension-change induced by the approaching ‘dike’. The most distended bits are going to link-up.

        The only won’t connect if they aren’t already sufficiently distended at depth.

        (I think the dike emplacement conception is the wrong connotation for the process we see, it can become that but it isn’t now. What it is now is a spectrum of possibility, one of which is to become a dike)

        Reply

  41. Magnus Tumi Gudmundsson, professor of geophysics at the University of Iceland :

    “This is a very interesting sequence of events; big news really in a geological context, even though an eruption has´nt happened yet, and hopefully will not happen. We are looking at the active rift between the plate boundaries in the middle of the country, where much of the volcanic activity has taken place. This particular area has been relatively quiet in recent decades; an intense episode like this has probably not happened for the last hundred years, perhaps not even two hundred years.“

    http://www.ruv.is/frett/seismic-activity-near-the-askja-caldera

    Reply

    • Yes. Indeed. Most commenters interviewed in Press last seven days have said this. Even I have noticed that its not normal have 1000 quakes per days 🙂 🙂 and have been avery active collect grahic evidence, from IMO and other available Internet sources. 😎

      Looking at chart, the intrusion has reached the “ring” road that encircles Askja / Öskjuvatn / Mountain (Volcano). Trivial question is, does it have a magma chamber or sill, still intact after the 1875 caldera event. My take on it, is despite reports to the contrary, It could have something below 8-10 km, if so, this meeting could trigger (explosive) event.
      Anyways if it breaks “up”, rather than continiue, and eventually stalling, it might hit water table (from below) and trigger phreatic-magmatic (Ash-y) event. *not expert* 😎

      Reply

      • This is getting exciting.
        Askja exploding, Bárðarbunga having a caldera colapse with a bing bada boom, the dike opening up the crust all the way down to the mantle with a Laki eruption and a hurricane storming in.

        To top it all I will probably get the first flat tire for a decade 🙂

        It will be a weekend to remember.

        Reply

        • OK, got three flats this summer (one actual), two “losing pressures” and one nail removed before blowout. That is record in one year (last decades). But missed, from where comes the Hawker Hurricane ??? 🙂 🙂 😎

          Reply

          • The Hurricane forecast was in the comments on earlier post if I remember correctly.
            Perhaps more like a plausible scenario than a forecast actually I guess.

            The weather has been calm and the forecast says it stays calm
            – A perfect recipe for a disaster such as an eruption the old men would have said.

            Reply

  42. I’ve being at Askja area a couple of weeks from now, and visited the caldera lake two days before the landslide.

    I never felt so close with geological events like this before 🙂

    Reply

    • If you had been at Drekil Hut when that 4.3 went off you’d have felt even closer!.
      When I was there, it was in dead calm, beautiful summer weather – could not imagine a more peaceful place.
      Wonderful country. Everyone should try to visit.

      Reply

  44. So, I’ve got a theory about how the mantle could get involved… here’s the points I’m reasoning from:
    1. Mantle material (solid) is denser than the rock above.
    2. The mantle is high enough temperature so that it would become liquid, given a low enough pressure.
    3. The magma in the dike is higher density than the upper crust, otherwise it would have erupted to the surface.
    3a. Dike magma remains below (5k?)m depth, where gas remains dissolved due to pressure.
    4. Given that the dike is filling the space vacated by the pulled-apart crust, the mantle remains under roughly the same pressure prior to the overhead passage of the dike, so mantle remains solid.
    5. The tension in the crust is the primary contributor to the dike progression…as the dike progresses, it serves to focus the stress at the tip past the point at which the rock fractures and spreads apart.
    6. At some point, the flow from the dike’s supply point will become insufficient to keep the dike liquid at the tip. This is making the assumption that it is being fed from Bardarbunga.
    7. When the dike’s tip freezes, the spreading (seen via constant spreading between dync and gssig) continues, due to liquid magma still being available to fill out the sides.
    8. So at the tip of the dike, we have a great deal of tensional force due to the dike inflating, but no liquid is able to fill out a void.
    9. Pressure drops at the tip of the dike, and the mantle begins to melt decompressively, filling the gap.
    10. As the dike’s sides continue to inflate, the mantle continues to melt, eventually reaching high enough for gases to exsolve, and then it’s a mad rush for the surface.

    What do you guys think?

    Reply

    • Er… lots of questions because I really don’t understand this at all.

      3. “The magma in the dike is higher density than the upper crust” – since the upper crust is solid rock, the magma is a denser solid?
      4. “the dike is filling the space vacated by the pulled-apart crust” – I thought a dike was like a tunnel – how can a tunnel fill space?
      5. “it serves to focus the stress at the tip past the point at which the rock fractures and spreads apart” – if the tip is “past the point at which the rock fractures and spreads apart”, does this mean the tip can move through solid rock? Or do you mean that the stress at the tip is higher than the stress in the rock? If the latter, then where is the tip in relation to the rock?
      6. Now I’m completely lost! When did the solid in point 3 become liquid? And given that it did, is all the stress on the tip (point 5) now solidifying the tip? Oh I see in point 7 that it is now frozen. So it’s gone from being more solid than bedrock to being liquid to being frozen all in a few hours or days. What temperature was it to start with? That seems like very rapid cooling.

      I’m so muddled now that I can’t get any further. 😦

      Reply

      • Hi , dont be disheartened, in reality this is an immensely complicated process and subject. Which is nowhere near fully understood by even professional volcanologists.

        Much of what is written is dufficult to understand because its “often” theories or peoples ideas who ve had no basic formal tuition in geology buts it s great and fun. Yet sometimes confusing for those whi have lol!

        So what you need to do is some 101 geology. Understand basic techtonics , core , mantel, plumes , types of magma, types of volcanco s and why they are different. I ll have a look around for somewhere where info all in one place or a good book on it.

        Reply

      • Answers and explanations by point:
        3. My reasoning that the (liquid) magma in the dike is denser than the rock above is that it hasn’t risen to the surface despite having the ability to fracture the rock it’s traveling through. That implies it’s denser than the top 5km or so of the crust.
        4. The dike is a vertically oriented crack, possibly discontinuous or braided in spots (incomplete separation of the two sides of the crust) with the top maybe 5-10 km below the surface, and the bottom at some indeterminate depth, but which is at least 15km or more deep, based on the earthquakes.
        5. I meant to say that the tension is highest at the tip of the crack, which serves as a focal point to concentrate the tension, in the same way that a crack will work its way across a car’s windshield.
        6. The magma in point 3 started as liquid, originating from bardarbunga, travels some tens of kilometers as liquid, and solidifies at some point.
        7. I don’t know exact temperatures involved, these numbers are speculation… I’d guess that the magma which is now at the tip of the dike started at about 1200 deg C at bardarbunga, and is now probably a few hundred degrees cooler, maybe 900 C?

        Reply

        • Lifeblack, you should study a bit of physics.

          Let us just take 3…
          As you heat up material it will dilate on an atomic level, ie that the material expands. Henceforth it is a Law of Physics that magma will have lower density than a cold rock. End of discussion.

          Reply

          • Carl, what you say is true if the magma has the same composition as the solid rock. However, I am doubtful that the magma is the same composition as the rock through which it’s intruding. I base my doubts on what I’ve read about Hawaiian volcanoes, where the magma chamber sits at a depth where the density of the liquid magma is roughly equal to the solid rock. I’ve read that as the magma sits, it preferentially crystallizes olivine, which precipitates down to the bottom, leaving the magma less dense, and sitting on top of the olivine-rich crystal cumulate. The rift zones also tend to have olivine-rich cumulates laying underneath.
            What it boils down to is what is the density of liquid peridotite at 5km depth compared to the density of solid basalt at 5km depth or so? I couldn’t find a good answer after some googling, but with your background Carl I think you might have some good figures.
            Btw Carl, I’m not too bad at physics… I’ve got a degree in biochem, and a masters in electrical engineering if that helps for background…

            Reply

            • PhD in Physics here…
              Iceland is mainly built out of basalt, the intrusion is basalt. The same material, so heated it would be buoyant.

            • Lifeblack, if a PhD in Physics does not convince you – how about an actual exercise of the grey matter? 😉 Work out the energy content of a cubic metre of thooleitic basalt at 1275 degrees Celsius which contains a substantial amount of water in the form of superheated steam (Google & read about the properties of superheated steam) and carbon dioxide.

              Once you’ve done that and grasped the subject, the answer to your questions should be self evident! Good luck! 😀

            • Carl, I’m highly respectful of your PhD, It’s just that I’m not 100% confident in saying that because the bulk composition of Iceland is basaltic, fresh intrusions at depth are also basaltic. Let me just ask you one question and then I’ll drop the subject: If the intrusion is less dense than the surrounding crust, by what mechanism has it split rock 40 km, and yet has not risen to the surface at some point along the way? Presumably the shallow rock is under the same tensional stress…

              re: milord P, energy content isn’t the question, but density.

            • Okay, I will try to explain this in more simple terms. Most of iceland consists of deposited unrefined basalt that has solidified. The are also layers of tephra in the top portion, and pockets of more refined material.

              Now, as you heat an atom it will expand. This is why iron expands when warm, and shrinks when cold. You can see the result if you search for images of solar curves on the internet. That might make you understand.

              Now, as an object expands it keeps its mass, but not its specific weight, ie a cubic decimeter of hot iron will have less mass than a cubic decimeter of cold iron, ie. it will have less density. Actually a lot less density if it is molten compared to room temperature.

              Now that we have logically proven that magma almost always has lower density than the surrounding rock we can deduce that it is buoyant and that you sir are wrong.

              Remember here that you are not arguing with me, you are arguing with a physical law, or in a sense of it. You are arguing with the Universe itself.

            • Lifeblack, I’m sorry if this statement of fact disagrees with you:

              You obviously know next to nothing about petrology, the properties of volcanic gases of which humble H2O is the most important. Do read up on the physical properties of superheated steam and the role played by it in rock and mineral formation. We have, very patiently I might add, tried to explain why your suppositions are wrong. Frankly, your replies quoting your academic merits as being equal to a PhD in physics, the subject matter being discussed, displays unforgivable rudeness on your part as well as your ignorance.

              Since you will not yield to superior knowledge (Dr Carl Rehnberg, PhD Physics) on a matter where you are a layman and refuse to accept that your speculations are terribly wrong, further discussion is pointless.

            • Milord p, I think the only point I’m not 100% in agreement with Carl is where I have doubts about the relative compositions of the dike vs surrounding presumably basaltic rock. I have no argument against what he is saying about the physics of liquid vs solid basalt densities, I find what he says to be entirely reasonable given his assumption of identical compositions.

          • Carl, here’s an illustration of what I’m getting at:

            Magmatic systems, edited by Michael P. Ryan, chpt 6 neutral-buoyancy controlled magma dynamics, pg 125:

            http://books.google.com/books?id=c4ONWE2UWccC&pg=PA125&lpg=PA125&dq=magma+%22equilibrium+depth%22&source=bl&ots=fB4GiVP0q6&sig=MyAxxUEcnQXXSdqVc53Hoe56e38&hl=en&sa=X&ei=I0D-U4GtOsK8igKjzYCoAw&ved=0CCYQ6AEwAQ#v=onepage&q=magma%20%22equilibrium%20depth%22&f=false

            DragonEdit: Lifeblack. FYI Carl is not running this blog professionally and he makes no money from it. He has a very demanding job, that takes a lot of energy and time. he needs his rest. What he does not have the time to do is act as a private tutor to an obtuse, obstinate, ungrateful and recalcitrant individual such as yourself. This is the final warning. Heed it or you will be blocked. / Pyrite

            Reply

            • You have misunderstod the paper. What it is talking about is the intra dynamics of a magmatic body functioning as a refining column.
              In that environment as the magma fractionates specific element will fraction out and as such will be buoyancy negative.
              It has nothing to do with the current situation in Iceland.

            • Hmmm… I’m not sure that we’re looking at the same document then, what I was reading was about lateral dike emplacement along a horizon of neutral buoyancy between basaltic extrusives and layered gabbros of the upper mantle. It seems to be highly relevant to the current situation. I found the description of what happens at the front of the dike when the fracture front is arrested pretty interesting, as a mechanism leading towards an eruption if the back pressure is high enough.

              And my apologies to the editors, I have a great appreciation for the collective expertise and handling of this blog, as I’ve been a reader (and rare poster) for several years now. It was not my intention to challenge Carl in his field of expertise, and I apologise if what I said has come across that way. I understand how the editors of this blog are less willing at this horribly overworked time to tolerate questioning of one of the blog’s stalwart and most knowledgable posters, esp if there’s miscommunication involved. Out of respect for Carls time, I’ll drop remaining questions and return to just reading.

            • Should have been an comment on the DragonEdit Lifeblack.
              I really don’t understand why it should not be permittable to have other opinions than Carl!!

      • Ok the dyke or fissure is the tunnel and its filled with magma , as the ground is pulled apart the dyke/fissure gets longer and the magma expands into it.

        This “split ” in the ground would probably be happening even if it was not filled with magma

        Currently people are un sure whether the magma is just coming/come from barbarbunga or has a second feed straight from below ( this would give magma an extra boost) this is seeming more likely as the tunnel continues to get further from barbarbunga and still be very active.

        Reply

      • @mopshell hi hoping you got this far, so for you the question s to understand which really lie at the heart of this , why the increased magma in/at bardarbunga, why the pulling apart action at the dyke,

        At the behest of upsetting those with lots of knowledge again I ll keep this simple as poss so you can visualise whats happening.

        If you imagine iceland (forget for now all the faults/fissures etc cause we re making a new one.) As a big piece of paper suspended in the air but fixed all the way around, you a large ball and go under the paper to where barbarbunga is, you push the ball up lifting the paper as you do so it becomes taut, (tension) if you keep pushing the fibres of the paper with separate and split, (the rift)

        Now think of the ball as a ball of magma, its pushing magma into barbarbunga.

        Think of the ” rift” as the split and weakness caused by this tension but the dyke is the bit of the rift that has filled with magma.

        Reply

    • Whoever said that the mantle is sollid? It is not. It is fluid, but pressure makes it behave as a semi-sollid. Think tar here instead of magmatic molasses. As the pressure is lowered it changes states from pressure semi-sollid into a fluid state, or in other words – decompression melt.

      Reply

      • I think I got my head round this like dry ice needs pressure to keep it solid. When pressure drops ice becomes liquid then gas giving up heat in the process

        Reply

        • Close, now make the dry ice oozy and you have it.
          A mantle plume is actually upwelling slowly moving mantle material.

          Reply

          • You guys have so much patience to help us understand these things. My brain is addled trying to understand all the theories etc on here in the last couple of weeks but I’m well addicted now. It’s a long time since science classes at school. Much appreciated

            Reply

      • I just want to make sure I understand the concept of decompression melt.

        I pour water into the ice tray and put it in the freezer. The temperature drops below 0C and this acts as a compression agent on the water such that the molecules now cuddle up to one another, ie are compressed together. I take an ice block out of the freezer and put it on a plate. The warmer temperature acts as a decompression agent – the molecules aren’t compressed together any more but have more space in which to move about. Is that basically right? Just think of me as your densest student ever! 🙂

        Reply

        • The problem with water is, that unlike most materials in the world, it shows a density anomaly when solidifying, i.e. the anomalous decrease of density when cooled below 4 °C. This is due to the polar molecule structure, so that the molucules are forced slightly more apart in the crystal lattice than when they are flowing freely. Curiously, pure silicon also shows this density anomaly. Tetrahedral crystal is the keyword. But dfm probably knows much more about it.

          Reply

  45. OK I’ve updated the plots and here are 2 still views before I poste the video.

    I have kept the day scale, but, as you will see in the video, I’ve changed from a day to day to an hour by hour presentation.

    Anyway, on the 2 stills, the dyke is still progressing.

    The first view has changed, it’s now viewed from the south East instead of due East.

    and from the top

    on the video you will see the quakes swarm “stall” with some backward action on yesterday and today’s progression

    Reply

    • Looks like the recent heading is about 15 degrees. Will be interesting to see if the slowdown will lead to a change in direction.

      Reply

  46. and here is the video

    First view is an hour by hour evolution showing the quakes’ position and magnitude. View is from the south East, with a 10° forward tilt.

    Second view is from the top, hour by hour also.

    Pay attention around 30” and 1’15” to see the “backward action” of yesterday then a new progression today.
    There may even be a tentative sill formation, look @1’15 coordinates -17, 64.8 or on the left of the “g” of “Dyngjujokull”

    Magnitude is given by the scale on the bottom of the plot.
    Date is given by the quakes’ color, refer to left side of colorbar.
    Terrain elevation is given by the right side of the colorbar.

    Quake data from IMO, quality 99%, terrain data from NOAA, made on Gnu Octave

    Reply

    • Great video, I like it without rotation. Good job. I didn’t realize that the dyke was flowing downward so much.

      Reply

      • You’re right about rotation, it can sometimes be confusing. I think i’ll stick to stills, with maybe different angles. But it takes more time, as you have to redo the sequence several times. Or I could try subplots, but I fear it will be too small to see properly.

        Reply

        • The video is really really good! It shows clearly how the dike or sill or whatever it is ( 🙂 ) stalled between 19/8 and 23/8. I was looking for that info earlier and now here it is! 🙂

          Reply

    • Absolutely love it. You see clearly like the pressure is rising in the dike until it snaps open a bit further at 1.05.

      Thank you DFM 🙂

      Reply

      • if I may dare some explanation of this earthquake active zone flux and reflux, it could mean that there is some obstruction, but the inflow of magma keeps steady. So there are some “backward quakes”, because of the continuation of magma arrival. Then the obstruction gives way and the progression resume.
        The small sill like structure means that, should there be a strong enough obstruction, some sills would form. Or maybe the progression would go up. Then it’s time to pack your things fast…..

        Reply

        • Now, if we could just do like a functional MRI on the ground beneath there, we’d know for sure 🙂 But yeah, that’s what I’ve been thinking with the back and forward thing, but I ain’t no expert. I really like the theory that there’s like a plug in the BB caldera, down below I mean, and the big quakes come because magma is periodically lifting the plug and streaming out (Ekström?), so it sort of comes in waves into the worm (my scientific term for the dyke). This is how my little brain interprets it.

          Reply

    • Absolutely brilliant illustration of the volcanic processes going on.
      To a neophyte, the long pause can be confused with a problem with the video. A kind of thermometer bar showing passage of time would make the start-stall-start process clearer. That’s minor though. The work is wonderful !!

      Reply

      • There is “date” and “hour” information in the title bar. But it”s true that if you don’t have the vision system of a chameleon, it can be a tad tricky. But the pause button exists too.

        Granyia finished the previous day squint eyed.

        On some previous plots I had a count of earthquakes vs total somewhere. I’ll put it back on.

        If you manage to keep the left eye on the count, the right on the date and hour and use your lower peripheral vision, you should exeprience true 3D.
        Do not do it if you have had previous epilectic tendencies. Eating carrots can help.

        I’ll reflect on the statu bar thanks, but I need some time to find the solution;

        Reply

    • Seems so, probably the upper one got destroyed 1875 (but I have not looked it up in papers). London Professor Geologist on RUV news just now, talked on small chamber under it (Askja) and if “Berggangur” gets there it might trigger eruption or erupt.

      Reply

    • Askja has several chambers if I remember Professor Hazel Rhymers explanation.
      But, I have a problem with Hazel Rhymer that is totally gonadal in nature. I see her and I think of other things than volcanoes.

      Reply

  49. Excuse my newbyness, please, but are the earthquakes also a partial cause, and not just an effect? What I mean is, is all the shaking, like shaking a capped Coke bottle, also causing more pressure in the system? At some point is it inevitable, because of all the shaking, that an explosion happens somewhere? Is it now just a matter of where the bottle is, which day will the cap come off, how quickly will it be unscrewed, how much Coke is in the bottle at that time, and how much Coke continues being injected into the bottle after the cap is removed? (Be gentle with any reply, pls, I think in metaphors and am struggling with finding an appropriate one for all this.) ❤

    Reply

    • The fizz in a coke comes from dissolved CO2 but it takes quite a lot of energy to make a bubble that can overcome the surface tension of the coke in a bottle to form a bubble. However shaking or vigorous pouring allows small bubbles to form which more gas can get into more rapidly and make the fizz.

      A classic way to demonstrate volcanic eruption is actually to shake a bottle of coke and then flick the lid off fast to show how the rapid degassing creates an eruption that is much more violent than the simple pressure would otherwise create.

      So yes, the bottle of coke analogy works just fine.

      There may well be a more detailed scientific explanation from one of the better equipped community members, but that’s the best I can do, hope it helps.

      Reply

    • We’re all newbies in one way or another. My comprehension is quite limited, but I can probably provide a little illumination.
      The cola analogy can be partially apt. Magma/lava often does have a substantial amount of gas dissolved in it, but the tendency to bubble doesn’t come from shaking, it’s fairly purely a function of how much pressure is present. So, no, the earthquakes don’t necessarily mean the lava is more and more likely to “blow.” Gas will expand explosively simply when the lava comes near the atmosphere, with its comparatively minuscule pressure.
      The quakes reflect sudden movements of solid crust/rock. Fracturing, pulling apart, sliding and sticking, that kind of thing.
      The quakes we’re following so intensely here are ones that seem to reflect movement of the magma, either pushing apart rock to form a lava-filled space, or rock being pulled apart by tectonic spreading, with lava filling in the gaps that form.
      Now, I’ve probably got some of this wrong, and if so, I trust we’ll both be further illuminated.
      Cheers.

      Reply

      • I think you covered a point I realised I missed. The idea put forward (by Peter?) that as a new opening is created some degassing occurs and rams the magma into it thereby contributing to further fracturing as a kind of jack hammer fits nicely.

        Reply

        • I saw a comment from someone asking why the magma doesn’t flow backwards when it hits an obstruction. Could you use a giant version of a sensor like they use to find water flow in a pipe based on measuring Doppler shift to check which way magma is flowing? Or can you tell this from the tremor?

          Reply

  50. I put this in the “Info on Bardarbunga” section so they can be found later, but thought I would post it here as well…. These links were posted in a previous thread by Sissel (if I recall correctly). I found them to be very useful to tracking the progression and quite interesting to “watch” as the quakes drop in. The first link is from the start of the event until now and the second one is day by day and you can go back in time.

    http://www.ijsland-enzo.nl/ijsland/actueel_aardbeving_5dgn.asp

    http://www.ijsland-enzo.nl/ijsland/actueel_aardbeving.asp

    Reply

      • Yes… another long time lurker, very infrequent poster popping out of her rabbit hole. Keeping an eye on things as we are flying to the UK next month (we have tickets the Ryder Cup in Scotland that we sure don’t want to miss)!

        Reply

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