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

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1,502 thoughts on “Bárðarbunga reader question”

  1. I think magma has already got into Askja. Or better to say, the rift extended into it.

    I think we don’t see a continuity because the area is ductile, some hot material. But good news is that if this is already happening, then no eruption has resulted. I think if it erupts, it’s going to be small but a bit explosive at Askja.

    The line of quakes is moving past Askja NE, towards Herdubreid. You can see that. But this is just my guess and speculation, Not an expert.

    Jon said he believes now we will see both an eruption of Bardarbunga and Askja.

    Reply

    • And where is Carl when things get very interesting?
      Maybe he just went crazy and booked a flight to Iceland;)

      Reply

    • What makes you think so? Alot of tectonic tension has been released lately. As well in the askja fissure. So quakes are bound to happen in the area. Not many quakes in between the tip of the dyke and askja. To my humble opnion the connection can only be there if the part of the askja fissure, the dyke entered is still more or less fluid….

      Reply

        • If there’s inflation, I don’t think it’s showing on the dyng GPS you have linked – I see on the chart heading that the last data point was August 10th. Maybe she’s got other data?

          Reply

        • Thanks IngeB for that. Seems very limitted and intermittened data to me. Not enough for me with my knowledge to draw any conclusions from it.

          Reply

      • Tension produces uplift, the tension did not start due to the dike. Askja will destabilize because the crust below is opening. The fissure going there would just make a mess plus confuse the interpretation of events. So I hope it stays at a distance.

        More likely the tension means Askja will make its own fissure swarms from the detritus of the old ones, and frankly that’s what it’s most probably doing (it does not want hand-me-downs fro Bardarbunga, it is an independent libertarian minded caldera and does not like slackers).

        Reply

  4. Comments are still getting messed up here – I see some of the later ones appearing before earlier ones.

    If I remember correctly, this kind of thing used to happen back in the prehistoric days of this blog when someone deleted a comment. Then the sub comments of the deleted comment would hang around at random places. If this is the case and given that there are >1300 comments on this post now (and I don’t suppose any dragon really wants to go investigate where in the chain of 1300 this problem happened 🙂 ), how about publishing a new post, even just as a placeholder with a sentence or two, so that the comments can be counted (and ordered) from the start again?

    Just an idea…

    Reply

    • Hi Ursula

      Indeed you remember the problem correctly, and I have deleted rather than trying to wade back through the comments to fix the source problem. All seems to be flowing again now.

      There will be a new post shortly 🙂

      Reply

  5. @ohr
    To quick-fix the problem I have had to delete those few comments. But, thank you for the coffee offer 🙂 /UKV

    Reply

    • Indeed – but remember there are only a few of us and we all have full-time jobs. I’m supposed to be doing mine now! Given the amount of comments I’m surprised we have only had to do two quick-fixes.

      If commenters refrain from posting the banned vedur.is links and make sure that all their comments are kept civil (as 99.9 percent of the commenters do) then there would be no need for moderation, and then the comment string would keep working just fine 😉

      As noted above, a new post is coming later.

      Reply

  7. Why cant IMO just simply do the ground tomography and show us the results… pletty please? 😛

    Reply

    • usually takes a large time consuming & expensive seismic survey and large computer cluster with some hands on by experienced seismic processors (at least for seismic exploration imaging). I imaging having permafrost areas (i imagine these exist here), makes life somewhat difficult also . I doubt if it could be done in under 1-2 weeks (not to mention the cost)

      Reply

  8. Hi! A small request to a dragon from a volcanoholic, icelandofilic lady.
    My computer crashed but is up and running again after reinstallation of the OS.
    I lost all my favorite links, for example to mirror pages for various webcams and plots of earthquakes, maps,, tremors, strain measures etc. If someting do happens there will surely be more interests so maybe….

    Could you add some links in a post that is easy to find? It´s hard to find them in thousands of comments.

    Thanks, Youre the best!

    Reply

    • Go to the top of the page and look under ‘Info on Bardarbunga’. Also, in the ‘Dragon’s Hoard’ there are lots of links, including ‘Wonder what;s going on in Iceland’ (just please don’t link any vedur.is or en.vedur.is ones here).

      Reply

  10. Here’s my plays if your in the U.S.: EPV, put options on DAL and EUO. I am quickly researching bottled water in Europe. Any other ideas?

    I know its slightly off topic, but since when is money off topic.

    Reply

  11. Equivalent depth, equivalent latitude, yet the quakes are over 1km apart. This is in the primary dike swarm, approximately 13 km depth. I’m quite curious as to how wide this is at depth. Not saying the dike intrusion is 1 kilometer wide down there, but the fact that we’re getting quakes measured at equivalent distance north and equivalent depth more than 1km apart is noteworthy at least.

    Translation: There may be a LOT more magma down here than the estimates have been calculating. (most estimates have been calculating using a 1 meter wide dike).

    Reply

      • why do you think they’re building that space station, for all the important people, they may take some women too (ok I am ducking down now to avoid the flying plates….)

        Reply

        • I recall that scene in Dr. Strangelove where he describes going under ground and having a plentiful supply of desirable women, of which there are plenty in Reykjavik.

          Reply

    • I seem to recollect Carl saying 1.03 km3 the other day. Apologies if I’m wrong – too many posts to go back through! I would agree the scale of this event is beyond any modern day comparisons, there are things going on down there we haven’t detected yet. The end of the world brigade are loving this stuff, I am hoping for a somewhat lesser event, although I agree with Jon, its going to be quite a show.

      Reply

    • http://www.visir.is/lengist-um-fjora-kilometra-a-dag/article/2014140829176

      Agust Gudmundsson, professor in geology at London University said in an interview yesterday that he believes there is more magma in the intrusion than 350 million cubic meters as some calculations have shown – even up to three times that quantity.

      He believes this is nothing like Krafla – as some have claimed – in this case it is the intrusion itself that is in control – not the magma chambers. He believes the source for the intrusion is a magmachamber at great depth 15-20 kilometers below the surface.

      DragonApproval! 🙂 / Pyrite

      Reply

    • You are assuming that the quakes occur in the dyke. They don’t – they are in the cracked rock around it and these regions can indeed by a kilometre wide.

      Reply

  17. A very big thank to quinauberon for the link to “Dust sources and deposition of aeolian materials in Iceland” by Olafur Arnalds. A pleasure to read, easy to digest – at last there came a paper on dust! And Of course I will come back to it when I have read it all 🙂 .

    Reply

  19. Long sustained rise in tremor on dyn. Reading the chart for the past days it seems whenever tremor went up a bit something gave way and moved, does this mean that this time nothing is giving way and it will just push harder and harder until something boom?

    Reply

    • This recent rise is very minimal compared to the other spikes as you can see. I would wait until we see a spike.

      With that said, we’ve had quite a few m5 quakes occur independent of tremor levels.

      Reply

    • looks like “the longest” slow increase we have seen so far? – normaly it has gone slowly down, then boom up.

      Reply

    • Until the past couple of days the tremor has risen sharply before a M5 and then fallen but in the last 2 days there hasn’t been much of a change a change in the tremor when there has been a quake, just this very slow rise.

      Reply

  20. IMO has published some paper on bardarbunga

    the link is available on the news part of their site.

    here is the latest general update video

    Bardarbunga earthquake animation 4D update 16 to 28-08-2014

    First view is from the north east (70°). It is an hour by hour change.

    Second view is from the top.

    The title bar shows date and time of the events.
    The colorbar supplies date information (dot color, refer to left side) and terrain elevation (refer to right side).
    The size of the dots gives event magnitude information (refer to scale on the plot)

    Data is from IMO, with 99 % quality (manually checked).
    Terrain data comes from NOAA, etopo1 (ice)

    It is clear that some activity begins under Aksja. The progression of the dyke intrusion goes on near Dyngjujökull.
    There is some additionnal activity under Bardarbunga.

    Reply

    • Wonderful animation as usual

      To my layman eyes the distance between Askja and Dyngjujökull seems compressed but I guess I’m totally wrong?

      Reply

    • I love these! I watch them at least three times (sometimes four…sometimes five… 🙂 ) because it all happens so quickly, I need several views to see it all – so much to see! Love it! 😀

      Reply

  21. re Drumplots:

    They must have really scaled down the amplitudes on the drumplots! I can’t see many of the reported quakes at all 😦

    Reply

    • Hi Robert, I think it was after that last big quake. They’ll probably go back up again soon once it slips off the charts… or another one will come along 😉

      Reply

  24. One thing I don’t understand is why the earthquakes need to be manually checked. Is it not an interpretation of data, something that an algorithm could surely solve?

    Reply

    • Nope, they already use an algorithm. Provided the quake is in a crack-free place, single and not too far away, the algorithm comes up with a pretty decent solution. But when, as here, there are hundreds and thousands of cracks where the waves get reflected and when there are many quakes simultaneously in the same location AND when there are quakes some km away… The automated solution invents what’s called ghosts, misinterprets multiple quakes as single ones, displaces them several km in x & y whereas z (depth) can be and usually is wildly wrong.

      Reply

      • Sounds fairly complicated, thanks for the reply. I still think if a human can look at the data and narrow it down then a computer should be able to do the same. The process is far beyond my comprehension level so I’ll trust that the experts have probably exhausted every possibility to come up with a better working algorithm.

        Reply

          • I’m sorry, Gigu? I’m new. I googled it and there was a social media page for a Gigu that had no friends.

            Reply

            • Maybe meant gigo – ‘Garbage in, Garbage out’ – usually applied to poorly written computer programmes.

            • Ok I got you. GIGO on this side of the map. Basically sums up what i’m getting at, should be possible to sort the garbage automatically, but again it is beyond me.

            • It boils down to phase picking. If the algorithm misidentifies a phase, it throws the whole shebang off. Phases have different paths, and the length of that path and what it has to go through have a lot of weight in determining where it came from.

              Here is an example (from Seismic Traveltime Tables by B.L.N. Kennett)

              Add to that the fact that the Earths crust is not homogeneous and it starts to get really hairy, really fast. As a general rule, the more experience that a seismologist has with a specific terrain, the better the picks. Some waves are easy to pick, others are not. If the ray-path to the seismic station has a layer of a certain kind of rock in it, or a layer of sediment, it will affect the travel times and in the end, the ultimate solution that is derived from that station’s data.

  26. Another interview with volcanologist Haraldur Sigurdsson (I’ll just summarize here).
    He reminds the interviewer of other eruptions with very long dikes, eg. Askja / Sveinagjá: about 70 km long dike. But he thinks still that the dike came out of a magma reservoir under Bárdarbunga.
    He compares the magma to tomato sauce.

    Nobody knows what will be, he says. But the magma is now at a location between Bárdarbunga and Askja where the crust is very thin, so that it would be easy for the dyke to surface there.
    And this could mean an effusive eruption like in Krafla, but it is not sure where the magma will surface, it could be everywhere over the whole lenght of the dyke, also under the glacier, which could mean a jökulhlaup.
    If it continues into Askja and hits the magma reservoir of Askja, it could become difficult, because there could be rhyolite within the magma reservoir. This would lead to a bigger explosive eruption.

    http://www.visir.is/island-i-dag–hus-tekid-a-haraldi-eldfjallafraedingi/article/2014140828924

    Reply

    • Now I am confused. Looks like the magma in the dyke moving toward ASKJA has been moving deeper over time. Is he saying it is now moving up?

      Reply

    • So the best ever Volcanologist, the man who quite literlly wrote the book on Icelandic volcanoes is as clueless as I am. I feel better now. Seriously.
      Just for the record. I am awed at the work of Haraldur. He is a Master.

      Reply

      • it will be interesting when it is all done and dusted to have a look at all that was written, as you said before it is history in the making. We have a front row seat here at VC, thanks Carl

        Reply

    • This dyke hasn’t simple structure. There is something pernament at 64.8 latitude and 16.9 longitude in the dike, and it has deep verticular structure. Despite of the dike prolongation must of earthquakes still occurs in this point. http://hraun.vedur.is/ja/bbgpseq.png
      At last in this point has place also some more swallow quakes – at depth 1.2km, 3,3km (3,1 magnitude!),

      Reply

  30. With respect to Jon Frimann I personally don’t think this dyke / crack has yet reached the Askja system. It’s rattled the Askja system a bit, but I think it has a few kilometres to go. The quake videos and maps just don’t show it reaching the volcano yet. Perhaps the older, hardened cold magma about Askja’s feeders is providing an obstacle.

    Reply

      • According to IMO news briefing, the dyke ahs reached the Askja fissure system…
        “Since yesterday, the length of the dyke under Dyngjujökull has increased by 1-1.5 km to the north, which is considerably less than in the last days. The dyke has now reached the fissure system of the Askja volcano and GPS measurements indicate that the area there is greatly affected”

        Reply

    • Yeah, I thought that was early. Each time I’ve checked it in the last few hours it appeared to want to make a jaunt east into some better ground for propagation. I think Askja is just responding to crustal tension in general and not due strain from the dike so much. Did Kverkfjoll respond to the dike stopping on the next ridge for a few days? So it’s strain that’s going on at Askja, though Jon did say that too.

      Reply

  32. I suspect that if the number/size of earthquakes were expressed instead as the total amount of energy released the figure would be on a par with or higher than Monday!

    Reply

  39. If Peter is around, here is an interesting paper on cavatation/bubbles.

    Seems there are some hypervelocity examples out there, 300kmh underwater !

    I still think this makes sense if folded into sonoluminescence. You could easily get some very large forces.

    Reply

  40. Pingback: Bardarbungan trilleri | Sääbriefing

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