The Calm before the Storm


Water drainage basins at the glacier bed for the principal rivers draining Vatnajökull. Subglacial water-filled cupolas, located under depressions in the glacier surface, collect meltwater and periodically drain by means of jökulhlaups. In order to determine water divide locations on a regional scale, a model was employed which assumed that water pressure at the glacier bed is approximately equal to the ice overburden pressure. – Vatnasvæði helstu jökulfljóta sem falla frá Vatnajökli. (From Reviewed Research Article ” Icelandic Glaciers ” By Helgi Björnsson and Finnur Pálsson)

First, a few reminders:

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The most important news from the morning is what the premier expert on subglacial eruptions, Professor Magnús Tumi Guðmundsson, said in an interview for RUV (in Icelandic):

Sigkatlar = Ice Cauldrons

Map (RUV) of the NW part of Vatnajökull showing the location of the Ice Cauldrons mentioned by Professor Guðmundsson

The last time this happened was at Katla in 2011 when there was a small, subglacial eruption that resulted in several such cauldrons and a small jökulhlaup that nevertheless was powerful enough to remove a bridge. This does not have to be an actual magmatic eruption. The enormous amount of heat introduced has caused tremendous hydrothermal activity which is evident from the blue, 2 – 4Hz tremor lines.

These “sigkatlar”, Ice Cauldrons, are from the days just before the 1996 Gjálp eruption (Visir, Is)

Earlier today, scientists from the Icelandic Meteorological Office and University of Iceland took a number of flights over the region. Icelandic journalist and pilot Omar Ragnarsson who reported on this issue was involved in another flyover. The biggest development was the discovery of a number of depressions, “sigkatlar” or ice cauldrons, in the glacier that caps the volcano’s caldera. These cauldrons number over a dozen and are relatively shallow, only 10-15 metres, and form a string that spans some 4-6 km along the surface of the ice.

When looking at the video: The flight path entered from Skaftáreldar, then overflew the Bardarbunga central volcano after which the aircraft circled the Dyngjujökull where there are several cracks in the glacier as well as a (monogenetic) cone from a previous eruption.

For the sake of clarity, it is perhaps best to divide the summary between the two areas of activity, Bardarbunga and the front of the intrusion moving north.


All events shown are over Mag 3 – the date and time of the event is shown in the title bar

Over the past days, mention has been made of a possible subsidence of the Bardarbunga caldera due to magma flowing out from under the Central Volcano and into the main dike. What is certain is that the massive amounts of heat introduced by this magmatic intrusion has activated the hydrothermal system – water in cracks in the ground going down several kilometres – underneath the volcano. This is evident from the heightened activity in the blue 2-4Hz line of the tremor plots. The appearance of the Ice Cauldrons mentioned by Professor Magnús Tumi Guðmundsson point to activity between the glacier and bedrock which can be explained by either a) the increase in hydrothermal activity, and/or b) an ongoing magmatic eruption, possibly a couple of kilometres in length as indicated by the location of the “sigkatlar”, ice cauldrons.

The Intrusion Front

All events shown are over Mag 3 – the date and time of the event is shown in the title bar

Continued earthquake activity indicates that the intrusion is still progressing northwards towards Askja but at a slower rate. In the interview for RUV, Professor Magnús Tumi Guðmundsson said that the dike may run as far down as a depth of 18 km which could be interpreted that it runs from a depth of 5 to 18 km at its maximum extent. Our own Carl Rehnberg, PhD, says that his personal tracking of the earthquakes yields this figure for most of its length but that it in two locations expands to 2.5 by 20 km.

Possible Jökulhlaup

According to Professor Guðmundsson “Around 30-40 million cubic meters [1,1-1,4 billion cubic feet] of water have flowed from under there but we don’t know whether this has been happening in the past days or just today [yesterday]. However, by what we can see on earthquake monitors there are no indications of a great volcanic eruption taking place.”

This while substantial is enough water to form only a smaller, yet potentially lethal jökulhlaup. The amount corresponds to the content of 12,000 to 16,000 Olympic size swimming pools (Olympic swimming pool = 2500 cubic metres).


with assistance of dfm and the dragons

This is the update with no zoom.

406 thoughts on “The Calm before the Storm

  1. We are on the “effusive eruption of the dyke near the northern limit of the intrusion” scenario, if anyone can reiterate what that entails from here forward, that would be very nice.
    Also, they have increased the aviation alert level to red for Bardarbunga.

    • To all, and especially newbies…
      in light of the upcoming event(s) where extraordinary demands on our Dragons is inevitable, at this time I would like to ask everyone to make as much effort as possible to research your own question before posting here. On the top of the VC homepage are tabs with an ever-growing library of information, and I highly encourage all readers to avail themselves of the links in their quest for knowledge, as well as review earlier posts which are always informative and full of data and discussion. This is not to say questions are not good, quite the contrary. But questions about something that was heavily discussed only hours before is not a good use of this blog space either.
      Our Dragons are doing a marvelous job in keeping VC operating smoothly…and we owe them all our full respect by adhering to the rules and spirit(s) of this blog…as well as keeping their workload to a minimum. We are entering uncharted waters as to what blogs like VC contributes towards the common good. I re-iterate, VC IS NOT AN AUTHORITY, and all communications should be kept in accordance with this in mind. We all are curious, but we all must recognize the uniqueness of the situation at hand.

      Note: I am not a Dragon…just voicing a private appeal

      DragonApproval: Thank you, Craig! MUCH appreciated! / Pyrite

      • Heh… funny you should use the Dragon moniker “Pyrite”… I had used various rock names for the server group at an ISP I used to work at. “Pyrite” was my private (utility) server. 😀 I did some amazing things with that little box.

    • Yep,
      Increadbly did creen capture VIDEO 00:13 (a minute or more) as I found it suspicuisly stable, and colour was red (not headlight blue-ish or whiteish). Four individual craters now and lava flow has started (REF: Símstöðin TV channel 30) .

  2. This fissure looks big. That much field of view that far from the camera…1-3km long, guessing. Maybe more.

  3. Pros: Now that the surface rift eruption has begun….what is the usual/natural progression of events? I know the system is dynamic and ANYTHING can happen…but what is the historical evolution? Thank You!

    • Depends if originating from Bardarbunga or mantle. If Bardarbunga, it should let off pressure because it has an outlet, eventually dropping the quakes. If mantle, it won’t matter.

      All Icelandic eruptions start with “small” lava flows somewhere.

  4. Just_Visiting August 28, 2014 at 23:18
    Trying again, because I’m really curious what I saw here. I was about to walk away from the computer when I saw two small flares. They died down quickly. Then about 60 seconds later, two more. These started small, grew, and also died down, though they lasted slightly longer. The screen capture is of the second instance. Any thoughts?

    Cpngratulations Just-Visiting, DING DING DING. You just won the honor of first person ever to spot a Bardarbunga eruption with a webcam!

    • I am quite certain that unless the camera was repositioned the dual flares were further to the right of the camera — near the edge of the picture — compared to the lava we see now.

    • I can’t find the dual lights, but here is a single in the same spot as the dual. The YouTube feed does not have a time on it! 😦

      • I think the eruption fissure extends into the direction to the right of the camera, it’s not all of it covered here.

    • That’s just wild. I hope everyone in Iceland stays safe for the duration! And then we use this tech to make peace among friends around the world.

  5. Who wants to travel there tomorrow?

    I thought driving Sprengisandur road to Nyidalur, and a small hike and camp for the night.
    Anyone wants to join?

  6. Unfortunately the icelandic webcam sites have been linked to several times in posts on Reddit that may very possibly reach the front pages of their subreddits. This will most certainly crash the servers.

  7. Forget the webcams. The link to the cams is out on reddit and 9gag, so they will be hammered on by the whole internet now… :((( At least we saw it first!

  8. What to expect next: probably we are just watching the very beginning of a long term rifting sequence of events in Iceland. Probably minor fissure eruption started on the glacier last weekend and caused the cauldrons reported yesterday. As rifting widens northwards, a fissure eruption occurs now at the north of Dynjujokull.

    We can expect it to extend further north and eventually it might reach Askja and cause another eruption there too.

    Eventually the eruptions just remain smaller like now, or grow bigger. If they grow bigger, then pressure changes in Bardarbunga can also trigger explosive eruption under the ice cap, but this is much less likely.

    Also if eruption grows bigger, it can remain long lasting but sort of efusive most of the time, and start to create a shield volcano if it remains for a long time. I expect an eruption to last at least a few days or weeks, but its very likely that the volcanism can remain active for months.

    Exciting touristic eruptions. Only problem is they are very remote.

  9. For anybody new coming here – the realistic answer to any of anyone’s questions about what might happen next is “nobody knows”. What we’re seeing is unique from what we know, so it may be small and blow out, and it may be something bigger.

    Best thing we can do is kick back and enjoy the show 🙂

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