What is going on in Bárðarbunga volcano

This is not a status update article. For Monday 10-November-2014 status update, please check last article. This is not going to be a long article since I have a long way to go in order to properly analyse all the data that has resulted from the eruption in Bárðarbunga volcano.

Activity in Bárðarbunga volcano before 16-August-2014

Activity in Bárðarbunga volcano before 16-August-2014 was a pattern of regular earthquake swarms and dyke intrusions. That was considered normal behaviour in Bárðarbunga volcano. It has to be considered if this where in fact the long term signs that eruption was going to happen soon. Earthquake swarms where also common in Dyngjuháls area, often with earthquakes that had magnitude 3,0 and stronger.

Nineteen weeks before 16-August-2014

It seems that some nineteen weeks before 16-August-2014 a critical point was reached in Bárðarbunga volcano. At that point it seems that pressure had started to rise inside the volcano. This resulted in change in earthquake activity that lasted until 16-August-2014 when magma started to break outside the magma chamber and making its way to the surface. This change in activity in Bárðarbunga volcano appears clearly on Week 15 and Week 16 and onwards.

Current changes in Bárðarbunga volcano

Currently Bárðarbunga volcano is subsiding and at the moment it is not going to start a caldera collapse if it continues in the same way as it has been doing for the past two and half month. Far as I can tell, it seem that magma is now being drained from two dykes (or sill) in Bárðarbunga volcano, while the dyke exit point is rather deep, with depth around 5 – 8 km (best estimate and it might be wrong). This appears to be drainage from the top, magma is going down the mountain (far as I can tell and that might be wrong too) and into the dyke. Rather than just rising from depth and going into the dyke, but that is also happening at the moment. How much magma is at work here I don’t know, it is however clear that there is enough magma in Bárðarbunga volcano to continue the eruption in Holuhraun for many more months. The drainage of the sill(s) explains the earthquake activity in Bárðarbunga volcano, it also means this earthquake activity is going to continue for many more months. It also means that larger earthquakes that have higher magnitude than 5,7 can happen, even if they have not done so yet.

The rifting activity

It seems that the eruption in Bárðarbunga volcano has started a rifting in Eastern volcanic zone in Iceland. That activity is going to continue for decades at least. This rifting means that more fissure eruptions are going to take place, both under Vatnajökull glacier and outside it (like Holuhraun eruption).

What is going to happen next?

While there is no way to be certain what is going to happen next in Bárðarbunga volcano since its eruption history is mostly unknown and has not been observed with instruments before. As the time passes the image is going to get clearer. For the moment Icelandic emergency authorities are preparing for an eruption under Vatnajökull glacier. Since an rifting is going to start south of Bárðarbunga volcano one day, when that might happen is not clear, since the situation south of Bárðarbunga volcano is more complex and has factors at work. One of those factors is Hamarinn (loki-fögrufjöll) volcano. It is clear that Bárðarbunga might or is likely to trigger a eruption in that volcano without warning. When that might happen is not known and that is always the case with volcanoes and possible eruptions.

New activity update for Bárðarbunga volcano is going to be written tomorrow (12-November-2014).

28 Replies to “What is going on in Bárðarbunga volcano”

  1. Very well written post, Jon!

    And it summarized pretty much what we do know, and what it might happen.

    Why do you think now, that a caldera collapse is less likely if events keep going this way?
    I also think that, based in past events, but the caldera can’t just be continuing to sink for a long time, and deeper and deeper. How much is too much?

    Or maybe a wider caldera can arise in the end.

    What mechanism prevents caldera of becoming very very deep?
    Why we don’t see 1000-2000 meters deep calderas in Iceland?

    1. The main magma chamber needs to empty before that happens. That magma chamber is located at 5 – 8 km depth. With just one vent erupting at the moment I don’t see that happen. That might change, but for now no collapse is going to happen.

  2. “It seems that the eruption in Bárðarbunga volcano has started a rifting in Eastern volcanic zone in Iceland. ”

    Isn’t that a bit chicken and egg, Jon? What I mean is, this is a *regional* tectonic event. Couldn’t we as well say the rifting episode destabilized the Bárðarbunga magma system and started the eruption?

    It’s my feeling that this is a event primarily driven by tectonics, and Bárðarbunga is a symptom, not a cause.

    Armann H. has said that the magma currently being erupted is 200C hotter than average Icelandic basalt, and is sourced direct from the mantle. It sounds as though this eruption is most like Laki, in everything except scale (and yes, Laki also had central volcano eruptions too of course)

    1. This started as an intrusion under Bardarbunga causing the stress field to emanate out from the caldera itself,there is no evidence of great stress elsewhere?Tectonic event?,this is a volcanic event?Of course the overall plate tectonics is causing the the basalt plume intrusion but that is the case with all plate boundary volcanics.

      1. Chicken and egg. What drives tectonics? Magma! And what drives magma out? Tectonics!

        Question is what moves the European and N American plate? It is magma under that entire plates, or magma solely along the MAR?

        Because the MAR rifts nearly everywhere, so the large tectonic plate movements must be connected to large movements of magma under the entire extent of each tectonic plate. Let’s think mantle convection currents.

        We have seen a large increase in quakes in Bardarbunga since week 20 in 2014, way before 16th August.

        We have seen an increase in very deep quakes along Kistufell and Dyngjujokull weeks before 16th August

        We have seen Grimsvotn erupting fresh new magma in 2011 from the mantle, first time since late 19th century.

        All indicates this is a regional event taking place, over a wide scale, across Vatnajokull at least. It’s not just a volcanic intrusion.

        It’s either a large tectonic movement or a large magmatic movement at the mantle level

        Chicken and egg…

        We know of a few things:

      2. Irpsit from what I understand ,Bardarbunga awakened with increased earthquake activity in the 1970s and this has brought it to the point it is now?Perhaps the regional stress feeds the activity and the caldera and the caldera feeds back the stress to the region,creating a self sustaining energy loop,which can be relieved only by eruption?

  3. The clumps of small eqs is interesting. Could be cracking of the caldera base due to increased water circulation. If water enters the mix a few kilometers down this could increase pressure and slow down the vertical displacement. Currently the GPS vertical displacement is steady. Or is that geophysicist now holding up the entire plug on his own 🙂

    1. sorry, but most of the comments here on “big rise” “big drop” “stopping” “increasing” etc are simply overinterpretations of very short-lived observations. There were always phases like that during the last weeks and nothing happened. And – again sorry – that´s also the case for Jons daily updates. Filled with “could be” “may be wrong” “do not know”. It´s fun but has not much to do with science.

      1. That’s because its not possible to analyse all the potential scenarios for Bardarbunga and its associated systems.
        However, its always good to hear informed opinions.

      2. Obviously observations measurements and experiments will always be difficult on this scale with everything happening underground. So yes, the scientific laboratory method is impossible as it is for astrophysics and climatology. Doesnt stop them having a good old speculate though.

      3. We know little about volcanoes. What we do know about volcanoes is far too little and gives us only limited view of what is happening in a volcano when it is an eruptive state.

        Scientists are going to spend next 100 years to analyse this and future eruptions in Bárðarbunga volcano. Just to figure out what is happening inside a volcano when it starts erupting.

  4. I’m not a geologist, so will keep this brief. It sounds like there are three volumes of magma here: a very large but slow-moving plume rising under Iceland, a magma chamber roughly 5 km under Bardarbunga, and a smaller chamber directly under the caldera floor. This summer the main chamber forced magma into the upper chamber. A dike opened at Hohluhraun, which is draining the upper chamber and also being fed directly from the main chamber. The pressure, and therefore the flow out the dike, comes from the fact that the caldera chamber is about 1 km above Hohluhraun. The caldera floor is acting like either a piston or a blanket, depending on how thick it is.

    Is this at least approximately correct?

    1. How could a chamber of basalt sit for centuries under the caldera floor and not erupt,evolve or solidify?The Holuhraun eruption magma is known to be deeper sourced,at least 10km and maybe a much deeper source.There is a pressure problem with the drainage model, in that the incoming magma is under far greater pressure and has far greater potential volume than what could possibly be forced out by a sinking lid.The subsidence is possibly caldera block slippage cause by caldera roof melting by a rhyolite reservoir,these blocks of higher density rock are subsiding into the lower density higher temperature rhyolite crystal mush?The higher density evolved magma is propagating to under the NNE rim of the caldera?The truth is probably different to what anyone thinks.

      1. Thanks for taking the time to answer newbie questions. I had thought the upper chamber, if it exists, had been “empty” until this summer. The term “empty”, or ones like “1/3 filled” are often used in nonspecialist literature. I never knew whether this meant empty like a cave, empty like a dry sponge, or empty like a deflated balloon. I think you also implied that this kind of magma has enough dissolved gas to greatly increase in volume when decompressed. That helps me a lot. Thanks and I will try to keep out of your way.

  5. Nasty weather again. Webcam at Jökulsarlon is shaking like crazy.
    I haven’t seen anything on Bardar-cams for a week now 🙁

  6. interesting, there is an apparent uptick in tremors, there were also at least 3 quite strong quakes in the last 3-4 hours but neither IMO nor EMSC have actually reported them…

    1. … but they (IMO) reporting EQs I can’t find on the drumplots 🙂
      Wednesday 12.11.2014 11:59:44 64.634 -17.372 0.5 km 2.2 90.01 7.4 km E of Bárðarbunga

      1. If the GPS-unit is working properly, the subsidence would have stopped for more than 24 hours already; including that strange upward bump by about 50 cm… What might that mean?

  7. Meanwhile, Haraldur Sigurðsson wrote also an interesting new post on his own blog. http://vulkan.blog.is/blog/vulkan/entry/1505445/

    He visited Holuhraun after some weeks again now, on the 7th and 10th of November. Because of masses of snow in the region, it took them 7,5 hours just to drive from Möðrudal (near National Highway No. 1) to the Dreki Hut in the Dyngjufjöll / Askja area.

    He thinks btw that the magma involved at Holuhraun has a very low viscosity (he is petrologist).

    The lava field is now moving esp. in eastern and southeastern direction, a little bit still in northwestern direction also, but it stopped to the northeast. The waterfall Skínandi seems to be on the safe side, up to now. In the southeast, the lava hits the river Jökulsá á Fjöllum and produces a lot of steam.

    Interestingly, in the near vicinity of the eruption site, there was no gas measured by them, neither SO2 nor CO2. Haraldur thinks, this would be because of a vertical draft at the site. The gas cloud high above them was very blue (SO2 acc. to the geologist).

    At the southern end of the crater row, they hit on something which confirms the importance of the tectonic element in this whole geologic episode which is part of a bigger picture: There were brandnew fractures there, and they could report rifting of respectively 40 and 80 cm at each of them. The fractures could even become dangerous to walking or driving people in the area.

    1. I would echo the comments about SO2. I spent several days at Holuhraun, on two separate visits, and we had no problems with air quality. None. SO2 meter only clicked off zero a couple of times.

      If you’re close to the lava, and/or the atmospheric conditions are a problem, then yes I’m sure you could have very bad air at Holuhraun. But it’s more common to have fine air there, and some other part of Iceland downwind is choking…

      Also agree with the rifting comments; the graben structure forming to the south of the eruption site was very clear when we were filming from the helicopter.

  8. Does anyone have the figures for the amount of plate divergence in Iceland since this summer? …I recall Jon mentioning at one point that it had spread farther in the last few months than over the last century.

  9. Hello! I’ve been watching the progress and data collection on this eruption since August and have a question and a personal, probably uninformed observation to contribute. Question first:
    I note that there have been disturbances in the GPS curves available at Iceland Met generated by the station installed in the Bardarbunga caldera. These disturbances seem to start approximately the same time each day, centered around 0 hour UTC. What is the cause of this? Is it an artifact? Thanks.
    Ok, now the uniformed observation (I’m no expert, so yeah):
    Having watched the time series of GPS displacements and earthquake occurrences it appears that the magma may have come up from below Bardabunga (noting that the evolution of the magma indicates a deep source for the Holuhraun magma), expanded into dykes N and E, then found it’s way through the tranverse fault to the neighboring fissure zone east of Bardarbunga’s own.
    It appears that once it found it’s exit at Baugur & Co (Sudrid, Nordid, Hemisearten, Krakkken) the forces parting the ground to the E and W became dynamically static, while the expansion pushing away the ground to the south of Bardarbunga began to subside and, late in the eruption, is now showing signs of relaxing toward it’s former state, which seems to me to agree that there has been a drainage from Bardarbunga.
    The difference in what I see is that since the magma is from a deeper source, magma residing in the upper portion of Bardarbunga’s throat has been drawn down to the point where it might no longer be a factor, and the magma’s route might be from below Bardarbunga, eastward into the transverse dyke, then north to Baugur & Co. This would mean that fundamentally, Bardarbunga has been increasingly decoupled from Baugar & Co as a source, with the magma bypassing the throat of Bardarbunga at depth. This means that the eruption can continue regardless of what happens at Bardarbunga, in my (again) uninformed view.
    But, as I’ve said, I’m not trained in your field and will be the first to admit it.
    Thanks for your patience with this observation.

    1. Yes, you could say that until now not much was known about this volcano, its magma is probably deep sourced and the central volcano is acting more or less as a sort of hinge.
      It also has probably erupted many times in the past in the way we see today.

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