Posted on by Jón Frímann

Hydrothermal areas grow larger in Krýsuvík volcano due to earthquake swarm

According to news from Rúv. It appears that hydrothermal areas in Krýsuvík volcano are growing larger following the earthquake swarm in the past few days. This same news also tells that the number of cracks in the ground have grown in numbers following the earthquake swarm, this allows more water to get into contact with the hot rock and that warms the water up fast.

Currently the earthquake swarm in Krýsuvík volcano is quieting down. But that might chance without any warning at all. But won’t be surprised if the earthquake swarm stops completely.

In my personal opinion this is a clue that magma might be pushing it’s way up the Krýsuvík volcano system. I get the clue from the increased hydrothermal activity in the this area. But at the moment it is too early to know for sure if this is going to result in a eruption or not. But if this activity continues as it has then a eruption is going to happen one day. That can also chance without any warning at all. But this type activity means that status of the volcano it self is constantly changing and makes it unpredictable. How eruptions in Krýsuvík volcano behave is also a big unknown.

Update: According to Rúv evening news (Icelandic, video) there appears to be magma related aspect to this weekend earthquake swarm in Krýsuvík volcano. According to Dr. Páll Einarsson geologist at Iceland University it appears that magma is the source (as stated above) of this weekend earthquake swarm. This news also says that there has been a lot of earthquake activity in Krýsuvík volcano over the past two years and this earthquake activity is not only tectonic as is common in this area. The news at Rúv also says that geologist in Iceland are wondering and unsure what exactly is going on at Krýsuvík volcano at the moment. But the reported inflation in the news at Rúv is sad to be 10 cm (I do not know if that number is accurate or not). But it clearly a reason now to watch the activity at Krýsuvík volcano. If there is a eruption in Krýsuvík volcano it is going to be a harmless (as it can be) lava eruption. Unless it is under water, but then there is a Surtsey type of eruption for as long there is water getting into the crater. So don’t expect aircraft problem if there is a eruption in Krýsuvík volcano.

Thanks to The other lurker for the news tip.

News about this. Use Google Translate at own risk.

Jarðhitasvæðið hefur stækkað (Rúv.is)

Blog post updated at 21:15 CET on 28.02.2011. News item about Krýsuvík volcano from Rúv added.

66 Replies to “Hydrothermal areas grow larger in Krýsuvík volcano due to earthquake swarm”

  1. Thanks, Jón.
    I believe this volcano finds its own particular way to release pressure.
    But as you say, one never knows.
    If I were there, I wouldn’t venture a dive in the lake… 🙂

  2. Not only teutonic movements in Krísuvík now, says Páll Einarsson geophysicist in the news tonight, everyone is watching and monitoring the movements closely now

    If however it comes to an eruption, the odds are that it will not be a big one nor very disruptive says Páll.

    The link to the TV-news is not up yet, will be in 30 min
    ~ http://dagskra.ruv.is/frsjonvarp/

  3. Jón, is there monitoring data on the flow rate or temperature of the rivers or lakes in Krýsuvík volcano area? I looked quite a bit under the Hydrology data in IMO website but I was not able to figure out which monitoring stations might be in the affected area.

    1. There are no rivers in this part of Iceland. The rock there is too leaky (the rain goes right trough the rock it self) to allow rivers to form in the landscape. The only reason because the Kleifarvatn lake is there is because it is below the water line in the ground.

  7. Maybe we just witnessed in a day things that we thought would occur in a much larger time span.
    Amazing!

  8. I was wondering, are the authories not concerned at all that this volcanic system spans out to the Reykjavik suburbs? and that is located between the international airport and the capital? And the hydrothermal plant near Krysuvik? In the order of ash-emission an eruption would do little harm but structural damage could be severe. (compared to the Eyjafjallajokull eruption)

    1. Good question. And something which is connected to that question what kind of topography is it? I mean if there is an eruption where would the lava go? Is the land flat or is it sloping southwards, northwards or any other direction which would direct the lavaflow?

      If it is low vicosity the lava could go pretty far in a short amount of time.

      1. This has been my concern all the time.
        Even if no eruption occurs, just a phreatic explosion could already be damaging enough.

      2. There is no population in this area. The next population to Krýsuvík is about 20 km or more away from it. There is one drug rehab center nearby. But it should not be a lot of issue evacuating that if comes down to that.

      3. Look at the satellite view on google maps. Reykjavik itself looks safe, but some of the southwestern suburbs are built on recent lava flows. Where the fissure opens will be important, because it looks like flows head directly northwest from the vents. If the eruption happens near the epicenters of the largest quakes, heavily populated areas will probably be safe.

  9. Seems like the swarm isn’t that intense anymore,
    Is it getting less or doesn’t that mean anything?

    1. That’s the fun thing about earthquakes and volcanoes. We simply don’t know what happens next, everything is possible.

  10. It has slowed down considerably. But given the events this weekend and the fast increase in tremors the swarm can pick up again at any time. Or it might enter a more calm phase. Lets just wait and see what happens. 🙂

    1. After ~5 hours of repose a first earthquake:

      Monday 28.02.2011 21:03:32 63.929 -22.046 2.3 km 1.8 90.02 4.7 km NNE of Krýsuvík

      Maybe this is the start of another cycle of activity?

      2. I wouldn’t go all crazy about specific depth’s as long as it’s not 100%, when you look at the reviewed earthquakes, (second to) none of them are shallower than 2km. This is what I think makes this rather interesting, if there is magma pushing, it definitely hasn’t pushed it’s last bit yet.

  11. Actually the most interesting signs would be a deep intrusion of magma. If the quakes are shallow like they are now I would think it is more of a hydrothermal phenomenon as Jón srote in the post. Earthquakes has caused water to be able to seep down and come in contact with hot rock which has not evolved to magma yet. This would cause alot or shaking.

    1. Remember that the crust is very thin here compared to other parts of Iceland, it could well be less then 10km deep. And we’ve seen these quakes.

      There is also a possibility that Krysuvik itself is a weak spot because on this location the crust is even thinner, which would explain the volcanism on this location. It’s possible that there has been a constant presence of magma around this depth, and that all that ‘has to be done’ is making it’s way up, and that’s were we could see stress-related earthquakes, which I think this swarm had it’s origin.

  12. Some interesting readings that could help (a little) us understanding something in what happening… (and what would probably not happening tomorrow…) in Reykjanes peninsula (rather than making amateur’s hypothesis) …
    “Use of relatively located microearthquakes to map fault patterns and estimate the thickness of the brittle crust in Southwest Iceland” – Sigurlaug Hjaltadóttir
    http://en.vedur.is/media/vedurstofan/utgafa/skyrslur/2010/2010_003rs.pdf

    1. Her fig 3-27 om page 82 of pdf gives a 3D image of EQ-derived peninsula faulting to 10km depth

      And I could not find – after a quick scan – many EQs below 10km since 1995, just one or two.
      If magma has come up from 16km it would be before 1995.

  13. Isn’t it possible they just hold back the data till they checked them? Just to make sure they only give the right data this time?

    3. IMO has a gale warning for the southwest. Looks like it has caused many non tectonic signals in the seizmometer network.

  15. Thank you, Jon Frimann for keeping us posted. Between you and others that also go to Erik’s blog, we get a good idea of what is going on. I really appreciate it.

  16. Well, here we go again. The capcha ate my post. LOL

    I just wanted to say thank you, Jon Frimann for keeping us posted on what is happening. With your input and others, it really gives us an idea of what’s going on.

  17. I think that a new earthquake swarm is about to start or might start soon in Krýsuvík volcano. But the only thing that can be done at the moment is to wait and see what happens.

  18. And I could not find – after a quick scan – many EQs below 10km since 1995, just one or two. If magma has come up from 16km it would be before 1995.

    1. Thank you very much for granting us your expertise, Dr. Cobbold.
      I was just wondering about how long ago monitoring systems were sensitive enough, or if there were enough seismographs to capture earthquakes with this kind of detail, such as lower magnitudes and depths.
      If I quite understand what you mean, if there is magma involved in the present swarm, it has been there for a longer time, or else, as I think you are suggesting here, the swarm is purely tectonic.

  19. There’s a big gap again where all the quakes happened on Sunday… what is going on ?

  20. “What size an eruption?” I think that’s what many wonder about now and, of course, the follow-up question, “How is it going to affect me?”

    If we go back to Eyjafjallajökull, the magmatic intrusion resulted in an inflation of up to 7½ cm over an area with a radius of approximately 15 km. That gives us a figure of 0.053 cu km which resulted in two eruptions of some 0.14 cu km. (If you feel there is a discrepance, just consider the amount of energy needed to lift a crust some 22-25 km thick 7½ cm in the air over an area of 700 – 750 square km!)

    If, and I say IF, there is a correlation between amount of uplift and the total amount of DRE erupted, the factor for Eyjafjallajökull is 2.64. Using that factor and, as I have understood it, the much larger area affected at Krísuvík – some 20 by 50 km??? – we arrive at a possible, hypothetical and VERY tentative figure of ~0.8 cu km using the reported uplift of 3 cm.

    Now to the factor of time. It took Eyjafjallajökull some 80 days to relieve itself of the excess and, again if I recall correctly, peak efficiency was around 60 – 70 tonnes per second. It is reasonable to assume that Krísuvík will not be utterly different.

    All this points towards a POSSIBLE and HYPOTHETICAL eruption of months even if there’s a line of fissures over a large area. Imagine a line of a dozen or so Fímvörduhalsi-style fissures fountaining and producing spectacular lava flows for somewhere in the region of two months.

    Were I in the tourist business, I’d be busy solving the logistics of getting a large numer of volcanoe tourists to Iceland, where to house them, where the best, safe spectating areas (hope they don’t compromise too much on the “safe” in favour of “spectacular”) for the initial phreatic events might be found and how to get them to the location, feed and entertain them.

    If I’m anywhere near correct here, what a bonanza for Icelandic tourism!

    1. Hm, not over for good now by the look of that. Just a pause until next time by the look of things.

      I am not expert in anything relating to earthquakes of volcanos, so if you are the press, don’t quote this.

  22. There are only few quakes at Krýsuvik at the moment. But one thing changed: The last quakes are all pretty deep with 7-12,5km.

    1. Keep in mind that this 12.5km earthquake has a very bad quality. (so do most of the quakes)

      1. This might because of a low pressure system over north Iceland or this might mean something. It is impossible to know at this point.

  24. Nice reasoning Henrik!

    Can anybody fill me in on the dynamics of rifts, or more precisely faulting in rift scenarios. I can’t get rid of the niggling suspicion that a magmatic intrusion will required a lot less seismic energy to open a fracture right slap bang on the MAR than under a volcanic edifice like Eyjafjallajökull, i.e. we might see a lot less EQ activity as a prelude to an eruption than we did at Eyjaf last year… anybody?

  25. Is there any specific reason why you state that any eruption here would be a ‘harmless lava eruption’ (I assume you mean an effusive basaltic eruption)?

    There could always be pockets of more evolved, more silicic magma beneath the volcano. Even if the current intrusion is basaltic (almost certainly), if it came into contact with more silicic magmas already present (as with the Eyjafjallajokull 2010 summit eruption) then more explosive activity could be triggered. And that’s before considering interaction with geothermal system(s) present in this area (which could, as you say, give rise to more explosive activity – but more likely of the phreatic or phreatomagmatic style, rather than Surtseyan, unless the eruption occurs directly under the lake).

    1. I guess this is done by analyzing the past eruptions. As far as I understood it, all of them were basaltic fissure eruption, so there is at least some chance, that this will happen again.
      And as far s I know, most of the explosive activity of Eyjafjallajökull was triggered by the contact with the water from the glacier.

      1. There was a substantial shift in the composition of lavas between the Fimmvorduhals and summit eruptions.

        At Fimmvorduhals the lava was a basalt with SiO2 approx. 47-48 Wt%.

        At the summit the lava was predominantly andesite (leaning towards basaltic-andesite in one sample) with SiO2 56-59 Wt%.

        SOURCE: HI/NORDVOLC
        http://www.earthice.hi.is/page/IES-EY-CEMCOM

        I think the general consensus is that on its journey towards the summit vent the basalt intrusion came into contact with an older, more evolved pocket of magma and the sudden input of heat into this older material is part of what triggered the eruption. Consequently the summit eruption had much higher silica content.

        The composition of the ash from the second phase also changed over the course of the eruption. I think it became more basaltic as time went on, which would also tie in with the later Strombolian activity. Indeed, looking at a section through the ash, distinct layers are visible and their colour changes a lot, reflective of their composition.

        I can dig out a photo of this section (that I took!) if you’d like. I also have ash samples from both early and relatively late in the eruption, collected by me near source, and I can vouch for their being a substantial difference in their colour and texture which I can’t attribute to simply the change in eruptive behaviour (i.e. Phreatoplinian to Strombolian).

      2. I know the data. My question is, if this eruption would have produced as much ash and dust without the contact to the glaciert.

      3. It probably wouldn’t have been fragmented so finely, but the total volume would most likely have been the same.

        Without the ice cover my guess is that it would still have been explosive to some degree, albeit not as much as we saw, probably then changing to Strombolian (as it acted later on, with more basaltic lava and no ice cover).

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