Posted on by Jón Frímann

Earthquake swarm in Katla volcano

Around 17:10 UTC an earthquake swarm did start in Katla volcano. This earthquake swarm is focused inside the Katla caldera at small point. The one earthquake that I have so far been able to record was an long period earthquake, but that suggests that this earthquake was created by magma movement. At current time I am not sure from where this earthquake did originate from. But from Goðabunga area in Katla volcano this types of earthquakes are common and no surprise at all.

At current time I do not know what this means for Katla volcano. But so far no increase in harmonic tremor has been detected on the seismometers around Katla volcano. But that might not start at current time, as harmonic tremor is only going to increase when magma starts to move inside the Katla volcano, like did happen in Grímsfjall volcano few weeks ago.

The location of this earthquake swarm strongly suggests that what is going on in Katla volcano is an dike intrusion in the Katla caldera. If that is powerful enough to start an eruption is an question remained unanswered at current time.


Area of activity is marked by the earthquakes. Looks like an dike intrusion into Katla caldera. Copyright of this picture belongs to Icelandic Met Office.

I am going to update or post new blog posts as this continues to develop. I do not think that this events are over. But it is hard to know for sure, since volcanoes are impossible to predict.

Post post updated at 18:39 UTC.

130 Replies to “Earthquake swarm in Katla volcano”

  1. Have earthquakes stopped or is it just the icelandic met office currently not reporting new ones? Can you see them on your helicorders?

  3. Jón,
    As the weekend approaches and news from Caulle are saying alert level has been lowered to 5, here we come with a new possibility to watch for.
    According to “astrological” odds, every weekend we’ve been having another eruption, so, we should take this “fact” into consideration… 😉
    Of course I am kidding, but it has been a long time since we’ve seen a 3+ quake in this area.

    2. SERNAGEOMIN’s latest report is still dated as June 16th

      It suggested that there were indications for greater concern.

      It would seem desirable to issue a more recent bulletin. You indicate they have done so.

  4. There is much activity in the Godabunga and Lagu hvolar measurements with a high spike in the last sequence. That was probably the mag 3.1 quake? What does that means Jón? And can you explain me what exactly a dike intrusion is? I was last weekend in Iceland and it was so amazing and interesting so I love your blog and follow the geological changes in this fantastic country

    1. Here is the simple explanation for dike intrusion in an volcano.

      http://en.wikipedia.org/wiki/Dike_%28geology%29

      https://inlportal.inl.gov/portal/server.pt/community/inl_seismic_monitoring_program/441/dike_instrusion/4443

      It is magma on the move, and it can be signs of an volcano waking up. Katla volcano is somewhat similar to Krafla volcano. But with an glacier. Last eruption was in the year 1918, so we do not know an lot about how Katla volcano behaves before an eruption starts in it.

  5. A year ago, before they installed the new, more sensitive monitoring equipment, we’d only have seen the 3.1 near Godabunga and few would have been excited. Well, a M3 near Godabunga is rare!

    1. I think it’s just the spike from the earthquakes and back to the level from before.

  7. Anybody think the sulphur smell in the river near Katla mentioned by one of the bloggers (forget who it was) a few days ago is a connection to the swarm?

    1. That could point to raised fumarolic activity below the glacier. And this can mean that there is something going on. But it can also mean nothing.

  8. That blogger is me, but the smell in Sólheimarjokull outlet river is normal, at least has been always there for the past year. Last week when I drove there was quite strong the smell, but the wind was blowing from the north (where Katla is), so that could explain the stronger smell. I don’t think it had anything to do with this.

    But we know Katla has been long dormant, and has been accumulating magma underneath for a long time (inflation), these earthquakes probably mean magma is pushing up. If this can manage to get through, we could have an eruption within a few weeks, this summer.

    Note that for Eyjafjallajokull the earthquakes lasted for 3 months before the eruption, for Grimsvotn there was only some increased activity 2 weeks before, but nothing on the days before. I don’t know how Katla behaves.

  9. Friday
    17.06.2011 20:57:50 63.644 -19.124 5.4 km 0.7 87.17 6.2 km E of Goðabunga
    Friday
    17.06.2011 20:56:47 63.639 -19.123 1.1 km 1.0 90.01 6.3 km E of Goðabunga

  10. Guys, this is not a joke. Swarm is right in the middle of Katla’s caldera. Have never seen something like that.
    Another sleepless weekend?
    Who could call RUV for the webcam fix? Or maybe the quakes affected its functioning?
    It has been working steadily so far…

    1. I think right now the phones have gone up in smoke of those responsible for the webcam Katla, so much time looking at Katla and miss a possible onset of rash.

    2. I agree with you Renato, this time seams different! Activity seams increasing again.

    4. Don’t forget that just because there is a big swarm in the middle of a volcano, that it will mean that the volcano will erupt. Swarms happen all the time in Icelandic volcanoes without them erupting!

      1. Thats right. I think the reason why a lot of people got excited (and probably some geologists had to take a night shift) is because nobody really knows what happens before an eruption of Katla.

    1. Yes, they are shallow, but the location is what makes them special for a lay observer’s eyes.

  12. EMSC informs a 3.8 at 17:36. But data come from IMO, I suppose.
    Magnitude ML 3.8
    Region ICELAND
    Date time 2011-06-17 17:36:32.3 UTC
    Location 63.64 N ; 19.11 W
    Depth 5 km

  13. I did manage to record two earthquakes from the last burst of earthquakes. Both of them where long period earthquakes. That is magma pushing it’s way up the crust. The earthquakes happen at random time, so it is hard to know what is going on.

    But I have an bad feeling about this. I must say. But at the moment the best thing to do is to observe what is going on.

    1. Jón:
      Given the small size of the swarm, couldn’t it be a discrete subglacial eruption kept within the levels of “uncertainty” given by GVP for both 1955 and 1999 “eruptions”?

      1. That does not seem to be the case now. So far it is just earthquakes. But last time it took ~24 hours to few days until that eruption actually did start (year 1999). So this might take few more days if it continues.

      2. Thanks, Jón.
        Take a rest. I think you’ll have little time to do so, if it goes… 🙂

  14. Probably a silly question, but….

    If this is magma then how come these quakes are a little shallow?

  15. First time I write here, but reading You Guys since many months. Just wanna say there’s one more “freak” out there, sharing the excitement and worries of world and especially Iceland’s volcanic potential. I think You’re quite an intelligent bunch of interesting nature lovers, and of course I thank Jon for sharing his knowledge. As a geologist it’s terrific to see how much sh… is posted at other places… I’ll be glad to participate the day I think I have something valuable to contribute.

    1. Welcome!
      It is good to have experts down here! 🙂
      All I can say comes from long observation. No idea about what might be taking place, but whatever it is, it is right in the spot, this time.

  17. Just seen this blog awhile ago. been checking the iceland met office every day since last years eyjafjallajokull eruption. never seen so much activity on katla. so pist the web cam is down when it could actually pop.

      1. Renato, can you clarify “right at the spot”. Isn’t this the spot in the caldera where it last erupted?

  20. Thanks. I don’t know many people who really are able to deal with natural hazards a rational way. Iceland is like “sacred ground’ in terms on earth’s potential, and I love it’s people for the way they live with their geological context. And many of You here observe, analyze and think instead of falling in panic and wild speculation. Let’s hope mighty Katla will be kind to her Icelandic children, but if anything happens let’s also hope that Iceland get’s some support and that society learns (I actually gave up hope on that… :-))

      1. Lurk,

        LOL A redneck, eh? We have a few up here. Some are called “miners”.

  21. Jon, if you were a gambling man, would be place your bet on this erupting over the weekend?

  22. Anyone from Eruptions blog over here getting a ‘501 Bad Gateway ” message for Eruptions? Hi Jón, glad you’re settled again for the summer, you’ll always have company over here!

  23. Hi!
    A long time ‘lurker’ I introduced myself on Erik’s site just now, but I think no one noticed! (I can take it!). I’m intruigued over the tremor on Grimsvotn (Grimsfjall) station. In my dimness I take it this station monitors Grimsvotn under the Vatnajokull ice sheets? Are we looking at renewed activity here? As a dumbo, would appreciate input from experts. Thanks, and my best wishes to you all. Clive

    2. Clive,

      I noticed. I just didn’t have anything to say at the moment. Welcome aboard here and at Eruptions.

    3. Nothing special at Grimsfjäll station. The blue signal has been extremely noisy since ages.

  25. Well, that it will erupt, sooner or later, is sure – as we don’t know and as predictions are always a “hot” thing this aspect is interesting, but not as important as the question about what part of the whole Katla system will finally be involved in the coming eruptive activity, don’t You think?

    1. This is not known. Its also not known what happens exactly before an eruption. The last one was 1918, so there are no measurements available from this time. Only eye-whitness reports. As far as I remember, they talked about earthquakes that could be felt before the eruption started.

  27. I am having technical problems with my email server. I cannot send any email from the domain jonfr.com and other domains on the server where this web site is hosted. I can receive email just fine and without any problems.

    I do not know if this is an part of an wider problem on my server. If that is the case, expect connection problems while this problem is resolved.

    While this problem is taking place. I am going to use other email addresses to answer any email that I get.

  28. And what kind of type of the erruption are we likely to see? Will it threat air traffic?

    1. This depends on the size of the eruption. Again, nobody knows this. A vocanologist said after the eruption of Grímsvötn that he expects something in this scale.

      1. Thanks Chris for your answers.

        How normal are earthquakes in this area? Seems like noone wants to jump to the conclusion that this swarm are indicating an upcomming erruption.

      2. Katla has tons of earthquakes. It’s actually in a fault zone. But these recently detected quakes have a different signature which suggests magma movement. However, magma frequently moves in dormant volcanoes without an eruption, so this doesn’t mean an eruption is imminent.
        Still, most eruptions are preceded by the detection of magma movement. Some have magma movement for years leading up to an eruption, but some only minutes or hours. And some have magma movement for years but never erupt.

  29. I think it is important to remember that the world of volcano seismology is a murky one and one not entirely understood. There are various models for the generation of long-period events and the various types of harmonic tremor.

    For example, studies of Sakurajima volcano in Japan suggest that oscillation of a shallow gas pocket may be responsible for pre-eruptive long-period events there (Tameguri et al., 2007) – sadly I can’t quote the whole thing as I only have a paper copy, sorry!

    Additionally, for Kusatsu-Shirane (also in Japan) it has been suggested that movement of geothermal fluid in a crack to be responsible for long-period seismicity (Nakano et al., 2003). I quote:

    “The results of the waveform inversions show dominant volumetric change components accompanied by single force components, common to all the events analyzed, and suggesting a repeated activation of a sub-horizontal crack located 300 m beneath the summit crater lakes. Based on these results, we propose a model of the source process of LP seismicity, in which a gradual buildup of steam pressure in a hydrothermal crack in response to magmatic heat causes repeated discharges of steam from the crack. The rapid discharge of fluid causes the collapse of the fluid-filled crack and excites acoustic oscillations of the crack, which produce the characteristic waveforms observed in the LP events.”

    I am not saying that magma movements are not the source of the long-period event(s) seen here, or that rock fracturing caused by such movements is the overall cause of the earthquake swarm. However, I am saying that it is worth keeping an open mind. While this could be due to a dike emplacement, it could just as well be due to geothermal activity. Volcanic seismicity is a horribly complicated field and there are very few hard and fast rules about this sort of thing.

    Let’s just keep watching and see what happens WITHOUT jumping to conclusions.

    ———————————–

    Nakano, M., Kumagai, H., Chouet, B.A. (2003). Source mechanism of long-period events at Kusatsu–Shirane Volcano, Japan, inferred from waveform inversion of the effective excitation functions. J. Volc. Geotherm. Res., 122: 3-4, 149-164.

    Tameguri, T., Maryanto, S., Iguchi, M. (2007). Source Mechanisms of Harmonic Tremors at Sakurajima Volcano. Bull. Volc. Soc. Japan., 52: 5, 273-279.

    1. Thank you very much for the feedback, James.
      As laymen, we appreciate your support.
      We have been watching those earthquakes on a daily basis, and although we are aware of the intricate patterns which may appear in volcanic systems, the speculation over possible, even unlikely, scenarios keeps us going.
      We have been through this Katla mongering before and the fact that such LPs were detected and then, followed by a strong 3+ quake, in an unusual location, caused us to resume the speculations.
      Thanks again. 🙂

  31. I am not liking the tremor signals that I am now seeing on SIL stations around Katla. They are increasing fast at current time. They are too big to be from the ML2.8 earthquake in Húsafell, so I know it is not that earthquake (at least I think so). Even if it was detected far and wide on stations around south Iceland.

      1. Jón:
        These quakes at Húsafell seem to be very strong. Wouldn’t they show in the graphs?

      2. They are mostly in ML1.0 to ML2.0 range. The strongest one was with the size ML2.8. That one did appear on my geophone clearly (Hekla, but not clearly on my Hvammstangi geophone).

        But they are not that strong that they should appear on SIL seismometers close to Katla volcano.

  33. It’s just showing high and mid-frequency tremor, which can be attributed to tectonic seismicity or even weather. Since it appears to be very isolated spikes, I would expect it to be simply rock (or even ice) fracturing. When you get low-frequency (red) signal, then things are slightly more interesting (and even then they don’t mean an enormous amount on their own).

    1. James:
      You will be surprised with Jón’s ability to “see” through these graphs…

      1. He does appear to be able to ‘see’ more from them than the people who own and run the seismographs (i.e. University of Iceland and related institutions)…

        If there are other sources of data that I am not seeing then so be it. However, the HVO tremor trace shows nothing but a relatively steady tremor level save for isolated, single high/mid-frequency events, apparently with no low-frequency component, which can almost certainly be attributed to brittle fracture. From the information I have, that’s the only conclusion that it’s going to be reasonable to come to.

      2. Jón is very cautious with respect to predictions and yet bold enough to go beyond where most scientists feel comfortable to go. That’s why we are here.
        If he says something weird is taking place, it most likely is, for sure.
        But that doesn’t mean he will be jumping too fast to conclusions, for he knows better than us all how unpredictable nature can be.
        The purpose of this blog is about “reading through” the lines from what IMO has to show. Nothing official, only sheer, well based, speculation and mature contemplation of Mother Nature’s deeds.

      3. Oh I’m not talking about IMO’s official statements, rather what goes on inside the relevant department at the university. Believe me there is plenty of speculation and discussion there, but even during the events leading up to (and during) Eyjafjallajokull 2010 they were very reserved. Not because of the risk of panicking people or being proven wrong – this was all internal – but just from experience.

        No disrespect meant to Jon, but I feel that a lot of the time he is rather biased towards the potential for an eruption. Talking to people for whom this is their profession and being on the same career path myself, a lot of what I see here does not tally with the data and how it is generally understood.

      4. Renato, my sentiments exactly. You saved me some typing 🙂

        Being in a scientific and university milieu and culture with its intellectual intimacy with these events commands an entirely different response to these events as opposed to the relaxed freedom here. However, when the 2 meet, its only grist for the mill that has plenty of benefits.

      5. James Ashworth: Oh I’m not talking about IMO’s official statements, rather what goes on inside the relevant department at the university. Believe me there is plenty of speculation and discussion there

        There is a strong tradition of Elitism in the UK. It’s a bit unfair to criticize overly rational people such as Jon for lacking objectivity.

      6. Jon owns & runs his own seismometers, so he has access to high-resolution seismic signals.

    2. This is an earthquake. Ice-quakes have different pattern then normal earthquakes.

      The spike suggests that it was an low period earthquake. But I don’t think it is going to appear on the automatic earthquake list on Icelandic Met Office web page.

      1. But the HVO trace shows no defined low-period anomalies?

        There was one movement on your helicorder which appeared different (sometime after 1am) but it is hard to tell without a close-up view. Is this the one you mean?

        As I was saying before, a single low-period event means very little and could equally be attributed to fluid or gas flow within a geothermal system.

      3. The guys within the university don’t consider the middle band to be low-frequency, really. Rather they were separating this stuff into low, mid and high frequency, as per the bands. They seemed to generally only consider the lowest band to be ‘true low-frequency’ movements associated with fluid movement.

  34. Been following this blog since Eyjafjalljökull last year, and my interest in volcanoes and geology in general has gone sky high. Wish I could read all that data, the tremor patterns and whatever. But I’m a total noob. It says nothing to me.
    Is there any website who could teach me how to interpret these tremor/quakes/whatever charts?
    Damn, if I knew it would be this interesting, I’d have chosen different classes in school 😛

  35. James:
    I understand and agree with your reasoning.
    And then again, if we could only be “there” – “inside the relevant department at the university” – we wouldn’t be loosing our times being here.
    We are this stubborn kind of people who would like to get in the discussion. Since we can’t, we are here, trying to acquire some experience from what we can get.
    Therefore all kind of experimented feedback is most welcome. 🙂

  36. I dont know if anyone has access to the GPS data for SOHO station and the other points around Katla other than the composite graph here?

    There appears to have been substantial inflation over the last year or so, but as it is a composite it is not easy to see if the rate of increase has elevated sharply in recent times.
    http://hraun.vedur.is/ja/englishweb/gps/cts/emyrfr2004.html

    I am also still fascinated by what might be causing the tremor patterns around Askja at the moment, which appear a little more lively in the last few days, after having settled somewhat – but still much more agitated than pre-grimsvotn eruption. Appears to affect all tremor frequencies, although the 0.5-1.0Hz band is less affected than the other two. I am guessing it may be a hydrothermal area, (but its not around a glacier) – but on the basis of my past observations over the last year or so, hydrothermals dont usually affect the 1-2hz range like this. Does anyone have any ideas what might cause such patterns?

    1. Having looked at all of the GPS data individually fairly recently, there has been a general inflating trend (when separated from the seasonal trends due to snowfall, etc) over the past few years (since 2004 at least). I don’t really see much of a rate increase, if any, in the past year or so.

      Also note that a lot of those stations will have been affected by Eyjafjallajokull as well.

      Certainly inflation continues, but doesn’t seem to be any more than normal. Looking at it on a day-to-day basis over the next few days may prove interesting if something is going on, though.

      1. On SOHO there is a noticeable jump at the beginning of 2011 on the vertical component, in comparison to previous years.

      2. It’s very strange. It’s very abrupt and I’d have bought you have been signs of it on the other components if it were ground deformation. I’m not entirely sure what’s going on there, although it’s interesting to note that it appears to have happened before…

    1. Did Katla give us a year without summer too, as well as Laki?
      The focusing of the quakes is very interesting. I look with interest what feedback you get.

    1. If that’s the explanation, then the SIL system is “losing” many quakes, as the graph does not contain the same behavior.

      1. To tell the truth I was only referring to the last few spikes (but not just any spike, I mean the tallest ones). They do appear to be coincident with earthquakes occurred under Katla.

    1. Earthquake table Date Time Latitude Longitude Depth Magnitude Quality Location
      Saturday
      18.06.2011 09:04:52 64.596 -20.570 9.9 km 1.8 99.0 18.3 km SE of Húsafell
      Saturday
      18.06.2011 08:50:20 64.599 -20.560 9.3 km 1.6 90.01 18.5 km SE of Húsafell
      Saturday
      18.06.2011 08:23:03 64.602 -20.569 8.0 km 1.5 90.01 17.9 km SE of Húsafell
      Saturday
      18.06.2011 08:22:20 64.583 -20.645 4.5 km 1.9 90.01 16.7 km SE of Húsafell
      Saturday
      18.06.2011 08:21:47 64.598 -20.566 6.6 km 2.2 99.0 18.3 km SE of Húsafell
      Saturday
      18.06.2011 08:20:32 64.600 -20.581 8.3 km 2.0 99.0 17.6 km SE of Húsafell
      Saturday
      18.06.2011 08:18:36 64.598 -20.582 9.7 km 3.2 99.0 17.7 km SE of Húsafell
      Saturday
      18.06.2011 08:15:18 64.601 -20.563 13.9 km 1.4 99.0 18.2 km SE of Húsafell
      Saturday
      18.06.2011 08:13:23 64.597 -20.577 5.0 km 2.7 99.0 18.0 km SE of Húsafell
      Saturday
      18.06.2011 08:13:16 64.593 -20.566 7.6 km 1.9 90.01 18.7 km SE of Húsafell

  41. @GeoLoco & Thomas Please join me in the “Dumb but learning rapidly corner”. Thomas here are some very useful notes on reading seismic graphs.
    http://qvsdata.wordpress.com/learning-links/understanding-seismograms-and-earthquakes/understanding-seismos-liss-helis/
    It was passed to me from Erik Klemetti’s Blog. That is also a place where you can learn from those who Know!
    http://bigthink.com/ideas/38859

    It is my experience as an ageing scientist that there is a very important place for “Gut feelings” . “Gut feelings” are usually the stimuli felt when the body or mind is reacting at the sub concious level. Everyone now knows of “reading body language” but before the early behaviouralists did their experiments and triggered more research nobody understood why, for example, they took an instant dislike to someone. That feeling was termed “Gut feeling” to explain the irrational.
    Without “Gut feelings” and the questions they trigger, science would not advance. Many famous scientists followed their Guts rather than the accepted institutional views. (Darwin)
    I am fascinated by Jon’s Native knowledge and I am really enjoying the discussions here and elsewhere between people who are passionate about their science.
    Best wishes and thanks to you all. Sorry if I am rabbiting on…. age does strange things to a previously rational Human being!

  42. Has there been any news about this swarm in Icelandic media yet? They are usually pretty fast when it comes to events like this.

    1. The location fits spot on as the volcano is said to be in the SW part of Langjökull. If it weren´t magmatic EQ´s i think the coincidence would be a big one.

      And at the samt time it hasn´t erupted since over 3000 years BC.

      Worth keeping an eye on in the future as it doesn´t seem to be completely extinct. And early records show a 13km3 basaltic lava flow.

      More info on GVP:
      http://www.volcano.si.edu/world/volcano.cfm?vnum=1701-07=

      2. Yes. There are something like 140 active or sleeping (dormant) volcanoes in Iceland, that are not extinct. The Wikipedia list ( http://en.wikipedia.org/wiki/List_of_volcanoes_in_Iceland ) contains only 40-50 of them.

        Prestahnukur is still active although it has not erupted for a long time. There are hot srpings in the area, and the base of the volcano is warm (see more e.g. at http://volcano.si.edu/world/volcano.cfm?vnum=1701-07= and http://en.wikipedia.org/wiki/Prestahnúkur ).

  45. Jarðskjálftahrina in Geitland glacier

    News Local 18thJune2011 10:09

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    Seismic eruption occurred in southern Langjökull. Photo / Vilhelm Gunnarsson.

    Jarðskjálftahrina became Geitland glacier in southern Langjökull at about eight this morning and went on for about 15 minutes.The largest earthquakes were over three levels and found, among other things Húsafell.

    One earthquake was then out at 9 and was much smaller.Since then everything has been calm since the area, as stated in the notice of service.

  46. @Diana: Am not a volcanologist, but specialized in rockfall and landslide hazards (governmental job in an alpine country). Agree to You a 100% about the gut thing. We have to show the politics models and numbers to convince them, but in fact I still trust the results of an analyze by experienced and “intelligent” field-guys more than any computers… Of course can’t say that to loud in front of most of my political superiors…

  47. Don’t forget that subtle 2.2 earthquake this night just 10km northwest of Hekla, at Burfell.
    Probbaly it was just tectonic, but its the largest earthquake close to Hekla in recent years. And someone also said that there was a spike on the strain in Hekla strainmeter.

    So, Hekla and Katla compete to see who erupts first!

  48. Just found you guys, fascinating information. I’m just interested in World events.

    2. Thanks Jon, appreciate all the info! First place I come to when the tremors appear on IMO.

  50. Just a short note to non-professional visitors: Tremors is not the same as earthquakes. An earthquake is a transient event, a burst of vibration. The vibration of a typical earthquake lasts seconds to tens of seconds. Tremors are vibrations that last much longer (minutes to days) and where the amplitude is not transient but stays roughly unchanged.

    Here’s one nice reference picture on the differences: http://en.wikipedia.org/wiki/File:Four-types-seismograms.gif

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