Posted on by Jón Frímann

Minor earthquake swarm in Öræfajökull volcano

Since early this morning there has been a minor earthquake swarm in Öræfajökull volcano. This earthquake swarm is so far just minor one, with the largest earthquake being ML2.0 at 4.3 km depth.

This earthquake swarm is most likely due to magma injection into Öræfajökull volcano. But this volcano is normally quiet and almost never has any earthquakes. But that has been changing during the past few years, but earthquake swarms have been getting more common in Öræfajökull volcano. Something that is in fact a big change from few years ago when no earthquakes where recorded from Öræfajökull volcano.

This increased activity in Öræfajökull volcano seems to be happening at the same time as there is increased activity in Esjufjöll volcano. The two volcanoes are not connected. But this might suggest a more inflow of magma under the general area. But that is just a speculation, based on rather limited amount of data.


Öræfajökull volcano is located to the south end of Vatnajökull glacier. Copyright of this image belongs to Icelandic Met Office.

The earthquakes in Öræfajökull volcano have been taking place in the main crater of the volcano. But it is important to know that currently there is nothing to suggest that a eruption is imminent in Öræfajökull volcano or in Esjufjöll volcano.

Interesting reading material on Öræfajökull volcano

The 1362 AD Öræfajökull eruption, Iceland: Petrology and geochemistry of large-volume homogeneous rhyolite (pdf)

31 Replies to “Minor earthquake swarm in Öræfajökull volcano”

  1. What’s so fascinating about Iceland is that there are so many volcanoes of such varied types. Some erupt frequently with moderate to medium intensity, yet have the power to occasionally surprise such as the large VEI 4 in Grímsvötn this may. Some erupt very infrequently, but when they do it’s usually towards the very large end of the scale. Some require decades of build-up such as Lady E while some erupt with little warning such as Hekla. But at all times there is activity going on, activity that teases and intrigues, activity that most of the time means nothing in the way of imminent volcanic eruptions, yet are part of the total picture, the Turner canvas that is Iceland if you will. Aaah…!

  2. This year we travel for the fifth time around Iceland. We started two days after the glacierflood in the south. We stayed near Eyjafjalla, going two days into Thorsmörk. Then we must go around Hekla, because the road in the south was closed. Some days we make trekkingtours at Skaftafell, then going to Kverkfjöll with a walk on the glacier and looking to Badarbunga. Next stop was Askja, then on the road around Herdubreid, Myvatn with Krafla and at the end of our trip some looks at Hekla.
    So, we saw a lot of volcanoes!
    And nothing happens!
    But I follow this blog since some days before we go to Iceland, because I thought that if something would happen all of you would know first and will try to explain.
    Thanks Jon and all the others! (And sorry for my English, I’m out of training!)

  3. The article linked by Jon is very interesting. The writers even give an estimate for the magma chamber size (>20 km^3) and filling time (a few hundred years). So, it is not entirely an unexpected event that the volcano seems to be waking up…

  4. Can someone please clarify the current discussion of inter-dependancy or commonalities between Iceland volcanoes and also between tectonic activity and volcanic activity? Is the discussion limited to only volcanic “eruptions/events” or is there room for discussion of other possible cause/effects in more general terms?
    The reason for my question, is here is California, the topic of “stress shadowing” and “stress transfer” is a much researched field at the moment, and by my account, still quite poorly understood. After the Loma Prieta earthquake in 1989, earthquake activity over a much wider area than previously thought has been markedly reduced. Prior to Loma Prieta, the S.F. Bay region was crackling with 5’s and 6’s for almost 2 decades beforehand….and now, only one 5.6 shock has occured in the area (~ 150 mile radius). However, farther to the south, damaging quakes did hit San Simeon and then eventually Parkfield.
    While the research focus is related mostly to earthquakes, and how one earthquake can either “load” extra stress into a nearby system or relieve it, other references have been made to volcanic activity (not neccesarily eruptions, per se) as “triggered” by far-away earthquakes and is intriguing. For instance, when the Denali/Alaska earthquake struck, minor volcanic-related actvity was noted at Yellowstone and Long Valley amongst other places (http://www.aeic.alaska.edu/Denali_Fault_2002).
    So, based on this observation alone, it appears that far-away earthquakes may “trigger” seismic events and alter volcanic behaviors that are not “directly” connected, but rather “indirectly influenced” (my term).
    Is it not reasonable therefore to reserve judgement on whether earthquake (tectonic) activity in Iceland can “influence” volcanic behavior elswhere on the island, even though the various volcanoes may not share the same “plum” or magma source? I would think if nothing else, crustal and mantel “vibrations” from an earthquake would be akin to shaking up a soda bottle then opening the cap (Woosh!).
    Thanks for any inputs.

  6. A small add to previous post:
    I forgot to mention that while volcano-to-volcano interplay may not be directly occurring (such as an eruption at one volcano triggering another eruption elswhere), this does not rule out that multiple volcanoes are being inlfuenced by a totally separate mechanism…i.e such as an increase/alteration in mantel/sub/mantel convection currents, or possibly something even more esoteric like accelerating changes in the planetary magnetic field, or that the solid inner core may be rotating at different velocities over time relative to the semi-molten outer core? (if so, then one can envision a sort of “cooking mixer beater” turning deep in the earth’s inetrior with the dough-like upper mantel getting “mixed” (which would be more randomized and harder to observe statistically).
    Anyway, so much to learn, and only one lifetime.

  7. Largest tephra since the ice age, then VE 1. Perhaps a VE1-2 is on the cards?
    This uplift in Iceland’s activity, could safely pass of as a few glacial floods and VE1’s and 2’s.
    What do people think?

    Henrik. JMW turner. Aaaah.
    You have very good taste.

  9. There is something going on under Herðubreið. There have been more than a dozen localised quakes at depth (~5 – 10 km) and there is an increase in tremor (green line) at nearby stations such as Askja that do not seem to be weather related. Is there an ongoing intrusion? Jón, could you take a look and tell us what you think please!

    Thank you!

    1. This is not volcano related. Appears just to be a noise from what I can gather at this moment.

      In regards to the earthquakes, it is hard to know if they are tectonic or because of dike intrusion. But this area is not in a central volcano. So my best guess is that this is due to tectonic movements, rather then magma movements in this area.

      1. Thanks Jón! I assume that Herðubreið is akin to Lady E in not having a magma chamber but rather a series of sills so IF (big if) this is an intrusion, it would have to be sustained over a long period of time (tens of years?), filling each sill successively until there is no more room, something then gives, and we have a Fimvörðuhalsi-style eruption somewhere in the general Herðubreið area?

      2. This area get’s its eruptions from Askja volcano from what I can gather. But this area is inside Askja volcano fissure swarm that extends in this direction.

  10. I guess Heidarbaer station is close to Herðubreið, yes? This station shows a sharp increase in tremor, about 2x, early this morning and sustained at that level since.

      1. The rise seems also to be on stations in vestmannayjar area, Asmuli and Mid-mork.

        Heidarbaer is located north of Hangill

      3. Magma-related tremors should show spikes on the 0.5-1.0 Hz band. As there is not any change in this frequency band for Askja station then I would say it’s not magma related. You can go back a few blog posts to see the images Jón put up showing examples of harmonic tremors. It’s very clear to see the difference between noise, earthquakes, and harmonic tremors.

  11. Yes, but this is unusual in that it is sustained more or less under the mountain. Previously, activity has been much more dispersed; near Herðubreiðalíndír to the south or southeast towards Askja. Also, the depth is much more consistent and “not all over the place”. I’m not saying anything like “an eruption is imminent”, only that this time, there definitely is something going on underneath Herðubreið, most likely an intrusion in my amateur opinion. 😉
    (I’ve been watching the IMO site daily for almost two years now)

    1. No, these kind of earthquake swarms have been regular over the past years. The fact that something is going on in the Herdubreid-Askja area has been clear for some time, what exactly is not clear.

      1. Are we into a game of yes – no – yes – no? I’m telling you that even if the swarms have been going on for a couple of years, they have been far more widely dispersed in all three axes – x, y and z – i.e. over a much larger area and varying a lot in depth and rarely more than three or four in the same xy location. This time, there are no less than fourteen with almost zero xy dispersion, unusually the dispersion in depth is greater even if that is close (within 5 km), therefore, this swarm is different from previous ones and thus something new.

      2. I concur with Henrik about this activity. And I see spikes in the red band too.
        What it may mean, I have no idea, but it is slightly different from what we’ve seen before.
        No yes or no, only… I don’t know. 🙂

  12. The world is magnetic above all else.
    Tectonics are ruled by that. So is magma.

    1. Most discount this as a weak energy. I believe there is more to it than we are capable of understanding yet.

      1. A weak energy over a long time is a lot.
        Iceland is a complex description of an outpouring of concentrated magnetic energy, like those flairs on the sun.
        OJ could be a flair or not.

      2. Thermal energy levels inside Earth are far more than magnetic energies. So thermal energy rules.

        Another point against your opinion: When magma solidifies, it retains the direction of the global magnetic field, as there no other magnetic field to rule it.

  13. @Jón, Carl, Lurking, Irpsit, Henrik et al:
    I would like to congratulate you all for the high level of discussion led by you people here in this blog.
    What I see here is the healthiest kind of speculation based, not merely on the observation of figures, but also on the knowledge in areas other than volcanic, mastered by readers and lurkers over here.
    It has been already said that this is the kind of debate that might be taking place behind the scenes of IMO offices and other such “official” scientific forums. Of course they wouldn’t dare to expose such bold thoughts on open air like what we witness here, but nothing that is said here is done without some kind of scientific basis to support, such as Lurking’s plots and Carl’s equations.
    This type of discussion without any kind of official commitment can lead somewhere. Where, I do not know. But thank you for allowing me to participate, albeit my contribution is narrowed by my lack of knowledge.

    1. Thank you Renato! As you say,”brain-storming” or “bull-sessions” can be very productive especially if there is “cross-fertilisation” from other disciplines. I well remember the discussions about Professor Foulger’s energy boluses as an explanation model and how the pattern of eqs over Iceland reminded Professor Peter of his own work; calcium propagation through a cell. In the end, it did not lead to any new explanations for Icelandic vulcanism, but it did lead to a broader and deeper understanding of science and was a lot of fun too!

  15. This is just a thought, triggered by “Cap Bondo’s” comments. The movements of the magnetic North Pole have been unusually large in recent years. There have been suggestions that a “flip over” between the North and South magnetic poles may be happening, something that has occurred in the past. Is there any data to indicate a correlation between movement of the magnetic poles and levels of volcanic/earthquake activity when this happens?

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