Small glacier flood from Mýrdalsjökull glacier (Katla volcano)

During the night (and when I had unstable power) there was a small glacier flood from Mýrdalsjökull volcano. Some minor harmonic tremor change was detected following this glacier flood. This even was small one, many times smaller then what did happen on the 8 to 9 July 2011. Due to security concerns the Civil Emergency Authority did close the main road in Iceland for this area. Since they never know how big the flood can actually be. The main road was closed for about one hour. This glacier flood was detected around midnight 20 to 21 July 2011.

This flood is actually so small it is hard to see it on the harmonic tremor plot from the SIL stations around Katla volcano.

Tremor plot from 07:50 UTC this morning. It is hard to see the harmonic tremor from this minor glacier flood. Copyright of this image belongs to Icelandic Met Office.

Tremor plot from 07:50 UTC this morning. It is hard to see the harmonic tremor from this minor glacier flood. Copyright of this image belongs to Icelandic Met Office.

Tremor plot from 07:50 UTC this morning. It is hard to see the harmonic tremor from this minor glacier flood. Copyright of this image belongs to Icelandic Met Office.

What happens next is impossible to know for now. But it seems that activity continues to be high in Katla volcano. All that can be done is to wait and see what happens. But I am going to continue to monitor the changes in Katla volcano as best that I can do until I finish my summer job (29. July).

Icelandic News about this.

Aukin leiðni í Múlakvísl og órói í Mýrdalsjökli (Ví, Icelandic)
Náið fylgst með Mýrdalsjökli (, Icelandic)
Hringvegurinn opinn á ný (Rú, Icelandic)
Breytingar í Múlakvísl (Rú, Icelandic)

425 Replies to “Small glacier flood from Mýrdalsjökull glacier (Katla volcano)”

  1. Hekla, VEI3 in the next weeks (a surprise)
    Katla, VEI5, in October (flooding will be the impressive part)
    Bardarbunga late 2012 to 2014, fissures in SW, several eruptions, VEI5 in total
    Askja, sometime by 2018

    1. I hope you are wrong. Your saying it could be a super volcano eruption, don’t need to scare people like that, I would hope no more than VEI 6 and would prefer something smaller. Think of the people living in iceland.

      Sorry for the rant, your VEI 7/8 scared me lol.

    2. Tempus23: Since the eruptive history of Katla indicates a fair few 4s, and the occasional 5, you’ve got a *serious* job of convincing to do to argue it might produce a 7 or 8… or alternatively, you could just look *extremely* foolish, and alarmist.


    3. Your “prediction” for 7/8 is foolish, or you have completely misunderstood the VEI scale!

      Katla’s caldera has an area of about approx. 100 km2. If Katla had a single caldera forming event in the past, it must have been a hefty VEI6 only, not a VEI7 yet (compared to other known similar event in the history). So, from that point of view too, your prediction is totally off the scale.

      1. Along Jacks line of thinking, consider Katla to be the top of a pipe.

        A pipe is a cylindrical structure, the volume of a section of a cylinder is V = πr²h

        From above “Katla’s caldera has an area of about approx. 100 km²”

        VEI is a measure of total eruptive volume… VEI-5 is greater than 1 km³, so this Katla “pipe” would have to evacuate a section of that pipe by one tenth of a km, or 10 meters.

        VEI-6 – 100 meters.

        VEI-7 – 1000 meters

        VEI-8 – 10 km.

        Now… go take a good look at Katla and the Mýrdalsjökull icecap on Google Earth or Nasa Worldwind, or your program of choice.

        Do you see any scaring of the terrain that looks like it could accommodate the volumes mentioned in this post?

        Just from eyeballing it… I’m gonna have to stick with Jack’s ≈ VEI-6 estimation. That’s the one that passed the “sniff test.” (i.e. uses sound logic)

      2. Bardarbunga is the only Icelandic volcanic system with demonstrated capability for a nearly VEI7 eruption, but only once (actually solid VEI6 with 30 km3 of products, about 8500 years ago). So, not even a real VEI7.

        Katla has demonstrated its ability for a solid VEI6 eruption, but only once (year 934 Eldgja eruption, 20 km3 of products).

        So there is not a single volcanic system in Iceland with demonstrated ability for a VEI7 eruption.

      1. Yeah… Katla and a VEI 7-8? Then what would yellowstone be? a VEI10?

        Thats damn folish even to linger at that scale and Jack @ Finland pointed it out to.

    4. Actually, VEI7/8 would mean end-of-life for Iceland and parts of the entire northern hemisphere! Remember, Pinatubo was VEI6, and VEI8 is 100-times bigger & stronger than that.

      This guy is just another one of those doomsday-2012 mongerers… Or even worse, a fear-loving journalist.

      1. Isn’t it true that there never has been any VEI7 eruptions in Iceland and there never will be (within our lifetime anyway)?

        2012 fans should maybe focus on some other location on earth for a doomamine fix. 🙂

      2. If there ever was, it would have been a flood basalt event. A VEI – 7 would have been about 5 times larger than Laki and Eldgjá combined.

      3. Please remember that for a certain VEI classification there are more requirements then ejecta volume, such as plume height. In case of a flood basalt, there would be little to no ash emission, so a potential ash plume would not reach far.
        This is one of the weakness’ of the VEI system.

      4. Its actually a major weakness.

        Non-explosive effusive events get a rating based on how much comes out of the hole. No rating as to how fast is comes out is made. (for an explosive measure, one would think that would be important)

      5. No, Iceland has not yet had any known VEI7 events.

        However, Laki (1783), Bardarbunga (1477) and Katla (Eldgja, 934) eruptions were all VEI6 events.

        However, based on laws of physics, a VEI7 event can not be ruled out in Iceland. Yet, no indicators give support to a scenario, that such an event is possible/probable in Iceland in the near geological future (say, before the next ice age).

      6. To the VEI6

        I think we have to point out, that those Eruptions happened over several months. Laki lasted for about 8 months and Eldgja probably to.

        I also think that we have to look at the differences from an explosive VEI6 Eruption like Pinatubo and an effusive Eruption like Laki/Eldgja. One releases a huge amount of Material almost instantly while the other releases a given amount over a relatively long period of time.

      7. The strongest explosive eruptions in Iceland were not Laki. That was only mostly lava.

        The biggest eruptions in Iceland, of ash, were Oraefajokull in 1362, Bardarbunga in 1477, and Akasja in 1875. Bardarbunga released huge amounts of both ash and lava. Hekla also very powerful in 1104, and Katla in 1755. But Oraefajokull and Askja were the strongest explosions in a short time.

        Some data point out to Oraefajokull being a VEI6 eruption in 1362 and the biggest in Iceland. Its difficult to tell which was the strongest in VEI scale.

  2. Here is my bet, but specific dates:

    Hekla, 3 August 2011, VEI3 for 10 days, first explosive, then lava
    Katla, 17 October 2011, lasting for a whole month (28 days), explosive VEI5 from caldera, and a minor fissure eruption from the flanks later.

      1. It his prediction, leave him be….Unless you can say for sure when and how big it will erupt, don’t tell people there wrong…it’s silly considering it hasn’t erupted left.

    1. Santorini has been going quite long already, albeit only a smallish eruption.

  3. I reckon Hekla will classify as VEI 4 this next time it erupts, but only just.

    I reckon Katla will be a strong VEI 4 or will reach to be a VEI 5!

    Does anyone know if Katla has erupted in it’s caldera and had a fissure eruption at the same time, like Grimsvotn did with Laki?

    1. The Eldgja eruption was the biggest (not counting a possible caldera forming event in the past), but I do not know whether the central volcano Katla erupted at that time.

  4. By request… I guess.

    1995 to 2010 earthquakes under Mýrdalsjökull.

    4D plot, color denotes quake magnitude. Do note that part of the quakes for the Eyjafjallajökull eruption appear in western edge of plot. The general location of Goðabunga is provided for a reference.

    View North

    View East

    I’m not sure if the blue cluster is the group that I note in the next post.

    (see next post)

  5. (continued)

    Perspective View of the same data.

    Alternate view point, a few degrees to one side.

    The “interesting cluster” may or may not be the same feature that Jón was discussing in the last thread.

    As for the “sheet structure?” remember that a lot of Iceland is made up of what is structurally similar to overturned bookshelves. This is from the expansion of the MAR and occurs as the different fault blocks lay over (half graben) as the crust forms and moves away from the spreading center. This is the basic underlying structure of Iceland, and may affect the orientation of dikes as magma moves to the surface. Alternately, it could also be a manifestation of structural weaknesses as the area accommodates tectonic stress. Since it’s under a volcano… it could be either scenario (or both)

    These are amateur plots of seismic events as recorded at

    Annotations are my own and do not constitute any endorcement by any geological organizatrion. I am not a geologist, I just plot stuff.

    1. You can also see a trend of earthquakes moving from larger depth beneath Katla, to shallower depth under Godabunga. Magma pushing up I guess..?


  6. My bet would be Katla on Saturday… I’m not home this week-end, it would be perfect!

  7. ESK and GOD are showing some nice tremorspikes at the moment.

    And thank you Lurking for those excellent plots. I wanted to see if there was any visible structure and to some degree it seems to be.

  8. Lurking thanks for the plots they are very interesting.
    If Katla erupts I think VE 3-4 with some fissuring.
    I think Hekla will be a VE 3-4 also a couple weeks after after Katla starts.
    After those I thin k Iceland will take a break for a year or so before resuming activity.

  9. Katla goes off September 5th and keeps going until December 3rd, VEI5.

  10. The plots above from lurking lacks time factor and includs the last Hekla eruption with its corresponding activety at katla etc. I would like time as a dimension to understand if its normal or somthing new.

    1. Actually… the data set doesn’t go as far as Hekla… part of Eyjafjallajökull, yes.

      And as noted, there was no time factor in it. That is remedied below.

  11. Many thanks Lurking. These Plots of yours are brilliant and produce yet more findings to discuss. You may not be a professional geologist but that doesn’t matter as it is the hard work of collecting the data and entering it into your programs that achieves something, almost tangeable that we can grasp. I for one greatly appreciate your time and work.
    I now wait for someone to interpret.
    As I see it there is what looks like a broad magma chamber at some 5 – 15 km depth. I am presuming this is the caldera. This chamber must be under pressure from the icecap and it is only a matter of time before some pressure is released by either ice melt or more forceful pressure from the MAR below . I think I can see how the magma could erupt along a line of fissures.
    Jon was right in identifying an “interesting cluster”. I shall watch that closely too!

  12. Heh… you have to be careful of cantankerous old ladies. Australia’s PM Julia Gillard found this out when she was waylaid by an elderly lady who wouldn’t buy the B/S.

    And we have Katla.

    As many of you know, Eyjafjallajökull erupted last year. What most of us (and me, until a few minutes ago) didn’t know, was that Katla was being sneaky. Hidden in that flurry of quake activity next door, Katla had a recharge pulse. Well, I can’t say it for certain, since it’s not my specialty, but that’s what it looks like to me.

    I took that data set that I was plotting earlier, and brought the area filter in a bit in order to eliminate the cacophony of quakes next door. This was in response to Sander’s 05:45 question about the trend.

    You see, there is no trend in those plots. Just lineaments.

    Those plots are just every event in the list thrown into a 4D plot. (no, nothing fancy, just lat-lon-depth-magnitude… magnitude being the color).

    Not wanting to be a smacktard, I decided to make a plot that would allow Sander (and the rest of us) to see if there was a trend.

    On the full 1995 to 2010 plot, I noticed an interesting diagonal ramp in the dots. I zoomed into that area, and low and behold… crossing the detection shadow of the Eyjafjallajökull noise (saturated seismos don’t pick up everything), was a trend of quakes.

    It looks like Katla caught a pulse of something that rose up from the depths… while we were admiring the spectacle next door.

    What’s that famous line? “Hello Nurse!

    1. For anyone wishing to verify the boundaries of the data set, the bounding box is listed on the plot.

      1. Its a pity that the plot does not include jun – july this year but guess that it would be like the period right after the Eyjafjallajökull eruption. Indicating that the activity at katla is higher after that eruption or together with that eruption for both the shallow and deep earthquakes.

      2. That may come tomorrow. I have 2010 to last weeks data in a separate file. (95 to 2010 is a bit large at over 260,000 entries for all of Iceland)

        I plan on using the same bounding box and exporting this set and merging with the most recent data.

        But… work takes priority.

    2. Additionally, this was not meant as a disparaging remark against the elderly… they just have a knack for seeing through the B/S, and they usually have a trick or two up their sleeve that no one even expects. That’s why they survive so long to become elderly.

      1. I hoped you were not alluding to me Lurking …… However like Katla, I have often surprised people with my activities and I keep all kinds of surprises in my lavender scented closets!! 🙂
        Likewise one should also treat gentlemen with access to vast amounts of data with respect, as it is amazing how figures and graphs can be handled to get a desired end result! 🙂
        Once again your talents have left me in awe. Thank you for your time it’s really appreciated.

        I am fascinated with that last plot. There certainly is a definite trend there , as you say broken by the eruption shadow.
        The trend is at an angle? Is this a normal direction for magma intrusion in this area because of the underlying structure you described in an earlier post?

      2. That plot is depth vs time.

        Essentially, if there was a quake somewhere in that latitude and longitude box, it got a dot noting how deep it was and what the time was in relation to all the other dots. The vertical axis is the depth, horizontal axis is the time coordinate. The color is the magnitude.

        As you can see, these weren’t very large quakes. They just slipped past us.

        The tricky part is going to be figuring out where in the lat and long box that activity was at. A focused single area or a a broad whole volcano trend.

        But… I have to do a fews long distance service calls first.

      3. To Diana above and Sander below:

        As I see it, Lurking is indicatng some upward movement of the earthquakes with time in the eliptical area. But, remember, the horizontal axis is *time* … so there is nothing to show earthquakes going at any angle or directionality other than up or down, since the vertical axis is *depth*.

        Perhaps it is more clear if you visualize a circular or rectangular area in the lower left of the elipse. That shows a cluster of earthquakes at some depth. Then if you visualize an area in the top right of the elipse, that also indicates a cluster of earthquakes, but at some hours later and at a much lower depth. So, taken together, a cluster of earth quakes occured early morning hours of 1/1/10 between 7 and 14 K depth, and then about 12 hours later under the same ground-surface area (or with in the same observational vertical column) there was another cluster of earthquakes between 1 and 5 km depth.

        So the earthquakes can be interpreted as rising in a vertical cloumn over that 12 hr time period.

        That said, I’m not totally convinced about that interpretation. But it is an interesting observation.

        Lurking, if you see this and if I have misstated what your plot is showing, please correct me. 🙂 … Great data plot!

      4. Thank you for that TBVHs . I understand what you are saying now. I think! LOL! My head is hurting from all this thinking today. I think I will go look for sheep on the Katla Cam 🙂

    3. Thank you 😛 So Just a blob of earthquakes no trend upwards over time 🙂

  13. Hekla strainmeter BUR analogue is acting erroneously. Since the BUR digital is more or less calm (up to now) I assume, Hekla is not starting an eruptiuon, but the BUR analogue meter is broken.

    1. I still think Hekla is going to have a small eruption before Katla. Icelandic volcanoes like to tease us!

  14. My guess:

    – Katla VEI4/5 with fissures, September 2011 to December 2011, disrupting traveling moderately.
    – Hekla VEI3 burst in 2012.
    – Hamarinn VEI2/3 in first half of 2012.

  15. Some nice INSAR studies of Katla would be nice, then you could actually see if there was any inflation or deflation.

    my guess would be:

    strong VEI4 to weak/middle VEI5 somewhere in the next 3 Years, probably not his year because there haven’t yet been any signs, that magma is rising from a deeper source.

    I think, even if the last big eruption from Katla was a long time ago, a VEI6 or stronger is a bit exagerated. A strong VEI5 might well be possible, but we don’t know.

    The thought that the eruptions at Heymaey and Surtsey might have altered the eruption pattern/intervall at Katla seems likely to me. I recently read a study, which suggested, that the Eruptions in the years 1970-1980 at Krafla directly influenced Inflation or Deflation at Bardarbunga. So it might well be possible, that those eruptions on the Westman Islands might have sucked the magma away from Katla.

    1. Hey,

      I reckon Katla will have a weak VEI5 (about 1-1.4 cu Km) eruption, estimating from the inflation data (which I wrote in a comment on a previous thread). I also agree with the theory that the eruptions in the westman islands released pressure from Katla, and also Eyjafjallajokull.

    2. Yes, for sure, INSAR plots for Katla would be definitive and therefore great to have!

      But are the GPS data just as precise? Although, they are less visually definitive.

      Here’s the GPS data:

      Looking at the GPS, to me it is very clear that nothing dramatic is happening at Katla, as far a deformation goes.

      And I’d expect some strong and clear deformation to preceed any eruption by at least 2 to 3 weeks , if not months. Does anyone have an inkling or historic data on wherether that is true?

  16. Hekla could go due to its regularity. Every 10 year, last time 2000. Symptom from glacier indicates Katla, but katla had strong symptoms about 1999 – 2002 also. Hamarinn? When did she had her latest eruption.

    1. Well hamarinn is part of the Bardarbunga system and when you search GVP all you get is bardarbunga volcano. And that contains alot of features. Below snipped from GVP website.

      “The large central volcano of Bárdarbunga lies beneath the NW part of the Vatnajökull icecap, NW of Grímsvötn volcano, and contains a subglacial 700-m-deep caldera. Related fissure systems include the Veidivötn and Trollagigar fissures, which extend about 100 km SW to near Torfajökull volcano and 50 km NE to near Askja volcano, respectively. Voluminous fissure eruptions, including one at Thjorsarhraun, which produced the largest known Holocene lava flow on Earth with a volume of more than 21 cu km, have occurred throughout the Holocene into historical time from the Veidivötn fissure system. The last major eruption of Veidivötn, in 1477, also produced a large tephra deposit. The subglacial Loki-Fögrufjöll volcanic system located SW of Bárdarbunga volcano is also part of the Bárdarbunga volcanic system and contains two subglacial ridges extending from the largely subglacial Hamarinn central volcano; the Loki ridge trends to the NE and the Fögrufjöll ridge to the SW. Jökulhlaups (glacier-outburst floods) from eruptions at Bárdarbunga potentially affect drainages in all directions. ”

      Looking at the potential danger from Bardarbunga central volcano it seems that is a very nasty piece.

      Now there is nothing to indicate any activity which would ensue an immidiate (this decade) eruption. And if there were an eruption it would probably be Hamarinn as she is showing unrest to some degree.

      But still. A century has passed without an eruption so it will be interesting to see what the next few years has in store for us. 🙂

  17. Does anyone know if tectonic plate movement in Iceland is measured in real time? With the current pattern of earthquakes I wondered if there was higher than average plate movement across the fault line?

    1. The Tjörnes Fracture Zone is a highly active System of Transform-Faults. So it is prone for earthquake-swarms and even capable of producing quakes up to Magnitude 7.

  18. Stainmeter in Burfell, close to Hekla, showing some changes since yesterday. Is this due to weather? Or could be related to some changes under Hekla? Weather is calm currently here.

  19. And…
    Why not?
    Compare Eyfjafjalla volcano and Katla volcano, compare the VEI eruptions and the years than we are quietly.

    If this notes are like this, a big katla eruption can be prepare for the future.

    I`am not a expert on this, but Katla is very inquiet since a few years (1995),… the request in a few days, months,… years

    1. No. Katla was quite active in arround the year than Hekla had her last erruption. 1999 – 2002.

    2. What are you saying, that they both go up together. Not 2 separate volcanoes but as 1.

      I doubt it sorry. They might both erupt they have before but I do not think even for a second that they will merge.

      Sorry if I have misunderstood what you wrote.

      1. I believe the the issue was if Katla was active at the time. Not if there is a connection.

        More of a “if a volcano erupts in Iceland, and not is there to see it, does it make any noise?” sort of thing.

      2. The problem is that there is simply to little data to support a theory like that. What is it? 3-4 events where records show that they have erupted at the same time. Not statistically viable in my opinion.

      3. It’s not my theory I just misunderstood what Tempus23 was on about. And might doesn’t mean will.

  20. Following the blog as usual, but I’ve kept quiet a long time now. Times are interesting when it comes to Iceland.

    If you need help with e-book somehow, let me know.

  21. Something strange appeared on Jon’s Hekla helicorder. What was that?

      1. There’s a small rise on tremors, which could confirm the increasing winds, but not that strong.

      2. Looks like it lasted about 5 minutes. Increasing, culminating, decreasing.

        What could cause that? Either the mother of all truck approaching and driving by or maybe a steadily increasing tremor pulse which then dissipates?

        But im with you here Renato. Looks wierd..

      3. Almost looks like a shallow volcanic earthquake doesnt it? Maybe to small but the shape is a similar match.

  22. Maybe it was the bomb blast in Oslo. I would rather had an eruption here. It is so surrealistic horrible… Have a little thought on all the Norwegians today :,-(

    1. I am thinking about Norway today. My son is living there. I think they will not have been in Oslo today though.
      I feel such sorrow for the victims and their families.

      1. Jelrik:
        I did not known about the attack until you mentioned.
        Took a quick look at the news: an inexplicable act of violence and cowardice.
        All my feelings go to Norwegian people today.

    2. I just saw the news after I read your post. So sorry to hear about Oslo!!

    1. Daniel:
      Yes, this one has indeed an interesting pattern. And I think it happened too late to reflect Norwegian blast.
      On the other hand, it is too “symmetrical” to be a tornillo, and had it been a quake, it would have shown on IMO records. So, let us wait for Jón to explain it.
      There is a huge storm forming behind Katla right now. You can see its development at the webcam. Probably, we will get tricked by its interference on the helicorder’s readings.

      1. Well the norwegian blas would have to be immense to show up on Jons helicorders. Its a 1000 miles or so between them and a whole lot of ocean. 😉 Would require a small nuke to make the helicorders jump. 🙂

      2. I agree.
        I like your “Truck theory”. Something approaching and then passing by. Makes sense.

  23. 19:40:28 63.628 -19.197 3.8 km 2.1 90.01 2.9 km ESE of Goðabunga

  24. Are there any volcanologists/geologists on this blog ? Or just people interested in Icelandic volcanoes?
    I have a question: For Katla (or any volcano covered with a glacier) it would take a tremendous amount of energy just to punch through (up to 300m thick?) of ice.
    Wouldn’t the severity of the eruption be suppressed by that? Also the amount of ice water that has to be melted – that would absorb a lot of heat?
    We have no active volcanoes on our mainland, only dormant ones, (last eruptions about 5000 years ago) and none covered by ice.

    1. Thanks for the article.
      I recommend people to read it.
      It gives us a more realistic perspective to present activity.

      1. @ Jonas

        the page from earthscience is a nice summary but nothing more.

        If you want to know a bit more than the usual shortened summary, then i would recomend reading the document i’ve linked.

        my condolences go out to all norwegians, it’s a sad day. my heart goes out to those who lost beloved ones.

      2. Thank you for that link Stephan. It was a good insight into the recent history and puts present activity into perspective.
        Comparing data from this article and present data (very roughly!) The recent Jokulhaups compare favourably with past patterns.
        I do think Jon’s “Interesting Cluster” spot is now REALLY interesting as it would appear that any eruption site may not occur in the caldera!
        I do think we may have to wait some time before an eruption and Irspit may well be right with Hekla beating Katla to it… But……..
        Who Knows?
        (My definition of “Some Time” as associated with volcanoes……A time range of between between 1 Hour and 500 years (Approx.)) 🙂

    1. Jelrik – I am really hurt by the Olso bombings and shootings. I have friends in Olso and north Norway and I know they will be shocked. Norway will always have British support – we have many things that we share. I send you my support and wish you all well.

  25. Jelrik – I was stunned and saddened to hear of the Oslo bombing. I had the wonderful opportunity to visit Norway in 2006: Oslo, Bergen and Tromsø. I found it to be a breathtakingly beautiful country with amazing welcoming people. It is unfathomable that such a violent and cowardly event could take place there. My thoughts and condolences are with all Norwegians today.

  26. Just heard of the Norwegian news, I add my voice to those sending condolences to all Norwegians here and at home.

    1. I also send my condolences to all Norwegians. I can not believe this has happened.

  27. Hi All,

    Bit of a busy week by the looks of things. Have to say Diane I was just about to draw my pen (key board just does not sound right) and jump to your defence! No need after that reply lol! Ouch! However I don’t think it was naivety at all, more a positive nature and encouragement, I think a few people in the world could take a lesson or two from that.

    I would also like to say Hi to all the scientists ( mainly from earth sciences in Iceland) studying Lurkers latest master pieces! If you fancy posting INSAR Photos from a few years ago and current ones I’m sure no one will mind.

    @geoloco not wrong about the Malamutes only thing is if you are taking them and the car you get them to tow it, safes on fuel! If you fancy having a look, I’m on face book search mitch.taylor2 either on face book or google. Any one welcome just send a friend request and mention the blog.

    Umm August 14th Explosive eruption giving VEI 5/6 followed about month later by a long duration fissure eruption ending at a VEI 7. More on that later.

    Climate scientists, from studies of Eyjafjallajökull last summer are saying that it had a 100 times greater affect on the climate than expected. Mainly due to the mean ash particle size being so small. Maybe this is why Europe/UK had one of the worst winter spells on record. Nice to be back.

    Have just seen the news

    My condolences to all Norwegians. Just beyond words.

  28. The earthquake that was ML2.1 did not show up on my geophone. So it was most likely a small event.

    On the VEI scale. Many have gotten the VEI scale wrong. As it does not measure how big eruptions are. But how explosive they are.

    “The Volcanic Explosivity Index (VEI) was devised by Chris Newhall of the U.S. Geological Survey and Stephen Self at the University of Hawaiʻi in 1982 to provide a relative measure of the explosiveness of volcanic eruptions.”


    More here,

    Now, this is a fact that matters. 🙂

    1. Could it be, that the 2.1 Quake you’ve mentioned could have been a low frequency quake. I think i might have read somewhere, that it’s pretty hard to calculate the magnitude of such low frequency quakes, due to the lack of monitoring equipement that is sensitive to those low frequencies.

  29. There is still thunderstorm clouds forming since about 4 days here in South Iceland. Today I saw a big black thunder cloud in direction of Hekla and Katla, probably was that.
    But the nanostrain at Burfell, Hekla still shows erratic readings.

    Tomorrow it is going to be rainy and windy here.

    1. I believe there is a geothermal power plant there, which sometimes gets rid of cold water into the ground. Which causes small earthquakes when it comes into contact with the hot rock.

      It could also be just tectonic earthquakes 😛


  30. Well… as promised and as Jonas requested, here are the time v depth plots that merge the old with the latest for the quakes under Mýrdalsjökull.

    Plot #1 is a revisit of the original plot that got my attention, with some new annotations indicating Katla’s last suspected eruption. Interestingly, it a lot more quakes in the 2002 to 2004 time range than during the supposed eruption. This could be just out right “odd” or it could be a reflection of less detailed monitoring. (technology creep)

    I have noted the eruption next door so that you can see how it affected over all detection under Mýrdalsjökull when Eyjafjallajökull’s summit erupted. (it got really noisy really fast)

    Plot #2 is the same plot as from earlier, but with everything up until today added in.

    I’ve marked where I think that that pulse of magma/stress came in from below.

    Do note that the more recent activity has a much more vertical “stacking” to the quakes. It’s a bit more broader in time, but very similar to the “stacks” occurring during the 2002 to 2004 non eruption quakes.

    Murphy’s law states that Jon is going to make a new post and this response will come up in the old thread.

    1. Caveat… I may just be seeing things in that pulse idea.

      Humans tend to see patterns in everything.

  31. New small quake swarm at Katla — and tremor looks interesting too, at least to my unpracticed eyes.

    1. Well, how about that. The cluster gets another quake. It’s not in the plot below.

  32. And a bonus plot since I had the file open.

    Jón’s interesting cluster. Perspective View, Quakes in and around it from 1/16/2009 to present. There are a few VERY loose diagonal lineaments. The one to the west sort of points towards it… but it’s very broad and may not be anything. There is a gap between the top if that broad group and the cluster. It may very well be nothing… but I figured that I would note it.

    1. Hi Lurking – As another long time lurker (unfortunately all of the good lurking screen names seem to be taken) I just wanted to let you know how impressed I am with your plots, and how much I enjoy them! Although most of my geophysics knowledge comes from this blog, they still give me a lot to ponder. This latest one almost seems to suggest a pyramid-like formation (magma?) converging towards the surface. But as you would point out, my brain is probably just looking for patterns! Please do repost this tomorrow if Jón starts a new thread then.

    2. Thanks Lurking. This is appreciated. I still am watching Jon’s Interesting Cluster.
      Just out of curiosity I had a look on Google Earth and the Iceland Land survey to see if there was any surface sign of activity (I was looking for a cauldron or something glacially odd ) in the cluster area.
      Google Earth was not useful as there was heavy ice cover and noting obvious in the area.
      This picture (With thanks to The national Land survey of Iceland) shows roughly the area in comparison to the IMO Earthquake map.

      And this a close up.

      There is a very rounded depression. Is this caused by glaciation or…….?
      My hopeful imagination brought a volcanic vent to mind!!! ROFL!

      Thanks again to Iclelandic Land Survey
      Also to The Icelandic Met office

  33. After the first glacier flood (which destroyed the bridge), I was also trying to make up my mind what was going on, like everyone else here. 😉 And yes, dopamine was also kicking in. 🙂 Was it a minor subglacial eruption or just hydrothermal activity? Together with the overall increased earthquake activity, I also started to believe that we are heading to a real eruption later this summer.

    But I must admit that I’ve changed my mind. I don’t expect anything to happen this year. Please keep in mind that I’m no geologist so my following conclusions might be wrong:

    There is no doubt that Katla is charging for an eruption. But I think what we see is a continuous and slow filling of old conduits with magma. At some spots magma is quite close to the crust, which caused a melt of ice, hence the 2 glacier floods.
    But as someone else here already pointed out, there are not many magma related, deep earthquakes. The distribution of earthquakes at Eyjafjallajokull looked quite different and it was clearly visible that magma was pushing up.
    The recent earthquakes at Katla seem to be concentrated at 2 or 3 locations, but a lot of them seem to be random with varying position and depth. Most of them are very small and shallow quakes. This is the reason why I think that we are currently witnessing a slow filling of old (and some new) small conduits in the mountain with magma. Some quakes might also be ice quakes.

    GPS inflation also does not look very convincing. Perhaps Katla does not inflate very much, though. But if lots of new magma would be pushing up, we should see a change here? For me, it confirms my theory that we only see a small intrusion and rearrangement of magma. No indication of eruption in the next couple of weeks.

    Looking at the history of Katla, there is no real eruption cycle visible to me. It is a very actice vulcano, but the eruptions are irregular. IMHO, even the 3 eruptions following eruption of Eyjafjallajokull might not really be a pattern. Besides, the first flank eruption of Eyjafjallajokull last year (fimmvordurhals or so) was a change of parameters and might have had an unknown effect on the Katla’s conduits.

    Recent history also tells us that there have been periods of unrest at Katla, the events in 1955 were probably even more alarming and not much happened in the end.

    Summarizing, I think Katla wants to remind us that she’s still there and she just announced that she’ll give us a good show… but not this year. 😉

    Sorry for this rather “dopamine killing” post, but it is only my personal opinion. Due to the lack of instruments at the last real eruption, we don’t have any comparatitive data.

    1. We all know that Katla will erupt, the only question is when. Personally, I would prefer to see a full eruption sooner rather than later, precisely because of what Jack @ Finland just reminded us: “The longer Katla lets us wait, the greater show we’ll see…”. As the media hype loves to remind us, Katla can be a dangerous volcano, and to my mind, the longer she prepares her eruption, the more potential there is for it to be life-threatening or life-disrupting for a significant number of people.

      Having said that however, I tend to agree with Dirk Sch. that an eruption is probably not imminent. The seismic activity appears to be sporadic with many tiny earthquakes. Is it possible, as Dirk suggested, that the Fimmvörðuháls fissure eruptions might have relieved some of the pressure build up in Katla? And could the jökulhlaups under Mýrdalsjökull also have been small subglacial eruptions that would delay a complete eruption?

      I think that we are all obsessed with Katla because of the spectacular Eyjafjallajökull event, and its oft-cited connection to Katla. It is exciting to focus on one volcano (the dopamine effect) and to postulate about what might happen, and when and why, etc. Added to that of course are the mesmerizing images of the changing weather patterns and sheep crossing in front of the Katla-cam. But remember that while we were watching Katla, Grímsvötn erupted. So perhaps while we are still waiting for Katla, Helka or Hamarinn or ??fjall will erupt first. And for me, that unexpected happening is exactly why following the volcanic activity in Iceland has become so fascinating!

      I apologize in advance for my naïveté, and will end with the usual caveat: these are just the ramblings of a blog-addicted language teacher with no real knowledge of geology or volcanology.

    1. Sissel:
      Nothing to thank about.
      What happened in Norway was a deep offence to us all.
      Norwegian nation and people have always been praised as an example for the world, a shrine of the most elevated values that keep our belief in mankind.
      This has been constantly repeated by the media during the coverage of yesterday’s horrific event, which deeply wounded our human pride.
      God bless us all.

  34. I noticed a steady increase in conductivity at waterstation 413. rising to 120 microSiemens/cm. In case of rain or elevated airtemperatures you woud expect a decrease in conductivity( just melting/rain water). At station 431 (during the flood) you se a drop in conductivity due to the large amount of melting water with low conductivity.

    Water with high conductivity has been in contact with vulcanic gas (sulferdioxide or carbondioxide)

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