Countdown to Hekla


It has been a long time since I wrote about Hekla. But, I guess nobody is surprised at what I am about to write.

Everyone with a genuine interest in volcanoes have their favorite volcano. As many in here know Hekla is my favorite volcano to bang my head against. Few volcanoes are as intricate as Hekla, and few have such a short run up before an eruption as Hekla. Normal run up time to an eruption is between 30 – 80 minutes from the first sign.

This time around has been different. But let us first recapitulate what has happened since the last eruption. For those who are curious about how Hekla works I would like to recommend my own post about her innards:


In 2004 Hekla had received as much new magma as was discharged during the 2000 eruption and sometime during late 2008 to early 2009 that figure had doubled. After that the inflation stagnated and no real uplift was measured at the GPS-stations with the exception of what was most likely magma moving between the different magma chambers.

During the summer of 2011 earthquakes was registered and a public safety alert was issued stating that Hekla was close to erupting. From then on Hekla has had earthquakes ranging from miniscule to 2M+ without erupting. For those who are not familiar with Hekla one should notice that she normally is aseismic, or in other words, that she does not have a lot of earthquakes.

From 2010 and onwards Hekla started to show a new feature that I dubbed “transients”. The transients are sudden rapid drops in the strain measured at the borehole strainmeters. These transients have only been seen before as Hekla erupted. They had before 2010 never been seen without an eruption occurring. A transient is in short happening as the mountain strains to open up.


On the 13th of March and onwards Hekla had a swarm of earthquakes and once again transients were noticed on the strain-meters. There was also harmonic tremor measured indicating rapid movement of magma. This caused IMO to issue a public safety warning, and the London VAAC issued a flight code warning Orange. This followed the exact pattern of how all the previously instrumentally monitored eruptions had started so far.

As we all know nothing happened in the end. We can now safely say that we know even less than we did before about how Hekla acts before an eruption. Because now we have to figure out why Hekla did not erupt when she should have. I guess someone will have a research career out of it in the end.


After this Hekla entered into a new phase never seen before, this time a phase of very rapid and unbroken inflation started. What happened is most likely that the earthquake swarm removed blockages inside the deep feeder tubes of Hekla enabling fresh magma to flow into the volcanic system.

The rate of inflation varies a lot depending on where the GPS station is placed. The big exception is Mjóaskard situated to the west of Hekla. It has only suffered an uplift of 5mm in the last 5 weeks. For the other stations the rate of inflation is between 15mm in Hestáalda and 32mm at ISAK. Average uplift is 16mm, and 21mm if MJSK is not counted. This type of rapid inflation has so far never been measured at Hekla.

During the entire inflation phase there have been scattered earthquakes and micro-quakes.

If the current rapid inflation continues there is a very low chance of Hekla not erupting. Yes, we do not know what is happening with Hekla now since we have never seen this type of behavior. But Hekla is constructed in such a way that she can’t take a huge increase in pressure without erupting.

Image by GeoLurking based on data by the University of Iceland and Professor Sigrún Hréinsdóttir. All areas are showing uplift on this image covering the period from 4th of April up untill now. The area with the highest uplift are due north of Hekla.

Image by GeoLurking based on data by the University of Iceland and Professor Sigrún Hréinsdóttir. All areas are showing uplift on this image covering the period from 4th of April up untill now. The area with the highest uplift are due north of Hekla.

If the inflation continues at the current rate Hekla will erupt. When? Well I am not going to make any bets, but any time from 1 hour from when you read this to 4 weeks. Remember that 4 weeks into the future the combined uplift in 2 months will have exceeded 50mm at many GPS stations. As seen on the image above the largest uplift is happening on the northern slopes. This is a known site for one of Heklas primary magma chambers. The area to the northeast are not showing correctly, there is uplift there too, but due to lack of a GPS station there the model get scewed.


Image courtesy of the University of Reykjavik and Professor Sigrún Hréinsdóttir.

I personally would not at any cost get closer to Hekla then 10 km from now on. And then I would stay in the car on the road. If you are closer the chance of you surviving is not good and 5 km the chance of you surviving the initial blast is pretty much nill.

What will the eruption be like? Here I will be guessing since Hekla has changed her behavior compared to the last eruptions. I would say that Hekla has remobilized old evolved magma during all that moving of magma, and this latest inflation phase seems to fill up a lot of old magma chambers. This causes me to fear a rather explosive start of the eruption. I would also say that there is quite a high likelihood of there being more lava erupted then was seen during the last 3 eruptions. I will hedge my bet by saying that I would expect it to be anything between a VEI2 and a VEI4 on the volcanic explosivity index, and that Hekla will effuse between 0.1 to 2 cubic kilometers of lava. Based on the GPS plot above my best judgement is that the eruption will start at the top of Hekla proper and then open up the fissure both to the south, but mainly to the north. Most probably the Hekla fissure will open over all of Hekla proper with a fissure extending to the Northeast.

For those who wish to follow the eruption, here is the Hekluvöktun page:



541 thoughts on “Countdown to Hekla

  1. Hekla is having a base wobble again.
    ….Talking of wobbles and the use of harvesting PC data ……The adverts chosen for me are Audio Books, 49% of camping Equipment, TVT mesh complications, Over 50’s Funeral costs insurance, How to lose weight link and Sexy Tunics (From a Larger size specialist).
    Now this is interesting! I am certainly not over large (Not many wobbly bits) and not interested in those insurance policies. When I croak, all I need is a cardboard box and minimal disposal fuss. Science/ medicine will get any useable bits, I won’t be needing them. People who care will remember me as I was in the happy times. My atoms will come back as something else…maybe a bit of a volcano one day …….. 😀
    TVT Mesh? I had to look that one up. No I have been lucky and had no surgery for “women’s problems”.
    Camping equipment looks good…maybe a bit hard on the arthritic joints but I would still give it a go!
    Audio books? Good for listening to when doing housework……I tend to listen to drama on the radio…Husband listens to audio books on his rounds (He’s a Postie)
    What I want to know is…I can understand the camping stuff…..I look at outdoor /wildlife stuff on line….But the rest? Purely age related is my guess and streotyping……
    How WRONG can the ad men and statisticians be? Just wait till they are 65+ What goes round comes round 😀 😀 😀

    • I just had an after thought on the above. The fact that I spend most PC time on VC I would have expected ads aimed at preppers, adventure holidays and house insurance….It would appear Volcanoes do not enter into the Ad man’s parameters of classification!

      • it is amazing just because a piece of paper says you are an older person, you will need all sorts of things I never even look at, I always felt out of sink with most of my own generation, I like learning new things, my kids and grandkids have given up trying to keep up with me, it is a hoot at times.

        • Hi Ursh. Yes my kids get a bit bewildered too. Grandkids think I have some sort of magic as the wild birds and dog appear to have conversations with me and my seedlings will dance when I sing to them 😀 (It’s really heavy lorries passing on the main road 500 yards away that makes them vibrate.) I believe in keeping magic in childhood. My step kids steer clear of asking and ” What have you been up to?” I chuckle at the glazed look they get when I launch into how veggies are growing and the latest on Hekla 😀

          • I am looking forward to having kids to one day befuddle by growing odd interests that they can not bend their head around. 🙂
            And grandkids to grab and take to watch volcanoes erupting to the utter horror of their parents.

            • Maaaam don’t tell the kids those things they won’t sleep, is some of the tamer things, but kids love scary stuff

            • it just happened that way, not planed at all, will see what happens in ten years time, now I will really go to sleep,

          • I actually had 4 kids and have on last count 10 grandkids, 7 great grandkids that should be all for now until the next lot gets older, the generations are all mixed up some had kids early some later, some I haven’t met yet, they live in different parts of Australia, another thing which I find unusual, I was born in 1943, my eldest daughter in 1963, her eldest daughter in 1983 and her eldest daughter in 2003, will see if it continues

            • That was a persistant pattern 🙂
              I wish you good luck with the 2023 greatgreatgranddaughter!

            • I feel sorry for your great great great Grandchildren when they start to try to workout the family tree 😀 What a fantastic family. How do you remember all the birthdays?

            • Pc helps, actually there is another pattern of that, I am a Picean, my daughter is a Taurus, grandaughter is Cancer and great granddaughter is a Picean again, like Earth/Water sun signs

          • Wife and I do not have Children, got family though, Wife is the Gardener and when one asks
            about a particular Rose, say Charles De mills, or Graham Thomas, eyes either glaze over or light up. As for me “YOU ARE DOING WHAT? this summer?” when I tell them I’m going back
            to flying Airtankers…
            Then i tell them the average age of Airtanker pilots is 57… 😉

    • I err… tend to avoid items that are shoved at me in advertisements. I also quit watching TV. One thing that I seemed to have picked up from my dad, is wanderlust… so I don’t live anywhere near my extended family. Turns out that he did pretty much the same thing, eventually winding up in Mississippi before he settled down. As for kids, none are actually mine. They are step kids. The same for their kids. When it’s about done, I’ll likely be alone. I’ve relegated myself to that fact. It’s hard to interest a kid in manipulating data sets, or scrounging info. To them I am just some odd semi-relative that gets quite animated when they act nasty to each other.

      Had a dog, but she died. Then the other one had some sort of brain cancer and nightly seizures… now he’s gone. At least I don’t have to chase him around the bedroom to pin him down so he doesn’t run into all the furniture every night. Now I have these two rat-dogs that I inherited from my step-son following his divorce.

      Best I can tell… I have no “magic” that can amaze the grandkids… though I do have the ability to perform minor miracles with their broken laptop or phone screens. I leave the onus on them about how to come up with the money to buy the parts. I do have some of the accouterments of my interests and career hanging in my room. A three large area planning charts on the wall, a “shadow box”, and a helical antenna that I built for about 154 Mhz. The antenna has a nice cardioid pattern (horizon to zenith with about unity gain) and is intended to pick-off aircraft comms. I used to monitor the scanner quite a bit. Had the unfortunate incident of recording county fire dispatch and EMS when a friend of mine’s wife passed away. It was quite awkward telling him that I had the whole radio dispatch sequence on CD. I haven’t really monitored since then. Yes, he has the CD now, though I don’t know If I could ever listen to it if it were my wife.

      • I think you have a lot to give, so don’t put yourself down, I like all the ‘stuff’ you do on VC, even some off it is beyond me at times, if everybody was the same it would be a boring world we live in

  2. Nice gps movement at a meter near Eyjafjallajökull, south and up seems to be begining a trend. May be related to Mrs. Hekla.

      • I would say that is seasonal. Remember that there is a tremendeous amount of glaciar melting now.

        • But, I think part of it is Hekla movement.
          One can actually follow Heklas uplift all the way up to close to Hamarinn. It is behaving as Eyjafjallajökull did before the eruption.

    • Could be Hekla or Katla. Both are currently with a significant GPS movement upwards. Katla has been a long time like that, but mostly on the north edge of the caldera. Hekla inflation is just a recent thing since last month.

      Both are heading for an eruption, the question is when. Both have been known to sleep for 200 years and in other ocasions erupt within a short period of time.

      Interesting is also that when a volcano seems near to erupt, neighbouring volcanoes also seem to show that uplift. So perhaps this one volcano oin this region that is greatly inflating and we are missing it. What if this is Tindfjallajokull, Vatnsfjoll or Torfajokull?

      • Is vatnsfjoll apart of the hekla region or system? Would not wish that to go off or Hekla to copy it!!

        • Vatnsfjöll is not a part of Hekla. It erupts wildly different magmas then Hekla so I can not be the same system.
          In many ways Vatnsfjöll is a bit of a dark horse, it got dormant about 2000 years ago, but is still showing ample evidence of being able to erupt again one day.

          • Carl, what is known or conjectured about the *reason* behind Hekla’s ‘different’ magma?Especially the very fluorine-rich stuff…

            I’m thinking is there a structural explanation; the fluorine has to come from somewhere; could it be the country rock? Partial melting in some kind of evaporite type of stuff deep in the microcontinent basement, something like that?

            • There have been a bit of hypothesis lofted about there being a slab of ancient crust going down there. The magmas kind of point towards it.
              I believe it is a microslab, but I have not seen any good conclusive arguments for it.
              It would explain quite a lot really.
              So, conjecturaly we work on the assumption that the fluorine is from remelted slab untill someone pokes a hole in that theory.

      • The dead center of inflation actually shows right at the northern end of Hekla.
        But, there have been other volcanoes inflating fairly recently, or inflating on their own.
        We used to have inflation in Svartsengi, Krisuvik, Bardarbunga, Askja and Herdubreid.

        Currently Hekla, Gimsvötn and Theistareykjarbunga is inflating. Currently it is Hekla and Theistareykjarbunga that is uplifting quickest.

  3. I wish twitter would remove that top tweet when you search for Hekla – it comes up with a tweet from 2010 saying that Hekla has started erupting – as wrong then as it is right at the moment!

  4. a video about Tectonic Europe, starting in Iceland to Scotland and the Alps, almost felt homesick watching it, reminded me of some climbs I used to make,


  5. Todays find of Herdubreid is an image from Google Earth. I just found some rather compelling top of the roof pictures from Herdubreid. Guess what, there is a crater lake ontop that is melted.
    The crater itself is ringed by a small glacer (really small), so the lake should 1683 meters elevetion be frozen all year around. It is not frozen.
    If there had been an eruption there 10 000 years ago I could buy into there being hotspring down at the base of the mountain, but not up at the top. And not enough heat to stop a permanent glacier forming inside of the crater.
    Also, the place look young.
    We need samples from the top, and from inside the crater. Also a sample of the water in the lake would be awesome. Then we could see if there is gasses being released into the crater lake.

    • Can’t see the lake on Google Satellite, itself. Google’s satellite view must have been taken later in the year as there is not much snow on it or the surrounding area.

      But the crater does not look very eroded so it must be younger than the last ice-age 😕

        • If lava is being pushed up into a 3 km ice cover it should really melt the ice equally, and that would make a circular mountain.

      • Hello!
        But you saw the crater lake on the picture?

        Also notice that the walls of the crater is almost uneroded, which is really odd since there is a circular micro glacier. I get the feeling that one is not very old at all.

        • Saw the photo, which if it was taken in Spring or early Summer, the lake could be melt water from the snow. The snow does not appear on Google Satellite – I guess the image was taken later in the year.

          • Yes, but it is at 1680 meters altitude. I am not so sure that the lake would melt fully. But, that is just an idea of mine. But, we would know if we could get a bottle of water from the lake.

    • Could the crater be some sort of Maar-like phenom say gas, ice and rock occassionally
      explode due to build-up?…
      Other than a crater lake..

  6. Pingback: Hekla-ing Egypt | Musings from the Chiefio

  7. I wonder if this Hekla eruption shall lead up to a Katla Eruption if Hekla Shakes the Ground too much. I have recently determined that Grimsvotn is my favorite of the Icelandic volcanoes.. The smoke looks very steamy like and rises slowly and straight up from beneath the Glacier in a majestic sort of quality.

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