Posted on by Jón Frímann

Interesting earthquakes 20 km WSW of Laki in Eldgjá volcano canyon (Katla volcano fissure system)

There are interesting earthquakes about 20 km WSW of Laki. The locations of the earthquakes suggests strongly that they belong to Katla volcano fissure system. Last eruption in this area took place around the year 934. When the Eldgjá volcano canyon was formed. That eruption did destroy a older volcano canyon located in this same area (lava flows volcano ash did fill up that canyon far as I know).

The earthquakes that have been taking place in this area are small. The largest so far has the automatic size of ML1.2, but only ~4 earthquakes have been recorded so far. But what is most interesting about this earthquakes is the depth. The earthquakes that has the best automatic detection by the SIL system has the depth of 0.7 km. But that makes the depth of ~700 meters and that is a shallow earthquake. Given that this area has only fissures and no activate volcanoes. It is not unheard of in Iceland that a fissure eruption to start with no warning at all. Last time this did happen was in Gjálp eruption in the year 1996. Before that a dike intrusion into the bedrock did manage to get to the surface in Askja eruption in the year 1878, when a 25 km long volcano fissure did open up (small compared to Eldgjá eruption around the year 920).

I do not know what is going on in this area at the moment. As the activity so far has been too small to make any clear picture of it. But Katla volcano is a big volcano and it is not out of volcano league to make a new fissure eruption instead of the regular caldera eruptions under the glacier as Icelanders have gotten used to over the past 1000 years or so. Last time this did happen there are suggestions that there was a also a eruption at the same time in Katla volcano caldera. But that this has only been revealed during research over the past 50 years or so in this area.

I have also noted that there is a small increase in earthquakes inside Katla volcano caldera, not far from Austmannsbunga. But at this moment it is too early too know what it means for sure. There is no eruption is imminent in Katla volcano when this is written. Just too be clear on that fact.

44 Replies to “Interesting earthquakes 20 km WSW of Laki in Eldgjá volcano canyon (Katla volcano fissure system)”

  1. Next time, Please do not use the the word quiet Jon, (: Just say “no one was hearding anything”. Mr/Miss Laki i am sorry we did not mean it. No need to double dare any other Volcanco’s, ok? Go back to sleep.

    1. It is not Laki that you need to worry about. It is Eldgjá volcano canyon. But we know that Katla volcano is getting close to a eruption. But if that results in a new volcano fissure like Eldgjá is a good question.

      1. You stated that such a fissure eruption could occur with little warning, but I highly doubt that. This fissure area has been inactive for a long time, and the crust has become solid and impermable ever since. So in order for this huge mass (which is under alot of pressure) to find it’s way above, a huge amount of energy will be released.

      2. Dike intrusion into the bedrock can start and have started without a little warning in Iceland.

        But when the dike intrusions start it is going to make a lot of earthquakes both small and large. Until then, it is going to remain rather silent.

  2. Mila Jökulsárlón camera, that position is, and where to look?
    thanks
    translating it by Google

      3. Sorry Chris,
        I was just joking; in my believe there is only one highway, the number one (ringroad).
        All other roads are secundary (or am I mistaking here)?
        Henk

      4. Ah, sorry, I missed that 🙂
        There is only one ring road, which goes round the country (no surprise 🙂 ). All other roads have bigger number (2 and 3 digits) according to their size and condition. Generally a 2 digit road (lets say the 41 which connects Reykjavik and Keflavik) are bigger and better maintained than 3 digit roads. The latter ones are often gravel roads.

  4. I only saw 2 earthquakes, one 700m deep and another 13km deep.
    Could this be tectonic?

    It doesn’t seem much, but we know Katla and Grimsvotn are both approaching an eruption, and we never know if they will erupt some massive lateral fissure.

    1. This has obviously been revised, now its two quakes in this area with high quality: One at 0.9km and the other at 0.7km. The later one is also thew shallower quake.

  5. There was also 2 more quakes in Vatnajokull. One in Grimsvotn, and another one in Hamarin, which belongs to Bardarbunga fissure. Could the 2 earthquakes yesterday actually belong to a Bardarbunga fissure rather than Katla?

    Veidivotn fissure is nearby and it belongs to Bardarbunga, it erupted (VEI5) in a massive fissure in 1477. Since settlement, 3 eruptions have occurred in this area, all more or less in the same area: Edlgjá in 934 belonging to Katla, Veidivotn in 1477, and Laki in 1783 belonging to Grimsvotn. All were very large and massive eruptions.

  6. I discovered this interesting book
    http://books.google.com/books?id=b1sXfJCiCHQC&pg=PA26&lpg=PA26&dq=1477+bardarbunga&source=bl&ots=rZvG8PweBd&sig=kmsJrwSpssD8mt18msoInx-IvWs&hl=pt-PT&ei=aa-2TfitHoON5Ab_qqDfDw&sa=X&oi=book_result&ct=result&resnum=7&ved=0CFQQ6AEwBg#v=onepage&q=1477%20bardarbunga&f=false

    It says, that Bardarbunga also had large fissure eruptions to its southwest around 900 and 1717 (which is a decade with many eruptions in Iceland). Then, it says, that Krafla and Bardarbunga might have a connection: generally inflation at Krafla is related to deflation at Bardarbunga.

    I look at Katla entry, and also said that the eruptions of 1963 and 1973 in the Westman Islands might have alleviated the pressure at Katla reservoir and delayed the present expected eruption. Interesting to see how these volcanoes are all connected! Maybe, the Icelandic plume brings magma together to these volcanoes before splitting into their different magma chambers, and this explains why one volcano might alleviate another one. If so, the eruption of Eyjafjallajokull already alleviated a part of the pressure under Katla chamber.

    Also activity in Vatnajokull tends to increase roughly around every 130 years, when volcanic activity in Iceland increases as a whole (which we are again seeing it now). This is way, activity in Vatnajokull seems to be increasing, and also activity in Reykjanes. But this is just what I have read.

    1. I don’t like it when people talk about fissure eruptions in Iceland. Very typically only Edlgja and Laki are mentioned as a proof of the conclusion, that it will take centuries before the next one occurs. Instead, looking at the history of them, I expect to see at least one before I leave this planet for good…

  7. If possible, could someone list out, say 5 things, That would point to a volcanco in Iceland that is about to blow. The second part: Then place Katla, Bardarbunga, Grimsvotn, Eldgjá Or Laki system and score them against that top 5. I did one, however i do not know very much at all. Then if people find this a good thing, we could change the data ourseleves when needed for a warning system. 🙂

    1. I don’t know much at all either, but my top 4/5 would be…
      Inflation
      Shallow earthquakes (preceeded by deeper earthquakes)
      Harmonic tremors
      Increase in hydrothermal activity
      Number 5? really no idea 😛

      My guess would btw go to Grimsvotn to go first 😛

    2. The problem with that is that volcanoes are unique unto themselves and follow their own modes of operation. Even those lowly “tectonic” earthquakes that are summarily dismissed as not important, could be the only indication that you have a Laki or Eldgjá event in the making. That area is a plate border, and the relative motion of those plates is what drives the activity. The magma intrusion and eruption is a byproduct of that.

  8. I think Grimsvotn will definitely go first. It’s so hard to know though with Iceland. We know Katla is long overdue for an eruption, and this activity at Eldgjá is interesting.

    I might be asking a stupid question but are the indicators to a fissure eruption like Laki or Eldgjá, such as inflation and earthquake swarms etc the same as those of an impending explosive eruption?

    1. Nothing personal, but be very very wary of falling for the media tripe.

      No volcano is “overdue,” let alone “long overdue.” There is no such concept.

      Lets take a look at the actual repose times for Katla in order to see if the term “overdue” has any relative meaning at all.

      http://i55.tinypic.com/vffbjd.png

      As you can see, on average Katla sits quietly by for about 64 years. 36.9% of the time it will erupt within 40 years of it’s last tephra/magma producing event. (12.3+24.6) Why “tephra/magma producing?” Because that’s how they determined it’s history, from those deposits.

      63.1% of the time it goes beyond at least 40 years before erupting.

      A watched pot gathers no steam, and when it comes to volcanoes, human time scales can’t cope with the slowness of the forces at work.

      Katla will erupt when it’s ready, and not a moment sooner.

      1. It is very notable, that 30% of cases Katla sleeps more than 80 years between the eruptions. She last erupted 1918, so we still have more than 1/4 chance Katla is sleeping happily at least another year… Or about 10% probability, she will still be sleeping weel in year 2150 when no-one of us is there to see her dancing!

        @David: So, I’d dare not to say Katla is “overdue” until during the next millenium!

      2. This is actually not clear. There have been small glacier runs in 1955 and 1999, so there might have been cryptic eruptions of Katla.

      3. Should have said 2060… In any case, 1918 was the last major eruption.

  9. Sander, I will take that bet. I think it will be the Katla system, maybe not Katla itself. I saw on the National Geo channel, a picture image from a orbiting sat, the katla area had allot of red pressure and it was moving north west after the last volcanco eruption.

    For myself i placed Ice cracking and increase in water flow from rivers, higher PhP in Lakes, some animals dead. Snowless parts on volcancos, local smell of suphur. I swear i did not see these things in any volcanco movie. 🙂

      2. Definitely yes!

        Grimsvötn sleeps typically less than 25 years, very seldom more.

      5. Very interesting figure… Looks like a main peak with two side peaks, i.e. wobble (main/driving frequency 40-50 years, side/modulating frequency 25-35 years).

  10. The account I recall reading of the Laki eruption spoke of a large number of earthquakes strong enough to be felt in the area in the week or two leading up to the onset of eruptive activity:

    “The preceding winter and the spring of that year had been unusually mild, and nothing seemed to foretell the approaching danger till towards the end of May, when a light bluish fog was seen floating along the ground, succeeded in the beginning of June by earthquakes, which daily increased in violence till the 8th of that month. At nine on the morning of that day numerous pillars of smoke were noticed rising in the hill country towards the north…”

    Nicol, 1844.

    Mike

    1. The “bluish fog” was probably degassing as the the fissure was starting to weaken.

  11. Could this activity has something to do with the Eyjafjallajökull erruption in 2010?

      1. I was just thinking that Katla might me going mad due to Eyjafjallajökull. It’s more then a year since that erruption and if history repeat itself it’s gonna wake up.

        But if this occurance is not related to Eyjafjallajökull then I guess my little theory was wrong 😀

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