Minor earthquakes where seen after the large earthquakes in Grímsfjall volcano

Following the two large earthquakes (ML3.5 and ML4.2) there was a swarm of small earthquakes in that area. The earthquakes where seen on Grímsfjall SIL station, but do not appear to have been strong enough to be recorded on other SIL stations around Vatnajökull glacier. This appears to have lasted until around 13:00 UTC on 13th of January 2011. But after that it did quiet down.

Plot is from IMO web site.

Icelandic Met Office tremor plot that shows the two large earthquakes and following minor earthquakes. This area in Grímsfjall volcano has been quiet since the two earthquakes took place few days ago.

56 Replies to “Minor earthquakes where seen after the large earthquakes in Grímsfjall volcano”

  1. Thank you Jón. I had imagined there would be a swarm, but weather didn’t collaborate. Any idea for the depths of the other quakes?

    1. I don’t know the depth, as I don’t think that IMO has the depth too. But the earthquakes where (far as I can tell) only detected at the SIL station on Grímsfjall volcano and one station is not enough to determine the depth and location of a earthquake.

      This is in fact a common problem for me when I record a small earthquake that only shows up on my geophone.

  2. A tip on the language, if you don’t mind:
    Where were you when …something big… happened? ~
    Hvar varst þú þegar …einhverju stóru… gerðist?
    In both languages, leave the ‘H’ out, and it’s a verb.

      1. Heh. A post about a typo typically contains a typo. 😉
        Actually I was surprised that giggle translate managed the job as well as it did – I was sure about the first part, but the rest was just guesswork.

  3. Vaguely remember Jón and Carl discussing the storm wind factor with regard to the recording (or non recording) of smaller earthquakes. Wondering just how many smaller quakes and swarms may have been missed during gale force winds over the past month.

      1. Okay, so when spring comes, it will probably give new data again? It is not a permanent shutdown?

      2. I think when they repair it is more optimistic view. As snow does not do well with this type of hardware. Even if it is protected from weather.

    1. Since Sigrún is pretty much making here living on watching signs of Katla doing anything nasty, and Austmannsbunga is the main center of activity at Katla I would hazard a guess and say that she will have it fixed and cleared as soon as possible. But when “as soon as possible” might be ontop of glacier in the middle of the winter with snowstorms and all… Well. Only a complete and utter idiot would take a hike up there if the conditions aren’t perfect.
      So the answer is everything from tomorrow to april 🙂

  4. IMO website has been offline for me in the last couple of hours. Are you people experiencing the same?

      1. It displays an error message unless I go to the root directory. But sometimes it takes a long time to refresh.

  5. With the risk of being a bit tedious (while I am doing laundry), what is up with Kreppuhraun?
    I thought somebody bright like Jón, Lurking or The other Lurker would have presented the definite theory of Kreppuhraun by now. Are you guys as stumped as me? Or do you think it is insignificant?
    Or (enter horrormovie music) is this the great and secret thing that “is not to be spoken about”? 🙂

    Seriously, anyone with an idea out there?

    1. I think the station got messed up in a storm by a flying piece of rock or something, and has been repaired afterwards, I can’t make anymore of it. Good luck with your laundry by the way. 😀

      1. I wasn’t thinking about it going quiet, but is fab that it came back online while I was writing my post. Nah, I was thinking about that weird activity that went on before it went quiet…

        Thanks, discovered that I would have to go comando tomorrow and be unmentionably lacking of unmentionables. And since the period of jingleballs is over it felt like a good time to do something about it.

      2. Ánd there is some other odd movement at HVA to. But that one has this pattern during storms, KRE, has never been acting odd during even the worst storms.

        But there is remarkable similarity between HVA och KRE this time.

      3. I don’t know where exactly this station is but maybe there was a pressure wave from an avalanche from the nearby Kverkfjöll-slopes. An avalanche can make a lot of noise and the pressure wave can travel farther than the snow.

    2. The link to Kreppuhraun works for me.
      And yes: it looks like something big has made it go crazy.

    3. If I see a major climb in high band stuff, and the low end barely notices it, I lean towards wind or something like that.

      I think Pieter might have it nailed.

      1. Yeah apparantly it got eaten. 🙁
        Quality was over 70% as I recall. There also were 2 M1+ quakes beneath Fimmvorduhals, but one of those also got eaten and the other one got downgraded, hehe. Now I’m back to studying for my Physics test about waves and curvilinear motions hehe. I better pay good attention so I might understand these wave-data Jon is recording better! 😀

      2. Ah, so you are a student of my speciality? Which level are you studying?
        Even though it is quite a few years since I wrote my thesis… 🙁 Ah, old age…

        I think the lost Fimmvörduhalsi quakes are from the problem with integrating the new equipment. I seriously hope there will be no eruption there during the next weeks. The entire system over there seems to be compromised.

        Good luck with your exams!

      3. I’m currently in my second-last form of high school. The test actually went pretty well, few questions about Keppler’s 3rd law/centripetal forces and I had to some calculations regarding coil springs and amplitudo and stuff.

        I really do like these subjects of physics, it explains many phenomenons in geology and astronomy.

    1. I hope to do that next week. But everything is going down from next week when I turn off my current geophone in Hvammstangi. Don’t worry, it is going to be replaced by a new geophone in a house here in Hvammstangi and housed by a guy how had minor interest in this.

  6. A few days ago we had a discussion about the “silence of quakes” in the area between Myrdalsjökull and Vatnajökull. The idea behind that discussion was that since it is a highly active rift zone it should be quaking as hell, but it is not.
    I then hypothetisized that it was due to the crust being highly tensile (rubberband effect) and will stretch highly before breaking.
    After reading the article below I find that my idea was not original, but that I was correct in my assumption. Yeah, I was correct about a volcano for once! 🙂


    1. Especially interesting was the parts of Torfajökull and Laki being responsible for the high tensility index. I would though like to also put some blame onto Katla and the Elgja fissures.
      Be that as it may, it is clearly a very tensile area able to contain very large amount of stress. If the authors had gotten their tensility index correct the quake that started the Laki eruption would have been truly stumping for being on Iceland. When I calculated it I came up with a number between 7,0 and 8,0. But perhaps it is not so strange, it was one hell of a rift that opened up. Basically the rift was 10km long (2,5km active) 50 metres wide on average and spanning all the way down to the MOHO. So it was one hell of a lot of energy released when it ripped open.

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