58 Replies to “Eyjafjallajökull is Time number 4th Buzzword of the year 2010”

  3. Well, now… how about that.

    Original

    09.12.2010 22:50:19 65.074 -16.447 -1.1 1.1 2 90.01 3.2 km WSW of Herðubreiðartögl

    Updated

    09.12.2010 22:50:19 65.074 -16.447 1.1 km 3.2 90.01 3.2 km WSW of Herðubreiðartögl

  6. Which proves “summat is wrong” as my comment above definitely did not use the bold tag. This one does though in case it might reset the error

  10. This seems unusual – is it correct?

    Friday
    10.12.2010 11:46:37 64.772 -20.536 42.1 km 3.0 88.66 6.7 km W of Eiríksjökull

    1. This is close to or in the area where the earthquakes have been happening over the past week or so. This is not a common area for earthquakes. But it is not unusual.

      1. I was also wondering about it because of the depth, I don’t remember seeing anything else so deep in Iceland recently

      2. This is indeed kinda weird, since the crust in Iceland is max 40km deep, and that part is beneath Vatnajökull, the crust at the EQ location is about 27km deep.

  11. I’m wondering about the tremor chart for Godabunga, which has had a similar appearance over many months now – relatively steady red and green, but extremely “spiky” in the blue. Could this be explained by a subglacial geysir, in which case you’d have a hydrothermal system adjacent to the cryptodome?

    1. The spikes in the blue range (2-4Hz) are due to the ice and due to the weather in the area. But the noise is mostly because the ice creeps alongside the rocks the sensors located on.

    2. Never talk about the devil, then she just puts on make-up… Godabunga changed earlier today when she noticed you looking at her tremor-dress. 🙂
      First change in a comple of months even though it is small and probably insignificant.

  12. Err, that quake that was raised has been tamped back down below 3. It lost it’s “arrow” status.

  14. Just popping in….
    i read this blog almost everyday but i have a question…..
    i just checked the tremor plots
    http://hraun.vedur.is/ja/oroi/allarsort.html
    and they are ALL going up….
    is this seasonal? or weather ? or is Island about to blow apart? (just kidding about that. well , a little anyway.)
    Best!motsfo

  15. Icelands most dangerous volcanos!

    As you know I have been playing with stats in the last thread to calculate the intensity of large eruptions in Iceland. While mathematica chugs path integers for us I will now present the top 5 most likely volcanos to make a big bang. Here they are according to the amount of Holocene large eruptions purely.
    1. Bardarbunga
    2. Hengill
    3. Katla
    4. Hekla
    5. Askja. With Fremrinamur, Hveravellir & Krafla as runners up with the same amount of Holocene instances.

    But I find this simplistic sumation of all holocene eruptions being crude. Some of these volcanos has had no large eruption in the last 2000 years or so. So I did a weighting where I disregard all eruptions older than BC 3000 and gave all AD-eruptions a positive weighting of 1,5. Then we get this list.
    1. Katla
    2. Hekla
    3. Bardarbunga
    4. Askja
    5. Grimsvötn

    And please note that Katla and Hekla are not far between in capabilities. Bardarbunga and Askja is also close, and mild-mannered Grimsvötn is all of a sudden looking like a benevolent volcano that just did a bit of reputation-building with the Lakagigar compared to those above.

      1. wow……..
        but ………
        just a few years ago we were all surprised when Fourpeaked Volcano erupted…. for the first time in 10,000 years….
        it was an eyeopener………….
        so i don’t count any volcano out.
        Best!motsfo

      2. Hi Motsfo,

        Did Fourpeaked really erupt? I thought it just had a period of fumarolic activity and went dormant again. Did I miss something?

      5. i finally found the pic i wanted….
        this is one i remember on the evening news and i must admit, i just assumed it had erupted from the view…………. this was in 2006…. how the years pass away.
        Best!motsfo

      1. And with that she celebrated with a 3.0… Life is strange, as I was working on the list of all known large eruptions Hveravellir had a quake in the main zone of its large eruptions when I was actually working on the Hvera part… Creeepy as hell actually.

  16. And for those wondering where exactly the quakes east of Langjökull is taking place…
    Enter Hallmundahraun, the AD950 VEI-5, 10 cubic kilometre eruption of Hveravellir, and Kjalhraun with more then 15 cubic kilometre of ejecta. The quake swarm at Langjökull is close to these two and they are just a couple of kilometres apart counting the central shield volcanos that produced them. And then we had the 3.0 banging on the doow 42 km exactly under the Hallmundhraun.
    So it seems like Hveravellir might be turning in it’s sleep before waking up.
    And this momma has never had anything weekish eruptionwise.

    1. And if I got the calculations correct the correction of the 3,0M will be significantly upwards since it was so deep, and the distance is pretty long to the stations. Since I haven’t done these calculations before I am pretty certain that I am not entirelly correct. But it seems like it would be above 3,5M.

    2. Mainly out of laziness… but what are the main volcanoes for Langjökull?

      That is, if you have it handy.

      1. That is Hveravellir & Prestahnukur as far as I know.
        Belonging to Hveravellir is a lot of craters and cones. Pretty much the only thing around that is a volcano on its own is Prestahnukur.
        At least as far as I know, but I guess that Jón would know if there is yet another volcanic system there.

  17. Large scale eruption probability!

    And the answers are:
    1. On pure statistical increase over a period we are now at (corrected) 2,22% risk annualy and counting for a large scale eruption.
    2. Counting in that we have quite a few students (volcanos) in our class we have a risk at 2.38%.
    3. Path integer probabillity summing over probabilistic history, in decade.
    27,2%+/-10%.

    Sofar we haven’t taken in reallity into the account. If we do that and give an increased value for inflation and quake-swarming during the last five years we get results.
    4. Path integer with pink probabilistics. 32,5%+/-3%.

    Oops… 🙁

    1. I can already imagine the headlines: “A Swedish experts predicts three cataclysmic eruptions will happen in Iceland within the next 10 years!”

  18. @lurking – I like that timeline graph – wonder what some of our prime candidates would look like…in case you are planning more road trips…. 😉

    1. Well, I was hoping for more members of that little group… two doesn’t make much of a crowd. That other volcano only has 3 events to poke at, but since they are in each other’s neighborhood, I combined the bell curves for them and aligned where we are on each curve. Sort of a graphical representation of the over all probability… of sorts. There is a skew factor that isn’t shown (not really sure how to best do that), and depending on your paranoid factor, getting out into 2SD land on the far side would indicate that things could be getting bad really fast… but that’s the wrong way to read it. The more likely scenario is there there are not enough samples (three is not going to cut it) or that the thing has actually gone comatose.

      Anyway… enough rambling. Here is the combo plot for those two. Don’t ask me about what the number on the vertical axis means… I think it’s the percentage for the curves, but I’m not sure. Think if it as a “monkey vs typewriter” sort of plot.

      http://i55.tinypic.com/2hq4g47.png

      1. I still think this is related to tectonic stress due to activity in the other four corners, but it was a perfect quake to start something in the future. Perfect magmatic waveform and interesting depth.
        But I do not believe in anything happening soon at Langjökull. But then since this is Iceland I am probably wrong.

  19. Here is a list of biggest lava fields in Iceland:

    http://www.jfi.is/wp-content/uploads/2010/03/jfi_vor_2003.pdf

    Efnismikil hraun og eldvirkni í 14.000 ár
    Árni Hjartarson
    Tafla 1: Stærstu hraun á Íslandi.
    Nafn Aldur 1) Leiðr. aldur Flötur-km² Rúmmál-km³
    Þjórsárhraun TH-b 7800 14C 8600 967 25
    Eldgjá AD 934 H, I 1070 780 19,6
    Stóravítishraun 11500 T 11500 460 18,4
    Skjaldbreiður 9600 S 9600 200 17
    Trölladyngja > 7000 S 9800 15
    Laki AD 1783 H 220 14,7
    Kollóttadyngja > 4500 S 8000 69.1 14,5
    Lambahraun 3700 14C 4100 200 10
    Skildingahraun >11980T 12200 250 10
    Bárðardalshraun > 7000 T 9100 400 8
    Heiðin há 7500 S 7500 150 6
    Búrfellshraun TH-i 3200 T 3200 6
    Kerlingardyngja > 4000 ? 6000 6
    Kjalhraun 7800 T 7800 150 6
    Þráinsskjöldur ~12500 S 13000 130 5,2
    Hólmsárhraun 6800 14C 7600 5
    Sandfellshæð ~12500 S 12500 120 4,8
    Þingvallahraun 9130 14C 10200 200 4
    Ketildyngja – Laxárhr. e. 4300 T 4300 300 4
    Tungnárhraun TH-d 6000-7000 S 7000 270 3,8
    Sigölduhraun TH-f 4000 S 3900 200 3,4
    Hallmundarhraun 1100 T, 14C 1100 225 3,4
    Hrútagjárdyngja 4000-5000 T 4500 80 3,2
    Leitahraun 4560 14C 5200 100 3

    1. Darn it, the website bumped my response out of order to the end of the thread. The previous entry was supposed to be a response to Motsfo and the discussion regarding Fourpeaked Volcano.

  21. Okay.. it was noted earlier. But it’s still weird.

    A very deep quake was registered on the MET site. 42.1 km deep. As noted at the time, that’s below the Moho.

    From 2.8.1 of Global Tectonics, 3rd ed.
    “The mantle … extends from the Moho, at a mean depth of about 21 km, to the
    core–mantle boundary at a depth of 2891 km. …it is believed to be chemically homogeneous [with] minor and trace elements, and formed of silicate minerals.”

    From 2.8.2 of Global Tectonics, 3rd ed.
    “The uppermost part of the mantle constitutes a high velocity lid typically 80–160 km thick in which seismic velocities remain constant at a figure in excess of 7.9 km s−1”

    So, if I’m interpreting this correctly, having high velocities implies a denser and non liquid state. In regions of high melt percentage, or outright molten, the velocity should drop. Additionally, S-waves have issues going through molten material. At greater depths, the velocity drops further. According to the text there are several issues at play that cause this (other than being hotter).

    This implies that the upper mantle (the area of the quake) is not the liquid ooze that we always assume it is. It has some stiffness, which would allow a quake to occur, though likely rarely. If that is what happened then there is some sort of process at play that caused the stress… other than the usual. Perhaps a larger push of material up to the spreading center. Dunno.

    Generally you only see the deeper quakes when a plate is subducted and the comparatively hard brittle material fractures due to stress. There is one line of thought that states that Iceland’s crust sits on top of another segment of crust. That might be what we see here, that lower crust or a part of it protruding down into the mantle.

    The problem is, it doesn’t show up in the Moho plot. Granted, my plot is a digitized and adjusted rendition of the Moho off of a graphic that I found, but other papers don’t show an artifact in that area that might be it.

    Anyway… here’s a plot of the area… and the odd quake. Perspective view.

    http://i53.tinypic.com/vhw9lh.png

    1. This is a error. The string of the earthquakes are like this.

      Föstudagur
      10.12.2010 11:46:37 64,772 -20,536 42,1 km 3,0 88,66 6,7 km V af Eiríksjökli
      Föstudagur
      10.12.2010 11:46:36 64,845 -20,811 7,2 km 2,6 99,0 16,9 km N af Húsafelli
      Föstudagur
      10.12.2010 11:46:36 64,879 -20,846 11,4 km 2,9 90,03 20,4 km N af Húsafelli

      This is the same earthquake. But the SIL system has some issues with locating it for some reason. I did record it this earthquake and I only got one set of P and S waves.

      1. Well, that makes more sense that what it was looking like. Nothing like having someone in-country to do the sanity check.

      2. I think so to. But I think it is the 42 quake that is the correct one and that the others are shadows reflecting on a tectonic fracture that goes deep.
        I saw the same on salines with soundwaves when I built sonars. Deep strong sounds reflected on the higher salines and termohalines. Also the timing for this is correct. If it had been a shallow quake the shadow in the depth would have been out of time sequence since the noice would have had to travel deep before reflecting. It would have been almost two minutes later, and it would have been significantly weeker.
        The 3.0 is somewhere between 3.5 and 4 when corrected for dampening effects. and that is enough to make shadows at 2.9.

      3. If I had the raw value of Jóns Helicorder I could have told with certainty.
        But a question would be enough.
        What are the delay-time between the P and S waves initial wave-front in as close number as you can get Jón?
        If you give me that I can check the depth of the quake better then even the MET can. After all, I invented that algorithm 🙂

      4. I also need as exact a position as possible of the Helicorder in qustion. This gives the level of exactidude that I can get out of the program.
        The only unknown would be what is between the places, but that shouldn’t matter.
        Wonder which sub it will say it is… Muaha!

    1. Yes, depending on the rock.
      But you forgot the distance to the measurement device. But 2 minutes was lack of coffee in the morning. I calced it on the speed of air.
      Judging from other speed numbers and distances I think are the stations it would be 7 x 2 (+5 or 9) = Y
      Good catch! Mental note, never write before coffee…

      1. Thank you, Carl!
        So full formulae would read something like this:

        a) “Time of observation – (distance from measuring device/speed of sound) = real time of progenitor quake”

        b) “(Distance from progenitor quake to reflection + distance from reflection to measuring device)/speed of sound in rock = time delay before sensor picks up a reflection.

        Coffee sounds good as it’s quite a few hours since my brain had its last dose of that mind-alerting substance.

      2. You’ve got it absolutly correct 🙂
        I’ve had my coffee, made todays beer, tequila and pear-brandy run (dinner tonight) so now I am ready for some calculations. But as I walked I was thinking on the problem.
        Since the stations are covering the north-east, south and east sides of the quake and not the north-west we already know that it is the deep quake that is the correct one, and that the others are bounces against the fracture. Then we also know the location of the more prominent features of the fracture since these are the shadows showing up.

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