Posted on by Jón Frímann

Two day long earthquake swarm in Krísuvík volcano

While this earthquake swarm in Krísuvík volcano does not appear to be big in size. It is clear that was rather long and might even be ongoing. But it is interesting how long this earthquake swarm did last. So far the time is about 2 days. It is impossible to know if the earthquake swarm is over or not. Current number of earthquakes is about 60 earthquakes so far.


Picture is from Icelandic Met Office graphic web tool.

The earthquakes are on North-South fault line according to the visual evidence. Depth of the earthquakes is from 12 km and up to 3 km at the moment. It is hard to know at the moment if this is due to magma inflow under Krísuvík volcano or just normal tectonic activity along the rift zone in Reykjanes.

Icelandic news about this earthquake swarm.

Hrina smáskjálfta í Krýsuvík (Vísir.is, Icelandic)

71 Replies to “Two day long earthquake swarm in Krísuvík volcano”

  1. Well, I don’t know what to make of it.

    From mid July to September of last year, there was a deflationary period and there was a cluster high, much of nothing, then a cluster low.

    Now there is a deflationary period and there is a trending sporadic cluster moving towards the surface.

    That’s contradictory to the July-Sept period.

    1. @Lurking (former thread):
      I am getting a bit confused here.
      In the lid example you said that “…as the area under the lid decreases pressure, the meeting point of the lid will move upwards as the two pieces of the lid move together.”
      When it started to make some sense in my poor brain, you show us a drawing pointing to an opposite direction?!
      What, because when the pressure decreases inflation occurs? |:O

      BTW: a pity you are no helminthologist. The big worms are digging their way upwards, we needed to know about their behaviour!

      1. Talking about helminthologists, where in the world is Passerby? I wince at the thought of something having happened to him.

      2. The example shows maximum contact, when inflated, on the lower segments/slabs/lids (pick one). As the area underneath deflates, the over lying terrain moves downward, and the point of maximum contact moves upward to the next layer that takes on greater stress as it pushes against it’s complementary layer on the other side of the fault.

        During inflation, the process is not as strong since the faults already exist… these being points of separation. Most seismic activity would be the creaking of newly emplaced magma or movement of the terrain to accommodate the needed volume.

        This is all just an idea. Nothing here should be construed as factual or authoritative. And… like I said, that period in July to Sept seem to be in opposition to the concept.

      3. Thanks.
        I begin to think I get the picture.
        Interesting reasoning on the deeds of Mother Nature – pure, abstract, imaginative.
        Not a helminthologist but da Vinci himself!
        Wish I were a painter or a sculptor to translate this into a piece of art.

  2. Among many other quakes at Krýsuvik volcano, I found these:
    Saturday
    26.02.2011 02:24:45 64.485 -17.506 6.5 km 1.2 62.01 14.3 km NW of Grímsfjall
    Saturday
    26.02.2011 01:30:28 63.987 -20.365 5.5 km 1.8 43.64 8.2 km SW of Árnes
    Saturday
    26.02.2011 00:45:23 63.636 -19.288 3.2 km 2.3 40.84 1.9 km WSW of Goðabunga
    Friday
    25.02.2011 23:46:08 63.651 -19.554 1.1 km 1.8 57.66 4.6 km SW of Básar

  3. I think we are not seeing any magnitude <1 earthquakes right now at Krýsuvík because of the weather?

  4. And the swarm in Krýsuvik seems to be rising in number of quakes.
    The earthquakes with magnitudes between 1.1 and 2.3 vary from 10 to 1 km depth; what does it mean, I don’t know. But we are entering the third consecutive day of continued activity.

    1. Even though Jón Frímann and others devotedly tried to explain what harmonic tremors looked like, i still did not get it when a tremor start to turn into a harmonic one, but the tremorgraph to be seen at Krisuvik look odd as do the neighbouring stations at vos and grv
      http://hraun.vedur.is/ja/oroi/kri.gif

      1. Birgit:
        That is the kind of graph that makes we think it over.
        There has been blizzard conditions in Reykjavik, so I don’t know how much it should interfere on this…
        But something is going to sprout from those geothermal springs. I don’t mean lava, but I would consider some sort of phreatic explosion. Pressure is rising…

      2. Yeah, i am trying to be a good pupil just like you are and try to learn. Some day there will be a new eruption in iceland even if not now and maybe then i will get what to look for in those graphs.
        oh btw something totally different and OT. During the Merapi eruption we said we might gather all the info on how to build facemasks and so on, to have it ready if it should be needed again. We could start doing this now while things are calm. (Says this and kicks herself for being a lazy a**)

      3. The o.5 – 1.0 Hz band (red curve) seems still very calm, so I would not worry about an impending eruption… The blue curve (2 – 4 Hz band) is most sensitive to weather-related effects.

      4. You just see the earthquakes at 4Hz band on IMO tremor plots. No harmonic tremor is going to show up until the following happens.

        1: Harmonic pulse shows it self. Happens when magma is on the move. This happened few hours before the eruption in Eyjafjallajökull volcano. That is Fimmvörðuháls phase of the eruption.
        2: A eruption starts.

        Until then we are only going to see earthquakes on the 2 – 4Hz band. I do not get any earthquakes from Krísuvík volcano (expect the largest ones) on my Hekla geophone. So I cannot tell you what type of earthquakes this are. Like I did with the Eyjafjallajökull volcano pre-eruption phase.

      5. OH Thank you, one step closer to finally understanding this. Till now i looked at your examples on harmonic tremors and thought.. they look hardly any different to me.

      1. Wonderful. And note the drop in graph where the deeper quakes show up. Almost like the area took a “gulp.” Which when you think of it…

  7. What is the exact location of the KRIV GPS station in relation to the present eq activity?

  11. The swarm showed some waning, but now got back at even more intensity.
    There was a 2.9 at 4.7 km depth, 90 % quality, and two other with similar magnitudes.
    This is new to me.

  14. Eq depths currently range from 1 km to 10-15 km. It looks pretty non-tectonic to me, but this is not a surprise to us…

    I was asking about the distance of the KRIV station as I thought about a second scenario (to that of Lurking’s). Lurking basically assumes that the KRIV station is sitting on one of those two plates. What if it is outside of those two plates but close to the plate boundary? Then we’d see downward movement at KRIV while there is inflation at the volcano (i.e. vice versa to Lurking’s scenario).

  15. Hi Jon,
    I wanted to ask your opinion. We are a foreign orchestra musicians and we go to Iceland to play concerts from March 2 to March 9 this year. Think there might be an imminent eruption?
    Thanks for your help.
    Mònica

    1. I don’t think there is a risk of imminent eruption. But if one happens you don’t need to worry about. Iceland government has really good plan to deal with that type of situation.

      You can go to Iceland and play on your concert without too worry about it.

  16. We will have to wait, because the qualities are to poor.
    Perhaps many of these quakes will be reviewed or deleted.
    But nevertheless, this is a heck of a swarm.

  17. How about the 3.6 in Eldey?
    Still poor quality, but looks like the whole ridge is being affected.

    1. Lurk:
      Difficult not to see I rising column from this last stack.
      Perhaps the perspective?

      1. No… that’s what the latest batch did. Started at 2.5 km down and spread upwards and downwards.

  19. We just had an earthquake, that could be clearly felt here in Reykjavik. According to the SIL network the strength was around 3,7.

  20. That’s a quake. And not that poor. Krýsuvik again.
    The intensities are increasing.
    Do I see seiches in Reykjavik lake?

  21. According to EMSC
    A 3.7 happened
    24 km S Reykjavík (pop 113,906 ; local time 09:05:59.5 2011-02-27)
    15 km S Hafnarfjörður (pop 22,289 ; local time 09:05:59.5 2011-02-27)

  22. The 3.7 was felt in Reykjavik? Wow, that´s astonishing, seems like the swarm is getting into a new mode.

    — been a reader here for months, 1st post now, love the blog —

  23. Biggest earthquakes during the last 48 hours
    Size Time Quality Location
    3.7 27 Feb 09:05:59 90.1 5.1 km NNE of Krýsuvík
    3.6 27 Feb 08:20:25 57.5 40.8 km ESE of Eldeyjarboði
    2.9 27 Feb 05:46:03 90.0 5.1 km NNE of Krýsuvík
    2.8 27 Feb 05:20:31 90.0 6.7 km SW of Krýsuvík
    2.7 27 Feb 05:20:33 90.0 5.3 km NNE of Krýsuvík
    2.5 27 Feb 07:05:02 90.0 3.5 km NNE of Krýsuvík

  27. just got online – that’s a lot of activity….

    (good it is sunday, I can take a look every now and then)

  28. I think I saw them at Austuvöllur cams.
    They are quite steady, the winds are not that high, and suddenly a jolt. Than, back to immobility. Different from the continuous shaking from the winds.
    Coincides with the reports.

  29. @Lurking:
    You need some rest.
    Me too.
    Tomorrow, lots of plots. Present activity is showing no signs of waning. For now…

  32. Wow, this is just crazy!!

    As seattlites pointed out it is interesting that many other stations (eg grimsvötn and katla) showed a low frequency jump some hours ago, was this just the krysuvik earthquakes that showed up? And if so why was it primarily in the low frequency when the original earthquakes at krysuvik were primarily in the high frequency? does the low frequency shockwaves move better through the earth?

  35. This is the biggest earthquake swarm I have seen in Iceland, since I start following the earthquakes maps (after Eyjafjallajokull eruption). Were as many quakes before the Fimmvorduhals eruption?

  36. Good question, is there an interactive map or database somewhere online where it possible to go back and see the numbers, strengths and locations of earthquakes graphically like in the IMO plots on a given day in the past , for example in the period leading up to Eyja’s eruption?

  37. The Eyja eruption had a similar EQ picture as this does. However since it is currently unknown if the tremors are tectonic or magmatic its hard to tell what will happen.

  38. Correction..If im not mistaken the Eyja eruption had over 1000 EQ´s before the eruption. But Krysuvik is on its way. The swarm doesnt seem to want to stop and is now over 340 EQ´s in the last 48 hrs.

  43. Hi all is there any relation with the swarm of quakes and the uplift of gps data available, of this area? if so this could be interessed, when there is any ullift it could point that some magma is flowing into this erea.

    regards

    Rick

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