Posted on by Jón Frímann

Earthquake swarm in Tjörnes Fracture Zone

Today (18 October, 2011) at 08:53 UTC a earthquake swarm started in TFZ. So far this earthquake swarm is small in nature, only about dozen earthquakes so far. But the largest earthquakes have been with the size of ML3.6 according to IMO automatic earthquake detection system (called SIL). There is a good chance that this earthquake swarm is going to continue for the next few hours. But it is hard to know that for sure at the moment.


The area with the earthquake activity in Tjörnes Fracture Zone (TFZ). Copyright of this picture belongs to Iceland Met Office.

There are no volcanoes in the area where this earthquake swarm is taking place.

Blog post was updated at 11:58 UTC on 18 October, 2011

164 Replies to “Earthquake swarm in Tjörnes Fracture Zone”

      2. GVP has gone insane, instead of the micro-icelandic volcanic Island I got Bridgeman Island Volcano in the Antarcti, which is exactly as far away as you volcanically can come from Iceland… 🙂

      3. No, you are just missing the “=” at the end. It doesn’t translate into the url properly. So you get the default page not found web site that GVP has.

      5. No. The one you found is new to me. The one I am trying to find was submarine & extinct (hence the difficulty in finding it again) and, if memory serves correctly, was nearer to Iceland.

  4. Think Bob was having a coffee break:

    1106061 18/10/2011 11:44:52 27.5800 -18.0139 15 1.6 SW EL PINAR.IHI

  6. The yearly summaries of seismic activity show – it seems to me – that the region is quite an active one in terms of quakes. Take the year 2009, for example:
    http://hraun.vedur.is/ja/viku/all/skj2009m.png

    or 1997:
    http://hraun.vedur.is/ja/viku/all/skj1997m.png

    I picked the years randomly, but other years show a similar picture. Except the early nineties (before 1994), where the region seems to be absolutely quiet. However, that may be a case of missing data.

    1. Actually, I read that they suspect that an eruption happened before the quiet time in 1994. But, that was just a theory.

      Otherwise it is a very seismically active zone.

  7. General question here: Recently there were a lot of EQ in the mediteranian sea (greece, spain, canary islands) along with the EQ swarms in the german/polish border area plus the EQ activity in Iceland – not to forget the recent eruptions in italy.

    Is all this somehow related due to a tectonic plate shifting? What i am trying to say is, is “our” tectonic plate traveling much these days and can this cause the recent EQ activity europe-wide?

    1. Possibly, there have been other EQs on the Mid Atlantic ridge. Also there has been a lot of activity round the Pacific Rim, which must ripple round the globe.

    2. The quakes in Greece, Turkey and to the east may be related to the activation of the Anatolian fault.

    3. No, it is just normal activity due to tectonic shifting. Nothing new.
      You also have the “Lurking technology skew”, ie that we now have vastly more equipment that is much more sensitive, so we find almost all of the quakes today. So, now it SEEMS like we have more quakes.

  8. Bardarbunga seems very active at the moment . This may account for the tremors at Skrokkalda and Grimsfjall.
    Tuesday
    18.10.2011 13:14:04 64.781 -17.301 3.9 km 1.2 45.96 4.4 km W of Kistufell
    Tuesday
    18.10.2011 12:31:14 64.775 -17.299 4.2 km 2.2 83.4 4.3 km W of Kistufell
    Tuesday
    18.10.2011 11:19:51 64.770 -17.308 6.7 km 1.5 99.0 4.9 km WSW of Kistufell
    Tuesday
    18.10.2011 08:44:20 64.769 -17.310 5.4 km 0.6 99.0 5.0 km WSW of Kistufell

    http://hraun.vedur.is/ja/oroi/grf.gif
    http://hraun.vedur.is/ja/oroi/skr.gif

    For those who are new to Jon’s Iceland Blog and not sure where this volcano is situated it is under the ice cap at Vatnajokull, next door to Grimsvotn. Here is a map
    http://hraun.vedur.is/ja/vatnajokulsvoktun/Vatnajokull.jpg

      1. I think it’s east from the glacier. Could be a part of askja fissure swarm? I don’t know which way it goes to the south an how far.

      2. Afternoon
        These clusters seem centred on a ? rift system NE of Kistufell and another to theSW of Trolladyngja where there’s a series of linear en echelon eruption cones rather than on Bardabunga

      3. It is the southern part of the Askja fissure swarm.
        I do really not like what Askja is doing right now.
        Remember that we have no current GPS-data. My calculations earlier today was on extrapolation of data 2007-2009.
        Sigrun has a plot, but I cannot find it.

        What I think that we had severe uplift during the large and frequent quake swarms in 2010 and early 2011 that we have not seen.
        Because what we are seeing now looks like activation of the entire length of the southern fissure swarm of Askja, and that has not been active at all since the eruption of 1874-5 VEI-5(large) eruption of Askja.

      4. Found this new text about Askja: Key, J., R. S. White, H. Soosalu, and S. S. Jakobsdóttir (2011), Correction to “Multiple melt injection along a spreading segment at Askja, Iceland”, Geophys. Res. Lett., 38, L10308, doi:10.1029/2011GL047491.

      5. It seems to refer to: Key J., R. S. White, H. Soosalu & Steinunn S. Jakobsdóttir (2011). Multiple melt injection along a spreading segment at Askja, Iceland. Geophysical Research Letters 38, L10308.

        Saw first the other one.

      8. Could the reason be the thinning of the Vatnajökull icecap? It seems that Höfn is moving up as it is known to have done since about 1900 when the icecap was at maximum. To a layman the others seem similar except of course for Grímsvötn that are all over the place.

      9. No, there is one situated directly inside of the caldera of Askja. It used to be accesible from Singrún Hreinsdottirs homepage before. You know that list with all of her research GPS:es. They are of course there, but I just can’t get the links any longer.
        I wish she did one of her marvelous pages, but this time of Askja. I wish I wish… 🙂

      10. SK:
        Höfn is mainly lifting due to the uplift caused by the removal of the 3km Icesheet that covered the entire northern hemisphere during the last Ice-age. We have even higher uplift in northern Sweden due to this.
        The Ice-age compressed this part of the world with a suspected 300 metres in some places, mostly so at the High Coast-area in Sweden.

  9. Is it possible that the eruption at El Hierro is coming to an end? The tremors have really died down.

      4. It is like Jón said many times now. The fissure will probably close down, inflation will start again, and then all of a sudden a new fissure vent opens up.
        To many vents had opened up, the systemic pressure in the dyke fell, magma flow slowed down, the fissures closed.
        Now we just have to wait for the next part of the eruption.
        I do hope they do not let the population of La Restinga back, because the eruption will most likely be even closer to land, or even onland.

    1. Could not agree more sunsets over eyjafjallajökull have been the same over the last week .

  15. Harold Camping predict judgment day on October 21 2012 ;).
    Maybe some volcano on Iceland will erupt that day.

    1. Hmmm……………..so far he has not been too accurate with that prediction. 2012? – he has deferred it again. Around the globe, volcanoes are erupting all the time, so it is more than likely that a volcano would be erupting. But if were to be the end of the world, it would be pure coincidence. I would not lose sleep over it.

      1. There is an idiot born every second… all of them ladled with twaddle! 🙂

        A drop like that would imply that Katla is having a VEI-6 and we missed it.
        It is probably ise on the dish. Grimsvötn did a 50mm dive in just few days out of ice… 🙂

      2. Dunno if Jon will permit this!
        Does Orkjuveita vave anything to do with Orcs (as in Lord of Rings)? Ie ‘orrible beggars!

        If they pump sewerage + gasses down Hengill into the MAR and via a few faults, ( as the other nights folly!!)you would get the gas, brown stain and ‘steaming floaters’!!!
        Sorry its wedding anniv ‘n’ Im ‘lubricated’ (The Singleton -Speyside)

      4. Or I might be wrong and it will be the pigbearsheep…
        For the 21th I have only one prescription, and it is MORE COWBELL… (really wonder if anyone knows this ref)

      6. Sea-lion
        sea-cow
        sea-horse
        sea-slug
        sea-snail
        (old)sea-dog
        sea-sheep???
        Anyway, Reykjanes ridge has joined the tremor party now!!
        what the hengill will mag6 do??

      9. Ahem, peter, for future reference.
        What would “The volcano known as Bob” be if you wrote it in one word in gaelic? By the way, is welsh a modern version of p-Gaelic?

        We should of course not use Icelandic if Bob showed up in Iceland.

      1. Or more likely, yet another GPS-satelite has dropped out of the loop, and gone dead on us. Problem with no new satelites being hoisted is that sooner or later, they all go poop on us. Thank Godabunga that I now how to use a sextant (six-tant, bahrgle…).

      2. Or the Reykjavik one they all measure relative too has moved. Lets blame the fracking at Hengill.

    1. This might be a small local event. I do not know if you have geophone or not. But long period seismometers are not good at recording local events at close range.

      1. It was a small and indeed local event, and I do not possess a geophone.

        – What kind of local event?

      3. A tremor caused when a herd of icelandic sheep passes by, while they are running away from Carl chasing them?
        😉

      4. This might have been a earthquake. But this also might have been a explosion. But it is hard to know that for sure without the exact time.

        But given the wave pattern. I would say that this was a earthquake with the size of ML1.0 to ML1.9 or something close to it.

      7. *Giggles*

        As my disclaimer stated; This was rather off topic.

        The “quake” was produced by (my then) unborn son in his 26th week of incubation.

        I reckon his mother might have felt it as a ML2 or so ^^

    1. Soooooo right in the middle! I love it when he “explores the studio space” – a bit like I imagine Carl&the Willing around the BBQ by the Dalek…

      3. Guess this must be the same fabric as Diana’s panty…
        Autch. I’m a sad person, I know…

      5. Oh, it’s in the link from the photo and there you find more sheeps…(perhaps that is what they do in winter times
        and …
        Now for Something Completely Different

        …volcanos!!

      6. I think You and Carl should have a few rehearsals so that you are ready for the big day……Tell us when and the other Ladies and I can give some constructive criticism 🙂

      1. Jon! That is such a diplomatic way of telling us to behave and stay on topic 🙂

      3. Sad news.
        Do you already have concrete ideas for the new name of your blog? It has clearly grown larger than Iceland. Great development around “Bob”.

      4. I am working on a new name. See earlier comments in that regards on few of the older blog posts.

        New name is going to be ready around new year 2012. This type of thing takes me a while to think over.

  22. …reminding me that there’s a warm bed waiting for a cold and rainy night ahead.
    Sheep well, volcanoholics of the wold. Erm, sorry, was the last one… Sleep well, of course.

  23. Given up trying to find that submarine volcano for a bit. So back on El Hierro:

    http://earthquake-report.com/2011/09/25/el-hierro-canary-islands-spain-volcanic-risk-alert-increased-to-yellow/

    – People are not allowed to return to La Restinga
    – Ramon Margalef has left Vigo for Tenerife (intermediate port) and El Hierro
    – The green stain which was a few km out of the El Hierro coast the last couple of days, is now in the La Restinga port and surroundings (this was predicted by Mr. Santana yesterday evening based on the maritime current and wind direction).

    1. Photos of the green stain in La Restinga, from AVCAN:
      http://a8.sphotos.ak.fbcdn.net/hphotos-ak-snc7/294744_2225251629674_1199261183_32114784_243923005_n.jpg

      http://a4.sphotos.ak.fbcdn.net/hphotos-ak-snc7/293630_2225252549697_1199261183_32114786_341643990_n.jpg

      Also, I was trying to get today’s satellite photos from either of the two MODIS satellites, to check on the stain/plume development, but no luck. It was completely overcast over El Hierro when Terra passed and Aqua’s orbit didn’t come close enough to see the Canaries. Tomorrow then.

      1. It has frightened away the RV Ramon Margalef too – it has gone back to do oceanography research in Vigo port.

    2. Me too. People should not come back to this yet. No way the air can be clean when the water is so polluted, whatever measurements say.

    3. Dunno.. if I had to have a vent that close I’d be pretty happy that the ash “cloud” is contained within the water.

      Of course, fishing would be out of the question, and gas emissions could be problematic if the wind shifts.

  28. While looking for Karen’s submarine volcano, I managed to google up this:

    Hardarson et al. 2010,
    Geothermal Reinjection at the Hengill Triple Junction, SW Iceland
    http://b-dig.iie.org.mx/BibDig/P10-0464/pdf/2308.pdf

    Apologies if this has already been posted, but I thought it might be of interest in light of the discussions around man-made earthquakes…

  29. Update 18/10 – 20:15 UTC: Video of the Jacuzzi Eruption zone filmed today Tuesday!. It is a surprise for us that the whirlpool is still present and it contradicts an earlier report that the stain and Jacuzzi was not noticed anymore. The video was published by Diario El Hierro a well informed local newspaper.
    If we put the video in relation with today’s harmonic tremors who stayed unchanged all day and connect it to the time if filming, which must have taken place during the morning hours, we would be surprised that the vent shut off completely. We expect that the eruption still goes on at a weaker strength?
    http://www.youtube.com/watch?v=NgyVcIDPyCI&feature=channel_video_title

    1. I try to compare the video to yesterdays pitures. Seems to me that we have more bubbles now. But maybe it stopped later on?

      2. Agree the bubbles are more intense in the clip. Also the sea is a lot greyer. Unfortunately nothing else is in shot so we can’t get a feel for its size or location.

      3. That is true Karen, there is no good reference for the size of the jacuzzi. Very difficult to say if it is bigger or smaller than yesterday. Hope they go on making videos, prefereable with a reference point on shore.

    2. Armand,
      I’m not an expert, but the vent has had no effect on the GPS inflation ( except perhaps to halt it) And I would not expect the venting to have done anything significant towards the release of the 50million cubic metres of magma accumulated under Hierro. That is comparable to the volume of magma erupted by Eyjafytlajokull and the sub sea activity is nowhere near that level of activity. So I think the vent and jacuzzi are a minor event compared with what might happen.
      But the youngest dated lava on El Hierro is 12000y old, so activity such as we see now may have happened repeatedly without detection and without lava appearing at the surface. For the people of Hierro I hope so. But for the experts it must be very difficult: less tremor , few earthquakes , static GPS. So they have less information on what is happening at depth than they have since July.
      Peter

      1. + more and more protesting people who want answers nobody can give at the moment. We might see images tomorrow from whats going on by a ROV who was carried by plane today – a story which is not over yet, even when it completely stops

      2. I suppose that, unlike Icelandic schools, geology and volcanology are not mandatory on the Canaries curriculum?
        A population that has been taught about what happens, the uncertainties, and the sheer scale of eruptions is more likely to accept safety measures than a naive population.
        Also Iceland gets an eruption every 5 years or so, so the authorities could send out evacuation notices around Eyjaf by text message.

      3. As I have said many times before, we are spoilt by the IMO, and so in a way are the Icelanders too… IMO is very very good, and that is why the Icelanders have learned to trust them.

      4. Iceland has a history of frequent volcanic eruptions so IMO and the Icelanders have had a lot experience, unlike the Spanish authorities & the population of El Hierro.

        Not sure the Canary Island and Spanish authorities fully appreciate what could happen, which is why they are not being as decisive with the population as they perhaps should be.

        There is enough data to show there is still a potentially large problem. No-one would blame the authorities for evacuation given the level of uncertainty at the moment; but they would blame them if evacuation was inadequate and there was loss of life.

      5. Life has learnt me one thing. If you are inexperienced, hire in a big gun to solve things, and learn as much shooting as possible while you are at it.
        They should have called for someone from either IMO or INGV. And then tried to learn as much as possible from all the wealth those two bodies have.

      7. excellent – looking forward to it. Nagoya data is not user friendly in its undigested state.

  30. Activity Vatnajökul area and Askja!

    There are 3 developments in the area of Grimsvötn and Askja:
    1. Grimsfjöll seems to be doing something that is not wind-related. My guess untill someone hits me over the head is that it is a small and gentle Jökulhlaup of melt water from this years eruption.
    2. Tremoring at Hámarinn volcano. Either due to Bardarbunga being restless, or as I believe more likely this time around, due to 3.
    3. Askja has entered a new phase of activity caused by the heavy influx of new magma. I think we will see an eruption within the next 10 years there. Due to location of activity that seems to be spread all over the vast Askja system, anything belove a VEI-4 would be a surprise. We have allready seen heavy, prolonged and frequent quake-swarms at Herdubreid due to magmatic infusion into the dyke running that way (perhaps into a secondary chamber at Herdubreid).
    We have also seen an accelerating (this replaces my earlier comment on new magma in Askja due to new information) magmatic uplift and intrusion into the Askja central Caldera. There is also evidence of both gravitetic increase and magmatic uplift into the Askja Lokatindur area with a quake-swarm hitting the fissure trending to the south (towards Hámarinn), we have also seen quaking and gravitetic anomaly shift and activation of the Sveinagja Graben.
    Pretty much the only area not affected is to the ESE. This activity seems to be in all of the known active parts of Askja, more so than during the 1874-5 eruption. This is the first time we have seen activation of all of the sites for both of the very explosive VEI-5s that Askja have had.

    Thank you to the person who gave me the minutia about Askja! It was very helpfull to receive the information.

      2. Well, Carl, Jón posted surface chart, less there. BUT THERE IS STORM at ALTITUDE (and this is affecting GRF meter). Today, as seen on RUV Weather News, there were lots of “mountain waves” over Vatnajökull and the southern mountains, including Mýrdalsjökull, these do not form unless wind is 25 knots OR MORE.

      3. You know, there is a windmeter at the at the SIL-station? So the wind chart is accurate to the SIL. There was a storm before, there will be a storm again, but right now it is “calmish”. But, I didn’t say it couldn’t be somethng else.

    2. Some of the tremor activity at Vatnajökull could be caused by run off from heavy rain, avalanches and / or melt water, given that there has been heavy snowfall in some areas.

      Difficult to say whether or not Grímsfjall is doing anything; the plot is always lively.

      1. I know, I just meant to mention Grimsfjöll in the passing getting to the new data of Askja. Seems nobody noticed Askja, and instead went on about winds on Grimsfjöll. 🙂

      2. Tonight I notice many things, but as storm is passing, these are just not reliable. Interesting how swarm close to Reykjanes lines up, possible dike intrusion? Kistufell quakes are possible indicator of movements in or about the Bárðarbunga system, but could be “reaction” from Askja area. Godabunga has also been active today (32 in last 48 hrs) . Only Hekla shows … nothing. No ups or downs either…

      3. I don’t think there has been a jökulhlaup sort of thing going on around Vatnajökull, because last night and also now the water measurements of IMO don’t indicate a such. http://www.vedur.is/#syn=vatnafar All of the rivers around it are “green”, just Skjálfandafljót does not have a lot of water which could be due to the wintery weather conditions in the region (snow). http://www.vegagerdin.is/english/road-conditions-and-weather/the-entire-country/island1e.html By the way, I’m not working for Icelandic Road Administration or such, just have the Icelandic habit of looking at these maps for information about current weather and road conditions (blue on the roads means snow or ice).

  31. The volcano known as Bob, if located in Wales would be ‘y llosgfynydd sy’n cael ei adnabod fel Bob’ (uh closvunnith sin kyle ay adnabod vell Bob)

    Yay!

    1. No, yllosgfynyddsy’ncaeleiadnabodfelBob would be the Icelandic name, we can not in all farness have an Icelandic name on an Icelandic Bob could we?

      The Welsh Bob would of course be HursjuttondökvulkanenBobupphär 🙂

  32. We have a bigger one: Yr Wyddfa.
    But its past its best, got a railway up it nowadays.

  35. Well, since people like prophets I must share my absolute favourite with you. Everytime life seems futile, or I am down, I read Hiroyuki Nishigaki. He is perhaps the looniest person to be still on the loose. His book is a must have, but for an entirely different reason than he envisioned when writing it.

    One of his pearls of wisdom is:
    “Besides shooting out a big blank from your buttock, you can feel as if your root chakra leaked sweet hot mucus.”

    Link to the front-page of the book, not for the faint-hearted (not graphic, just mental assault on sanity):
    http://www.sfwchan.com/pics/69658311.jpg

    1. Maybe not as Loony as you think!
      Like many ideas and concepts of the Far Eastern cultures it is difficult to translate them into English. I believe his discussion about space travel is more about gaining a similar mental state as in transcendental meditation.. but I could be wrong.. his Engrish is really not good!
      However In Tai Chi it is essential that you breath correctly to gain inner energy. This breathing entails releasing and constricting the muscles of pelvic floor and lower core muscles…ie clench Butt…. relax butt .
      Hey! and it does work! Honestly…. Tai Chi lowers blood pressure, keeps you supple and relaxes you… I have be practising now for 6 years. I could go on but I get boring 🙂

  37. Using the latest data from Prof. Sagiya’s GPS network, and obtaining daily rates both from actual measurements and interpolated 2 day rates for missing data, I then took ten midpoints for those stations and the average rate of the two endpoints in order to lock in a more realistic deformation set.

    The reason is simple, DPlot uses a simple quadratic function to fit the surface (that or linear) and there is no way to account for the stiffness/pliability of the crust. I don’t have the skill needed to fabricate a more realistic deformation model and am not really sure how I could apply that to a spread sheet once I figure it out.

    Meanwhile, this should be closer to reality that my previous vertical deformation plot.

    http://www.youtube.com/watch?v=7s8z8FBXAnE

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