Posted on by Jón Frímann

False alarm at Grímsfjall volcano [updated]

I really did think that something was going on at Grímsfjall volcano today. There was something going on. But whatever it was. That does not appear to be volcanic or related to any volcanic activity so far. Most likely this was a change to hydrothermal activity in Grímsfjall volcano or some movement of the ice covering Grímsfjall volcano close to the seismometer on top of Grímsfjall volcano.

But so far Grímsfjall volcano remains quiet.


Picture is from the web site of Icelandic Met Office. Copyright of this picture belongs to them. Click on the picture to get full size.

The change in the tremor plot can be seen at the end of this tremor plot from the web site of Icelandic Met Office.

Update: This odd behaviour on Grímsfjall seismometer continues. So I am wondering if the false alarm might not be so false after all. But a eruption is not starting. It lacks the earthquakes of a magma pushing it’s way up the crust. But there is something going on at Grímsfjall volcano. That is for sure.

78 Replies to “False alarm at Grímsfjall volcano [updated]”

  1. Jón, could the earthquake at Bardarbunga be related to Grimsfjal?
    Friday
    25.03.2011 21:14:34 64.669 -17.438 2.7 km 1.4 79.34 5.3 km NE of Bárðarbunga
    Shaky day for Iceland.

    1. If this is a dike movement that has not yet created a earthquake swarm that might well be. But it is impossible to know until something more happens.

  3. How about the small quakes around Hekla?
    Couldn’t they mean the unrecorded signs of a pending eruption which weren’t felt before the new monitoring system ?

      1. But only the high frequency bands have an anomaly, so this can’t actually be induced by magmatic moments can it?

  5. Updated Grímsfjall plot. The cumulative seismic moment doesn’t much hint of a substantial increase in slope. Until that plot series gets it’s nose seriously bent out of shape, turning upwards, my intuition says Grímsfjall remains as a tease of a ‘failed eruption’. 😀

    When I am demonstrated wrong, I will gladly accept being told to go eat my hat.

    1. Well I think on these short-term events the cumulative seismic moment won’t give us any hint. This plot streches over more then 10 years, so even a large quake will apear like only a tiny tiny increase. Also we haven’t seen much earhtquakes lately, so I’d say the line would rather go flat than steep up. 🙂

      1. A quake has just happened:
        Saturday
        26.03.2011 18:13:08 64.398 -17.334 3.6 km 1.5 90.01 3.0 km WSW of Grímsfjall

    2. Raving

      “When I am demonstrated wrong, I will gladly accept being told to go eat my hat.”

      Noted. What flavor of fedora do you prefer?

  6. Jón, I’ve been wondering about how are you doing with your moving plans.
    I’m just waiting for the end of the usual “post-summer drought” to recover, so I can afford all the books I need, from your Amazon link, and resume “donation mode”. 🙂

    1. I plan to move back to Iceland no later then July. But if the company that I am renting my apartment from allows me I am going to move back to Iceland in early May (end of April).

      That is going to put a rather unpleasant gap in my work for the months when I have to live with my mom and dad. But that is just how it is. But next summer I am going to have to work and to pay down my debt faster. All next winter is just going to be school for me in Iceland. But I plan to get off welfare by getting qualification in few fields. So I can work on them on the side when I am writing this blog, eBooks and more.

      1. Jón,
        Let’s look at the bright side of things.
        I know that family sometimes can mean a lot of hassle, but also they are those in whom we can always count on.
        You have an ongoing, long term, project there.
        Perhaps this was not the best time to take such a big step.
        Meanwhile, you can count on us.
        🙂

      2. The exchange rate of 21,70 ISK = 1 DKK is quite bad. This is also part of the reason why I am moving back to Iceland.

        But I have also found out that it is hard to monitor volcanoes over 2000 km away from them.

        So I am going to just take a longer trips (up to a 1 year or more) and travel more and just live in Iceland instead.

        Thanks for the support as always. 🙂

      3. This was a necessary step for me. But my plan didn’t work out as I had hoped for and that is just the way it is.

        At least the danish that I have to learn in school in Iceland is going to be easy.

  8. There has been some small earthquake activity around Hekla, both to the west and to the east.

    I think this could show something. If in the next couple of weeks earthquakes start under Hekla and an eruption happens, I wouldn’t be surprised.

    1. The earthquakes located west of Hekla are purely tectonic and they happen on small faults which run throughout whole South Iceland, they are unrelated to Hekla.

      The earthquakes located east of Hekla are related to Torfajokull volcano, the earthquakes that happen within this caldera are caused by subsidence or because of hydrothermal processes.

    2. I’ve always been told that to get a feel for how a volcano is going to behave, take a look at how it has behaved in the past. It’s usually pretty similar.

      With that in mind, remember that Hekla’s last event had virtually no run up in quakes. They broke south west of the summit, migrated east and north becoming more shallow, then arced north to the summit and popped the cork.

      All in less than a few hours.

      In fact, the quakes only became strong enough for a person to feel them about 30 minutes before it erupted… and that was if you were standing over top of where it happened.

      Let’s just say that Hekla is not the safest place in the world.

  10. Still, I think we are getting pretty close to a Hekla eruption. These little changes in stain-meters and increase in quakes around. Might I’m wrong.

    Could someone post me please the earthquake map 1 or 2 days before the 2000 Hekla eruption, before 2004 Grimsvotn eruption, and also before the Fimmvorduhals eruption? I don’t know where to get this data.

    ps: steep increase in tremor in Hveravellir, and still the tremor at Grimsvotn for the past 2 days

    2. Hekla is non-seismic throughout non-eruptive phases, the earthquakes that do occur within the vicinity of Hekla are all purely tectonic. There are lots of papers and studies about this, so if you don’t believe me, find it out yourself.
      So far, there has not been a good way to predict Hekla eruptions, only small changes (snowfree-patches, dry streams) might be (not proven) indicators of an impending eruption. The earliest volcanic-related earthquake that happens are about 30 minutes before the eruption, which is the same for strain-measurements.

      I do agree with you that the volcano is ‘overdue’, but that’s just pure statistics. There have been many larger dormancy-periods of Hekla.

      So what I am actually saying, no one knows. You can’t know, we can’t know, no one knows.

    3. Strain measurements near Hekla corrected with barometric pressure have been pretty anomalous during the last week. Burfell and Hella are not anymore following each other like they used to (except a few transients).

      1. Yes, I know there is no clear way of knowing Hekla warning. I know also those quakes are ascribed to purely tectonic.
        But call it a feeling that Hekla is about to go. It’s also my wish!

        I am under so much expectation as possibly the pressure is under the volcano now. Lol

    2. I think he said he was going somewhere. Something to do with his work. Can’t remember where, but I did not get the idea it was perminant, so perhaps he will be back.

  12. Looking before the 2000 eruption, Hekla had only 2 earthquakes about 10Km SW, one month before the eruption. Usually, the area has no earthquakes at all.

    Since January, 4 earthquakes have occurred on that same spot. This hasn’t happened in past months. So, I think an eruption will happen in soon. But, you never know with volcanoes.

    1. Yeah, we are all expecting something to happen at Hekla, but I think Pieter is right.
      The only reason we would have to think differently now would be the fact that the monitoring system is far more sensitive than back in 2000, but then again, more sensitive to tectonic earthquakes, which leaves us in the same position.

  13. A minor earthquake swarm is ongoing at Reykjanes peninsula. It is not far from a small mountain named Keilir. Most earthquakes in this earthquake swarm have so far been less then ML2.0 in size.

    1. An eruption at Keilir would be a pretty awesome sight, from Reykjavik.
      Furthermore, the mountain just looks like a pyramid, and is so well seen from the city.

  15. LurkDood, looks like that wave that started in the Baja gulf ‘might’ be hitting the Laguna Salada. Also a mini swarm including a 3.4 just south of the SAF terminus.

    Maybe nothing, but watching for more.

    1. My bet is on the 4.1 at 27.761°N, 111.782°W as being in that wave “set” (for those listening in, this is a purely hypothetical construct)

      But… the area around the Laguna Saluda is quite noisy.

      The problem is that I have no idea of how fast these “waves” are moving, or what is normal. The entire fault system hooks and binds at different locations, and how quickly the stress would traverse that is a guess. Also of note, is that the entire system is alive with smallish events all the way up to Rouse Hill (San Jacinto fault) and of even more interest is the group 5 miles NE of Indio. That bears interest since that is a knuckle point where the SAF turns back to the west north of the Salton Sea… in other words, right in the locked area of the SAF where it pushes that mountain range up.

      4. You are right, in this video looks like a low cloud.
        Just converting & uploading better (earlier) version where either the cloud is coming from very specific gap between mountains or there is steam rising.

      5. It is just clouds. As Katla doesn’t make any steam. But the hydrothermal areas are all under ~600 meters thick glacier and don’t make it too the surface.

  17. If its any consolation, I’m not really sure that Hekla follows typical volcanic behavior. Being an overgrown fissure structure, it might be tectonic forces that set it off and not magma accumulation. It just goes with whatever it has stored up when triggered.

    Of course… I could be wrong. Wouldn’t be the first time.

    NOTE: THE G/D JAVA ADVERTS BLOW GOATS AND MAKE CAPCHA ON A PHONE NEAR IMPOSSIBLE.

      1. Registered users don’t get capcha. So that is one way to get rid of it. I have to have it, otherwise it would be a spam bot festival in here.

    2. What ads are you speaking about ? This blog currently does not have a mobile plug-in running. But I plan to add it soon. So better times are coming for mobile users. 🙂

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      The side adverts are no problem, but the one that demanded front and center pissed me the [expletive deleted] off. This was with pop-ups disabled. I finally managed to get past it by turning off Java, backing up to the previous page, entering the capcha, turning on Java, then hitting submit. Even with that, the @#$ phones auto-correct “feature” forced me to try that about three times since it figured I meant something else when I entered the capcha. I expected that.

      1. I don’t allow any pop-up ads on my site. So please let me know if that happens. As I am trying out a new advertiser called Chitika.com. I just have banners from them.

        I think that you might have suffered from a lack of window space on your mobile device. But I have many small ads on the site and that all takes up space on a small screen.

  19. It still looks like a cloud forming to me. That happens when warmer saturated air hits colder air and starts to condense. Here in the UK we see it a lot in spring as the land warms, because warm air rising hits colder air above and here we often get enormous clouds building rapidly. If the build very rapidly e.g. 50 sq miles of cloud from blue sky in 30 mins, they turn into spectacular thunderstorms.

      1. This is odd. SKR and KRE show nothing peculiar. Yet, they are the closest to GRF, and they should show something is Mister G (Grimsfjäll) decided to start a show.

  21. Hi, newbee here again, I have been watching the earthquake and tremor charts for a wee while now – I do understand the whole concept of harmonics and the sound waves generated BUT … idiot question, can you please explain the significance of the Hz bandings and what we should look for to show trouble brewing. I realise its the blue 2-4HZ wavelength that is significant but why. The blue 2-4HZ readings have also lifted from the base line is this also significant?

    (a thousand sorry’s to all those who are far more up to speed and are groaning at me.. I just find this all facinating and would love to learn more ..)

    1. Red band (0,5 – 1,0 Hz) is the most relevant for magma movement. Blue line is very sensitive to weather effects (e.g. wind), and the green line seems to be affected e.g. by ocean waves (especially on coastal locations). Magma movement is sometimes seen also in the green band.

      As Carl used to say, all errors in this post are on the house (of Jack @ Finland).

  22. … em thought I should add I do know the hamonics can be a signal of magma moving in the lower chambers of the volcano… just in case you think I am completely stupid…

    1. No question is stupid… unless it’s a repeat of the last question that was just answered… unless of course more elaboration is needed to explain it… in which case it turns into a vicious cycle of repeated material… 😀

      Lower frequencies do propagate further, and has been mentioned, the bands have different things that show up in them.

      Harmonic tremors and background tremors are two different critters though.

      Harmonic tremors are a pretty specific indicator of magma on the move. The key is to pick out when that background tremor has actually turned into that signal. I’m not sure if that distinction can be made on the tremor plot… it does show up well on Jón’s helicorder plot when it’s close enough to register. The tremor plot just doesn’t have the close in time scale so you can figure it out.

      Another waveform that you might see on a helicorder, are tornillos. Dunno if they occur anywhere but Galeras, where they were first noticed (South America), but they seem to be artifacts of magma popping the fissures and opening up new passages. They make a screw shaped waveform. (hence the name)

      1. Thanks Jack and Lurking, so the trick is to study the pattern of earthquakes (actual and historic) and then the tremor graphs. I will also go and do homework on Galeras, thank you.

        I am a novice compared to you guys but am just fascinated with plate tectonics.

        So do you think the current activity in Grimsfjall is a sign that she is awakening? Would the tremor graphs indicate we are seeing the beginnings of an eruptive phase? Or can the normal background tectonic activity consistent with a constructive boundary give misleading signals?

      2. It will take a lot more to start an eruption. There will be at least a M3+ earthquake and they will probably be preceeded by many many other smallers earthquakes, days before the eruption.

      3. I took a peek in the history book, and I found out that Grimsvötn run up in 2004 was like this: 7-4 days before the eruption about 2-6 earthquakes a day, 4-1 days about 5-15 earthquakes a day. The eruption itself had a couple of M3+ earthquakes and dozens of smaller ones.

      4. The 1996 Gjàlp eruption seemed to have popped out of nothing (: earthquake silence).
        That could also be due to the lack of good measurement equipments around that time.

      5. I thought the Gjàlp was a result of that odd “non double couple” event under Bárðarbunga. Essentially Gjàlp was a convenient place to stick the magma.

        http://rses.anu.edu.au/~hrvoje/Tkalcic_etal_BSSA2009.pdf

        Note to the new… “double couple” describes the waveform’s “focal mechanism” solution that seismologists use to determine / describe a faulting mechanism. (which way the fault plane lies and in what direction the two sides moved)

        The non double couple event described in the paper showed no volumetric component, such as magma entering or leaving the system. One guess is that something low moved up and the sides around it moved down to fill the space… or vice versa.

        Either way, shortly after this Grímsvötn popped the cork at Gjàlp, leaving a few people scratching their heads over a possible interconnectedness between the two systems.

      6. The station “Hot 11” in the pdf file is where I used to live. They had the station there when I was 15 years old at my mom and dad farm.

  24. When Grimsvotn erupted in 1996, there was a big silence and only a couple of days before, major earthquake activity started in Bardarbunga. In 1998 and 2004, the eruption only had a minor swarm about 1 or 2 weeks before. So, look for a swarm and then you might have the eruption following within a few days.

    Hekla is even worse. Maybe one or two earthquakes in a couple of weeks before, then it pops out of silence. I like your theory, lurking, that Hekla is triggered by tectonics. If that is the case, then we might see a break from the 10 year eruption pattern, due to the big earthquakes in 2000 and 2008.

    Eyjafjallajokull was a very different case. A big swarm started out of the silence in late December, and it continue at a big scale, for 3 months, until the eruption started. It was clear that something big was coming. I wonder if Katla follows the same pattern.

    Does anyone knows the earthquake behavior before the eruptions of Askja 1961, Eldfell 1973, and Krafla in the 1970s?

  25. There seems to be another swarm of poorly located earthquakes at Krýsuvik volcano.
    And scattered small quakes all over the country.

    1. The scattered small earthquakes all over Iceland is normal. But the earthquake swarm in Krýsuvík volcano is growing. But it is also interestingly dense and confined to one location. But that is rather unusual. But it has happened before when a small fault is on the move.

      I am going to write about it soon as I finish fixing my Gentoo Linux Os.

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