Posted on by Jón Frímann

Earthquake swarm in Presthnjúkar volcano (Langjökull glacier)

A earthquake swarm of 70 something earthquakes have been taking place close to Presthnjúkar volcano in Iceland. This activity is tectonic in nature and is because of the rift zone. This volcano is located close to south end of Langjökull glacier, but Langjökull glacier covers two volcanoes (north Hveravellir and south Presthnjúkar). One at the north end and a other at the south end. This volcano last erupted in the year 3500 BC (?) according to GVP.


Picture is from Icelandic Met Office web page. Copyright belongs to them.

The earthquake swarm in south Langjökull volcano.

Earthquake swarms are common in this area and happen regularly. But last large earthquake swarm in this area was in June 2009. The largest earthquake that did happen today was felt in nearby area according to Icelandic news.

Icelandic news about this earthquake swarm. Use Google Translate at own risk.

Skjálftahrina á milli Langjökuls og Þórisjökuls (Vísir.is)
Jarðskjálftahrina í Langjökli (Rúv.is)

177 Replies to “Earthquake swarm in Presthnjúkar volcano (Langjökull glacier)”

  1. What does No one has been gosórói. mean?

    I would anticipate the obvious but that is never a good bet with Google Translate. 😛

  2. It is interesting to observe how swarms keep coming in an alternate, rotative, manner.
    The MAR is a very busy feature, indeed, and provokes a shift of tensions/accommodations through these “waves of swarms” that may eventually cause one of the “squeezed” magma chambers to erupt.
    Ever since I’ve been closely watching the earthquakes in Iceland I have come to the conclusion that there are many forces at stake here, and it is hard to pinpoint one volcano from another without taking into consideration the MAR’s routine.
    More Smørrebrød to Jón and müsli to Carl!

    2. I wonder if any work has been done along the lines of doing statistics or data mining on all this quake data.

      1. I’m pretty sure that some one is looking at it.

        That research group the published data on the “never before seen swarms” near Askja had used the SIL listing as back end data to augment what they collected.

        Personally, it took me a few months to find a semi-authoritative formula to convert the ML over to an Mo (moment magnitude). But even with that, it’s still sort of a crapshoot to try and compare to official published data on some of the volcanoes. I still think that they have the real Mo squirreled away somewhere. I’m up in the air about whether the other M value in the SIL list is an Mw or not. Logically, it should be. It’s the one they publish on the MET site and it would make sense that you use an ad-hoc standard that matches most of the press reports of other regions.

        The problem with that is that it could be wrong.

  7. Prestahnukur it very interesting volcano. According to several resources, it is said to contain a small magma chamber. Yet, a typical eruption is VEI0, but gives out 0,1 – 10 km3 of lava! And, it is still active with volcanic fissures that lie in direction southwest-northeast. They are said to reach among others under the glaciers Þórisjökull and Geitlandsjökull-Langjökull.

      2. Question ( maybe stupid, but…):
        Why is the MOHO in this picture like a trench? I thought that in the rifting zones (MAR) the MOHO was less deep… So in my understanding it should be excactly the other way round ( if you know what I mean).
        Or have I understood something wrong?

      3. Iceland is somewhat of an enigma.

        The Jan Mayen micro continent and most likely the fragments that make up Iceland are the remnants of continental material fractured off of Greenland and Europe when the Atlantic opened up. The whole of the Jan Mayen became submerged underwater and were welded to the Eurasian plate. (Jan Mayen island is the only part above water)

        The pieces that make up Iceland are possibly two micro-plates consisting of continental crust sitting on top of oceanic crust. This seems to account for why the crust in Iceland can be up to 40 to 45 km thick. Usually, Oceanic crust is much thinner, especially at spreading centers. Even extensional areas on continental crust usually wind up with thinning. (Basin and Range Province of North America, African Rift Valley etc.)

        This odd geometry would explain the thickness and the composition of some of the lavas that show up in Iceland.

      4. Thanks, Lurking. That makes sense.
        ( I was already afraid that my intensive reading the last months had scrambled my memory about these features *s*)

    1. this one shows the faultplane, am i right?

      thank you very much for the similiar plott and the two others : ) i really enjoy viewing your plotts!

      1. Well, if there is a fault plane.. it’s a rather diffuse one. No where near as defined in the last swarm that seemed to track along the edge of a dike.

        Lets just call it a lineament of what may be related fault planes.

      2. The faults there are NE-SW and E and W directed. Due to the West Iceland Fault Zone. That fault zones lies between Langjökull and Snæfellsnes volcanoes. It goes up to Vestfjörðs at it most north-western point.

        It is active, but is quiet most of the time.

  10. This has probably been mentioned here before, nevertheless ….

    Iceland earthquake locations are available for viewing in Google Earth

    Here is a Google Earth screen grab of the current situation at Langjökull

    2. It would be nice if it worked. The only think I have ever been able to get to work from that site are the bloated historical quake sets.

      1. It’s a lake.

        In the screen cap, Raving has geologic features turned on, and one of the features are bodies of water. That’s a polygon shape on a lake. (doesn’t mean there is water in it, just that its a lake or lake bed of some sort)

      2. See my post on ■Eartquake swarm in Hengill volcano
        about the EQ swarm going on at Yellowstone along with rise in harmonic tremors and a possible cover up by USGS.

      3. There is no cover up by USGS.

        There is however a lack of rational thinking among many people how believe this nonsense.

        (Yes, I might insult people. Deal with it as a grown up!)

      4. I don’t think it’s a cover up. Nothing I’ve seen on the helicorders or in IRIS Buds waveforms indicate or hint at some sort of hidden activity.

        The magnitude of some of those events would show up on several seismos across the region and it just isn’t there.

        The key thing about the various networks is that several different groups operate them. USGS, University of Utah etc.

        The Buds interface can be found here:

        http://www.iris.edu/bud_stuff/bud/bud_start.pl?BUDDIR=/budnas/virtualnets/ALL

        If you pull down the seed data, you will need a program like SeisGram2k to look at the individual waveforms.

        Its coded in Java, so it should run on pretty much anything. (and it’s free)

        http://alomax.free.fr/seisgram/SeisGram2K.html

      5. So bottom line then is why does the Univ of Utah and other quake reporting sites show the swarm, but there is nothing on the USGS site?

        Interesting how there was such a rash of internet activity about this.

      6. Why? Because they don’t comb through the data as well in order to make sure that the automated systems aren’t mis-reporting.

      8. Sorry, my mistake. There is no swarms shown on the UofU site. Just read some false info and saw all the spikes on the webicorders and came to the wrong conclusion. I can only see the “supposed” swarm on the site below which states it gets its feeds from USGS.
        http://quakes.globalincidentmap.com/

        So thanks for all the responses and reality checks on the hype out there. Very much appreciated. My initial response was that these were false quakes being deleted so its nice to have confirmation.

      9. Lastly, I can understand how the average naive web surfer out there looking for info could get very confused and paranoid about an entire swarm being deleted because they don’t understand the nature of false positives in quake reporting. To them, they see it, they believe it and when it is deleted, they cry foul.

        Just naive

      10. Heh…yeah, I’ve seen that site before. I tend to avoid it.

        A few months ago they held a Mag 6+ in Russia for about 2 or 3 days. USGS didn’t show it, none of the other Euro sites showed it. Much gnashing of teeth was done on the … “discussion” sites. Eventually it quietly disappeared off of the globalincident site.

        A mag 6.0 is strong enough to be picked up on a huge number of seismos.

  11. @Lurking:
    “Renato Rio says:
    February 12, 2011 at 23:12
    @Raving:
    Wow!
    This is something that was missing.”
    Please, don’t get me wrong.
    So far, the only EQs we could see on GE outside the US were those stronger than 4.5.
    I meant this to be a complement to your plotting, in terms of geographical details and so on. Thought it could be a help to superimpose your plots. 🙂

    1. No prob. I do stuff with the data that Google Earth can’t do. In fact, the only program like that, that I thought was any good was NASA’s World Wind. In it’s quake plots the the Z-axis was semi represented in the plot. (not well, but at least they tried)

      [note, they use the dot Net framework, which brings along it’s own baggage of “yech”]

  12. Not meaning to belabor a point, but here is a wave set from the seismograph at Old Faithful Geyser in Yellowstone. This covers the 24 hours of the 12th of February.

    http://i52.tinypic.com/4uho93.png

    This data, and most of the data from all of the seismos in Yellowstone… and many many other networks is publicly accessible via IRIS. You can pull time slices narrowed down to just the period of the quake you are after, and do your own phase picks and analysis. (A bit beyond my skill set at the moment)

    I’m pretty sure that if there was anything to see here someone would have noticed.

    1. You should shout out loud and tell them.
      But this line is meant for the seismologists. They are the ones who should have more interest in dismissing this hoax.
      As for me, still waiting for the bisons to start running.

      1. Just you wait: tomorrow they will line up with their graphs saying that the solar flares are at a maximum, the moon is full, the poles are shifting, etc. and that the authorities are cheating on people, and probably we can see some mass suicide in protestation against HAARP.
        I’m done. I can’t guarantee I will stand within the limits of a civilized educated being.
        This is the price we pay for good monitor systems and lack in education.

  13. Please leave the conspiracy stuff outside. Thanks.

    Hardware and software is going to continue to make errors and pick up noise and register that as a earthquake.

    1. There is an explanation for the American preoccupation with ‘conspiracy theory’. It goes back to the U.S. War of Independence and the British tradition of ‘Paternalism’.

      In Britain, there is an attitude that the lower class (inexpert public) is incapable of acting or deciding in an intelligent manner. Thus they must be ‘talked down to and told what to do’. The British public has formed a cultural identity which accommodates and rebuffs such paternalism.

      Remember Tennyson’s Charge of the Light Brigade

      Half a league, half a league,
        Half a league onward,
      All in the valley of Death
        Rode the six hundred.
      ‘Forward, the Light Brigade!
      Charge for the guns’ he said:
      Into the valley of Death
        Rode the six hundred.

      ‘Forward, the Light Brigade!’
      Was there a man dismay’d?
      Not tho’ the soldiers knew
        Some one had blunder’d:
      Theirs not to make reply,
      Theirs not to reason why,
      Theirs but to do and die:
      Into the valley of Death
        Rode the six hundred.

      The American Revolution was encouraged by those who embraced it as a libertarian response to paternalism. ‘Conspiracy Theory’ is perceived as being a paternalistic ruse which is used to dictate to a populace which cannot be trusted to decide for themselves.

      2. Interesting and beautiful.
        But, if I understood it well, somehow, one kind of paternalism has been replaced by another, even more stupid.

      3. As a U.S. citizen, just want to say that conspiracy theories, paranoia and mistrust are rampant and it is the apathy that is simultaneously rampant being poked by those of us who grew up in the 60s. Flower children, ya know… So anything that is “Now you see it, now you don’t” tends to ramp things up!!

      4. Must be a pervasive theme…

        ” … forward he cried from the rear,
        and the front rank died… ”

        Us and Them, by Pink Floyd.

      6. Nah, quit several years ago. Too much CO, which tends to form a really tight bond with hemoglobin and is hard to remove from your system. Once your blood is saturated beyond a certain point there is no more room for O2 and your cells start to die off.

    1. Really interesting, thanks for sharing. We’ve indeed seen this kind before the last few weeks and it took a small pause for the cause, but now the anomalities seem to be back. Interesting to see if this time it leads to something.

  16. The BUR borehole strain-rate (red) is normally not moving very much, but during the past few weeks it has shown fluctuations from time to time, and often rather the opposite to STO (blue). It went back to normal a few days ago, but has started to look strange again.

  17. By the way, there was a M2.6 earthquake near Grimsvötn. It was a single event but the interesting fact is that it was at 3.4km depth, which is not unusual, but most earthquakes occur less deep here. The size of the quake is also relatively large.

      1. Nothing…
        If you re-look at the tremoring you will see that it is the high 2-4Hz thats gone up, and that the 0,5-1Hz is stable. This indicates wind. And there has been a lot of that lately. About 55m/s of it 😉

  18. The residents of Buchenweg 14 in Arzbach in Germany just got their asses massaged by a 4,5M. Though it was 6 km down.
    The Goethe Gymnasium and the Schiller Pre-school was slightly shaken, but that is perhap’s a bit philosophical.

    2. Any idea of how deep the limestone bedding is there?

      According to preliminary phase data… and if I’m reading it correctly (don’t get your hopes up, I don’t know what I’m doing) then the strike plane is about 163°.

      That would make it roughly parallel to the prevailing river cut. In other words, the placement of the river was determined by preexisting weakness in the rock. Similar to the way that some of the sinkholes in NW Florida follow the trek of the ancient Port St Joe transform fault.

      1. Limestone beddings in Europe are never that deep.

        I think you got derailed by the 3,5 afterchock, the 4,5 is quite some ways away from the river (12km). It was at number 14 Buchenweg in Arzbach. The German locationing equipment is pretty amazing for a country that has few quakes, they put in one hell of a network after “Alter Mann” accident in the Lengede-Broistadt mine to track the blocking in the areas mines.
        http://en.wikipedia.org/wiki/Wunder_von_Lengede

      3. Mu logic on the bedding is that the movement of the basement rock/crust fractures the overlying limestone.

    3. Omygod! Eiffel volcanic field is reawakening! Germany will be swallowed by magma!

      Okay not, but the earthquake is part of the system which induced volcanism in southern Germany.

      3. Yeah, that was kind of my point. If anything will happen in this area of Europe (volcanowise) it will probably not be before the icelandic hotspot has wandered over here, and then we are talking quite some time even at geological timespans.
        Hope you are fine over in the land of Hof and Sort Guld?

      4. I am doing fine here in Sonderborg. But I am getting broke and I still need to buy some more house items (cheers, tables, lights, etc..) before I can settle properly in. That is going to take some time for me to do all that.

      6. Jon, are you situated close to the medieval training centre owned by Åalborg/Århus university?

      8. @Jon:

        I think I was not clear enough… Århus university owns the Sandbjerg Manor, situated some 5 km NNW from the Sonderborg centre. I’ve been there once in the 1990’s. It’s a very nice place, they even have some medieval buildings there.

  19. @Carl le Strange on müsli:
    I live only 20 km away from the Epicenter, my ass was massaged too.

    1. So, they have an error in the waveform?

      “The mine Neue Hoffnung (transl.: new hope) was operated with 300 workers from 1883 to 1913 with a total depth of 440 m”

      “Depth 5 km (3.1 miles) set by location program”

      1. I am still thinking about it, because it seems to be a to small mine to have caused it. But on the other hand, the region is riddled with more than a hundred mines. It might also have been a genuine slip.

      1. The overlay does not fit well on the underlying map, so be careful with interpreting it. For example the points marked “Cologne” (that’s where I live) are quite different on the map and the overlay. Other points are quite wrong too.

      3. Interesting… Depth 12 km, and 30-35 km from Laacher See. Quite near to say, although I suspect nothing special will happen.

  21. I did make a decision on volcano and earthquake blog for Europe. It is going to be it’s own blog at separate blog page.

    I do not know when I might be able to set it up, as that depends on when I get ADSL connection and my computer hardware. So people might have to wait a while for that.

    1. damm, i would like to know how those typos get in there, i read my post before i post them, do i need some glasses?

      ps. and here would be the page with the other data for Myrdalsjökull/Eyjafjallajökull

      back to the question about the inflation at Sólheimaheiði: any ideas?

      i don’t want to get histeric answers, because i think there must be some reasonable answer (Error in the GPS-Data?)

  24. Hi all
    There was an antenna change on SOHO last week (7th february), we have the wrong antenna information in the current processing. This is just an \equipment jump\ which will be fixed very soon.
    Best
    Sigrun

    1. wow that was fast : ) Thank you Sigrun!

      so now we can confirm that it’s not inflation.

  26. @Sigrun:
    And while I am at it, thank you for the nice plots of the GPS-timelines that we make wild theories about.
    We amateurs don’t often get the chance to say thank you to all you pro’s out there that write all of the interesting papers and make all the hard work that brings us all the joy.
    Thank you!
    Carl

      1. Oh haha didn’t see your post, I wonder if this is related to a magma influx of some kind, or if it’s just tectonic.

      2. The 1980 eruption was also preceeded by a M4.2 earthquake which occured 3 months before the eruption.

  28. It’s being claimed that it’s tectonic… but I have to wonder about the onset of what appears to be a tremor then the quake occurring. The seismos outside the crater don’t show that.

    1. What are the arguments for a tectonic earthquake rather than a volcanic? I don’t have any knowledge of distincting these two, but what I found out is that this earthquake occured at the northern slope of the volcano, just as the first major quake leading to the 1980 eruption did.

      1. If it was on the slope it sounds more like something coming loose. It is after all the season of frost-cracking. Albeit, it is a rather large quake for a piece cracking off, would probably take half of the mountain falling for that.
        I guess you meant it was under the northern slope?
        I cant see if it is long-frequence “gurgly” quake or a sharp “cracking” quake on the plot. I guess that Lurking is better than me at interpreting the graph.
        But, when looking at the crater-heli it looks more “burply”, så it might be a bit of squishy material in there, but if it is new material? I wouldn’t even dare say.
        http://www.pnsn.org/WEBICORDER/VOLC/VALT_SHZ_CC_–.2011021412.html

    2. According to Google Earth, they were under that stubby ridge to the north of the volcano, next to Spirit Lake.

      Pulling down the KML/KMZ files for the Quaternary Faults doesn’t show a suspect fault system running though… but those hills didn’t get there by themselves. There are likely hundreds of them that no one knows about.

      Still… that lead in to the quake gives me pause.

      As for tectonic vs volcanic, in the spectra response for the quake they are supposed to be able to distinguish the two… that and the focal mechanism that they get when they solve all the waveform picks. I’ve been reading on it… it is a bit complicated (beyond me for now) and it takes experience to do it right.

      2. The interesting thing would be the ground deformation. After all I would hazard a guess and say that is what is needed if it would erupt again.
        After all, that is what the Helens is infamous for.
        So untill anybody finds figures for that it is probably just large tectonic or cooling quakes. After all if I remember correctly she deformed half a metre a day before erupting the last time.

      4. Stand corrected, Helens is not really my speciality volcano:)
        But it just amplifies my point, if we start to see some severe deformation, then we will know.
        Is there anyone with a nice deformation link out here?

      6. Well, as Erik pointed out over on his blog yesterday, there was a bit-o-wind ripping through the area.

        This would answer the most vexing question… why, if the earthquake was located 4 to 6 miles outside of the crater, did the seismo in the crater see what could have been a magma tic signal, while the seismos that are closer only saw the quake with no leading rumble?

        Because the crater seismo is up high in the volcano. (remember, half the rim of is is missing from the flank collapse, and is pretty well open with no blocking of wind.)

    1. Jón, I finally figured out “why” my comments sometimes fall to the bottom of the page (like the one above)- it’s the captcha thing. If I type the captcha wrong and then try it again without reloading (refreshing) the blog page, my comment ends up down here. Oh well, now I know.

    1. I wish there was a GPS for both Hveravellir and Prestahnjukur. I am interested in if there is any inflation going on.
      Even though I seriously doubt that Prestahnjukur is about to erupt, feels like it is a bit to dormant for that. But, caveat, it is Iceland after all…

  32. I get my stuff in this week. But I might not get it going until next month (after next week). As I do not have the money to buy a used table for 275 DKK (about €36). I also need a new monitor for my main PC. But that costs about 999 DKK (about €133) where it is cheapest. But I might be able got a used pc monitor for a lot less money.

    Any and all support in this matter is welcomed. (I hate begging for support to be clear on that.)

    I am also looking for a power converter for amitech 17″ LCD screen, with the model number MSV-WR170C.

    Thanks for the help in the advance. 🙂

    1. I bought 2 books on Amazon.de, via your website “entrance”. I really do hope you get something of that.

      I can’t help you with the technical equipment but maybe someone reading here has something that you can use.

      Here in Switzerland we have something were used articles are brought, often managed by the Salvation Army, which they then sell again, but real cheap. Whatever you think about the Salvation Army doesn’t matter, ( and they don’t ask) but I have gone to look every now and then when I needed something ( table/chairs, homework equipment (cutlery and so) and even book or CD’s) Maybe they have something similar in Denmark.

    2. Whale Wars’ site has an area where it posts a wish list for equipment and supplies and of course has a link for donations. Would it be possible for you to do something like that?

  33. @Regulars:
    Couldn’t we do something about it?
    After all, for a theatre ticket price we could keep on having fun over the blog and engage in a “higher scientific cause” . 🙂

    1. If anyone wants to donate then that can be done with PayPal. I have not yet closed the account and created a new one (I have to do that because I moved between countries, PayPal demands). But I have closed down the MoneyBookers account permanently.

    2. Well it is not magmatic since the low frequency hasn’t budged.
      But the levels are low so it wouldn’t take much wind to make a change. But it seems a little bit to consistant over time for being wind either.
      Exactly what it is? Hm, well… ehm…

    3. No this is actually induced by weather. You can see this pattern at most of the stations, some are a bit different in form then others but they all have the same pattern.

      1. But those values rise same day when was earthquake swarm and values is still higher than before that. I think maybe there is tiny connection.

  36. Anyone got a comment for the last 3 quakes ?

    Date Wednesday 16.02.2011
    Time Latitude Longitude Depth Magnitude Quality Location

    00:30:17 63.642 -19.272 5.8 km 0.0 32.97 1.1 km WNW of Goðabunga
    00:30:04 65.071 -16.409 1.1 km 0.7 32.43 2.1 km SSW of Herðubreiðartögl
    00:29:56 63.589 -19.382 1.1 km 0.0 30.15 8.6 km NE of Skógar

      1. So, ah… exactly how deep do frost quakes go?

        That Goðabunga quake was 5.8 km is the waveform was interpreted correctly. (it’s a big if, I know)

      2. I would take that 5.8km with a pinch of salt as the quality is a mere 30 or so. This is probably an automated report and after this has been reviewed (if it will be) by someone I wouldnt be surprised if the depth gets revised.

      3. @Frost-quakes
        I think I can answer that one with a pretty good degree of certainty since it is basic physics.
        A frost quake is produced as water freezes and expands in a crack in the bedrock. The size of the quake is determined by the size of the volume of water. The larger the amount of water, the larger the area cracked will be (this more for the others than you Lurkmaster).
        The depth of the freeze cracking is determined on how deep the temperature drops below zero, ie. freezes.
        As an example I can take the current ground freeze in the city in Sweden where I live. We have had continous minus degrees (celsius) since the first of november, and currently we have a balmy spell of minus -25C. A heck of a lot colder than in Iceland that is. The ground frost spreads deeper governed by 3 factors, time, temperature and snow-coverage (works as an insulating opposing force to ground freeze).
        In Sweden we dig down water pipes and sevege pipes more than 2 metres to avoid them freezing asunder. Currently the ground frost here is 1,5 metres (5 fot).
        We have a lot of snow, but I would still hazard that Iceland don’t have deeper ground frost than we do for obvious reasons.
        So, a maximum of 2 metres is the answer to your question, not counting that the crack-fissure of the rock itself might expand a bit more down. Perhaps as much as a 100 metres in extreme cases.
        So, a frost quake is only a frost quake if it registers at ground level or down to lets say 0,2km to be certain. Any deeper and it is something else.

        Tidbit, the swedish word for ground freeze is “tjäle”, as far as I could find there was no specialty word for it in english. Tjäle is an unpermanent form of permafrost, and there is no permafrost in Sweden, nor Iceland.

      4. Frost quakes have been ~ 0.7-0.9 km “deep”, so I don’t buy the “very cold” theory even if the temperature drops a few degrees

  37. Well now that the EQ´s has been reviewed we can see that it was NOT frost quakes as the depths of both is confirmed to be a 5km or more.

    Wednesday
    16.02.2011 00:30:17 63.639 -19.279 5.1 km 0.5 99.0 1.4 km W of Goðabunga

    Wednesday
    16.02.2011 00:29:57 63.638 -19.276 5.2 km 0.5 99.0 1.3 km W of Goðabunga

  38. Sorry The other lurker, the “cold” theory is not a theory, it is a phsyical fact based on natural laws.
    So, unless there is permafrost in Iceland, and there is not, the maximum depth possible is as stated above. If any “freeze quake” (in swedish tjälskott) permeates down that far it is due to idiosyncracies in the measuring device. Ie, it cannot locate the tjälskott well that far up.
    The other and more obvious explanation is that it is not a tjälskott at all, instead it is probably ground cracking caused by shifts in glaciers, magmatic cooling, or any other non-freeze related process.
    I can though come up with a special circumstance for a deeper tjälskott, but it is not very likely. If you have a well aired cave in which cold air can enter and go out at another location (U shapped caces… not common) it could create its 2 metre maximum tjäle at a deeper level than normal. As I said not likely.
    If we look at the formation figures for permafrost it takes 1 year of continous minus degrees to form 4,4 metres of permafrost, 350 years to form 80 metres and a whopping 775000 years to form 690 metres of permafrost. I did not know that Iceland is under a cold-spell that has lasted that long… 😉
    http://en.wikipedia.org/wiki/Permafrost

    Tidbit 2, the swedish word “tjälskott” is rather nifty, it combines the words tjäle (ground freeze) and skott (gunshot). And that is actually how you hear a tjälskott (frost quake), as a gun being fired. It is high-pitched, well into the auditory range, so it is very distinctly separated from a regular quake, and most stations will not even be able to pick up them due to them being rather higher in frequency than an earthquake.

    1. Frost quakes can occur also when ice breaks due to warming. I rememebr seeing a TV documentatry on russian scienctist comparing these icequakes to earthquakes, and learning a great deal of them just be comparing them.

      2. I could argue that 😉
        (but really just saying, I couldn’t add that up)

        A. If frost quakes, they really should be in the plurals, not singular quakes
        B. They should not behave like ping pong* balls, should they, (*appearing first in the south, then in the mid-highlands and again in the south, doesn’t that break some sort of natural law ;I )?

      3. Ah, well that would depend on the weather patterns.
        But the frost quakes are probably all those serial mini-spikes that show up on the SILs now and then in cold weather. But I have a problem of seeing them causing larger quakes (above 0,5), or quakes lower than a few hundred metres (even when calculating in equipment limitations).

        But, I find these “odd” quakes interesting even though they are not tjällskott. Something is causing them and I would very much like to know what it is.
        For Langjökull and Hengill I could imagine water going supercritical (steam explsosions), and at Godabunga I would guess at heat induced fracturing of rocks. The last one would then be fracturing close to mines blocking up, and with that I mean rock ontop of the magma in the crypto-dome getting put under tension untill it breaks at the weakest points and fall down, probably at the same time as the magma either raises or falls a little. But here I am just theorizing, and I should probably state for any journalist that I might be dead wrong.

      4. For the Langjökull (and mayby also Hengill) I’d say the quakes were of tectonic origin. They occured in an area where there have been larger earthquakes and swarm than this one, this doesn’t imply any magmatic activity, it’s just part of the natural rifting system.

      5. @Pieter:
        Well, I didn’t say they where magmatic, but both Hengill and Prestahnjukur is highly active zones hydrothermaly speaking.
        Hengill though might very well have been magmatic since the area has had stages of high inflation recently. Prestahnjukur is as far anyone know dormant on the brink of comatose, but as you say tectonically active.

      6. Would it be complete nonsense to ask if the solar flare which occured monday (and is expected to reach it’s peak on earth tomorrow) might have effect on the received data? (since it is transmitted by radiowaves(?))

      7. @Pieter: No. Those solar eruptions generate plenty of RF garbage which only disturbs “sensible” communications by introducing transfer errors. It is up to the transfer algorithm to correct them, or re-transmit. If the algorithm does not do that, it is due to the lazy-ass developer of that piece of crap code.

      8. @Jack @ Finland & Pieter

        Funny you guys should be talking about the X class flare and accompanying follow effects.

        While it doesn’t track the flares themselves, the daily X-ray flux from the Sun is affected by the flares that occur there.

        This idea of a Solar connection to earthquakes is not a new one… if I remember correctly, it runs along the lines of particles from the Sun accumulating in the Earth and causing a shift in mass or something to that effect.

        No, I don’t believe in that idea. To me, in order for a phenomena to be plausible, there has to be a mechanism that can be pointed at to explain it. If you don’t have that, you might as well be chasing ghosts. At times, it is sensible to chase ghosts, but there has to be a lot of verifiable evidence to point to the existence of the ghost. (Note: if you not a fan of “ghosts”, replace that word with “goats”, the logic works just the same)

        So… though not a plot of particle emissions, I do have a plot of the daily Solar X-Ray flux in a scatter chart compared to daily earthquake counts. (yeah, I was so bored I actually did that plot)

        Here it is:

        http://i55.tinypic.com/2zzj2f7.png

        It’s about 10 years of data. In that 10 years, if there was really anything to the idea of some sort of connection, I would expect the correlation coefficient to be better than -0.0695.

        My caveat, as always, this isn’t my field of expertise, I just plot this stuff for the hell of it.

  41. I’m falling in love . . . . with your plots Lurking, absolutely love them and the interesting data you keep.

    If you are so bored (sometimes at least) could you do a graph for me based on regression of several variables, pretty please ?
    Be sure I’m not asking for anything tiny or small 😉

    1. Depends on how large the data set is and if I can wrangle it into something manageable. Remember, I’m not a stats person and that was my first try at doing a correlation coefficient. (working off of cliff notes here)

      So… as long as it isn’t anything that is legally binding (NDA’s excluded) or determines some sort of safety threshold, I’m game.

      I am looking forward to the incoming CMEs ( the count is three from the last I heard ) since I will be able to see if my next plot holds true. In that daily flux table, I think I saw a proton count feild, and I already have the quake counts. (BOSEG)

      … umm, given the wide range of the readers here, I think I need to explain that colloquialism/acronym. It means quite literally, “Big ‘ole sh#t eating grin.” Its the sort of expression that you see when when, for example, a group of guys laments that the really hot girl has already gotten a date for Friday… the guy who has the date just stands there grinning.

      1. And I who thought that the BOSEG was what plastered to your face after (europe) a succesfull date (american, third date) with the above-mentioned hot woman that is totally out of your leeague.
        The same dude will if he is rather lucky have the WHATJUSTHAPPENED-face during their wedding ceremony.

        If you are female the same goes, just think Fabio or something else that you find unobtainable, and then imagine that smug smile that would be plastered on your face. Difference though would be that the woman would have the INYOURFACE-face during the wedding.

    2. Holy CARP!!!

      I just had a Capcha (at tinypic) with the mathematical symbol for PI in it. I tried a “P” and it took it. Wow…

      Anyway, here is the scatter plot of Quakes per Day vs >10 MeV, >100 MeV, and >100 MeV proton daily flux.

      I didn’t do the correlation coefficients… based on the plots I’m not really sure that it’s needed. It sort of speaks for itself. (hint, I don’t see a correlation, other than all data points hovering about their average)

      http://i51.tinypic.com/351xsvb.png

      Yet another nail in the “matter form the sun causing quakes” idea.

      There are actually trained statistic people who stroll through here… if you see something in that plot that I’ve missed, feel free to chime in.

      1. Flux vs count ? Isn’t that like compairing apples and bananas ?
        What connection are we looking for, something similar to ebb & tide ?

        Shouldn’t you compare magnitude with magnitude rather than count (quantity) ? Just asking.

        Will put up the other data sets tomorrow, no state secrets, official data online.

      2. Well the argument usually given is that an increase in particle flow increases stress… and that causes the number of quakes to go up.

        The value plotted is actually the proton fluences, which is given in protons/cm2-day.

        Since it’s a daily value, it crosses over to the daily quake count quite well for comparison purposes. If there were a connection, it should pop right out.

        As for the term flux, it is a bit inaccurate, I am using it in the idea “flux is defined as the amount that flows through a unit area per unit time”, but my usage is more of the common concept of it, and not an energy flow. So, you have got me there. I had just finished doing the X-ray flux and didn’t think about the fact that what was being plotted was actually different. (the X-ray was a bona-fide flux)

      3. The strongest solar flare ever (during the last few tens of years, measured with X-ray flux) is said to have been X45 (4th Nov. 2003), where X1 denotes base scale of 1e-3 W/m2 of radiative power (roughly X-ray energy per square meter per second). So this X45 is something like 5e-2 W/m2.

        Well, the average solar output is about 1350 W/m2 at Earth’s distance. And, it varies on a hourly/daily/weekly/monthly/annual/decadal/centennial/millenial basis with about one percent. So this 5e-2 W/m2 extra due to these eruptions is, like we used to say, like a fly’s fart during a storm in Sahara.

        @Lurking: If you want to look into this, check the effect of variability of solar radiation output on a daily scale, and on an annual scale (check also http://en.wikipedia.org/wiki/Solar_variation ).

      4. Yeah, I’ve seen that article… read over it several times. (it’s a really good article)

        I even took the periods of the Hale, Gleissberg, Schwabe, Suess, and Hallstatt cycle periods and did a synthetic run, summing the output on a several thousand year plot and looked for correlations to the envelope of the “400 year history of sunspot numbers” graph.

        And yes, I did find one. Every peak and trough matched with the exception of an extra cycle that showed up in my plot. It was one spooky arsed graph. IF that plot was accurate, things are not gonna look good in the future. There is a large trough that showed up in my curve that lasts for about 50 to 60 years with a fast run-in, and an equally fast exit.

        The bad part is that graph is probably gone. I did it about two years ago and have yet to locate it.

      5. Man I really hate it when the bold tag gets away from me.

        Here is a quick reconstruction of what I was doing about two years ago with this thing. As you can see, the envelopes are very very similar in form and shape… the hard part is finding out where on the synthetic run there is the best match.

        Another problem that would have to be done… and I have no clue where to even start, is to weight the synthetic cycles to match what their contributions are in the real world. That would give the best chance of finding a correlation.

        But, like I said, its spooky… and aggravating because I can see similarities but I just can’t put my finger on what or where it is. You get them to almost match and then one end of the plot doesn’t fit, fix it and discover that this part is off… etc.

        But based on the shape, and the way that the synthetic one tracks… it’s gonna be interesting if it’s real.

        http://i55.tinypic.com/6tmxc0.png

      6. Well, simple high-school physics would have told the same story: There is no connection!

        This is like comparing apples to moons, or paper to bulk baserock.

      7. You understand that… and I understand that. But there are a cadre of people who don’t seem to get that. My plot is a way for me to validate that, and to get an idea of just how ludicrous some of the claims are.

        Plus, it gives me a tool with which to counter some of the claims.

        “Oh yeah, how do you know?”

        ‘Here… show me in this plot.’

      8. Hm, I wouldn’t be surprised if you actually could find a connection between weak quakes and solar flux.
        Don’t worry Lurking, I haven’t fallen off the waggoon. Of course there is no real connection. But the measuring devices could possibly be affected enough to register crap during the really large fluxes.

  43. Grimsvötn had a few rather large quakes the last 24 hours. Would the time be there already to start counting down? It has been constantly deflating ever since the last jökulhlaup.

      1. Oops yes ofcourse, and I wasn’t suggesting an imminent eruption, but my feeling is that it won’t take long.

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