Update on Herðubreið

View from Askja towards Herðubreið with Herðubreiðartögl to the right. Notice the youngish lava field in the forefront. Photographer unknown, click on the image for details.

View from Askja towards Herðubreið with Herðubreiðartögl to the right. Notice the youngish lava field in the forefront. Photographer unknown, click on the image for details.

The earthquake swarm at Herðubreiðartögl has now continued unabated for four days without a letup, during the first two days there were 4 earthquakes above M3 with the largest earthquake at M3.9 and by now the count of earthquakes has passed 1 000.


Image by the Icelandic Met Office.

Image by the Icelandic Met Office.

As such this is not the largest earthquake swarm to hit this volcano, but it is definitely a noteworthy earthquake swarm. Most of the earthquakes have been ranging between 8 and 5 kilometers depth with a few above and some below that depth.

After the larger earthquakes, especially the M3.9 the frequency of the earthquakes went down for a while before returning to earthquakes with a higher frequency. The baseline (bottom of the tremor graph) has continuously been slightly elevated with clear and visible tremor peaks during and after the two largest earthquakes.

Notice how the bottom of the blue field rises during and after the two largest earthquakes. Image by the Icelandic Met Office.

Notice how the bottom of the blue field rises during and after the two largest earthquakes. Image by the Icelandic Met Office.

The GPS-network does not give a lot of clues, probably due to the lack of a comprehensive GPS-system in the area. The nearest accessible GPS-stations gave a slight deflation dip before and during the onset of the earthquake swarm, probably related more to temporary crustal thinning as the tectonic plates started to suddenly move apart. As the swarm progress normal values returned.

Currently nothing is pointing towards an eruption starting, but the longer the earthquake swarm continues, the higher the risk becomes that a magmatic conduit forms, the trail of the earthquakes seems to indicate a stack building through the crust.

In this 3D-plot by DFM you will notice a slightly tilted wedge that has formed, the tilt of the wedge is probably due to the tectonic boundary being tilted in the same direction. Here is DFMs explanation of the plot:

“On this video, the quakes are shown according to magnitude. A scale is given on the plot. The left scale of the color bar shows the date, the right shows terrain elevation. The first part is a 360 ° rotation. The following parts show the quakes according to other orientations. The main activity seems to move to the west in a parallel plane. Look at 0’22. Data from IMO and NOAA, made on Gnu Octave 3.2.4 (Linux).“


The same trend is also quite visible on this plot by KarenZ showing longitude versus depth. The tilted wedge is here showing clearly.

CARL, DFM & KarenZ


219 thoughts on “Update on Herðubreið

    • Some previous beach balls for the area from EMSC. Note this does not include any for the current swarm:

      • I think that there is supposed to be a subduction zone but cannot recall where I read this. I’ll have to Google around a bit.

        • There is one suspected in the Southern Icelandic Fissure Zone. And maybe one at eastern Iceland.

      • Ah, should have though about that option.
        Please note that these are above M5.5
        Icelandic earthquake tend to all be rift quakes in most places. The only really big surprise is the highly enigmatic double-couple event at Bárdarbunga.

    • I have never seen a published beach ball. But this is a clear rift zone and there is nothing to believe that this is not classic rifting and that the beach balls would show exactly that.

  1. Here is an update showing the location of EQs >1.5ML Lat v Lon:

    Image and video hosting by TinyPic

    Open link in a new tab and grab the html for websites from there. 🙂 chryphia
    Ancient Codiot Dragon learned a new thing today 🙂

  2. Would be pretty epic if Herðubreið would start erupting. Although it would be pretty sad if that gorgeous tyuya top would be damaged or comprimised by such an event. Still can remember my first time visiting the area when I was eleven. We camped at Herðubreiðarlindir, walked towards the edge of Öskjuvatn (and I marveled at the people that made their way down to the shore of Víti). Then my dad’s van broke down while crossing Ódáðahraun and had to be towed by my uncle to the nearest town. Took fracking forever at that

    • Yep. “Old style” here you “see” the waves as they flas up and down, like them you see on photos or in movies where they “write” ink on paper, most often fastened to drum like machine part – basically electronic version, that can be scaled and “changed”, as often seen in Canaries 🙂

  3. Just wondering if there is the possibility for more than one eruption site ala 2010.
    Are there any signs of long period events?
    Is this swarm headed downhill ? or will it head back up?

    • Not sure, reading the updates and posts from this site, the IMO does not think one will happen soon.

      Could just end up staying at this depth and slowly just stop. My thinking is, more earth quakes, bigger earth quakes and above 4KM are required before an eruption is discussed in terms of weeks or months away.

      Thanks Carl for the updated post, Hope the coffee stays good and strong.

      @Islander, Any word from the local media on the rising temperatures in Askja lake? Lots of snow on the webcam, wonder if some of the lake is Ice free.

    • Right now very few of the earthquakes have magmatic signatures.
      @Rick: On the sat images the lake has been ice free, but that is about everybody knows. I agree that an eruption is weeks if not months away. But, this is Iceland so an eruption will occurr sooner or later.

  4. Just one thing. 🙂

    You mentioned deflation, but it seems that the deflation was prior to the swarm. Since the onset of the swarm, the deflation seems to have atleast stopped if not actually reversed. That is, if we are looking at the same station. 😀 I remember you posting a link to the HAHV station the other day, to the multi-year plot. The 90-day plot shows more details. 🙂

    • If I did not mention it in the post (thought I did) so yes, the deflation was shortlived and reversed quickly and the figures are now normal.
      I check details on short plot, but always go for the long plot to see if the scale is significant enough for me to even bother mentioning. Long term plots is what is important otherwise one will “see things” very often in Iceland 🙂

  5. OT. Really OT.

    Ron Jeremy is a porn star. A rather prolific one at that. In his 34 some odd years, he has appeared in about 2240 titles1. One of his more noticeable attributes is his extreme body hair, he has, on occasion, been referred to as the hedgehog. If ever you needed an example of Neanderthal traits… Jeremy’s body hair would be a good sell. He has done cameo appearances in non-porn movies, usually appearing for the comic aspect of it. He was the piano player for the midget fight scene in Kid Rock’s Cowboy Way video

    So, why do I mention him? Well, the queen of twits evidently got drunk and wanted to fight him. She got her arse hauled out of a strip club in Louisville Kentucky at an event hosted by Jeremy. Seems she was pissed off that he parodied her music video where she was astride a wrecking ball. Many in Hollywerid take themselves too seriously. I think she is a fitting example of it.

    … well, she’s got six more years left in her. Let’s see if she can make it past 27. Statistically, that seems to be about the time that some aging stars and starlets bite the bullet and turn up dead for some reason or another. Either not quite able to handle the stress of not being “all that” anymore, or the lifestyle catching up with them.

    1) Internet Adult Film Database.

      • Ya know the cool part about it? It fits the demeanor of the parties reportedly involved… All too well.

        As originally reported, her alleged claim to him copying her video theme is total bullshit. Parody is covered under fair usage and she wouldn’t have a skinny leg to stand on.

    • Ron Jeremy is far from a dim-whit. His father is a physicist and his mother was noted book editor who served with the O.S.S. during WWII. Jeremy himself is a teacher specilized in teaching special education children, he is also notable for attending the school where most future CIA agents went (Cardozo High School in Queens), while there he studied in the same class as future CIA boss George Tennet.

      • Never intended to characterize him as slow witted. The Neanderthal comment was in regards to his large quantity of body hair.

        Besides, I hold the Neanderthal species in high regards my self. It seems that just about every time you turn around, some researcher has discovered something about their nature that places them on a par if not further along than the more gracile “Homer”Sapiens.

        In fact, the only dim wit that I was referring to was twerkie the kid. Even in the (made up) story, Jeremy was given the role of laughing at her antics, which would be fully in character for another two-bit hollywood bimbo.

        If any sleaze bag publicity agents don’t like what I have said… it’s my opinion, deal with it. That’s how you packaged her.

        • One thing I find interesting (since I had to google Miley Cyrus) is that there are probably far more people who are aware of who Ron Jeremy is compared to the Miley person.

        • And that just illustrates how farking pathetic it is. Miley “all grown up” was apparentlly the target image, but there is more to maturity than grinding your arse in some idiot’s crotch while you sing.

          …and they call that entertainment? I think Jeremy has worked with more talented actresses.

          • Well, out of more than 2000 actresses he is bound to have worked with more talented actresses somewhere along the line.

            • We know, we are just meta-debating what should count as being a celebrity 😉
              On the other hand it took me five years to learn about Justin Bieber… and if he hadn’t abandoned his monkey in Germany and forgotten his bag of pot in Sweden I would never ever have gotten to know who that dimwhit is. I am probably a terrible person :mrgreen:

            • The Monkey bit was funnier than hell.

              It reminded me of an incident back when I was younger where my dad and I were busily searching the trees in a park because some random lady had lost her monkey. A euphemism of “monkey” just kept racking your brain when you stopped and thought about it.

  6. Serendipity be my midle name…
    At the same time I wrote that all earthquakes was tectonic some with magmatic signatures snuck in during the night. Nothing to write home about, but interesting.

  7. OT.

    The High Definition Earth Viewing (HDEV) experiment aboard the ISS was activated April 30, 2014. It is mounted on the External Payload Facility of the European Space Agency’s Columbus module. This experiment includes several commercial HD video cameras aimed at the earth which are enclosed in a pressurized and temperature controlled housing. Video from these cameras is transmitted back to earth and also streamed live on this channel.


    To learn more about the HDEV experiment, visit here: http://www.nasa.gov/mission_pages/station/research/experiments/917.html

    • Beautiful in my “Space file.” played this in background while watching :

      Wife knows she’s married to a frustrated spaceman…

        • I wish I could invoice them and make them pay for what they’ve done.

          They are at the root of various nuances in human behavior and triggers for emotional turmoil that push you to odd actions and cravings.

          I know, you meant “invoking.” No biggie. As a bonus prize, here is one from a movie. See if you can identify it.

          • The group performed in the German “Rockpalast” TV show in 1983, the same year Peter Schilling released “Major Tom”. Never saw the Heavy Metal movie, but I like the title of another song of them “Ohm sweet Ohm” 🙂

            • In regards of Major Tom and Space and Ohm Sweet Ohm…
              Here is the original version of Space Oddity by David Bowie, not the more famous 1972 version.

              And in regards of the original, here is Ohm Sweet Ohm by Kraftwerk

              And something very rare, Tanzmusik live from 1973…

            • Very good, though John Candy was not a “name” at the time.

              Trivia for you. In the first scene after the astronaut has made re-entry and it pulling into the driveway, “Grimaldi” is the name on the mail-box. It is also the name of the strip that section of the movie.

  8. Wednesday
    07.05.2014 22:47:26 65.134 -16.380 4.1 km 2.8 90.04 4.7 km SSW of Herðubreið

    • That is normal. Swarms seem alternate from north to south and back. Rarely much on both sides. This was said to me by very very knowledable person at IMO once. Yep. “Been there done that.”

      • I’m not all that surprised either. Some activity is predictable other activity is not. Herdubried was doing some of this activity in January and the swarm it went up into the Tjornes Fracture zone. The Earthquakes stopped at Herdubried shortly there after. It was a guess but I thought that is was realistic.

      • Oh, you have missed the Flaming Volcano Drink recipée Down Under. Google it with the words Flaming Volcano and Volcanocafé and you will find the best drink ever 🙂

  9. WARNING, this is an OPINION of a non geologist.

    Based on the sheer number of quakes in the ongoing Herðubreið swarm, I am of the belief that the only thing lacking there is a source of pressure. The crust is throughly fractured pretty deeply, enough to reach any lurking magma. If there were a source of gas rich magma, it probably would have gone by now, or be on it’s way. Lacking any definite signals, I am beginning to think that this is going to be a non-show.

    Do keep in mind that I can be very wrong. After all, I don’t know what I’m talking about.

    I’m tired and am off to bed to dream sweet dreams of phreatomagmatic eruptions and flaming hobbits being hurled through the air. Failing that, bar-q-qued Smurfs will suffice.

    • I like this idea because it sounds logical to me, being a non-geologist and a newbie in the field.

      I am surprised that so many quakes are occuring on the same spot and depth. Shouldnt the crust there be really fractured? Where does the strain come from in the already severely fractured ground? Unless there is actually magma present that is causing the strain, and perhals something more viscous, since some pure liquid Basalt should have less trouble getting through the cracks and would cause less strain I assume.

      But, to repeat the sir above me, I too can be (and probably am) very very wrong. After all, I don’t know what I’m talking about. 😀 But the best way to learn is through mistakes. 😀

    • If we take Laki for example, we do not really know how long the earthquake swarm before the eruption lasted. What we do know for certain is that the part of “felt earthquakes” was 3 weeks. I am of the opinion that it takes a while for the tectonic plates to whiden enough to form the prerequisites for decompression melt.

      I am going to be so bold to say that if a rifting event lasts that long you will have an eruption starting regardless of where it is or if there was readily availiable magma in the beginning.

  10. Bazingaa!
    These two listed quakes is actually one quake, it is the first earthquake that I am comfortably as calling an MT (magma-tectonic) event. It starts with a gentle slope increase in harmonic tremor that rapidly increases untill a sharp break occurs and after it has a long coda for its size indicating magma movement. Remember, one MT-event does not an eruption make. It just proved my point that if something hammer tectonically long enough in Iceland it will turn into a more magmatic event leading up to an intrusion.
    08.05.2014 06:27:55 65.130 -16.386 8.6 km 1.7 74.24 4.7 km N of Herðubreiðartögl
    08.05.2014 06:27:50 65.171 -16.389 11.1 km 0.6 54.33 1.9 km W of Herðubreið

    • Interesting. I was looking at the ASK drumplot, but the mag. 2s in the morning have scaled it so bad that there is no tremom visible anymore. And the SIL infrasound plot is also too “crowded”. 🙂
      So I guess that unless you can see the actuall more raw data, its hard to classify specific quakes. So then basically the swarm was tectonic in origin, with some MT events, and now probably getting more MT, based on the Laki example above. 🙂
      I guess that it is impossible to say what type of magma would be involved? Tho as an intrusion it should 99% be Basalt at deeper levels, with probable later conversion to Andesite as it rises through the fractured rock/ground, in theory making atleast the initial stages of the possible eruption more explosive/ashy, with later itruding basalt reaching the surface in a more “pure” form through cleared vents, making it maybe more Hawaii style. 🙂

      Just some thoughts, so you can get the idea how the situation looks like through rookie perspective. 😀

      • No, all fissure volcanoes in Iceland are pure basalt from the upper mantle, or in varying degrees containing deeper mantle material. As the rift starts to open up the upper mantle starts to transit into a molten state as the pressure is lowered. This process is really fast as evidenced by the samples from Laki (see my Laki series) so their will be no evolved magma components. Evolvement of magma is a process that takes tens of years up to hundreds of years. Only fast rate converter I know about is Hekla that can do it in just a few years.
        But the fissure eruptions in Iceland are processes taking no longer than a few weeks, so there is just no time for evolvement to occur. Laki and Veidivötn was highly explosive in the beginning, but that was mainly due to gas release (explosive) and the insane amount of thermal upwelling sucking all available old ash upwards.

        • Oh I see. I understand now. I made a faulty assumption because I dont yet know the basics, like magma temporal conversion rates. 🙂 Thanks for the heads up.

          • At Eyjafjallajökull you could see the transitions quite clearly.
            First you had pure basalt fire fountaining out of the Fimmvörduhals fissure, after that the Andesite from the 1821 eruption, and later the rhyolitic mush from the 920AD eruption came into play as it was reheated by the new basalt. It gives a mental image of the times necessary for magma to transit from basalt via andesite onwards to dacite to rhyolite. It also depends on the volume of the melt and the temperature of the initial basalt.

    • At first I thought you had a real winner there. Looking at the other photos put it into context as being a local slump of the hillside rather than definitely being a surface manifestation of the actual fault.

      But, fer the record, a Mag 6.0 strike slip yields 7.24 km down dip rupture width and an average displacement of 12.02 cm, Max of 14.13 cm. The surface manifestation should be on the order of 7.76 km, depending on depth of the quake. (4.9 to 12.3 km at the 95% conf level)

  11. So if a rifting eruption occurred here, that would be slightly different than usual I believe, correct?

    I only say this as I’ve seen that Herdubreid is off the primary fissure swarms in the area on a few maps, but I would guess that’s much more of a gray area.

    • The thing with Herdubreid is that it is poorly known if it has a fissure swarm or not. Some sources call it a fissure less volcano, but I highly doubt it.
      My guess is that an eruption here would mostly be in the Krafla style, or as Islander calls it, A Tourist Eruption 🙂

      • Interesting to note!

        If I remember correctly, once a fissure reaches a certain point in decompression melt generation, it becomes a self-sustaining system until enough energy has been released to accommodate for the rift itself, right?

        • Basically what happened at Laki. There the rift caused melt to start and before it all was over roughly 150 cubic kilometers of magma had formed that caused either a humongous intrusion, and the smallest part formed the eruption itself. Pretty good work from a self sustained system.
          The amount of melt seems to depend on the length of the fissure and the width of the fissuring more than anything else. X times Y = amount of melt.

    • Definitly messy, it was first located at 10km depth in the Nuxco bay, but it is now moved inwards into Mexico and at only 2km depth. If that holds Lurking will get his clear surface break.

      • Some idiot on the USGS’s page on FB is claiming that it was due to an earth-faceing coronal hole.

      • Interesting. I am looking at USGS database, which has the quake manually reviewed and centred at 24km depth. o.O

        • It is back at ten km at EMSC-CSEM, I would go with USGS on this on since Mexico is their back-turf.

      • Teleseismic wave of this event seems to have already moved over Iceland. The SIL stations are really amazing at capturing these events. Tho all stations around the world can capture these events, the “infrasound” (not sure it is the correct word) plots are really good at pointing out these events.

  12. Great news everybody!
    The Burfell Dalek-cam is now back and is improved with a zoom of the Dalek and Hekla.

  13. Does someone know how I can find Long Valley caldera on GVP? I tried searching by name, country, magma (Rhyolite), type (Caldera), and nothing.

    • Long Valley isn’t in the GVP database. The GVP database is very expansive, but any volcano that hasn’t erupted for 10,000 years has a decent shot of being omitted from the list. It is a bit inconsistent since they list volcanoes like Yellowstone or Valles (which both haven’t erupted in a very long time), then omit Long Valley from their database.

      If you’re searching for info, you’re probably better off just doing a simple google search. If you want a very academic (and often difficult to read) perspective, do a long valley caldera search using http://scholar.google.com/

  14. I’ve noticed the swarm near Herdubreid is starting to show more slightly northwest of the Herdubreid edifice now. Previously, everything was centered on the ridge directly to the south of the main summit, but now it’s showing up elsewhere. Interesting to see if the rift line starts to spread further south or north from here (a few quakes also occurred further south along what would seem to be a possible rift line, although not enough to be substantial at this point).

  15. All right, after finding out that Igor Pro, the 3D plotting program I use, doesn´t like negative earthquake magnitudes, I now can achieve certain rotation maneuvers again! Yay!
    Unfortunately I still failed to get a proper timelapse working, like dfm can do. Instead I took a brute force approach by deleting row by row of earthquake data and later reversing the video with the Blender video editor….phew.
    Here, a few hours later, is an updated 3D plot on the Herðubreið earthquake swarm until 8 May, zoomed in a bit more. Again, the recent month (in cold to warm, enlarged) is overlayed on to the previous seismicity starting 1995 (in green).
    The timelapse shows almost 10 years of seismicity, facing north. I think it shows some delicate patterns. Enjoy!

  16. Possible foreshock to a large main earthquake in the Southern Icelandic Fracture Zone (Sprungur).
    So far rated as a M4.1, but posibly even larger.
    08.05.2014 23:14:01 63.997 -20.483 6.4 km 4.1 90.11 9.6 km ESE of Hestfjall

    • Unclear as of now, but Hekla did not like that one bit.
      I think that if a larger earthquake hits as a main shock then Hekla will blow like a beer can put in a bonfire.

      • I don’t know where you live at (not my business), However, you do know where you live at (hopefully).

        Here is the MMI vs range for the quake using the non West Coast model.

        1 – Not Felt
        2 – Weak
        3 – Weak
        4 – Light

        In the West Coast model, the energy decay is greater and the effects dampen out faster. The other model (the one shown) uses the decay one would expect from the eastern US. (less fault systems for the energy to transit). Given that the area is pretty faulted, the energy tranfer may have been more like that in southern california, in which case the plot would be wrong. Think of the plot as what you would expect with better coupling and energy transmission.

        • I happen be in Reykjavik City tonight, but as I said, felt nothing. But was fighting computer at the moment, so I hold that responsable.

          • Well, like I said “not my business.” I don’t want to be accused of stalking anyone. Hopefully you won the computer fight.

            OT but subtopic related. I had to meet the truck from the main office today to offload a lot of superfluous gear that I no longer needed in inventory. I had a chance to look at the amount of damage in the client’s office down there. They had flood waters up to about two feet above the floor. It had gotten to every printer and PC there (and the brand spanking new server). And get this, the PC’s were hanging from a bracket at each station and not sitting on the floor…. but they hung low enough that the water got to them anyway.

            • Yep, won (It did not die). But its old, it might die of its own accord one day 😉

    • Foreshock? Small chance of that, no? I would be looking a Hekla allot if a bigger one came along or I am wrong that it would have no affect. I just see it as match and petrol station.

      • Most likely yes. There is a couple of honking large magma reservoirs under Vatnajökull. Both Grimsvötn and Bardarbunga rank in with ginormous reservoirs. And that dampens things a lot.

        • The general location, the size of the event and the amount of pent up energy in the area. That combined with behaviour before previous large Icelandic earthquakes. This could release a larger quake in the area. We will see in a few days.
          Please do note, I am not at all saying that a larger quake will follow, I am just noting that there is a chance of it.

      • It was probably even larger judging from the distant ghost at Hveragardi. My guess would be a M4.4

        • Exactly Carl. Empirally for me this is a 4.5 (or even possibly 4.7). Not more than a 4.9 I guess. But more than a 4.1.

          Last 4.3 in Reykjanes/Bláfjoll I did not felt it. If thisis felt in Reykjavik, then can be bigger.

          I clearly felt the wave coming from the east side. Just 3 seconds. Nearly impossible to distinguish the two waves as the event was local.

          Well, question is how long until the main event. The wait is a kill as we all know. This is the same for Tjornes.

    • Its a different area. This is further east.
      I have said this before. Both Thingvellir and Árnes expect big ones. Árnes has big ones quite regularly, like twice a century, and last time was early 20th century, so yes, maybe this is a foreshock for a M6 near Árnes (west of Hekla), and this fits the series of 2000-2008 earthquakes, now 2014.. usually in SISZ things go like a domino within a few years of each other.

      • I agree with Irpsit on this. And if this quake happened where the automatic system put it, it was in virgin terrain that has so far not had a large fracturing event.
        Irpsit put it quite well the reason why I am suspecting that there is a possibility for an even larger mainshock.

    • This one was placed right in-between between the two 17 June and 21 June 2000 quakes.
      Both I felt very hard. But this tonight I missed it. Small movement now. But unshure what.

  17. I guess I need to either find or re-create my power band plot for SISZ. That was the one Carl had a cross discipline epiphany on from the seeming wave interference pattern of the data points.

    Tinypic scavenged the data space for the image and it’s no longer available there.

    @Carl. If you saved it to your drive you may find it under it’s tinypic name ic4kdv.png

    • They are not finnished with it. The Ghost is still there. I fully expect this to land in the M4.2 to M4.4 region in the end.

  18. if a larger quake does occur, and I mean IF, it will be interesting to see what effect it will have on Hekla, if any.

    • Likely nothing, nothing tonight, nothing in fore-see-able near future.
      But future is always coming, at steady rate even 😉
      We never know. It might in end.

  19. Strange. Quake (3,9 R) toinght seems almost “alone” and strain stopped droppinf, and started rise again within a few hours. This then nothing but “singular” event. Perhaps too early tell, but the quakes are almost too few to be a “swarm” (8-10 or more, I guess, one can call a swarm).
    Hope nothing “dominoes” … 🙂

    • The speed with which the strain perked back up makes me wonder if this was not truly a foreshock. No way that this can have released all the pent up energy in the area.

  20. At one time, I set up a rectangle that encompassed the SISZ and did a calculation for moment magnitude for the quakes occuring there over a period of years. It made a pretty fascinating plot, but due to the way that TinyPic relegates its storage space, images expire over a period of time and are removed, the space then being re-used for other pictures. The plot that I made went bye-bye. What was really wild about it, was that it seemed to have some sort of pattern not that dissimilar to interferance patterns that you see in some wave phenomena. No one ever came up with an idea of why this appeared that way. I have long searched for the original image on my system, but have failed to locate it.

    However, I did locate the original extracted data file. The problem is, I can’t give you the dimensions of the box. But here is roughly what the plot looked like.

    At the time, I had done a comparison of USGS Mo values for the few quakes that it had in common with the listing for Iceland, and at another time I had found IMO’s actual calculation. I don’t know which method that I used to derive the Mo values.

    So… until I can figure that out (again), this is mainly for entertainment and rumination value.

    Of note is that this recent event happened in one of the higher power nodes of the plot. I haven’t checked to see if these nodes specifically relate to any of the sprungur or not. (cracks)

    • It appears from the data file, to have a latitude range of 63.75°N to 64.25°N.

      Upon thinking about it, these nodes may be the locations of the dominant faults along here. From reading, I have found that the surface manifestation of the cracking/faulting, rotates to align with transform motion as you look deeper. I can’t remember the reference, but it was discussed in one of the fine papers that IMO and it’s various researchers have put out. A similar thing is occurring at Walker Lane in the California area as a “formative” transform fault is being initially manifest by a series of transverse faults that is evaluated to eventually rotate and align with the dominant motion. (Walker lane accommodates a significant fraction of the relative motions of the North American and the Pacific Plates. The San Andreas takes up the rest.)

    • I remember those plots quite well and a lot of rumination was to be had about them. You did one that we could pinpoint to the Sprungur. It was an awesome revelation.

    • Nice! Very distinct differences can be seen between the SIFZ to the left, Hekla right of the center and Torfajökull to the right. It seems that the earthquakes in the SW end of the sprungurs are considerably stronger than the NE ones, I assume SE is where the swarms start generally?
      Image and video hosting by TinyPic

      • I did a stunning set of math on that progression and proved that you can apply acoustic formulations on it and that the energy transfer in the area follows third order harmonics.
        That set of math was not appreciated by the powers that be and more or less it resulted in me starting this place. I have always intended to get back to that work since I think it says something profound about how fracture zones operate. Biggest problem is that I do not really know what the profound thing really is :mrgreen:
        The reactions I got from a few people to that work has actually steered me away from writing much where I apply my speciality in physics on geology. I was not a happy camper on that day… But in the end everything turned out into the best thing ever and this place came to be with all the wonderful people in it 🙂

        For the rest, in Cryphias plot (and in Lurkings original plot that is lost in the mist of time) you can see an interference pattern. This is due to energy (in this case motion energy) always being carried through a medium as a wave with peaks and lows and intermodulations depending on the properties of the medium. This is a profound part of physics that to my astonishment has not been fully understood by most geologists. Basically they are forgetting a law of physics. So what I originaly did was to deduce the properties of the Hreppar micro-plate from the plots by Lurking and prove that the harmonics that the wave progression produces follows a third order harmonic pattern. Sorry if this is a bit complicated to understand, but with a bit of wikipedia you will most likely get the general gist of it, and it is pretty important. Down Under will find that this helps with understanding teleseisms and how they can affect nearby faultlines and not farflung ones.

          • That was a lovely way of presenting what I am describing. One should though note that the interference pattern in something like the Hreppar is far more static (slow in changing) and will repeat itself without a change of the basic pattern for a long time. Thus you get the interference pattern that shows up like bands in the quake plot.

    • Kinda like Carl said it would be. 🙂

      A general question: About Hekla, which strain station is more “legit”? I know that Burfell is a fairly good indicator, as proven in 2000. But what about the Hekla station? Is it a better indicator of strain changes in the actual Hekla fissure, or is Burfell more reliable because it has been “tested” in an actual event? 🙂 The Hekla strain station is not showing as much of a change from the mag. 4.3 as the Burfell, even tho they dont seem to be that far apart.

      • Both are of course legit, but Burfell is the known culprit so I tend to put extra trust into that one.
        HEK is closer to the fissure, but it is untested in comparison to the others.
        In this case I think that the BUR showed a pressure drop to the west of the station, and that would explain the lack of movement on the others. Ie, BUR is closest to the earthquake.

        • I should though say that both BUR and HEK reacted to the earthquake, and it did it by moving in opposite directions. Exactly as you would see at the onset of an eruption. Before an eruption the motion would though be much greater.

        • Thanks. It is kinda like I was thinking, that both are good enough, but it is a bit better to have more faith in the proven stuff. Hekla is already tricky as it is, without the 12424521 stations to monitor and interpret. 😀 It will be really interesting to monitor the interactions between Hekla and the SISZ, shall there be more activity.

          And thanks to Chryphia for the link. 🙂

          • Not a chance in hell to be brutal. 🙂
            Remember that the far greater teleseismic wave from Chile roared past just a short while ago. And what a 9.2 can’t do a measly 6.8 won’t do either. Remember that Chile was about 600 times more powerful and 2000 times more destructive.
            No, the pent up forces involved in a seismic zone is so humongous that the comparatively tiny effects of a teleseism will not matter at all. Erthquake progressions have been noted, but almost always on adjacent faultlines.

            • Butterfly effect.
              I know that often events look at temporal coincidences, as the intensity and distance is not enough to be known to trigger others. Like a Laki eruption triggering a devastating earthquake in thingvellir region, some months later. But this happened in 1784

              Another one, and recent series of coincidences is in July 2011. First the event at Katla (subglacial eruption or not, something a bit larger happened there), and just days later a similar glacial flood (some also talked of a unconfirmed subglacial eruption) at Hamarinn. Hekla was experiencing a rash of a few earthquakes also that week. So, 3 volcanoes had 3 events within a week. Unrelated? Yes, accordingly to conventional geological knowledge. But chaos theory could suggest a link of a tiny nudge of one triggering events on another volcanic system some 100km away. It´s not as far fetched as it seems.

              In 1960 and in 2010 big earthquakes in Chile led to a volcanic eruptions just hours or days later. The volcano was quite far away, but this happened. And twice.

              Same is M5 earthquake at Bardarbunga triggers the 1996 eruption of Grimsvotn a few days later. No magma connection, but perhaps a butterfly effect link.

              Maybe same thing happens now. But the butterfly effect links are very very difficult to read between all the common activity all over Iceland nearly always, and a lot of noise. You cannot prove it. At least I can´t think of a way of foing it. But the tiny link could be there, lost within a lot of events, variables and noise.

              ps: note I am quite attracted to chaos theory, so I have a bias towards it.

              Interestingly, many times has SISZ experienced big events, and Hekla never erupted after them. Seems quite resilient. Let´s see how Hekla replies now.

            • Irpsit, there are two things one has to remember about Iceland.
              1. Shit always happens all the time.
              2. There are two things linking the shit together. The MAR and the Plume…

              Quite simply, one does not need to search for a butterfly when you have two exploding whales on the beach :mrgreen:

            • @Henrik:
              Beware the source. Gillian Foulger is pretty level-headed, but there is a lot of Bullhork published at Mantleplumes.org. I have had to debunk two totally insane papers published there. One of them coincidentally put your arse straight over a mantleplume…

  21. Magnitude ML 3.4
    Date time 2014-05-09 10:17:39.5 UTC
    Location 63.68 N ; 23.37 W
    Depth 13 km
    Distances 88 km SW of Reykjavík, Iceland / pop: 113,906 / local time: 10:17:39.5 2014-05-09
    54 km SW of Keflavík, Iceland / pop: 7,930 / local time: 10:17:39.5 2014-05-09
    50 km W of Grindavík, Iceland / pop: 2,539 / local time: 10:17:39.5 2014-05-09

    • Updated to 3.6.
      Probably felt in Reykjanes and at Iceland´s international airport.

      This is a tectonic location too, but can lead to eruptions there. In fact, one day, one will happen there.

      • Looks rather magmatic origin. Quite deep. 15km deep.
        Earthquakes in SISZ have been known to trigger earthquakes in Reykjanes, but usually it´s only with the large ones, not small ones like yesterday´s event. More like 6.5 quake in 2000 triggered a 4.5 in Reykjanes just 5min later, if I am not wrong.

        • You are correct, but I think this is related to Reykjanes itself, a reactivation of last weeks swarm there.

  22. On the SISZ earthquake. Woke up quite relaxed today. I will camp with some friends tonight, just a few km west of the epicenter (on another fault location) tonight. I am not very concerned. Eventually a big earthquake will happen, but that is part of life. Larger events can occur today or in days ahead, perhaps only a few years from now, or only some decades from now. My opinnion is that a large earthquake will occur in the SISZ within the next 10 years, the last of the recent years series of earthquakes that started in the year 2000. Yesterday´s event does not qualify as a swarm, so it seems unlikely to be a readjustment or a main shock. (Notice: I am not an expert, so take my writting with a grain of salt)

    It can be good to re-read the nice post from Jon´s blog some years ago. He thinks this is a foreshock to a big one (like Carl, and also I agree) The history of SISZ earthquake show they often got up to anm estimated M7 (about 500 times stronger than yesterday´s 4.3) and have done quite destructive damage to houses and towns in the south in past centuries (with loss of human life too). Some big ones have also opened surface fissures large enough that people could not cross them.

    Big quakes in SISZ happened all the time between Hekla and Eyjafjallajojull (important note: without triggering eruptions there) to the region just east of Hengill. One big event triggered the formation of the Geysir, some centuries ago. Others flattened houses or lowered the ground 1 meter in spots, even leading to water coming out of the ground.

    It´s also a good time to re-read the IM´s article on the 2000 earthquakes (link is http://hraun.vedur.is/ja/skyrslur/June17and21_2000/all.html). Two earthquakes happened then, around 6.5 and 6.3, the second one about 4 days after the first one. In 2008, a 6.1 earthquake happened further west. In the 2000 article, they have described the amount of energy that the fault accumulates over decades since the last big event in 1912. They have said only 10 to 25% of the accumulated energy was released in 2000. Of course, in 2008 more energy was released, but still the energy released is only 35% of the total, accordingly to simple calculations.

    The events in SISZ come in all sorts of fashion behavior. Domino style, within 10 days, 5 big earthquakes happened one after the other, from east to west (1896). Single isolated larger events occur also, with longer repose times in between. Repose of 1 year between main events also has happened. Or many decades of repose, sometimes. Or in 1294 an Hekla eruption leads to the big quakes in SISZ. In ocasions events can lead to appearance of geothermal springs.

    Displacements are in order of a couple of meters in those M6 or M7 events. Yesterday earthquake had a displacement of only a few cm at most. Earthquakes of this intensity are quite common in Iceland. There has been events of similar size (M~ 4.5) offcoast in Reykjanes, near Reykjavik in Bláfjoll, at the Tjornes fracture zone, and in Herdubreid, in recent months (in Herdubreid just a few days ago). And it´s not only the SISZ transform zone that suffers this moderately strong earthquakes. Tjornes region, in the north of Iceland, also experiences this, has been actually experiencing large swarms in recent months and is expecting a big one even more likely than we in the south of Iceland.

    Transform zones are regions where the plates move side by side. The south side of SISZ moves east, the north side moves west, causing N-S fractures and ridges aligned parallel to each other between Hengill and Hekla. The resulting microplate between SISZ and Langjokull-Hofsjokull then is supposed to move counter-clockwise. This is good, because then my house is moving from facing northwest to facing a more south location, allowing me to have more sunshine indoors during the winter time. Have a good weekend!

    Carl: feel free to write this as part of a next post, if you want to. Its not in best writting style for a post, so just add it if you want to.

    • I have a better idea Irpsit. Todays post is allready in, instead it would be wonderful if you could put a couple of hours into what you wrote above and email it to the VC mail, that way we have a nice post. The subject merrits attention 🙂
      If you could find images to the article (preferably wider than 700px) it would be awesome 🙂

      • Excellent idea, but not this weekend.
        I have quite a lot of projects to work on, including studies (Saturday), time to be with family (Sunday), and I go camping with friends tonight, at SISZ current “hotspot” (tonight). So quite crazy ammount of things to do 😉 Well, its Icelandic summer, people get very busy

  23. Well, when I go crazy whenever I focus on my interests. A bunh of these earthquakes are 1 mile depth and deeper.

    I know Grimsjall hasn’t been a focus but there was a tiny move up on the chart within the last few days.

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