Few points about Iceland geology

Here are few points about geology in Iceland (just because I cannot sleep at the moment). This is also a offshoot of this blog post here.

The basic thing that needs to be known about Iceland is the fact that it is just a island over a hot spot. In every other terms it behaves as expected by a volcanic island on a rift zone. There is a lot known about Iceland geological features and volcanoes. But there is also a lot unknown at the moment. There is nothing mysterious or strange about that. We just don’t know this at the moment, but in the future we hopefully are going to know this. As each eruption or earthquake swarm teaches us more about Iceland and how it works.

I have seen a lot of wrong things about geology in Iceland on this blog in past few days. For instance the claim that energy travels trough a fault zone with N-S bearing (mostly). The volcanoes in question where Hengill volcano and Hekla volcano. This volcano do not exchange energy over SISZ. It simply just does not happen, as law of nature does not allow for it to happen. The following natural laws prohibits this energy transfer (and there is no way around it), Laws of thermodynamics, Inverse-square law, Conservation of mass, Conservation of energy, Momentum, Angular momentum and whole a lot of other physical laws that apply in nature.

I know one of two thing about physics too. As I fully apply that when I am considering what a volcano or a earthquake swarm might be up to in Iceland.

The evolution of Iceland during the past ~20 million years is also a factor in this. As there are many fully formed rift zones, but there is also a lot of failed rift zones in Iceland. There might even be new failed rift zones being formed today. But it impossible to know that for sure at given time. Since we have no way of knowing what is “new” and what is “old”. Research into this matter is going to shed some light on it. But that might take years of hard work of scientists for years to come.

The basic evolution of Iceland from 15milyr ago until the today. Copyright of this image belongs to its owner.

This is the best picture that I know of what they think is the Iceland hotspot. Copyright of this image belongs to its owner.

There is also the thing about the crust in Iceland. But it is believed that part of it might be from a old continent. But majority of it is currently covered with newer layers of rock and sediments. But studies have also suggested (or proved) this. The following papers can be read on this subject.

Older crust underlies Iceland (pdf)
Continental basement under Iceland revealed by old zircons
Continental geochemical signatures in dacites from Iceland and implications for models of early Archaean crust formation (ScienceDirect)

This in part explains the difference in crust thickness when it comes to Iceland.

The thickness of the crust in Iceland. Copyright of this image belongs to its owner.

All pictures above are from this study into the Iceland mantle plume (they are trying to disprove it existence). Iceland & the North Atlantic Igneous Province

Here is a different map of Iceland volcanoes, fissure swarms and age of the lava fields.

Iceland and its volcanoes. Copyright of this image belongs to its owner. This picture is from this web site here, Post-glacial rebound of Iceland during the Holocene Click on the picture to get full size.

Similar map. But in colour. Copyright of this image belongs to its owner.

I hope that this clear few things up about Iceland and how it works and might work. Since we are still learning and there is a lot of things that we do not know about how Iceland actually functions. But me and professional geologists and scientists are doing there best to learn about how Iceland works.

If there is a claim about Iceland that just sounds crazy, it probably is crazy and not based in any actual fact about Iceland and the geology that makes up Iceland.

119 Replies to “Few points about Iceland geology”

  1. Jón:
    This is refined Science you’re granting us with.
    Many thanks for the extraordinary reasoning.
    This blog rocks!

  2. Jon, With all due honor, many thanks for your work! You may know a few things about physics but it seems you’re vertainly not a physicist. Hence a few comments from a real physicist.

    Laws of thermodynamics apply everywhere, that’s true. They are easy to understand in isolated systems (no mass or energy transfer across system boundaries). However, Iceland is not an isolated system, not even an closed one (mass transfer forbidden, energy transfer allowed). Iceland can only be considered as an open system (mass and thermal energy transfer from below). Open systems are very difficult to understand as you got tom include the interaction with the environment within your equations. In practise, only heavy computer modeling allows for that. This means, that you can not state that thermodynamics prevents this or that, unless you have a proof for your statement.

    If an phenomenon is governed by the inverse-square law, it nearly always means the phenomenon one or other way follows spherical symmetry. tectonic and volcanic events almost never follow spherical symmetry. Typical tectonic “sources” (earthquake locations) are points near surface or in a plate edges (i.e. near or at a surface). Typical volcanic “sources” (magma) are lines or volumes near a surface. Thus, they follow half-spherical, cylindrical, or plane symmetry. For these symmetries, inverse-square laws simply do not apply as these conditions do not fulfill the most basic assumptions of the law.

    The laws for conservation of mass, energy, momentum and angular momentum are IMHO more often abused by non-physicists than used correctly, due to the fact that again they apply for closed systems only! Iceland is a open system, i.e. mass is exchanged with the environment (the plume!), energy is exchanged (hot magma below), momentum is exchanged (plume push from below), even angular momentum is changed (the conduits are not straight as a line). So for Iceland, you got to account for these changes, or you do not apply the laws mentioned above correctly.

    Physical science (including volcanism) is all about verification. Hypotheses, that are verified by reality, become established theories. And, extraordinary claims need extraordinary proofs. As a professional physicist, I like Carl’s theory. He has given a prediction, explained the mechanism, the governing relations, the source and the consequences. It’s fairly complete, i.e. ready for testing against reality. Yet, on your side (I’m sorry for this), you have only a claim. No explanations.

    Remember the status of physics on the 1880’s? Physicists all over the world actually believed, that they know everything that can be known in physics. They had two minor problems. Photoelectric effect and black body radiation. they could not explain those yet. By the time they found the correct explanations, those explanations revolutionized the whole natural science. Not only physics, but also chemistry, biology, astrnomy, etc.

    Or in the beginning of 1900’s? First Thomson found electron, and Rutherford found proton. Everything ok, charge balance was intact. Then Chadwick shook the world by finding neutrons.

    In reality, physics is more about “never say never” than any other science…

    1. Jack, I doff my cap and bend my neck in respect sir! I’d only like to add the following: The strongest point about Carl’s hypothesis is that he has defined the Popper Falsification Criteria for it (“If…, then my theory is incorrect”). This is true science. If a theory has been falsified, it must be discarded in favour of one that hasn’t. Only in the rare case such as the state of Physics c.1880 when there was no other theory to explain the anomalies (the Photo-electric effect and Black-body radiation) can the old teory be retained – for the time being.

      An example is the Eyjafjallajökull > Katla linked eruptions theory of Professor Pall-Einarsson. Up until 2010, there seemed to be some evidence in favour of such a theory. Now, with over a year since the E eruption died down and the only scientificable verifiable fact is that newer, more sophisticated onad more plentiful detection equipment will detect more activity, his theory must be discarded as false. Another caveat to observe with such a theory is the large ad-hoc component or crutch required in order to overlook, or rather, ignore the need to explain why the process never works in reverse. I find it extremely sad to hear from reputable witnessess that in spite of this, Professor Pall-Einarsson still clings to his pet theory rather than give it up when it is clear that the falsification criteria he never bothered to define have been met.

      As real scientists may notice, this is Science Philosophy but then my academic background is Linguistics and History, two soft “sciences” to where unfortunately small minds such as Chomsky gravitate, minds that interpret and invent scientific “methods” by which their beliefs and fancies can be transformed into carreer-making discoveries and laws. This is why I firmly believe every individual with pretentions towards being a scientist must define, abide and obey the criteria by which his theory stands or falls.

      To his very great credit Carl has done exactly this.

    2. If inverse-square law where not at play here. You would feel it every time there would have been a earthquake in Iceland.

      Iceland is not a isolated system. That fully true and all that. But planet Earth is a isolated system in terms of geology. As the Earth does not gain or loose energy out to something else. Geology in Iceland is governed by those laws, like everything else on this planet.

      Last time I checked, the planet Earth was a sphere looking thing in Space.

      Now. I do not have time to fully explain this. But I hope this is going to do.

      I am not a physicist and I never claim to be one. But I fully understand what I am applying here. Since I have been thinking about far more complex things then this thing here. I am going to give you expamles later on this. Hopefully no later then sometimes later today.

      1. In terms of geology, Earth is still an open system. Earth gains some mass from space (meteorites, occasionalla major ones). Locally the geological effects due to space impacts can be the determining factor, but I suspect Iceland does not have any such well-known major features. In terms of geological energy I agree with you (no outer sources). And, I also agree on Earth’s shape (to get some basics correct).

        However, Iceland is different. I think Lurking got it right: When you talk about connection, you have to define the mechanism first. After that we can start talking about the extent of that connection. It plays a major role if the connective mechanism is a common conduit (pretty local or tight connection) or if it is a magma plume from the core (pretty loosely defined or nearly continental connection). The connection can also be due to common environmental reason (e.g. volcanism generally in Indonesia), or Mt. Fuji eruptions after major Japanese earthquakes.

        You know, when ever there’s a qauke is Iceland, mechanical energy is transferred from the point source away to the environment. However, it depends entirely on structure of environment. Spherical symmetry holds, if the environment is both structurally (e.g. no ground water, faults, stresses, etc.) and materially (identical materials, identical density, etc.) completely homogeneous at all directions, up to the distances the quake can be seen. Which, by the way, does not hold true for Iceland not anywhere else on Earth.

        Iceland is very heterogenous, you know that. Hence you should know that inverse-square law serves well as a possible first-hand guess, but if you want to know more, you’ll have to open your mind to see the real conditions (e.g. faults, layering, stresses, etc.). I believe, that inverse law plays stronger role in Iceland that is widely assumed. This means that mechanical interactions (e.g. stress, vibration, pressure, etc.) can be seen much farther than expected (based on inverse-square law only).

        This is one of the reasons Icelandic geology intrigues me. Many of it’s details are not yet explained. While “the conventional geologic wisdom” applies here, too, it seems sometimes lacking in its ability to explain every detail.

  3. “For instance the claim that energy travels trough a fault zone with N-S bearing (mostly)”

    The only problem is that it likely doesn’t quite apply to the Sprungur region. The prostulated Hreppar microplate’s southern boundary is not well defined. In all likelihood, this boundary exists as a transform fault still in formation. The sprungur and associated faults are surface expressions of the forces at work there. Riedel shear structures would likely not align with the prevailing motion but would be oriented off axis.


    For those who tire of Wikipedia links, some stuff on transpresion and transtension.

    Stretching lineations in transpressional shear zones: an example from the Sierra Nevada Batholith, California

    Tikoffa and Greene


    Ductile shear zones and associated stretching lineations are generally considered to be the result of two-dimensional, simple shear deformations, with stretching lineations interpreted to rotate into parallelism with the direction of tectonic transport with increasing deformation. However, stretching lineations perpendicular to the inferred tectonic transport direction are displayed by some shear zones. Field studies in the Sierra Nevada batholith have revealed a single shear zone (the Rosy Finch-Gem Lake shear zone) that contains both steeply-plunging stretching lineations in older metamorphosed sedimentary and granitic rocks, and shallowly-plunging stretching lineations in syntectonic granitoids. Dextral sense-of-shear indicators are found in all these units and deformation occurred simultaneously along the length of the shear zone.”

    Journal of Structural Geology
    Volume 19, Issue 1, January 1997, Pages 29-39


    Figure 11 from the following linked document.



    1. Hreppaflekinn micro-plate is in it self not well understood and defined on any geological map that I know of. To make matters worse, there has been little research into Hrepparflekinn micro-plate means when it comes to geology of Iceland.

      The same goes for suggested Tröllaskagi micro-plate.

  4. @Jack @ Finland says:
    August 23, 2011 at 05:12

    Well, that explains why my thoughts on energy dissipation in tsunamis falls a bit short. I always considered them a point source for non-fault system related events (island calving such as ever touted La Palma scenario.)

    I don’t remember who, but some one told me I was full of hooey. I’m guessing I’m wrong because of focal mechanisms as the energy is launched from where ever the event occurs (topology).

    Would I be correct in equating this with the “near field” vs “far field” that is seen in antenna operation?

    1. Yes! At the point of the initial earthquake, the tsunami behaves like a wave from a point source. But quickly (more than the ocean’s depth away from the source) it transforms first to a cylindrical wave (read: symmetry), and finally to a plane wave (read: symmetry).

  5. Jon,
    I incredibly appreciate Your blog, and Your efforts, but the last posts where a little too “black or white” in my opinion.
    At an average day, I leave home at 6 and come back at 6. Then care for my kids like 2 hours. The rest of the time I do what I can with the little energy left. You might have seen a bit of what this can mean when You had Your last job. So I really didn’t find/take any time to really “qualify” myself as a scientist and professional geologist among Your blog’s community. And I can’t stay people who open their mouth too wide without having prooven what they are worth. I’m actually not in the position to give any advice, bot allow myself to do it even though, let’s say “as a friend”. Avoid this too hard yes/no, right/wrong positions. Serious scientists with heavy background take care about how they present their work. Intelligence has nothing to do with studies, of course, and You’re a clever guy, but it needs a lot, and I really mean a lot, of work and time until one can allow himself to throw with references to natural sciences laws.
    It’s a bit too easy to just decide about the (im)possibility of energy transfer like has been done the last days.
    Please don’t take this bad. I’m absolutely not a native english speaker and hope I didn’t somehow express anything too harsh. You’re some kind of hero to us Iceland nerds, but I always thought it helps to get some critics from time to time.

    1. I have never taken a “black/white” approach to this. Not in this blog post or any other for that matter.

      But last time I did check the world is governed by certain laws of nature. That is unavoidable fact regardless into the way people look on this.

      1. No doubt about that. Just that we don’t understand all of nature’s law’s and how they interact, and especially in complex systems of which we only see a tiny part.
        Not that I thought You were the 1/0 kind of person, just that event nature’s law’s can be surprising in their application, at least for us who don’t always see the full frame inside which they apply. And as long as we can’t cut Iceland open in some way, this will be the case in matters of energy transfers under our feet.
        Didn’t mean to push You in any corner, and always appreciated Your open minded approaches.

  6. Thanks Jules. That took a bit of wading through. but it really is most interesting. A detailed investigation of what is under the geothermal area at Hengill concludes
    there is a
    “low resistivity vertical cylindrical body below Olkelduhals at depths ranging 3-5 km, and
    spread as an elongated structure oriented NW-SE at greater depth. ”

    I think many of us concentrate on the magma beneath Iceland and forget the huge water content trapped in the rocks. This of course will alter the way volcanoes and earthquakes behave.It must play a huge part in the fracturing system.
    Interestingly the large number of Earthquakes located in and around Thingvallavaten are mostly the result of cooling. Now this is something I have not thought of before. I wonder if this is true along the other places of ‘quake density?

    Jon you are so right.
    So much to learn about your geologically active and complex country. I still hold that as the non linear Schrödinger equation proved the impossible to be possible by proving ocean waves can, and do take energy from the surrounding waves. This causes an anomaly of irregular (and previously thought impossible) wave size and frequency. So maybe there is some mechanism yet to be found and proven that will explain the different behaviours of Volcanoes.
    Jon you are so right when you say ,
    “If there is a claim about Iceland that just sounds crazy, it probably is crazy and not based in any actual fact about Iceland and the geology that makes up Iceland.”

    But you are so wise as to say “It PROBABLY is crazy…..!
    This leaves it open that one day some mad, crazy scientist may just stumble across some new directions in thinking

    One thing is for sure the learning curve is certainly rising since 2000. So much research! Iceland is in the forefront of this and the whole world is benefiting either from the more accurate prediction of events or from the harnessing of geothermal energy.
    Iceland Rocks!

  7. Well, I have a degree in physics and a masters degree which including statistics, and I hear what you are saying Jon and I agree with you.

    I just want to give you my vote of confidence.

    Great blog!

  8. Ok, I do not really have a background in any scientific discipline (will never claim to either), but I know the odd nugget of information. (Please Disagree with me if I am wrong) What is the problem with thinking of volcanic systems acting like an interal combustion engine? Jon you say that hengil and Hekla do not share a magma chamber but surely the source of the Magma is the same. Also as a gas filled semiliquid, could it not be that as super heated gas pressure increases in Hengil it pushes the magma closer to the surface at Hekla?

    1. The difference between Hengill volcano and Hekla volcano is this. Hengill volcano is a rift zone volcano. While Hekla volcano is not (from what I can gather at the moment).

      The source of the magma might also be different, as there is difference in types of magmas that the volcanoes are getting. At least that is what this seems to be taking place in Iceland best to my knowledge.

      1. I agree on the differences.

        Still, their behaviour can be connected (to a degree) via an external “actor”, e.g. an external pressure, even from the mantle plume itself.

        IF this was the case, the connection would not be direct, and not even from Hekla to Hengill (or vice versa), but indirect, and from source X to Hekla and Hengill. It does not really matter which case is the correct one, as the consecuences may still be identical to each other.

      2. And this is due to the fact that correlation does not imply causation!

        Nothing can be stated on causation unless you can define the mechanism of the interaction/connection, as Lurking already stated.

  9. Jón, you have and always will have my vote of confidence.
    The things that have been theorized here lack verification, but they cannot be considered impossible and that’s enough.
    We are here to have fun and to hear what each other has to say, based on his or hers own experiences. Crazy or not, these things were not invented out of the blue. Numbers and plots have been shown. They might have not got the official interpretation, and likely, never will. We lack evidence, either statistical or factual, before it all will be proven possible or impossible, crazy or not. This is the basis of scientific development.
    In principle, I believe someone who is ready to eat his heat in case he’s wrong. And if he is, I’ll share a piece too (if he let me do so). A scientist from the official forums doesn’t have the guts to do so. Neither should you.
    So, you are playing the role you should here: to try to show us evidence which can make we all have a great feast of hats to be eaten.
    But relax! It’s fun. It’s intriguing. It’s entertaining. It’s challenging.
    But this is your duty to say: – “You guys are going against all principles of volcanology.”
    And we’ll gladly eat our hats. We are none.

    1. @Renato Rio, The rule states this.

      “Correlation does not imply causation

      “Correlation does not imply causation” (related to “ignoring a common cause” and questionable cause) is a phrase used in science and statistics to emphasize that correlation between two variables does not automatically imply that one causes the other (though correlation is necessary for linear causation in the absence of any third and countervailing causative variable, and can indicate possible causes or areas for further investigation; in other words, correlation can be a hint).[1][2]

      The opposite belief, correlation proves causation, is a logical fallacy by which two events that occur together are claimed to have a cause-and-effect relationship. The fallacy is also known as cum hoc ergo propter hoc (Latin for “with this, therefore because of this”) and false cause. By contrast, the fallacy post hoc ergo propter hoc requires that one event occur before the other and so may be considered a type of cum hoc fallacy. […]”


      Even if something looks like that it might be created by something. It does not necessary mean that it actually is like that.

      Now, looking at the earthquake data and seeing some pattern is perfectly normal. Because human beings (me too) are hard-wired to see pattern where none exist in reality.

      That is just the way it is.

      It is also important to notice that dataset from the year 1995 too current day is way to small to build a claim like this, even if it is just a idea.

      1. And there is another glitch in the data sets since 1995: Today we have more and more sensitive instruments recordings quakes. This means that we see more quakes – stuff that we missed in earlier years.
        This is something that can be seen in other fields of research as well: For cancer for example, the case numbers rise. They rise in reality, but not as steep as somebody could think, when he compares statistics about case numbers from the 50s and today. Today we have ways more sensitive methods to detect them, and there are more people. And this is a fact, which is hard to correct for.

  10. Mystery earthquake of today did happen at 09:11.42 UTC. It was a strong earthquake that did not appear on IMO automatic SIL list. Give the P and S wave I am estimating the distance to be around 300 to 400 km away from my Heklubyggð geophone.

    I would guess that the earthquake took place somewhere on the Reykjanes ridge.

    If that is not the case, this might have been a earthquake in Katla volcano. But that is just a idea given the data so far.

    1. The tremor peaks at the SIL stations seem much higher around Katla than in Reykjanes

    2. IMO now showing:

      23.08.2011 09:11:33 63.663 -19.323 1.0 km 1.1 99.0 4.4 km NW of Goðabunga


  11. First of all I find the discussion between Carl and Jon very interesting. I like the two sides, Carls fresh thinking out of the box and challenging dogma and Jons wide knowledge of the known facts on icelands volcanoes. I have to say that it is a nice theory that Carl has come up with, but I have some problems with it. Now I am not a physicist (I am a cell biologist who enjoys amateur geology) so there may be some things I have not understood but here is my take on the theory:

    Most quakes at the Hengill rift zone are no bigger than 3 on the richter scale, corresponding to ~2 GJ. Now that is a hell of a lot of energy at the point of release, however, the distance from Hengill to Hekla is ~100km, if we assume the energy travels equally into all directions in a half sphere with a radius of 100km that sphere has a surface area of 2000000km2 at Hekla. Now I am unsure how big the Hekla target is but 10km x 10km seems reasonable that means that it recieves 1/20000 of the energy released from the Hengill area and this is assuming that non of the energy is absorbed under the passaged and all the energy is absorbed in Hekla. 1/20000 of 2GJ is 100KJ. The small Mars bar I have in front of me contains 228kcal * 4,19KJ/kcal = 955KJ or almost 10 times the energy that Hekla recieves. This is why I believe there is no important energy transfer between those areas with the current earthquakes sizes. Now if you have a much greater earthquake that is a different matter of course.

    1. Carl mentioned, that typically the quakes affecting Hekla at all are at least M4+, preferably M5+ . M4.0 is 32 times stronger (more energetic) than M3.0, and M5.0 is 1000 times more energetic than M3.0.

      1. I am still nok convinced that the energy transferred is enough to shift rock in large enough quantities to trigger an eruption even if you bring energy focusing/interference to the table. I can believe it for M5.0 and upwards, but these are very rarely seen in the mentioned area. If the theory is correct a few quakes should thus be enough to trigger Hekla. Fortunately that should be easy enough to look for ie count M5.0+ quakes and calculate cumulative seismic moment.

      2. Query – if the energy transferred to resident water content in the volcanic system in preference to magma (which would require significantly more energy to mobilise), could the pressure build up from any steam within the magma conduits create a force that was large enough to shift rock? Just thinking out loud, as we already know that meltwater that seeps down into volcanic systems can be responsible for explosive eruptions, so surely water contained deep within rock could do the same? I hope this makes sense

      3. To clarify – I meant water seeping into volcanic systems during an eruption can make eruptions that were already occuring explosive – not that water seep specifically causes them per se.

      4. Below about 2.3 km, not likely. At that point the pressure of the rock/area is above the supercritical point of water. No how much heat you throw at it, water cannot go into a vapor state.

        Water may be there, but about the only thing it can do is to modify the solidus temperature or go into chemical changes with the rock. (such as serpentinization)

      5. It’s not that it shifts the rock and causes and eruption.

        The energy would be contributing to the total energy and participate in raising the temperature and increasing the melt production rate.

  12. Jon, I enjoy reading this blog and the various debates, arguments and discussions than ensue. However I feel that your dismissive attitude to Carl’s theory is very shallow and more than anything disrespectful. Now I’m not sold on Carl’s theory but it is an interesting argument, which was very well presented. Doesn’t mean its fact, neither does it mean its wrong – It’s a theory/hypothesis that would require to be scientifically assessed and researched, so I have no idea how you can discredit it so simply and without due consideration and respect.

    1. Science is not about feelings. It is about facts, figures and evidence. So far I don’t see anything that even supports Carls idea.

      Claims demand evidence. When I claim something, I at least try to keep in line what I am seeing. When I am wrong, I am wrong and that is that and nothing more of it.

  13. Jón, this is the mystery quake?

    23.08.2011 09:11:33 63.663 -19.323 1.0 km 1.1 99.0 4.4 km NW of Goðabunga

  14. This is normally a place where people are nice to each other. I’m not saying it still isn’t, but something is changing the athmosphere.

    Jon on his “blog owning” side against Carl and his hypothesis, some people saying “I’m a physisist and this is the way it is”.

    This blog is truely informative and interesting for those interested in volcanoes. I hope it stays that way.

    I think Carl is a funny person creating lots of interesting comments, but I still think Jon who is the blogger can’t let someone spam the place totally with weird theories without putting his foot down. I’m not saying Carl is wrong! I’m not qualified to do so. But sometimes he is cutting edges a bit too freely and sometimes completely wrong. At least when it comes to areas where I have deep knowledge (which is not geology :-)).

    I do hope everyone can continue posting happily ever after.

    1. Really? I read that more as a bit of bombastic rhetoric on the part of Jon than anything else.

      A loon theory is one thing, what Carl has offered is far from a loon theory. One glaring difference is that Carl did not state with certainty that “this is the way it is.” He gave us a hypothesis that in reality should be examined on it’s own merit. Instead he was met with a sort of puffed up “I know more than you do” childish sort of school yard B/S. (and in that there was some outright wrong info, or a misunderstanding of fault dynamics)

      When ever you have an interdisciplinary junction of ideas there will always be room for misinterpretation, specifically because some concepts are totally foreign across the aisle.

      The response that he got went against the grain of open discussion.

      Nah, completely different read on my part.

    2. No one is qualified to judge between different theories without experimental data. It is reality who has the only right to be the Judge for our ideas. Not Carl, Lurking, not me, no one. And, I think no one has attempted to do that. We are just discussing about the merits and weaknesses about different ideas / hypotheses / theories. Sometimes the discussion gains some heat, do not be afraid of that!

    3. This is normally a place where people are nice to each other. I’m not saying it still isn’t, but something is changing the athmosphere.

      I agree, AK. While I’ve been reading and enjoying Jon’s posts as usual, I’ve been refraining from reading readers’ comments over the last couple of days.

      Jon, you have my appreciation for all you do here. Thank you.

    4. Behavioral science:

      Phase One: Belonging. Strangers that meet tend to find points of common interest, what unites them. Differences are deliberately being ignored.

      Phase Two: False Comfort. Having found common ground, people get along famously, agreeing with one another but all the same, differences are noted and “stored” for later retrieval.

      Phase Three: Control. “Are we really as united and alike as we thought?” “Do we work in a way that I find acceptable and if not, can we change?” “Do I really want to belong to this group of people?” This phase is characterised by conflict when previously noted differences are brought up and hashed out. The tone can become rather harsh while this phase in in progress.

      Phase Four: True Commonality. All differences have been sorted to everyone’s satisfaction and those who cannot accept the new group dynamic have left. “Because of our differences, differences that are now acknoledged and accepted, we are much stronger and much more effective as a group.”

      This is derived from the great Israeli Chief Psychologist of the Six Days War and Yom Kippur War, Ben Shalit. Ladies and gentlemen, do not alarm yourself unduly! The current discussion is a sign of health and part of the evolution of every group of human beings.

    1. Red is not that much along the others yet… Thermal stuff? Or a new jökulhaup?

      1. But still far from being unusually high – just a bit higher then the last few weeks – much lover actually then a few months ago (back then it was probably caused by the sun melting the ice).

    2. Goðabunga seems to be the only station where blue and green are rapidly rising, in Eystri-Skógar for example blue is actually falling, and at other stations the rising is more moderate.

      1. We just have to wait and see, don’t we? Whats the closest station to Katla, btw?

  15. Hi Jon – thanks for this fascinating discussion here today. The ideas which have been exchanged are more complex than I can follow in one reading so I will come back to look at them again. Very informative and much appreciated.

    1. It does this once in a while. There are herds of migrating elephants that pass over the sensor once in a while. Without other data points, I just ignore 🙂

  16. Holy Geez!!!!!!!!!

    I feel a very strong earthquake in BOSTON! The whole house is shaking!

    Only other previous one felt was a small one about 25 years ago.

    This one felt big! And that isn’t supposed to happen in BOSTON!

    1. Both EMSC and USGS web sites are slow at the moment. But this might have been a intra-plate fault earthquake that you have there.

      Expect aftershocks in next few hours and days ahead.

  17. Virginia
    Magnitude: 6.0
    Origin time: 2011-08-23 17:51:05.8 UTC
    Epicenter: 78.10°W 38.02°N
    Depth: 10 km
    Location: automatic

  18. BreakingNews Breaking News
    MORE: Eastern seaboard quake felt in NY; Pentagon evacuated – from wires
    há 2 minutos » BreakingNews Breaking News
    Widespread reports of an earthquake, centered, reportedly, in Virginia – from NBC News broadcast, twitter http://t.co/Gajetkd
    há 4 minutos

    1. They just mentioned the earthquakes on channel 4 news here in UK, some building damage in New York apparently.

  19. Lurking, do you have any knowledge of the area in Virginia where the 5.9 quake hit or of the area near Trinidad, Colorado where the 5.3 hit? Strange set of quakes, eh?

    1. Well, lets try this on for size.

      Magnitude 3.4
      Date-Time * Sunday, April 04, 2010 at 09:19:14 UTC

      Location 38.599?N, 80.916?W
      Depth 0.1 km (~0.1 mile) (poorly constrained)
      Region WEST VIRGINIA

      Guess what happened. The following day an explosion occurred in the Upper Big Branch Mine in West Virginia and 25 people were killed. The reason? (despite the media hype)

      Gas build up.

      No matter how you slice it, that gas accumulated, the ventilation system couldn’t get it out fast enough and the thing went off when the mixture was right and there was an ignition source.

      This region is prone to quakes, though usually they are much smaller. Some thing of this size is in about the 70 year range from what I’ve heard. I haven’t verified it but the bobble head press wheeled in a geologist who stated that it was on the Rampano Fault. That fault is a product of the collision of the North American continent and the building of the Appalachian/Blue Ridge mountains as various islands were scrapped off and plastered to the continent. It roughly sets the boundary of the mountains and Triassic sedimentary rocks that lead down to the coastal plain.


      As for Colorado, it’s that pesky Rio Grande rift zone making noise again. Eventually it will eat the Rocky Mountains… that is if the Mid-Continental rift doesn’t wake up from it’s slumber and go at it from the North



      1. From what I have gathered, an answer would probably be something like this:

        Eyjafjallajökull, which has only a 200 m or so thick glacial cover, still retains almost all of it in spite of a quite large and prolonged eruption. A small glacier, Gígjökull, which flows north out of the crater and is part of the larger one, suffered a substantial but not fatal reduction. Vatnajökull lost very little even closest to Grímsvötn, which had an even greater eruption albeit one of much less temporal duration.

        Should Katla have a similar eruption to either of these, not much of the up to 700 m thick (IIRC?) glacial cover would disappear. However, in the extremely unlikely but not altogether impossible case of an eruption producing a large lava flow on the order or 10 cubic kilometers or so that can happen on Iceland once every 500 to 1500 years, then it is quite likely that a large part of Mýrdalsjökull would melt. It would not however disappear completely.

  20. http://earthquake.usgs.gov/earthquakes/recenteqsww/Quakes/usc0005ild.php
    M5.9 37.975°N, 77.969°W
    Very interesting as the depth is listed as only 1 km. There are very few earthquakes in this area and this is the largest I could find on record (M5.8 was recorded in 1897). But there is a seismic zone there that has the potential up to M6+ with an estimate of 1 such per 100 years. So I guess they have their earthquake for this century now!

    One thing I just learned, is that earthquakes can be felt and cause damage over much further distance on the east coast US than on the west coast or in other areas. I have friends in Toronto and NYC who felt the shaking from this quake. I’m not sure why this happens, can anyone explain?

    1. There is a subduction zone in the making in this area (according to the theory anyway). It is going to be ready in about 50 million years.

      1. 50MY… yeah I won’t worry much about it. 🙂

        Do you know why this earthquake was felt as much as 500km away?

      2. It has to due with the crust. As the crust in this area is less fractured and more solid it transfers the earthquake waves better then fractured crust on highly active areas.

        It is not uncommon in this type of area that large earthquakes are felt up to 1200 km away from the epicentre of the earthquake.

      3. An Easy Coast U.S. subduction zone? So that will mean volcanoes on the East Coast! Damn, and I thought I was in just about the most geologically safe place on the planet! Okay, now I have to face a dreaded 50 million year countdown. 😉

      4. Same thing with the other side of the Atlantic. The UK and Portugal should also become a subduction zone. In fact, violent earthquakes (M 8 or 9) have been occurring in Portugal every couple of centuries. But this would only be a subduction zone like Chile, in some million of years in the future.

      5. Part of the Pangea Ultima theory, which if true the UK won’t be part of. It ‘will’ remain an island at a higher (& colder) latitude. Which doesn’t matter really as humans probably won’t exist long before then!!

      6. Hey Worzel Us Brits , if there are any left, will have adapted well to the cold. We got a head start on the rest of the world! Could we bump into Iceland?

  21. Godabunga tremor meter (god) has “Blue & Red band” rize is likely due higher winds (god is situated on a mountain peak) a low pressure area is approaching Iceland from the west. I do not take sides on them “transients” between Hengill / SISZ / and Hekla are true or false. Only theoretical, but I found out now the Hekla Volcano “watch” page by IMO has been updated – and two more useful GPS stations added.


    1. sorry… “Blue and Green” bands… and wind seems picking up on Jon´s helicorder.

  22. I live 470 mi = 756 kilometers from the mag 5.9 EQ in Virginia, and it startled me by shaking my whole freak’n house while at the computer, so I posted it as it was happenning. It was very strong then tapered off over a minute or so. Sorry to be off topic, but that was so extraordinary … not supposed to experience earthquakes in Boston. (And from 756 km away!) Thanks for the replies with info on it. I couldn’t connect to the live seismogram sites at that time … too much traffic I guess.

    1. Boston and all in USA Take print outs of the recordings from the seismometer readings and photos of any cracks or damage. Then if you need to claim on insurance you have all the evidence. I had to do this to convince my insurance company out ceiling had cracked because of an Earthquake. They told me “You don’t get Earthquakes where you are”! (North West England)
      I proved them wrong with printouts from the BGS site! We had had a 2.8 but our 120 year old brick house is built on sandy terminal Moraine material.
      They paid up.

      1. How thick is the loose material before the solid rock, do You have an idea? Do
        You know details about the foundations?
        How many floors?
        Seems like an interesting case of local / site effects. Did Your insurance / governtal instance ask You to take some measures? Is there any established management or prevention system in Your region? Never heard of anything like that for GB. But if yes am keen on learning as I’m implementing this kind of stuff where I work – just finished and published mapping of soil types (in matters of reaction to seismic input). Thanks for info, but only what You know without any time investment.

      2. I read on web it startled people in downtown Boston also, and people evacuated buildings. But no one is reporting damages from what I read. No damages to my house, but thanks for the info re insurance. I believe the soil I am on is very soft and suspect it to be much above bedrock, which may exacerbate shakiness. Just to floors and a finished basement.

      3. Finished basement and only 2 floors leaves good chances that You will not end up in a collapsed building that easily…
        A thick layer of loose stuff between the bedrock and You leaves space for possible surprising amplification of the amplitude, but with the kind of house You live in an do to the regional seismicity there’s not much to be done I’d say… 🙂

  23. Ok. We had three such 6+ events recently in Iceland (two in 2000, one 2008) and I felt them all (both P and S waves) very, very well indeed. So I only say “been there, done that….”

  24. @Seattleite
    eastern Us has a fairly solid bedrock that conducts earthquake energy very well the New Madrid quakes toppled chimneys in Boston, calf and in general the west coast is so fractured that the energy gets dissipated by the faults locally rather than being transmitted any great distance

  25. Regarding the discussion between Jon and Carl, there is a simple way to go. We should plot what happens at Hengill (including cumulative earthquake energy) and Hekla eruptions. The trouble is going to be having data before 1947, when Hekla was dormant for a long time; I am less confident that this was a period with less activity at Hengill. But I might be wrong. Carl, this should be easy to test. At least for the last couple of eruptions in Hekla.

    1. The only data I have goes back to 1995.

      Got a link to an older set? I’m game.

  26. The other trouble is: with Grimsvotn, sometime in 2010, cumulative energy was bigger than that one in 2004, and no eruption occurred. Something else needs to be accounted. However, it seems that eruptions in Grimsvotn only occur when that threshold has been crossed, and magma paths are free (which happens if the volcano erupts often). I think a connection between Bardarbunga and Grimsvotn can be occurring too.

    Between Hekla and Hengill, a link seems much less likely to exist, but I am still open to the idea. One should even go deeper into the question, and ask why volcanoes like Hekla and Katla exist, when these are nearly outside (or at the edge) of the rift zones. Maybe the fact they are at the rift edges, explains their unusual activity and intensity. And something else needs to be accounted that explains why they would erupt.

    All these erratic periodicity in volcanoes is little understood and should be more researched deeply into.

    1. Isn’t it interesting that Icelands volcanoes occasionally occur in pairs?

      Bardabunga – Hamarinn
      Grimsvotn – Thordarhyna
      Vonarskar – Hagongur

      With the larger volcano central to the fissure swarm being to the Northeast and tending to erupt more primitive magma (mafic), and the daughter to the Southwest leaning more towards evolved magma (felsic).

      And though not really having a Big Sis / Little Sis relationship… Katla – Eyjafjallajökull… with Katla being larger and to the Northeast.

      Things that make you go hmm…

  27. I am not a geologist or physicist, just a guy trying to gain knowledge. I do know though that in life, if you dismiss things because they sound crazy and go against the things you think you know without even giving the chance to be disproven, you will not learn to your potential. Even if the theory is completely false you will learn so much through disproving it that it will be well worthwhile. We could have a conversation for days about theories that were dismissed as ludicrous until something was discovered that was unknown that led to a different train of thought and finally to a resolution. You readily admit that there are many unknowns about iceland geology so I don’t understand why you don’t think things you think are known could be flawed.

    1. There is a fracture zone between the volcanoes. That is the reason why this does not happen. As I pointed out, the known connection between volcanoes is when a volcano cuts into a different volcano. But that is the case with Bárðarbunga volcano and Torfajökull volcano. That mix is a explosive one, as can be seen in the landscape in that area.

      Carl has also once again vanished. I do not know why.

  28. @Irpsit
    I too wonder why there are volcanoes on the east side that are very active and nothing like this happens on the west side.
    Logic says they should.
    All we have to speculate with so far is a mantle plume that affects the East side only.
    This seems so very specific. The plume must be quite small at it’s head.
    We in the UK have earthquakes that are happening because the land is still rising after the weight of ice in the last ice age, thus releasing pressure. I wonder if Icelandic rocks also react like this?
    Just throwing in another spanner to clog the workings of our understanding!:)

    Good morning Jon and everyone. nearly time for my second coffee and all seems quiet in Iceland.
    Wishing everyone a peaceful day….Mine will not be too peaceful!

    1. Good morning!
      Your island (piece of continental crust) could be compared to a boat, that was loaded on one side and not on the other (diffenrent thickness of the glacier cover if You compare north and south). So now that it has been unloaded, it “tilts” to gain its horizontal position in the water (mantle). I imagine this can cause stress and lead to earthquakes, but not of the same kind as the ones due to “internal” stress generated by tectonics. I’d pretend, based only on a quick thought during my coffee break, that this is a phenomenon which can be nearly neglected when observing the icelandic context with strong forces that act because of tectonics and volcanic phenomena.
      But it’s interesting that big artificial lakes have lead to vertical movements of several meters in short times (month and years). Yes, the ground on which we stand is not as solid as we may think. I ones spent 2 days in the field with an old geologist. The kind of guy that lived for his science and reads the landscape like he saw through the topography and drew profiles instantly on his mental sheet of paper. We were eating sandwiches and talking about modern measuring methods. Then he suddenly said: “Well, young colleague, the earth breathes. Whether we measure it or not, it does and will go on doing so.” We both had a big smile on our faces because this was so “felt” and “unscientific”, but what a beautiful thought… Completely off topic, but isn’t this whole blog thing very much about sharing this kind of thought too…

      1. Thank You GeoLoco:)
        I have missed you and your lovely comments. You speak with a lot of heart and common sense. Just like that old geologist. I too had a mentor when I was young, Edwin Beer. One of the men who discovered Rayon. He was also a Geologist for ICI in their early days. He roamed the world and his house was a magnificent clutter of his memories and knowledge. Some specimens he gave me were wrapped in newspaper one piece of which had a review of Rudyard Kipling’s new books!He died aged 107 and my children were lucky enough to walk with him in his garden and they loved him.
        I am so honoured to have known this man.
        I remember a documentary recently about Volcanoes where Dr Clive Oppenheimer stood in front of a crater and joyfully announced “Listen, you can hear her breathing.”

      2. We, human beings, our passions, our thoughts, our heart and our fire, let’s just add love for it’s always good, are at the beginning of every even most “dry” scientific process and theories. Some might not like me for this, but I only trust the result of modeling when I find hints for them in the field, and somehow can “feel” them. This of course is never read in my official statements… 🙂 Our brain treats more data than we can put to paper, as nature is always more complex than any model. Which climate models include the influence of dust from space, which tectonic theories count the energy inputs by meteorites? I made my schools in the modern times, learning to use recent methods to convince according to today’s standards. But I find it extremely precious not to forget how “we” worked with less dependence on technical stuff.
        Well said Mr Oppenheimer. And it’s nice to share thinking and geopassion with people who bring additional life-experience.

  29. Quiet, yes. Seems no words left unwritten in Hekla “transient” discussion. I am not convinced it was interpreted correctly, perhaps part of a much, much larger scenario. There seems some going on however. But no near quakes or other signs near Hekla … yet at least … but on GPS plots it seems have moved … 5 -8 mm to north (?) since yesterday… and there are drops on strain meters now and then this morning.


  30. Öræfajökull just complained about the quietness. A new 2.0!

    Who knows maybe this one will go before everyones Hekla, Katla, Krysuvik and Hamarinn. Although I guess we would need a period of some serious quaking before it would be able to.

  31. That means there’s not likely to be any further eruptions in Iceland during my lifetime. I find that hard to credit. 😉

  32. I am sorry about lack of new blog post. The school is starting and that has kept me busy since yesterday.

    I am also without internet for the moment and at least until ~9. September or somewhere around that. As I need to set-up a wan router for my network.

      1. Thanks Jon. I was about to query that spike that has appeared on most SIL graphs.
        Are you working in the school or taking a course there?

  33. What with the latest 2 earthquakes? Depths of 43km/73km? This is far beneath the MOHO in this area, so, equipment/system failure?

  34. Hi Jon, I am not a seismologist but I find following your blog and the Icelandic Met Office fascinating. In a future post please would you explain more about the hot spot photos and how they fit on the maps of Iceland – I tried unsuccessfully. Cheers. Karen.

  35. Good point maynard, at the very least you learn why things do not work the way one thought

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