100 years of Icelandic volcanism


The steaming top of Hekla. Wikimedia Commons.

The steaming top of Hekla. Wikimedia Commons.

Statistics and volcanism does not exactly go hand in hand, especially since it tends to end up with idiots claiming that volcanoes are “overdue”. A volcano is never overdue, they may shift patterns of their eruptions, go into extended periods of dormancy, or pretty much do anything that they jolly well pleases.

It is always far better to study their current behavior if you wish to predict what they will do in the near future.

It might though be good to have knowledge on what the volcanoes have been up to in the past century or so, especially if you wish to ponder upon whom amongst a set of volcanoes are the usual suspects.

Before we go, it is good to keep in mind that Icelandic volcanism is very much about black swans. Or in other words, unexpected volcanism in not so commonly erupting places. For all points and purposes pretty much any spot along the spreading parts of Iceland can erupt, and have done so previously, and will do it again.

I will start in the north and go south in this exposé. There are two places that I will not mention, and that is the eruptions that has occurred north of Iceland in the Tjörnes zone and I will not go into the ones that have occurred out in the Reykjanes Ridge. There have been eruptions there in the last century, but among other things those small eruption was more likely to be Mid-Atlantic Rift eruptions than Icelandic, and we do not know exactly when they happened.


Krafla volcano photographed by Alex 73 / Wikimedia Commons.

Krafla volcano photographed by Alex 73 / Wikimedia Commons.

This volcano is one of those cyclic volcanoes in Iceland that is mainly driven by rifting episodes. The length of the cycles are approximately 200 years give or take, sometimes Krafla jumps a cycle or more, but it then tends to get back on track. It rarely if ever has eruptions between rifting episodes.

Between 1975 and 1984 the volcano suffered 6 separate rifting eruptions of diminishing size and prior to that it erupted 1724 to 1746 in six separate rifting eruptions.

A good bet would be that we will not see an eruption at Krafla until somewhere between 2170 and 2230, if it does not skip a cycle again. An eruption now would be a true black swan event. It may though have a few intrusive episodes and seismic crisis in between without any eruption occurring.


Askja volcano with the Viti crater lake in the foreground.

Askja volcano with the Viti crater lake in the foreground.

Before the large 1875 rifting eruption of Askja very little was known about this large volcano. In the Global Volcanism it is cited as having had an eruption in 1797 at Holuhraun, something that we now know was not true, that was an eruption from Bárdarbunga and not Askja. It is quite likely that the volcano erupted between the recorded eruptions of 1300 and 1875, but that the eruptions was to small to be noticed.

After the massive VEI-5 eruption in 1875 we come to the timeframe we are talking about in this article. The period between 1916 and present.

Between 1919 and 1961 Askja had a series of 8 eruptions, they are probably part of a larger eruptive cycle that started in 1875. All of these 8 eruptions have been small scale ranging between VEI-0 and VEI-2, and even as effusive events they were pretty small for happening in Iceland.

Askja has had several episodes of inflation and deflation in the period after 1961 and has also had several seismic episodes with earthquake swarms. Even though Askja is one of the larger Icelandic volcanoes and has a proven track record of large eruptions it has the record of being the least well monitored volcano on Iceland.

Currently there is nothing pointing towards an eruption occurring soon at Askja.


Holuhraun eruption from the air. Wikimedia Commons.

Holuhraun eruption from the air. Wikimedia Commons.

This is one of the 3 largest volcanoes in Iceland. It is situated on a large fissure swarm that feeds directly from the mantleplume under Iceland. Historically it has produced some of the largest effusive eruptions since deglaciation, only rivaled by a few other Icelandic eruptions. It has also had numerous other eruptions and up until 1910 it was the most frequently erupting volcano on Iceland. And then, nothing.

For some unknown reason Bárdarbunga switched eruption frequency completely after the minor eruption of 1910. There have been a few uncertain eruptions that might have happened, or not, out in Loki-Fögrufjöll.

In 1996 during the final phase of the Grimsvötn Gjálp eruption Bárdarbunga came back to life during a small VEI-1 eruption that created a 4 kilometer high ash column. The eruption was very brief and would probably not have been spotted unless it had been witnessed by volcanologist studying the far larger eruption at Gjálp. This eruption happened inside the caldera.

I am not going to go into Holuhraun here in detail, I am just going to state that this rifting fissure eruption was a purple swan among a heard of black swans. In the aftermath we have had to rewrite entire chapters on how Icelandic volcanism can operate. It was the largest effusive eruption in the last 100 years.


Grimsvötn glacier with a nunatak in 1972. Wikimedia commons.

Grimsvötn glacier with a nunatak in 1972. Wikimedia commons.

After the majestic Saksunarvátn tephras 8230 BC, this the largest of Icelandic volcanic systems have suffered mainly from small frequent eruptions, lulling many into believing that it was not able to operate big explosive eruptions.

With the exception of the 4550BC Botnahraun (Laki) and the Skaftár Fires (Laki) there has mainly been small VEI-2 eruptions emanating from Grimsvötn. The only exception to this was the 1873 VEI-4 eruption. All other larger eruptions have been emanating from Thordarhyrna, and it is possible that the Laki eruptions originated from that particular volcano and not Grimsvötn.

Between 1919 and present 12 confirmed eruptions have originated out of Grimsvötn giving an average between eruptions of roughly 7,5 years between eruptions.

During this period something changed inside of Grimsvötn and it started to suffer from larger eruptions. In 1996 the Gjálp fissure eruption happened and that was rated as a VEI-3 and was the largest effusive eruption up until Holuhraun during the last one hundred years. It erupted again in VEI-3 eruptions in 1998 and 2004.

In 2011 Grimsvötn kicked off in what was the largest explosive eruption in Iceland in the last 100 years. The massive VEI-4 eruption surpassed the 2010 Eyjafjallajökull eruption within hours and before being done it had surpassed both the 1947 Hekla eruption and the 1918 Katla eruption. To date it is one of the 3 largest explosive eruptions in this millennium on the planet.

Why Grimsvötn has changed into more energetic eruptions will be covered in an upcoming two-part series of articles in here.


I am here breaking stride a bit. There has been no confirmed eruption out of Thordarhyrna since the 1902 VEI-4 eruption. I am though briefly going to mention it since it has historically put in rather large and frequent appearances.

Thordarhyrna is the second largest of the central volcanoes on the Grimsvötn fissure swarm and this is one of the longer repose periods for this volcano. It has caused large rifting eruptions and the bulk of the larger explosive eruptions out of the Grimsvötn fissure swarm.

This volcano is rather likely to put in an appearance sooner or later, I am very much looking forward to that since there is so much that we do not know about it.


Hekla from taken from the side. Wikimedia Commons.

Hekla from taken from the side. Wikimedia Commons.

Hekla holds the record of being the oddest volcano on the planet. For many reasons this volcano should not exist in the realm of what is physically possible. First of all, it erupts magma that should not exist in Iceland.

The magma is bi-modal, during eruptions it first erupts calc-alkali andesite that is extremely rich in volatiles, it then in the blink of an eye changes to calc-alkali basalt that is low in volatiles. This creates an extremely explosive initial phase that can hurl large lava bombs 40 kilometers or longer. Then it effuses large amounts of basalt unexplosively.

It is also a very young volcano; it roared into life 5150BC and has since then built a majestic edifice shaped as an upside down boat hull. It exists on a local fissure that is basically as long as the volcano and this fissure is not connected to the larger tectonic rifts in Iceland.

Unlike all other volcanoes on the planet this volcano does not do run up sequences prior to eruption. It does not inflate in any great respect, and it does not do prolonged earthquake swarms. Instead it has a brief smattering of small earthquakes running for about 30 to 80 minutes before it rips open. No other well instrumented volcano on the planet is known to have the ability to erupt without giving off signs first, especially after a decade long repose period.

After Hekla came into existence it had 6000 years of doing only large scale eruptions. Up until the 1104 VEI-5 H1-Tephra eruption it had only had 9 eruptions, the tenth being the 1104. All of these eruptions were large, ranging from borderline VEI-6 to very large VEI-4 eruptions.

Then it changed pattern, enormously. At the same time the adjacent Vatnafjöll system shut down. Between 1104 and 1845 Hekla suffered from 11 eruptions.

Then, in 1947 Hekla kicked in an even higher gear with. From 1947 to 2000 the volcano had 6 eruptions, one per decade on average.

This points towards why it is almost impossible to use any kind of statistics on a volcano. They can change their pattern in the blink of an eye and go into a much higher frequency for a while, and then go dormant for a thousand years or so.

Problem with Hekla is that we do not know what it will do now. Will it go dormant for a prolonged time? Will it continue erupting about every decade? Will it start to erupt even more frequently? The jury is out on this and the only answer to all these questions lie within that rather nasty piece of work that is Hekla.


Fimmvörduhals erupting prior to Eyjafjallajökull. Wikimedia Commons.

Fimmvörduhals erupting prior to Eyjafjallajökull. Wikimedia Commons.

When Eyjafjallajökull innocuously came into life at Fimmvörduhals it was in the form of a gently strombolian action. Where the lava come from is still debated, either it came via a feeder system of its own, or it was fed from the Gódabunga cryptodome that coincidentally is not a part of the adjacent Katla volcano.

As Fimmvörduhals shut down a finger of lava worked its way into Eyjafjallajökull proper where it found a source of old rhyolitic mush and an unexpectedly explosive eruption followed. The eruption was not particularly energetic, nor was it that big. But it ran for quite some time until it had barely achieved the VEI-4 status.

Pretty much this was a small volcano having a maximum sized eruption. But, this eruption will forever be famous for having shut down the European airspace stranding a lot of passengers all over Europe, including me.


Katla and Myrdalsjökull basking in the sun. Wikimedia Commons.

Katla and Myrdalsjökull basking in the sun. Wikimedia Commons.

Historically this volcano has had the highest eruption frequency in Iceland, and to top it off, the largest eruptions on average together with Hekla.

This means that Katla on average belts out one VEI-4 every 40 years, and this has been going on for 8000 years.

This makes the latest lull into somewhat of an oddity even though it is still not entirely unheard of. The only real eruption in the last 100 years was a VEI-4 back in 1918. It was of comparative size to the 1947 Hekla eruption and the 2011 Grimsvötn eruption.

First of all, let me state this. Katla will erupt sooner or later and when it happens it will most likely be on the slightly larger scale. VEI-4 would most likely be the smallest size, with a medium sized VEI-5 in the upper end. When will it happen? Well, there are no signs as of now of an upcoming eruption.


Surtsey forming in 1963. Wikimedia Commons.

Surtsey forming in 1963. Wikimedia Commons.

The Vestmannaeyjar sits on a formative rifting faultline that most likely will take over as the new landfall point of the Mid-Atlantic Rift in the near geological future. Eruptions here do not form central volcanoes as in the rest of Iceland, at least not yet.

It was a tremendous black swan event when the Surtsey eruption started in 1963, nobody really thought it would happen and it was also the first island formation that scientists got to study up close.

As the eruption wound down nobody thought that they would see another eruption in the Vestmannaeyjar, and if it happened it would be yet another island formation. Nobody thought that an eruption would occur close to a previous eruption site.

In 1973 the next black swan occurred and landed on Heimaey. The eruption started without a lot in the way of a run up sequence. The locals felt a string of earthquakes during the hours prior to the onset of eruption. It is possible that there had been small earthquakes that was not felt prior to that and we will never know since there was no instrument record of the start of the eruption.

What is interesting with the Vestmannaeyjar eruptions is that they might represent a new stage in Icelandic volcanism with more frequent eruptions taking place out there. In the end this black swan may turn into a white swan.

Final words

Lava flowing at Heimaey in 1973. Wikimedia Commons.

Lava flowing at Heimaey in 1973. Wikimedia Commons.

One thing to remember with Iceland is that it suffers more black swans than this article gives credence to. Odd rifts open up now and then, some volcanoes erupt very seldom, and often eruptions take forms that are unexpected.

In the end there may have been more black swans in Iceland than white ones. Currently the most likely next eruption is Grimsvötn, but it could equally well be something unexpected, and that is what makes Icelandic volcanism so addictive.


158 thoughts on “100 years of Icelandic volcanism

  1. “In 1996 during the final phase of the Grimsvötn Gjálp eruption Bárdarbunga came back to life during a small VEI-1 eruption that created a 4 kilometer high ash column. The eruption was very brief and would probably not have been spotted unless it had been witnessed by volcanologist studying the far larger eruption at Gjálp. This eruption happened inside the caldera.”

    This is interesting and raises many questions. For starters – what was the state of the system in Bárdarbunga that it was able to produce a small subaerial caldera eruption as a side-effect of Gjálp – but managed to refrain from doing so throughout the entire Holuhraun episode so far???

    • It is a good question.
      One should remember that there had been a string of M5+ earthquakes that was double-couple with no net displacement. They are interpreted as being cold topside magma changing place with deep warm magma.

      The last of those M5 earthquakes started an earthquake swarm in Grimsvötn that moved over to Gjálp. So, probably what happened is that in this case the new warm magma trickled into an old cold reservoir and localy the pressure became to high for the lid.

      During Holuhraun the only moment there was high pressure in the system was when the magma entered from the north into the magma reservoir, at that moment it could probably have gone off upwards, but instead the weakest point was towards Holuhraun. After the caldera wall breached to the east the pressure was lower in the magma reservoir than prior to onset of eruption.

      • I was wondering about the caldera subsidence at Barda during the eruption at Holuhraun: does the caldera floor “float” atop the magma chamber and subside when the level drops (like a boat moored during the onset of low tide) or is it more like a wine cork getting sucked into the bottle if the wine is pumped from the bottom of the bottle? The reason I ask is I always wondered how the floor could subside so far and then just … stop …and then what?

        [Beware – stream of consciousness ahead]

        If it was sucked in, any recharging of the magma system would[could] push it back up and the side of the plug would[could] be weakened thus making it more likely to have an eruption along the caldera wall, yes?
        And if that breaches the wall, that would[could] make for a large – very large – debris flow, no?
        And all that ice/water reacting with the magma/lava can’t be good either, can it?

        This would[could] differ if it was floating though. There should be less stress on the plug as a result and any recharging of the system could be easier for the plug to accept – thus making it less likely to have a breach along the wall and a nasty eruption within the caldera (as a direct result of the floor rising and falling.)

        Wow, sorry about this…. it is a more convoluted question than I originally conceived.

        • I would say that the wine cork and suction/pushing is more apt as an analogy.

  2. Great post as ever, you’ve covered all-but-one of the Icelandic volcanoes I could name without the help of Wiki. That one’s a doozy, though: what about Oraefajokull? That booger’s got a bit of historical form, after all.

    BTW Hekla as the world’s strangest volcano? It’s strange, yes, but can it compete with one which erupts crupts lavas of, essentially, crude washing soda (Oldoinyo Lengai)?

    • Hekla being strangest? I would agree with that. Structurally, it’s not even a stratovolcano. It’s a fissure cone-row that is the size of a stratovolcano.

    • Öraefajökull erupted in 1727 the last time.

      And yes, Ol’Doynio Lengai is supposed to erupt that. It is remelted bottom of the Tanzanian Craton, so quite natural.

  3. And, for the uninitiated. “Black Swans” are essentially events out of nowhere. A true black swan is an event that is statistically highly unlikely. In keeping with Nicolas Taleb‘s definition, a Swan is so improbable, that it is considered impossible, it’s effect is profound, and after the event, it is explained away. “Well, if we had known about {whatever} we would have expected it”.

    Though some Icelandic events may not have a catastrophic effect on people, the potential is always there. And since people are always trying to shoe-horn volcanoes into being on or off of schedule via stats, well, it seems appropriate to use the Black Swan term since stats are already involved.

    • Incorrect. Infinite Probability means that it will occur, given enough tests.

    • Lurking: “an event so improbable that it’s considered impossible”. Surely, by that definition, none of the volcanoes listed by Carl are Black Swan candidates? All have had large eruptions in the (mostly recent) past, and are confidently expected to have more in future, something of which both IMO and the Icelandic public are, I am sure, well aware. Therefore; no Swans. Now, an eruption from, say, Snaefellsjokull, perhaps might qualify?

      • I would say that both Surtsey and Heimaey are black swans. And definitely Holuhraun. Remember that Holuhraun I was attributed to Askja. And the reality was so far out there that it will bring on a re-write on the entire book on Icelandic volcanism.

        • Point taken re Surtsey/Heimaey. Agreed, I didn’t engage brain before putting fingers in gear. But the next eruption from Hekla or Grimsvotn; probably not unless they do something completely without precedent. Otherwise we would be classifying every eruption from a volcano with a dormancy period of more than a decade or two as a Black Swan, which would be ridiculous

          • I totally agree, Grimsvötn, Hekla and Katla would be considered as white swans as long as they do not do anything really bizarre.
            That Bárdarbunga erupted was not a black swan in itself. But the style and where it did it was a black swan in my world.

            One thing that could happen, but be highly unlikely is an eruption between Langjökull and Hofsjökull for instance. Or any such unlikely place. Problem is that Iceland has a problem to do things like that rather often.

          • As I said a rhyolite eruption from Bardarbunga,would be a black swan.An eruption more expected from a subduction zone caldera than from a divergent plate volcano.Having said that rhyolite eruptions in Iceland are not unprecedented so that would not even be a black swan.A black swan is a Paricutin volcano erupting outside of Liverpool in England…🐸

      • Valid point, but my defense of the use of the term comes about from the fact that Black Swans are descriptive of a phenomena that comes about using statistical probability.

        In the case of Icelandic volcanoes, yes, they are quite regular, on the whole. But any one volcano can not be nailed down to a specific behavior. Statistics is really only effective at overall behavior. Once you try to get too specific with statistics, things go badly very quickly.

  4. Very nice article: makes me curious, too, about when and where Iceland will erupt next. Grimsvötn is a good chance, but I’d say fifty-fifty at least that it will be some place no one is thinking about in this moment. Or maybe Hekla ??? How many times will Etna or Fuego or Soputan erupt before the next Icelandic eruption?

    Also worth noting is that while Hekla’s eruptions kind of sneak in like thieves in the night, Eyjafjallajökull was working at least for 16 years on its eruption, producing a huge amount of instrumental data, which a posteriori permitted to track in much detail the timing and character of magma movement, and the path leading up to its eruption.

    • Fuego does between 4 per day up to 4 per hour, Etna quite a few a year, and Soputan goes at least once a year. So, several hundred is likely.
      Iceland does one about every 3 to 4 years, but they all tend to be interesting as they happen. And I stick to it being fifty fifty that it will be something unexpected too, and it is within that the charm of Iceland lays.

        • I guess my view upon it is coloured by seeing it go boom in a nice puff every so often. But the paroxysms are beautiful. Sigh, now I want to go back home again… 🙁
          Weird how fast Guatemala became home for me.

          • Carl-my wife loves Guatemala -she’d go back in a pair of seconds..

  5. Great article, I have a tendency to check IMO’s website, lol.

  6. From Carl’s statement that no volcano is ever overdue, I conclude that the longer the quiescence time, the lower the chance of an imminent eruption. Therefore, the most likely place for the next eruption must be the most recent one – Bardarbunga.

    • Truth is, a volcano erupts when magma makes it to the surface. This is not a linear process, neither at depth nor close to the surface. It’s like us catching the flu. We do that when there’s a virus circulating and we’re not immune to it. Does not necessarily happen at regular intervals, in the sense of “because it hasn’t happened for so much time, it must happen within the next so and so many months or years”. If it doesn’t happen, it doesn’t happen. (Now, tell me: is that BIG science or what ??? 😀 )

      • Yes, complex processes can give random output (e.g. weather), but can also end up being regular (like Old Faithful): complexity is hard to predict. In Iceland, being a MAR, one can assume a fairly regular magma supply at depth. Predicting a certain number of eruptions over say a millennium may therefore be fairly safe. Predicting where the magma will erupt next is not.

        I had the impression that the GPS’s in central Iceland showed a little deflation over quite a large area last year. I am a bit out on a limb here! If this were due to the 1km3 of erupted lava from Bardarbunga (the estimated volume of the deflation was of that order), that would show that it affected the pressure over a much larger area than the volcano itself. The magma movement from the eruption would have affected rock temperatures around the dykes. An eruption does affect the local equilibrium. It could make a nearby eruption either more likely or less likely. How is that as a prediction?

        • This is what I wonder as well, you shake things up a bit and what happens, look at the Hamarinn GPS, what does this movement do to the system as far as opening it up, maybe closing it down, hard to say.

        • Iceland is around 100000 km2,so if you could extract 1km3 evenly over the entire Icelandic landmass ,it would drop by 10 millimetres?

          • something like that. It wasn’t over all of Iceland though, only the central region, so a much smaller area

        • Good question Albert.
          If we look at the usual suspect, Grimsvötn, it deflated during the eruption due to the process you are describing. The pressure lowered, but as soon as the eruption ended rapid inflation started, faster than at any time before in its recorded history.
          My guess is that the effect is temporary in adjacent volcanoes. In the short term I think it would delay the eruption, but in the long term it is what is happening under the volcano that is important, and the fact seems to be that the rate of magmatic influx under Vatnajökull has increased in the last decade or two.

  7. Great read Carl

    I am going with the next activity at Hammarin. Just because nobody else is

    • and, I’m actually okay with that. 😀

      Being wrong helps you keep your perspective.

      • Just avoid going back to read your predictions in blog posts,that is truly cringe worthy..😅

        • Science is about making predictions. That is what makes theories testable. Being proven wrong is not a disaster: it is progress. Of course the theory should be justifiable. That is the nature of science.

        • Actually not.
          My spectacular failure was Hekla. It had a series of borehole strain changes looking like it might erupt, the smattering of earthquakes came, looking exactly as it should from previous eruptions. In the end a lot of glorious nothing happened.
          I was certain it would erupt, IMO was certain that it would erupt.
          In a way the missing eruption was a black swan event.

        • If the theory can only proved by correct prediction,who decides whether the theory is justifable?

          • It has to fit in with existing data, and it should be plausible within the known processes. The more implausible the theory, the stronger the evidence needs to be. It took ages before the theory of dark energy was accepted by scientist, but Relativity was accepted very quickly as it fitted in so well with the physics of the day. The discovery of gravitational waves, shortly to be announced, will be accepted as long as the detection is strong enough, as we already know that have to exist.

          • I would suggest how radical a path to investigate,depends on the progress on paths already investigated,if a dead end is reached,then another path however unlikely should be investigated?

          • Dark energy?

            That’s still in flux.

            I was reading recently about a new and rather appealing theory. A complex balance of dark matter and dark energy has been postulated in order to explain observed apparent changes in the rate of expansion of the universe over time. The new theory I read does away with all that by simply ruminating on the fact that the change IS indeed simply an apparent change – and postulating that the true underlying cause is much more simple and elegant than ‘dark matter’; time itself is slowing down.

          • Right now I think most physicists would be careful to discuss time, if it even exists in any other capacity than direction. Why? Because we quite possibly have lost our reference.

            I am a far crappier physicist than our own esteemed Albert, but even I am reeling after the latest hubbub where our trusted C might not be a constant after all. If true it could indeed explain a lot of weird fringe effects we have had to come up with ad hoc solutions for.
            At best it could just mean that we have the wrong speed for C, or the worst case scenario that C is not a constant at all. We indeed live in interesting times right now.

            Time = The sum of the speed of our particle movements and our observations of outside particle movement speeds, as observed by an outside observer. (That is my interpretation). Now, ponder what happens when you rip the constant C out of that equation.
            I guess time went from being relative to being irelative 🙂

            And now over to Albert.

  8. Next wild guess for a black swan would be Herdubreid. It came back to life with a quite strong swarm around 2007 and one in May 2014 and is showing activity ever since.

    • It is actually not such a weird bet.
      Herdubreid has most likely had a small eruption after deglaciation. There is an undisturbed tuff cone on the top that has not been altered by glacial ice.
      The intrusion in question has moved quite a bit to the north since 2007. It started at Upptyppingar and meandered upwards and northwards. By now it has almost gone past Herdubreid.

      • Going past Herdubreid, what’s up that way? Krafla waking up again?

        • Between Herdubreid and Krafla you have Fremrinamur central volcano.
          But, judging from the 3-dimensional trajectory of the intrusion in question it should pop up far before that, or just stall and become an old frozen dyke intrusion of some considerable length.

          I think that this intrusion would need a second pulse of magma rising the same way to produce an eruption. There is just not enough magma for it to surface.

  9. I tend to think that volcanoes do behave somewhat predictably, but that the conditions are very much subject to change, and one should know that there is a good chance of a prediction going wrong at any given time due to unknown changes in the system. Also, certain volcanoes are much more predictable than others.

    The main problem we tend to have with volcanoes is that people tend to pick sample sizes that are way too small. This is partially a result of volcanoes not erupting often enough (with a few exceptions), along with a human tendency to NOT see things in a geological time scale, but rather a human time scale.

    Take Katla for example: it has erupted in an extremely predictable manner over the last 10,000 years. It very predictably has a VEI 3-5 eruption approximately every 40-150 or so years (average around 80). There is natural variance here, but the enormous sample size shows that it has been one of the most pattern-happy volcanoes in the world.

    On a smaller-sample size scale, researching the eruptive past history of Pinatubo allowed scientists to save thousands of lives by understanding that it has a tendency to do VEI 5+ eruptions every 1000 or so years.

    The tough volcanoes are the ones that tend to do a little bit of everything. Volcanoes such as Vesuvius for example run a range of explosive eruptions to very small-scale eruptions, with time intervals that do not seem to make any sense.

    Also, there is a small bit of truth to any given volcano being “due”. Yes, volcanologists and scientists tend to hate this term, and generally for good reason – it’s a gross over-simplification and usually doesn’t account for an accurate sample of a volcano’s eruptive history. But in a very basic manner, if you turn a hose on and place a balloon over the spicket, eventually the balloon is going to burst. The one assumption here that may however be errant is the assumption that volcanoes have a steady and constant supply of magma coming into their system. The more realistic model is diapirs (blobs) of magma periodically rising through the crust and assimilating into the magma chamber region. For some volcanoes, this may be relatively constant, although I’d wager most volcanoes are a bit more irregular.

  10. Just because I was at Masaya volcano over the holidays, I have been watching her. It is now closed to the public and the incandescence can be seen for several km’s away now. You had to be at the crater rim to experience it on DEC 28th. I have noticed the seismic activity has really picked up just in the last 24 hours. I tried to copy and paste the link here to the recent seismic activity. Any thoughts from the pro’s 😉


      • Hello Bill!

        Sorry that your comments got stuck pending moderation.

        In regards of the plot, I am not that good at the antics of Masaya, but in general I can see pretty much every type of volcano related earthquakes and seismic unrest in it. Tornillos, fracturing brittle quakes, VT-quakes.
        That is one unhealthy volcano.

        • I would though say that since I do not have a record of seismograms from this particular volcano I am not in a position to say more than that it looks angry.
          One would need GPS-trajectories over time, gas-measurments and so on and so forth.
          Masaya is though a rather large volcano, so it could do all sorts of things without having a large eruption. It would though be cool if the lava lake returned once more.

          • Poking around on Gurgle Eart, I am struck with the question, is Masaya a Somma Volcano? It is situated in what appears to be a older larger caldera type structure.

            Maybe a “cryptocaldera”? N/M. not so crypto…

            “The complex volcano is composed of a nested set of calderas and craters, the largest of which is Las Sierras shield volcano and caldera. Within this caldera lies a sub-vent, which is Masaya Volcano sensu stricto”

          • It is one of those rather complex caldera formations that make central America so interesting.
            Since the plate is hardly moving the calderas tend to go caldera at almost the same spot time and again creating these serial large eruptors.
            Atitlán is just a bigger version. It went caldera 3 times over a period of 10.5 million years during which the center of caldera forming eruptions has moved 20 kilometers. That is tectonic motion that is 1.9 millimeters per year.

            The total velocity is of course much higher, but the overlaying plate is held stationary by the MAR (a bit more complicated, but still basically true).

      • Geolurking, If memory serves me well the park rangers said the caldera is actually 54 km in diameter and there are several volcanos/vents within the caldera. Pardon my ignorance if I said that wrong.

        • I think they got it wrong.
          El Ventarrón Caldera (That Masaya is a part of) is 11.5 by 6 km. El Ventarrón if memory serves is intersecting two other calderas of equal size. So let us say 15 by 12 for all of the calderas. I think that is a pretty good estimate since I could not find a figure for El Ventarrón I and II.

          • Wickerpedia states that the park is 54 square kilometers. So I think we have it there 🙂

    • Carl,

      I have been watching the stream off and on through out the day. Seems like the lava has definitely made it all the way down to the lower saddle today. I noticed the change in color of the material that seems to be slowly making its way down the volcano. I assume you are hearing that on the ground too.

      • Sadly I am not at home today Bill, otherwise I would be sitting near the lower of the two cameras watching the show.

  11. If Hekla is erupting volatile-rich andesite, then Hekla’s magma comes from subduction. The obvious explanation would be a microplate. Probably as the spreading center has jumped from the peninsula south of Reykjavik to the archipelago (soon [geologically] to be another such peninsula) at Vestmanneyjar, some of the piece of plate in between these two areas along a NW-SE direction has carried on moving to the SE on momentum, buckled, and been forced under the newly spreading crust just to the NW of the new MAR portion. The volcano’s youth reflects the fact that the spreading center jump itself is young, Holocene or not very much older, and it’s probably doomed to be short-lived as well, once the old rift site fully “welds shut”.

    Its odd behavior (with very little pre-eruption “noise” in particular) and atypical structure for a subduction volcano probably reflects the combination of a subduction *magma* with a surface vent produced via rifting processes, and the bimodal eruptions may indicate that the second part of each eruption is basically a “standard” MORB eruption. So, the microplate produces puddles of subduction magma under the Hekla area; then ongoing MORB rifting pulls the area apart, the pooled magma degasses and rapidly ascends to erupt, and then MORB basalt follows, in each cycle.

    • Problem is that the basalt is not MORB derived, it is a calk-alkali basalt.
      There is probably a slab under there, but the andesite is most likely not a product of subduction, it is more likely that the slab under melts and give the odd basalt.
      The process involved in the creation of the andesite is rather baffling.
      I have an idea about how it happens, but I need to think more about it. To be honest, I am thinking about writing a paper on it so I will keep that to myself for a while.

  12. And if we take a detour from Iceland, this is the new record for harmonic tremor at Fuego in Guatemala. The current paroxysm is turning out to be pretty big and the general trend seems to be towards bigger paroxysms.

  13. Hey guys

    Its irpsit!
    It has been 1 year since i last wrote in the blog but needless to say i am still alive
    Had big personal changes in my life and left Iceland and travelled afterwards, with very little access or time to internet

    Now i am in Indonesia for some time, a great land of volcanoes, and i need advice of you to know which volcanoes are currently more in risk of eruption in soon

    As far as i am aware i know of new and recent activity in north sulawesi (Soputan), Egon in Flores, mt bromo and semeru in Java and rinjani in Lombok, sinabung in Sumatra, but on these volcanoes i know little about their recent level of activity

    Anything to be aware of?

    • I would meander over to Soputan and go “Ah” and “Oh” at seeing a supervolcano erupt. But that is me.

    • As far as I know, Rinjani stopped erupting at the end of last year, no activity going on there now.

      Soputan’s eruptions seem to be brief episodes, similar to paroxysms at, like, Fuego, Etna … but in between quiet. The last paroxysm was just a couple of days ago and seems to be over.

      Not all too far from Soputan are ever-active Karangetang in the Sangihe islands, and Ibu and Dukono on Halmahera island, both active since many years but quite remote.

      Semeru seems to be its regular self, and nearby Bromo is currently also erupting.

      Finally, there is Batu Tara, erupting very much the way Stromboli does, but since the volcano is much smaller, much more of its ejecta fall down to the very base and into the sea.

      Oh right, on the other end of Indonesia is Sinabung, now in a phase of frequent, powerful Vulcanian explosions nearly always accompanied by pyroclastic flows.

    • Hi Irpsit, was wondering how you were, glad to hear you’re alive and well and somewhere warm!

      Regards, Mike

  14. Hi Irpsit… Good to “see ” You. Whatever are you doing in Indonesia? (I am being nosey!) Glad to hear you are OK.. but you really must stop this Volcano chasing round the world…it can get addictive 😀
    Hugs ((((Irpsit)))))

    Nope, could not find any problems with your comment Diana.

  15. Carl Thank you for this concise resume of the volcanism in iceland. You may well have to rewrite some of your post sooner or later. There are a lot of grey, muddy little cygnets waiting
    to learn to fly!

  16. I will briefly transate todays activity at Volcán de Fuego.
    Today a new record in harmonic tremor has been reached and also a new record for the volcano in regards of pyroclastic flows.
    The ash column reached 4.8 kilometers and repeated fire-fountains reached a height of 400 meters above the crater.
    The ash will mainly move towards the Antigua and Guatemala City as the wind has switched due to a cold front.
    It is likely that the airport will close due to ash-fall.
    I will relay any information I get from Conred and my family.

    Take note of the Seismogram, the station is placed well outside the volcano. The signal is intermittently so strong that the station blanks out. And the rest of the time the signal is hitting maximum recordable signal.
    There is a risk that the eruption will strengthen further.



    • Just to show how bad the signal is right now. This seismometer is situated next to Pacaya. It rarely shows any signal unless Pacaya is erupting. Now it is showing Fuego tremor.


        • Just to give a sense of it.
          The first seismometer is 7 kilometers away from the base of Fuego.
          The other one that shows Pacaya is a lot further away. First you have the distance from Fuego via Antigua to the volcano of Agua, then you have an equaly long distance until you reach Pacaya. It is about 35 kilometers between these two stations.
          So, this is really strong seismic signals we are seeing.

          • Wonder if it could be heading to an eruption similar to the one in 1974.

          • A pretty safe bet is that new magma has risen up from the deep reservoir under Amatitlán.
            The earthquakes that preceded the first paroxysm during new years ever was unusually strong, and it has not calmed down since then, quite the opposite.
            At the moment I think more that we will see bigger and more common paroxysms.

          • Any chance of a flank collapse here? I doubt it would be a high likelihood, but I know the volcanoes in that area close to the Atlantic have a distinct history of collapsing, including a few events from fuego itself.

            Would have to imagine the more basaltic nature would be a good thing however.

      • And a duty technician just turned the gain stage all the way down to the bottom. I should have saved how it looked prior to that.

        • If you have a way of looking through the folder of your browser’s cache, you might be able to still find it with thumbnail view… that is, unless your have closed and reopened your browser.

          Sorry, can’t tell you where exactly that is at, all browses are different.

          Using backarrow with your browser won’t work, it will just pull the fresh image.

  17. I’m from Florida. I live with fools.

    ROYAL PALM BEACH, FL (WPTV/CNN) – A south Florida man is apologizing after throwing a live alligator into a Wendy’s drive-thru window.

    According to authorities, it started when Joshua James placed an order at the fast-food restaurant in Royal Palm Beach, FL.

    He took his drink, reached into the back of his truck, and pitched a 3.5-foot alligator through the drive-thru window when the server turned around.

    The incident happened in October, but James wasn’t arrested until this week. [Unlawful possession of the alligator, as well as aggravated assault with an alligator. Which technically means he hit someone with it.]


    As for the gator, Fish and Game released it into a nearby canal.

    • I think there must have been drugs and or alcohol involved, if not then you can’t fix that kind of stupid.

      • His mother stated that it was definitely a prank, “That’s what he does.”

        • Oh, in that case it’s ok….Just a good old boy havin some fun..Go about your day nothing to see here. (sarcasm)

          • South Florida is far from just “good old boys”. Those people are extinction events waiting to happen and one of the reasons I have my “Homo Stultus” theory. It’s pretty difficult to be an optimist with them around. As a species, Homo Sapiens is long extinct.

            I can just see it now. “Doctor! Doctor! Why does it hurt then I think?”

            The movie was less a comedy that it was a prescient look at our future. The first 2 minutes will lay it all out with crystal clarity.

            … and, just in case any South Floridians are reading this and take offense. Congratulations! You are still capable of some level of thinking. The problem isn’t relegated to S Florida though, I see examples of this decline everywhere. Yes, even with myself. I too have pulled some pretty boneheaded stunts in my time. (try falling off a truck while being perused by an angry copier. Common sense said to not be there when the copier arrived, so using an even more ancient primate skill, I snagged a hand hold and swung out of the way as the copier blew past me.)

          • Try Putting a Bobcat in a Jeep Wagoneer (the big one) with three
            Bluetick hounds, and closing the door. One of my redneck (the Hatfield
            side) relatives did that on little hunting expedition . He had shot the cat
            thought it was dead and tossed the still very alive Bobcat in the seat
            of the Jeep. Just to see the reaction. The cat proceeded to defend himself very nicely and the hounds reacted by cornering the cat under
            the driver’s side. The hounds were not about to get close to 35 pounds
            of snarling buzzsaw. My Relative decided to open the driver’s side door.
            Where the cat was. The cat exited the Jeep up and over his head and
            followed closely by the three 75+ pound Blueticks. So he got clawed by the cat which survived the encounter,ran over by three hounds and
            the discovered that the cat had shredded the new seat covers and
            there was a combination of dog and cat feces all over the car.
            Then he lost his keys. It was his wife’s Jeep. and it was three miles
            to the nearest phone.

          • Bobcats are not to be trifled with. I imagine it was quite spectacular. The dogs, being in a group, we’re in their native form since all modern dogs are so closely related to wolves. The wildcat, well, there’s a reason for the name. He’s cornered by what appears to him to be a pack of wolves, a natural competitor and threat. So, the cat is gonna be quite upset and just want a way out. And your relative provides it… and serves as an ad hoc tree to a well adapted tree climber…

            The only way it could be better is if there was a video 😀

    • I’ve seen a few videos decrying it as not being a documentary and then going into a diatribe about IQ being a poor measure of overall intellect. Okay, that’s fine, but the end results are what they are, and are manifest all around us.

      I have a tendency to highlight some of the more bizarre ones when I find them… everything from the two guys busted for stealing an eggbeater, to the guy in Ohio busted for unlawful carnal knowledge of a picnic table. Carl found an even better one, but I can’t post it here… this are occasionally kids who read this blog and it would not be appropriate. I remember a particularly gruesome one from years ago that involved a band sander, and a stapler to try and self remedy the injury, and the subsequent infection. The stories are there, you just have to pay attention to find them as they go flying by the news feeds. And don’t get tangled up in a band sander and thrown across the shop by it.

  18. Somewhat on topic for the sub discussions going on here. I recommend viewing the whole 10 minute video. It’s entertaining, and enlightening.

    “Physicist Richard Feynman explains the scientific and unscientific methods of understanding nature.”


    • Feynman is one of my favourites. He was stark raveningly mad, but he was a genius on a grand scale.
      He was also the teacher of my teacher in physics. Not that Fredkin is that much less of a mad genius…
      What put Feynman in a league of his own was that he was adamant that things should work in the real world. He was also a pretty decent engineer.

  19. Good post to Hobbes on the one before this one. Catching up on my reading. Does anyone have all the current active volcanoes together on the same global map?

    My husband had been in the hospital due to chest pains. He had a stint put in an artery on his heart. May have another one put in if medicine doesn’t help. He’s doing quite well.

    Now off to read the post above. 🙂

    • I think that Hobbes is working on something like a world map of eruptions.
      But, it will take some time to produce, and it will be hard to maintain.
      It is up to him if he has the energy to do it.
      After all we are talking about tracking week after week what between 60 and 100 volcanoes are doing.
      The words “monumental task” is rather apt.

  20. There is another star on Bardy’s map today. A confirmed 3.3 from last night. :3

    • In December of 2014 I took a helicopter into White Island. Hiked up to the crater lake. Quite beautiful actually. Colors were bright yellows and greens. I have several videos and pics. I’ll see if I can post them when I get home later.

    • I tried to compare this to the movie above, from 2.5 years ago. I think I can see where this view is from and how it fits in with the movie. the lake level seems very similar between the two. Of course, such lakes are not particularly stable: they can go up an down a lot depending on how much heat from below and how much water fall from above. So it may be surprising that the level is so similar.,

      Regarding the comment above whether 6 meter inflation would normally be due to magma: I think if this happens say in Kilauea, it would generate a lot of excitement. But calderas do go up and down. The width of the caldera is probably more indicative: Kilauea has been regularly expanding for years, so far by perhaps 50cm. The lava lake goes up and down by 50 meters without much happening. The width gives you the volume of the magma chamber. The height can change enormously just from the magma moving around a bit. In caldera such as Campei Flegrei, the dominant effect is from underground water and water sloshing around can raise the floor by meters – and take it down again. The pillar of Puzzuoli show I think 6 meters of up and down movement and that will largely be due to water. On the other hand, the last eruptions there were preceded by inflation of 30 meters or more and that was certainly magma. So both happen.

      • One thing to remember with White Island is that the water table is very high on the island. Or more to the point, the water level is oceanic level, and the lake is pretty much at that level. The island like all volcanic islands is very porous, so water would be coming in at the same speed it is being boiled off, even during a fairly large eruption.

        People tend to forget how fast a large caldera can inflate due to fluids shifting. Be water or be magma. They almost always have large reservoirs of both, and those reservoirs can shift location very rapidly.
        Few calderas do slow and steady lift up. Instead they go in weird spurts and then nothing. And other volcanoes inflate at a pace you can set your watch to like Iwo Jima and Ischia.

        And while my brain is rambling. One of the few videos of a phreatic blowout on Iwo Jima turned out to not be phreatic at all. Instead it was heat affecting an old 16 inch shell from Iowa that had fallen into the ocean. As the spot inflated up and became the new beach it dried out and heated and “boom”. Volcanic artillery is something of a novelty. Cryptoshelling with magmatic release…

        • Cryptoshelling – I like that one. Never knew that bombing volcanoes could be that dangerous!

          • They are still finding shells that is pushed up out of the sand.
            During the days before and during the entire Iwo Jima campaign they both bombed and shelled the island with thousands of tons of bombs and shells.
            If memory serves (Henrik will correct me) there was 6 battleships and 10 cruisers going at it 24/7 for 3 days together with a few carriers prior to the amphibious landing, and before that aerial bombardment had been staged for 7 months.

        • Carl,actually the hydrothermal system is sealed from seawater.

          Edited since the link didn’t work.

          • Reading does not mean that you are supposed to only take in what is supporting your standpoint.

            I have been there running around the place. The island like all other known volcanic islands of this size is porous as hell. What current research says is that the volcanic system is closed of from the water (no shit), nor is the hydrothermal system at depth. But the lake itself is something else. The lakes normal level is the same as the water table that is the same as the ocean since water will percolate in through the sponge that the island is.
            Large rain storms will heighten the water level, high activity often lower it through boiling. There are therefore 3 different factors at play. But I have noticed that you enjoy hanging yourself on a single fact and then dangle forever.

            Get the picture, there is nothing going on there. At least nothing that is out of the ordinary. White Island is a rather interesting place for a picknick, but as a volcano it is seriously over-rated and it will not blow up and destroy the world as you seem to hope.

            I feel like I am talking to a Belieber ranting on One Direction… Sigh.

      • Albert the lake is 6 meters higher than when that video was taken in August 2013 and the camera angle is different ,as the current view is a more recently installed camera that was not in use in 2013.The small circular portion of the lake emitting steam is the 2012 vent and the location of the spiny dome that appeared after the 2012 small eruption.http://info.geonet.org.nz/pages/viewpage.action?pageId=3801265

  21. So this was posted by Fransesco Spadafina on Volcano Cafe’s FB page. We knew Masaya was up to something with all the seismic activity…..the lava lake is back!

      • Nice video.

        I bet that hole gets quite lively when it rains.

        • And there we go again…

          Shall we say it is rest time for a week for violating rule number 1.
          Personal insults is not okay in here.
          See you in a week.


        • Pinatubo’s main blast occurred during the middle of a Typhoon. Nicaragua can have upwards of 1,524 mm/year. I imagine that rain and run-off directly into the pit will immediately flash to steam with little mixing.

          • Whoops my friend, as you well know, Pinatubo is in the Philippines not Nicaragua. The rain must have been from a typhoon in the Philippines. Too many volcanoes under discussion easy to have a slip of the lip :smiley: :smiley:

    • But the real question, is how long until they stick LIGO on the moon?

      It would provide a really nice baseline…

      • For this the baseline is not so important: stability is crucial. NASA had been planning to put LIGO in space, but withdrew. ESA took it on and a few months ago launched a satellite to test out the technology. There is hope.

  22. Quite aware, Pinatubo was the best example. About the only difference that I think it made, was moderating the so2 content of the plume.

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