Was Puyehue Cordón-Caulle really a VEI-5?

The eruption of Puyehue Cordón-Caully taken in the morning on the fifth of June 2011. Photograph taken by Pedro Rebolledo, and used under Wikimedia Commons.

That the question even exist is a bit of an oddity in modern volcanology, after all we have known amply how to take ejecta-depth measurements to create Isopac-maps since 1956, more about that below.

The reason that this question has prevailed is that there are anomalies in the numbers proven for the eruption, compared to the results that these numbers give. In other words, the figures point in one direction, and the conclusions drawn in another direction. And the variance is big, and nobody has succeeded to explain to me why X suddenly becomes a Y in the other end.

What if there was a work in Volcanology of such standing that it is the Golden Standard to be measured against, like the kilogram and the meter references that used to be in the vaults of the French Academy of Science? Or, something as momentous as Albert Einstein’s theories of Relativity?

Thankfully there are two of those in volcanology, one is Iain Carmichaels work on Thingmuli (reference below), the other is Thorarinsons work on the eruption of Hekla in 1947-48 (reference below). All later works in volcanology rely on these two.

Carmichael made petrochemistry a staple diet of volcanology, and Thorarinson showed that Isopac-maps was a reliable way to determine size of an eruption. In this case I will invoke Thorarinson to split the difference on Puyehue Cordón-Caulle, below abbreviated as PCC before I write Cauliflower by mistake again.

Now let us talk about the eruption, and compare it to Hekla, I will be doing that from the principal paper about PCC, by Pistolesi et al (reference-link below). But before we start there is something that I must state from the paper. The authors in words talk about the eruption as a VEI-4, but in numbers it becomes a VEI-5. This is something that must be reconciled.


Puyehue Cordón-Caulle 2011 in numbers

Image taken by NASA Aqua Satelite. Image used under Wikimedia Commons.

The eruption started on the fourth of June 2011, and the bulk of the ash was produced in the first 48 hours (roughly 75 percent). The eruption was declared over on the 21st of April in 2012.

The height of the ash column from sea level during this period was 11 to 14 kilometres, so roughly 9 – 12 kilometres of columnal height from the vent.

Now, let us look at the depth of the ash. There are 13 layers of tephra that are quite distinct from each other, either from changes in wind-direction, or changes in petrochemistry. The by far thickest is the layer 1 from the first 48 hours.

Isopac-measurements was taken at 70 different spots out to a distance of 240 kilometres, ranging in depth from 0.1cm to 30cm. To do this well you do a random dispersal pattern and stick to that without any cherry-picking.

We know for a fact that ash ended up in several places from the initial blasts across the southern South America. Nothing to odd about that.

But, there is something mentioned in the paper that is borderline bizarre. And that is a claim that ash would have travelled across the southern hemisphere to reach the continent again on the 18th of June. That seems improbable due to the low columnal height.

I do know that there are several good professional meteorologists in here, one of them could perhaps explain this with a jet-wind or some such, I surely can’t.

Now, the suspicion about cherry-picking. “At section 7 (Fig. 1, 240 km from the vent), the Unit I deposit, collected on a tombstone relatively sheltered from winds…” (Page 6; Pistolesi et al). So, to find the ash they needed to search for a wind-sheltered spot to even be able to take samples and measure the depth? Intriguing.

The reason for them cherry-picking is that this is basically not a paper about the amounts on explosive ejecta volumes, it is a paper on stratigraphic layering. As such they needed to find as thick layers as possible to tell them apart.

At the same time in Argentine they estimated the eruption to be 100 million cubic metres in explosive ejecta, giving the eruption as just precisely a VEI-4. This is quite interesting, and I will get back to it in the conclusion.

Now let us go back in time, to a place where volcanologists had lunch between exploding vents.


A musical interlude: History of Science

Back in the day scientists wrote in an easy style, not that unlike an action novella. This is why Sigurdur Thorarinson comes across like an eighty’s movie action hero in an extremely serious academic paper. As I read his works, I always feel that he walked around with a catchy eighties theme-song echoing between the volcanoes of Iceland.

The reason for this is simple, back in the day it was popular to go to lectures in what was new in science, and what was newly discovered. Also, people read a lot of books about science, and it was almost mandatory to write popular books about your discoveries.

Sigurdur during a televised lecture.

That made the style in the scientific papers easier too, because if your audience fell for you and made you a star, well then, they would read your papers too.

Einstein is a great example of this tradition, you can even today go and buy a book that he wrote explaining relativity written in simple sentences, and that uses parables and analogies to explain the concepts. If you wish you can obviously go deeper in some more mathematical examples.

He also did massive lecture tours that was completely sold out. Who would’ve thunk that scientists once made more cash on being stars than they got from their University salaries?

But, even for that time Thorarinson was a bit of a character. The part where he and colleague walked up Hekla during the eruption and stands between two explosively erupting vents at the top while bus sized lava bombs bop down around him definitely made him into a legend.

In part why so many people are sceptical of science today is because they never get into close contact with scientists. People tend to trust people they have met, regardless if they have understood everything, and science have forgotten their obligation of educating and entertaining the people.

Some obviously have this skill; Albert is a stunning example of this. Whenever he gets around to writing that definitive coffee table book about astrophysics, well I will be the first to pester him for having my copy autographed. It will be a stellar read.

Now dear reader, how about I shut up and return to what I was writing about?


Hekla 1947-48 in numbers

This is a unique photo, almost completely unknown. When it was first published 70 years after the eruption it made my heart sing. “The photo was taken by farmer Þorsteinn Oddsson at Heiði in Rangárvellir. He died in 2008. The photo is taken at 7 am on March 29th in 1947 when the eruption had begun twenty minutes earlier. This unique and historic photograph has never been published before. Photo/Þorsteinn Oddsson” Picture and quote of caption taken from Iceland Monitor.

Thanks to Oddur, an intelligent and reliable man (he was a farmer in Iceland, and a lot of other farmers have saw the same thing), we do know that the eruption started at 06.41 local time on the 29th of March in 1947. We also know that it started with Hekla pushing up a 100 to 200-metre-tall spine extrusion at the Toppgigur (top vent).

The spine was probably the leftover lava in the Toppgigur from the last eruption. Please feel free to consider the force needed to lift a huge honking lava plug 100 metres up into the air in two minutes. After that the well shaken warm champagne bottle was uncorked.

At 06.51 a powerful earthquake was felt from Hekla and the mountain split across its length in a large explosive eruption. At both the north and the south ends lava spewed forth, but between that ash, tephra, lapilli and lava bombs hurled out. Lava bombs was later found more than 30 kilometres from this initial blast, so Oddur was lucky to not be hit out in his field.

This is the classic picture used to calculate the height, it was taken 120 kilometres to the west at Vatnslöysuströnd at Reykjanes. Private collection.

During the first two hours the ash column reached a height of 27 kilometres with a +/-10 percent accuracy, well into the troposphere. During these two hours 90 percent of all ash of this 13-month long eruption was ejected. The total amount of explosive ejecta was 220 million cubic kilometres, so during the first two hours 0.198km3 was coughed up.

That leaves a columnal height of 26 kilometres with the same uncertainty as above. The column height is given from a photograph taken 120 kilometres away, witness statements from the farmers, and a pilot. It was also noted in degrees from the horizon by two ship captains.

The total lava amount was 1km3, making this the largest Icelandic eruption until Grimsvötn 2011.

During the eruption and in the year after Thorarinson went around all of Iceland taking hundreds of ash depth measurements out on the fields. If any sample was sheltered or unusually deep he noted that and did not use them.

He found that ash depths in the wind direction during the first two hours of the eruption (NNE) was between 1 and 50 centimetres, he never got lower readings since he ran out of Iceland to measure from (in other words, he hit the coastline).

He then made a map with isopac-contours drawn on it, and from that he could accurately calculate the amount of explosive ejecta.



I could obviously go on and on about the various figures and comparing them, showing that Pistoleti et al, are talking out their wazoo. Problem is that I am quite convinced that the mistake is an honest one.

In the text they talk about small to medium sized explosive eruptions in the range of VEI-3 to VEI-4, and they seem to state that this was a VEI-4. I am therefore quite convinced that a human error somewhere crept in and they got a decimal-comma moved in the wrong direction.

The text parts fit quite a lot better if it is taken into the context of 100 million cubic metres (0.1km3) of total ejecta. And that is after all what the Argentinians came up with.

Now that I have given you an example of a larger and more powerful eruption, the Argentinian volcanic authorities calculations (based on Chilean raw data), the logical steps, the data, and so on.’, you can yourself do the calculations if you wish. I am not about to beat a dead horse anymore Fennimore.



The pertinent articles


Sigurdur Thorarinson; The eruption of Mt. Hekla, 1947 – 1948 (1950). Private copy.




131 thoughts on “Was Puyehue Cordón-Caulle really a VEI-5?

  1. Since nobody hasn’t commented for 3 hours, I get to do the honours myself.

    We are officially in yellow on Grimsvötn. Nope, not yellow alert, just that the earthquake counter popped into yellow for the third time since the eruption. In itself a sign that the trend is going for the next eruption since they are starting to come more often.
    Still not enough though.

    • If the trend continues we will have the next yellow staple in November/December and an eruption at around April.
      Dang Albert! 🙂

    • Ohhh < 3
      Thank you Carl for showing this data
      Grimsvötn is my favorite Icelandic volcano
      Because he is the molten active and most gooey in Iceland. And probaly the most molten system in Iceland.
      I knows that Katla is pretty active too with 400 holocene eruptions? I think.

      Your comming Grimsvötn article will be an intresting read too.

        • I enjoys your articles alot : )
          Im curious on many things about Grimsvötn

          I have so much questions and ideas
          its not possible to put into an article.

          This volcano is intresting
          As it is the most active, molten and most open conduited in Iceland and probaly the hottest too ( 2011 where impressive composition wise )

          But maybe I should try to figure out my own Grimsvötn article

      • The yellow bar level is adjusted so that only the top few count. So what was yellow two months ago may not longer be. That shows activity is increasing.

        • You are correct Albert, but in this specific case no prior-yellow was de-yellowed.
          But they are shaking in fear of rapidly being de-yellowed. Yellow bars are after all quite yellow-hearted.

          (I admit, I giggled when I wrote this)

        • Two more today without any yellow bar disappearing. I think one will disappear in a few days though.

    • An unnamed volcano halfway between Late and Fonualei (2 barely subaerial volcanoes) that also erupted 2001

    • Thanks for the article, Michael. I had heard about a rock floating in the ocean, but didn’t hear the size. Amazing that it is approximately the size of 20,000 football fields.

  2. Here is ash from this eruption. Not usable for measurement since it is floating on a river. I used a ‘best estimate’ of 1.2km3, based on 0.75 km3 from the main eruption and 0.3 km3 afterwards; this includes the lava. The lowest ash estimate I found was 0.2 km3. There was a LOT of uncertainty regarding the volume, because much was deposited in quite inaccessible places in Patagonia. In my opinion, if it was VEI 5 it was borderline. You may well be right that it was VEI 4. Don’t forget to add in the pyroclastics (0.08 km3)


    Hekla 1947 was scary.

    • Problem is that there never was 0.75 cubic kilometres of combined explosive ejecta from Cauliflower for layer one. The numbers given are all wrong for that. 0,075 is closer.
      So, let us say that the total was 0,2km3 giving it points for being tenacious.

      • By the way, Cauliflower is a fine name for a volcano. Many ash clouds resemble a cauliflower.

      • If we take the median of reported figures for the whole eruption (0.2-1.2) we get 0.7, which is what I thought it was before I saw the paper in question.

        • I can live with that figure, because that puts into the fairly believable realm, visavi columnal height and ash depths.

    • Does anyone have the original source for the 10^8 cubic meter Argentine Estimate?. From the Pistoleti et al paper a total volume of > 1 km^3 for the total of all the layers does not seem out of the question, but it certainly could be much less. Again, the largest source of uncertainty of volume based on Pistoleti et al again seems to boil down to the amount of fine ash that was deposited further than ~240 km downwind. This problem remains for the fitting of both exponential and weibull fitting methods. Granted there is always the problem of representative samples, particularly the ability to distinguish between primary vs reworked deposits.

      I would see a VEI OF 5 as being earned if the mass of all the tephra (Including proximal pyroclastic density current deposits) adds up to 10^9 tonnes or 10^12 kg. This would be the mass of 1 km^3 of tephra if the average density was 1000 kg/m^3 (specific gravity of 1.0). The density of well sorted pumice lapilli beds tends to be quite a lot less than that, yet many historical plinian deposits contain a large fraction of their total mass in very fine grained, vitric rich ash with a prominent size mode in the tens of microns. Such fine deposits can have densities as low as ~300 km/m^3 when freshly fallen and undisturbed, but tend to compact quickly to densities closer to 1000 kg/m^3 once wetted or tamped down. These fine grained vitric ash layers often contain several times the mass of proximal lapili sized pumice for a given eruption and extend several hundreds to > 1000 km downwind.

      Finally, there is the unresolved problem of how long an eruption may continue, with multiple phases and pauses, yet still be considered a single eruption, rather than multiple discreet smaller eruptions.

  3. “Over three hours”… sorry, I would have chimed in but was having an odd dream about beta decay in what should have been a gripping novel about a nefarious organization eliminating non productive child laborers to make room for replacements. Essentially, a sort of Bond novel instead of a bland nightmare.

  4. Hmmm…interesting talks about cherry-picking data. I’m not a fan of tossing out the outliers (unusually sheltered or unusually deep ash in this case) samples.

    Mainly what they do is affect the standard deviation. Sometimes the odd bits actually mean something, which is why I don’t like throwing them out.

    • If you have outliers you can either do what you suggest, or what was done here. The important thing is that you clearly state what you are doing, and handing over the raw data.
      In the case of Thorarinson you can recalculate with the outliers yourself, or not.
      In the case of Puyehue Cordón-Caulle we do not know what the non-cherry picked data would be, because there is none.

      I think you see my point now?

      • I would think, in a purely random sample set, that if just as many low outliers as high outliers are tossed, then that should have minimal impact over the full set. The problem is knowing that with certainty.

        • well not all distributons are bell-shaped, for one,

          In the case of sampling ash and rocks from a recent eruption, outliers could be things like: 1. this are has much more ash even though it is further away. 2) much less ash over here 3) ash has a dfffernt color or consitency in a few place, 5) over here we found pumice but not much ash, 6and over here we found both pumie and a lot of ash.

          Good to have a clear plan of attack and maybe even a hypothesis before you sat collecting data/

        • Yes, I am aware of some tainted data shapes. Whataburger french fries for example, show twin peaks in the cumulative distribution of their lengths.

          I think this has to do with total average length of the original potato verses the average width of the potatoes. To me, this indicates that there is a very good probability that they use actual potatoes to make their fries, as opposed to McDonalds who use a reconstituted extruded slurry of ground potatoes. (Ostensibly to control the water content and get a consistent french fry.)

          I have yet to sample the lengths of McDonald’s fries, but I have a strong hunch that they will generate a classic normal distribution. (Supporting my idea… so a selection bias would be for me to actively seek data points that support the bell curve… something to be aware of and a good motivation to keep all data points just to be sure) I would still likley reject shards of french fries like I did with the Whataburger set. I considered the sub quarter inch lengths to probably be from broken french fries.

          (as for the Whataburger sampling exercise, I had an hour to kill in Defuniak Springs while out on service calls, so I measured my fries.)
          {It was imperative that I arrive exactly on time so I had to “burn” an hour.}

          I don’t know why, but for some reason, I still have that spreadsheet. Length is in inches (US).

          Their average source potato is about 3.9″ long with an average width of about 2.6″. A pretty normal sized potato by my reckoning.

          I’m not really sure how to evaluate the “Curly Fries” available at other fast food places. (Arbys) ← They make a really good Reuben on Rye if you can keep them from putting nutmeg on it. {18 E 9 Mile Rd Pensacola, FL 32534 pretty much lost my business because of that stunt, I will not return there} → The one in Crestview and over in Defuniak Springs I’ll use, the only thing they do is push Pepsi {yech} products. Since I stick with ice water or Tea on the road, it doesn’t matter as much. I took it up with the 9 Mile Rd manager at a later date and she claimed they never use nutmeg. I still view them with suspicion. (She found it odd that I demanded NO nutmeg on my Reuben.)

          For the millennials. Nutmeg=”Punkin Spice” as found at the hyper-expensive designer coffee shops. Speaking of such, I saw an strangely named knock off up in Cantonement Florida. “Lava Java” Strictly drive through. Knowing the tastes of hardworking locals, it’s probably straight up strong dark roasted coffee with maybe cream and sugar as options, though I have not tried it. That’s about what I make when I need a jolt to get me started in the mornings. Something pretty close to CPO mess Coffee.

          (Something I found quite odd when I made CPO, the coffee was quite good. I had expected near rancid hours old coffee sitting in the pot, but it gets cycled quite often by the CPO mess staff and is nearly always fresh…[redacted] What is said there, stays there.

        • Yes.

          And to further expound, ash is finicky, at some spots what is just a few centimeters will become several meters.
          Worst are basal flow sheets, they can go from a centimetre to a hundred meters.

  5. I’m sure I remember a picture at the time of the ash plume from Puyehue Cordón-Caulle having circled the globe and returning the to vicinity of the volcano. Can’t find it now, so I could have dreamt it. The best I could find is this:


    There’s also a page about simulating the plume (although the actual link to the animation doesn’t work):


    (I realise with two links in the post I will be in spam prison for the rest of my natural life. Send sandwiches.)

  6. I also remember back on 2011, seeing pictures of ash from Puyehue Cordón-Caulle spreading outside of South America and into other continents across the South Hemisphere…

    Another volcanic news just IN:
    A major volcanic pumice raft has been spotted in the Pacific near Tonga, from an eruption that could have happened recently. My guess is from Tonga itself. Wherever it was (under water), it was probably a big one.


  7. Saw a video from a sailing vessel that got stuck in the pumice raft. All grey to the horizon, with big waves. Looked really odd. Captain said that they will need some serious hull painting.

  8. Continuing some discussion from the previous post, Carl mentioned this in response to me bringing up and questioning the enormous so2 spike that occurred approximately 12k years ago based on the GISP2 so2 data. These spikes also line up with the end of the Younger Dryas period at roughly 11500 BP.

    “I do not think we have a problem really to tie that to something.
    That is when Iceland went bonkers as the glacial ice left.

    Basically you had all of the big hitters going off at almost the same time (geologically speaking), chief among them the 50km3 Theistareykjarbunga eruption. But, most of the shields was constructed at the same time, together with large eruptions at Krafla, Fremrinamur, Herdubreid and Askja. The list really just goes on for volcanoes that went bonkers around 13000 years ago in Iceland.”

    I’ve heard this idea brought up multiple times, but I think when you actually put it under closer scrutiny, it doesn’t really stand up to me. Here are my qualms with it.

    1. Regardless of the size of Iceland’s eruptions at the beginning of deglaciation, the output rate simply was not enough on a yearly basis to put large single-year spikes in the so2 charts. Theistareykjarbunga was large, but it was a 50 year event. Other icelandic volcanic activity during this period was similar in that it was large, but spread over a rather long time as opposed to intense 1-year eruptions. The GISP so2 chart shows 1 year spikes that are enormous, suggesting more traditional 1-off events as opposed to slow but large shield building activity. Even if we saw Theistareykjarbunga going at the same time as Krafla and many of the other large shields, I doubt the so2 levels from these eruptions was enough to spike the so2 chart here to an absurd level on a 1-year basis.

    2. Even if these shield building activities could collectively cause large So2 spikes, the dissipation rate of so2 from the atmosphere would cause the so2 levels to diffuse too fast to create a large spike. Given that these were large, but slow effusive events, the so2 signature would more likely be gradual as these volcanoes released so2 into the atmosphere over a period of years, not within a singular large spike.

    3. Deglaciation likely played a big role. There is an obvious uptick in the so2 spikes around the time of deglaciation, and higher “background noise” of so2 during this period, but the spikes would indicate singular one-off events rather than gradual output. The gradual output is likely more related to the background level so2 caused by the shield volcanoes.

    4. Recent history of Icelandic volcanic activity does not show significantly large so2 spikes during major rifting episodes. I get that these did not happen concurrently with other big shield building events, but even if you were to take the so2 spike caused by the Laki eruption and multiplied it by 8, you wouldn’t get the output seen with the enormous spikes here. And while I think activity was certainly elevated at this time, I do not think we saw a year where there was the equivalent of over 8 laki sized eruptions occurring at the same time. That’s an extrapolation, but I think it provides some perspective here.

    5. Past spikes in the last 10k years are correlated almost strictly with explosive eruptions. A while back, I tried mapping these spikes to specific eruptions. Some are more obvious and clear compared to others. See that here: . Given, we haven’t had many enormous effusive events in the last 12k years to compare against, but the 1 year spike signature seems to be more obviously tied to explosive volcanism.

    Given, there is also a lot of evidence that points toward Iceland as a source for these spikes, but I’m highly skeptical of this claim, and think more research should be put into other potential sources. As I often say, I think we tend to pay too much attention to Iceland on here due to our own biases.

    • How would Alaskan or Kamchatkan volcanos fit with eruptions caused by deglaciation? Kamchatka in particular seems to be understudied per my understanding, as well as the possibility that much of the ejecta could be expelled directly into/over the Pacific.

    • Thank you CBUS, I should really make a post of this. The answer is far to complex for a comment.
      I would just like to point out that half of the eruption from Theystareykir formed Theistareykjarbunga och a period of about 50 years, exactly as CBUS said. The other half was far quicker and happened at the beginning in the form of the Theistareykjarhraun, it was probably around a 3 month or so event.
      There was also a few other very large eruptions around the same time. But, I will have to come back on it.

      • Even in that case, that puts Theystareykir’s initial eruption phase in line with one of the larger rifting fissure events. Not insignificant by any means, but enough to dwarf an So2 spike that occurred from Toba? Hard to say.

        One thing I wish I could find that has eluded me is Taylor Dome or southern hemisphere So2 data that goes back to this period around the end of the ice age / younger dryas. Lurking posted some stuff a long time ago that I can find in google image search, but nothing that goes past 8000 years bc unfortunately.

        • My point was more that I think this might have been a double whammy.
          It is surprising how often those ones pop up in volcanology.

          My favourite is Thera and Aniakchak going off in the same year.

  9. This is a bit off topic but I would appreciate comments from those who have experience of seismic events. This as reported in the times today.

    “Residents described hearing a “guttural roar” as their houses shook when a large tremor hit near Britain’s only active fracking site this morning.

    A seismic event measuring 2.9 on the Richter scale was recorded near Blackpool at about 8.30am yesterday, the British Geological Survey said, causing brief panic among those living close by. The tremor was stronger than those that forced the shale gas firm Cuadrilla to suspend fracking in 2011 at the same site.

    Heather Goodwin, of Lytham St Anne’s, about five miles from the Preston New Road exploration site, said: “The walls of my house shook. There was a really deep, guttural roar. For a moment I really thought my house was going to fall down.”

    • It must have been blasted close to the surface to be heard well since it was so tiny.

      Normally earthquakes tend to sound like a large lorry driving past, a deep rumbling noise.

    • And from a contrarian point of view…

      Frack generated quakes tend to release strain that was already present in the rock that was building to a larger later event that won’t have a chance to occur now that it has been released.

      • On that part fracking can be a good thing.

        One day I should write an un-biased fracking article. Going into the pros and cons of all the versions of fracking that exist. I think it would be a good thing all around.

        • It would certainly help those in UK, right NOW!!

          Might well end up as a standard reference and UK govt might pay for your advice. Who knows.

          • My experience is that the only way someone will cut you a check is if you say what people want to hear.

            Do not be certain that I would say what you want to hear, so do not sign a check yet. 😉

      • That is true. However, any slip will transfer stress to other regions of the faults or other faults, and can bring them closer to failure. So it is not quite as simple. Putting liquid on a surface held in place by friction is bound to give results – perhaps not quite what you’d want though. But this quake seems rather large for the very limited fracking that was going on. I am wondering whether something else happened – perhaps they triggered a mine collapse.

        • M2.9 is not that special. England has several per any given year.
          But, I was also pondering the mine part. The description in the news of the sound seems to be pointing towards a very shallow source, like one of the preponderence of old mines that England has.

          • A trona mine in Wyoming had one of its large chambers collapse a couple of decades ago (killed at least one, and I think another died from wounds later) and the “quake” was over 5.0 and felt over a large area.

          • I’m not sure if continued discussion on this topic is permitted. ON the assumption that it is:

            1) I go with Feynman here, whatever is the truth, no matter how unpalatable, you should know it.

            2) I am somewhat amazed that methane isn’t being extracted from the cut and drop mining done here for many decades, surely that would be more than enough fracking!

            3) As a country the UK will need some gas for decades and certainly for backup usage and some space heating. As such if we have plentiful supplies then not (in effect) buying from Russia seems sensible.

            4) I can see no reason why physical damage assigned to fracking (including a significant amount not actually due to fracking) cannot be compensated for but the real problem is if there are injuries or fatalities.

            5) The UK does have a higher population density than the USA.

            6) By its very nature prediction is difficult, particularly of the future, and even in the UK the geological structures are poorly understood, in particular the stress configuration of known faults let alone unknown ones.

            7) Trying to control global CO2 production by restricting UK gas production has no effect. I think its fair to say that the UK is doing more than most given its location and will continue to do so.

          • Oh, we do permit debate as long as it is friendly and about a subject that is discussed. So no problem with this line of discussion farmeroz.

            In parts I do agree with you, with one great exception.
            The doing enough part. I hear that a lot here too, that we do not need to more things in Sweden since we are a piddly nation with few people, and that we have done enough.
            I do not agree.
            Yes, both England and Sweden are comparatively small on emission of CO2 and have done good things, but if everyone uses that argument, then everyone is in shit creek.
            We all need to do more, and then some more, and more again. Ie, turn the screw consistently in the right direction.
            If everyone does that, the pain will be small and evenly spread. 🙂

            And if nothing else, both the UK and Sweden can do what we both are good at, sticking our thumbs in others eyes and declare how spiffingly good we are at saving the planet. Smugness is a common artform between our countries when we feel that we are indeed superior.

          • The Uk contributes with about 1% of global emissions. In fact, about 50% of the global emissions are caused by all countries in the world except for the top 3, which contribute for the remaining 50%.

            The top 3 are: China with 25%, US with 15%, and India with 5%.
            All other nations contribute usually with less than 1%.

            Russia has 5% of the share, Japan 4%, Brazil 3%, Canada 2%,South Korea 2%, Saudi Arabia 2%, Australia 2%, Germany 2%… many other nations contribute with just 1%, but all together make up for a significant share of the total.

          • This means two things:
            – The US and China, as major players, need to make some major cuts (cutting about half of their current emissions)
            – All other nations need to aim quickly to a carbon neutral, especially all the other richer nations that make up for the bulk of the other half of emissions (like Europe, Japan, Australia, Canada)

            I am assuming that we need to dramatically cut emissions to get down to 25-30% of current emissions is our mid-term target (and assuming that China and US are contributing to 50% of the global share)

            A) If every nation in the planet does their utmost efforts and all go almost carbon neutral (their emissions being only 5% of current amount) but the US and China only reduce their emissions by half, then the world is left with 27% of our current emissions: quite good. This means all nations in the world can have a big impact, even if China and US stay a bit behind in their cuts (a realistic scenario)

            B) If every nation in the world does something more attainable by reducing their emissions by 50% and the US and China go the extra mile and reduce their emissions by 75%, then the world is left with 37%: not enough. This shows that its more important that the other nations do a collective combined effort, other than just waiting for China and US to lead.

            C) If every nation in world cuts emissions by 75% and the US and China only by 50%, this means the world is left with 37% of their current emissions. This shows compared to option A and B, that it’s really important for all the other nations to really do severe cuts, and aiming to become almost carbon neutral, as main cuts are just not enough!

          • I find myself in the slightly weird position of having to defend China here.
            They are pulling their weight on reduction.
            I was recently in China and noticed how quiet the city of Qingdao was since half of the cars and all busses was electric. Their train-system is un-paralleled on the planet, and they are expanding it wildly.

            I then went to one of their inland factory cities. The owner there talked about how much better the air was this year compared with the year before and that almost all smog was gone now.

            Last year China closed down the 10 000 topmost polluting factories in a single day.

            I have been in China many times in the last decade, and the difference is really starting to tell now. And they really mean it, either the chinese are onboard with the party green line, or they are out in the cold (literally).

            As I was there I talked to a party official who was openly snickering that they will be below the US in 5 years time in regards of global pollution, and I believe they will do it.

            Now, why are the Chinese of all people so eco-friendly all of a sudden? Well, they closed down those 10 000 factories the day after half a million died from the smog.

    • See above, real altitutde was 7000 meters, and no stratospheric injection.

      Last eruption to do a stratospheric injection was Kelud by the way… that was a honker.
      What I find funny is that this is the second time in a week that people say that a volcano has done something that is in reality quite uncommon.

      • I use the “observed VA” portion of the VAAC reports (over the summit) when I do the Mastin et al calculations.

    • Pawel, both of those are using VAAC prognostication, ie the flight level warning.
      The corrected real data was 7000 meters. Initial reports are almost always confusing and wrong.
      Problem is that these initial reports tend to be reiterated after being found out to be wrong.

      • This is the reason Western civilization will fall.

        Let us interpret this as a violation of Rule 1 “Be nice”, and hand out a warning. /Admin

          • You look like a red beet from Russia

            Blatant violation Rule 1 “Be nice”. 24 hours to sleep off the potato sauce is mandated. /Admin

            Edit Add: (from a lesser admin.) This is actually a rather shoddy ad hominen attack and is beyond “Blatant.” It it repulsive. It also tends to indicate a vicious lashing out because the argument is effectively lost and nothing else comes to mind. If that is the route you are going to go, at least make it entertaining. Enjoy the time-out.

          • What’s funny is that people always assume it is the other side that is entitled and pseudo-oppressed.

          • A friendly note here.
            All comments about moderation will be sanctioned.

            The proper way to discuss moderation is via email to the Administrators.

          • Comment removed, we are not to start a discussion about politics.
            Do not be so easily drawn into a flame-war.
            Warning handed out for continuing a clear VC Bar subject (if even there) when Admins have left grumpy notice. /Admin

          • Okay, let us try this.
            Any comment in this comment thread that is not explicitly about this particular volcano will be removed.
            We are not allowing political flame-wars in here.

            My grump level is increasing by the minute, and so is my blood pressure, and I am already on blood pressure medication.

      • The incorrect report was quite quickly corrected. A simple mistake but VAACs are always on the side of extreme caution so if they even slightly suspect a large eruption they will report it. As for VolcanoDiscovery, you can be sure that if a large eruption had happened I would’ve done a post on it by now if Tom Pfeiffer hadn’t. I do my best to keep the site up to date when Tom is busy which is most of the time! For the record, the only eruptions since 1991 that sent ash higher than FL650 were Lascar 1993 (FL800), Manam 2005 (~FL750) and Kelud 2014 (FL850). In comparison, Pinatubo made it all the way to FL1400!

        • Thank you mjf, it is good that you pointed this out, especially since you are one of those doing the issuing of VDs notices and it was used as a source.

          Also really good examples for the FL, that tells something about the level of power needed.
          For the others, Kelud and Grimsvötn are tied for largest eruption since Mount Hudson in 1991. Both of them are stated as VEI-4, but they are a hair from the VEI-5 limit. Kelud was short and brutal (1 hour), so it had an insane columnal height. Grimsvötn did it in a slightly slower pace peaking at 20km height.

  10. Things are more complicated than you think. Everyone can be right, but not everyone will be able to say a word that will be close to the truth.

  11. my smart ol Da used to say…” Want to know who’s right? Watch which way they are jumping over the wall.” Said to me 65 years ago.

    • Indeed. A big fat juicy kaboom.

      Thankfully this time nobody was hurt because the volcano was closed for tourists.

          • I think I’d want to be driving my boat faster! Scary stuff. Thank you for the video!

          • Truly a moment when you need to rapidly change your pants.
            You can hear the fear in their voices as they scream “faster faster”.

          • Here’s a Youtube link for those who don’t use Facebook:

            This is scary stuff indeed to have a pyroclastic flow this close to a boat!

            This is a longer version of the same pyroclastic flow video from Facebook, and show other shots of Stromboli’s explosive activity.

            If you look closely at the 1:50 mark, you will notice how dangerously close one boat is to one of those PFs.

          • it looks like roughly 150° of arc centered on the SdF experienced PDCs or at least ballistics. Even more of an arc experienced brush fires. It’s getting to the point where the limits of the SdF aren’t as much of a barrier than they used to be. Apples/oranges, but sommas such as Pacaya and Barren have started to see lava flows escaping over the back of the ampitheatre. If that summit bench gets much higher, things could get interesting. Of course, if it gets oversteepened, things could likewise get bad.

  12. A stern warning from the Administrators!

    In regards of what has happened in the United Kingdom today.
    We deal with volcanoes and related scientific subjects, not the effects of political actions on this scale.

    So, to avoid flame wars in here we are hereby informing that we will remove every comment that is about what has happened today. Repeat offences will be awarded with a 24 hour cool down period.

    There are other forums for this discussion.

    As per usual, any comments about moderation is to be taken off-list via email.

    • Completely unrelated to what happened today:

      There is at least one political joke I think it could be acceptable for this blog, which dates to 2010.

      When Iceland experienced an economic meltdown (the collapse of its banks in 2009-10) and there was a political dispute between the UK and Iceland (the UK wanted cash from Iceland because UK customers lost its money in the bankrupted banks), Icelanders replied: we send you ash, not cash, because we do not have the letter c in our alphabet (which is actually true).

      Then again, this is just about Eyjafjallajokull and an Icelandic joke. Please do not go political on this one too 😉

      Actually Eyjafjallajokull was just the first such event since a hiatus of perhaps several decades, but it happens quite regularly throughout history. Askja deposited a fine ash layer in Scotland in 1875. Laki aerossols covered a large part of central Europe in 1783 and launched much ash into the UK (it was known as “sand summer” back then). It’s possible that other big eruptions in 1755, 1477, 1362, 1104 have also done the same.

  13. We are now officially back in Kansas again.
    Grimsvötn just had it’s 26th earthquake of the month, that is one more than the previous highest month.

  14. I have to side with Carl on this one: http://www.spaceweather.com is not correct regarding colorful sunsets

    All these colorful purple sunsets cannot be caused by the eruption of a Papua New Guinea volcano. Because the volcano is located in the southern hemisphere and the colorful sunsets are located in the northern (in the US west coast)! So its not possible even if the volcano injected gas into the stratosphere, which it didn’t.

    But Carl suggestion is probably accurate. What has happened in the Northern Hemisphere that injected last amounts of particles into the atmosphere and lies just westwards of the West Coast?

    Answer: the Siberian fires that burnt a record 4-12 million hectares.

    • Obviously I am not 100% sure of this. The only other wild guess I can think of is that the Americans just started secretly a geoengineering program in face of our climate emergency and so the continent is experiencing colorful sunsets. But I don’t actually this, so my guess is still the Siberian fires.

      And with that logic, then the southern hemisphere would also experience colorful sunsets in soon, due to the mass smoke injection by the Amazon fires.

      If its not the fires, then it’s a mystery.

    • I’m gonna have to lean towards the fire explanation. We get vivid sunsets due to occasional controlled burns and some that are not so controlled. We also get the sweet smell of burning cypress, which is fine until your sinuses go ape-shit.

      • Re the fires…. Alaska has been on fire since early June…. and the sun glares when seen like the dragon of the north and we are so tired of the fires and smoke. sigh… No rain for so long but rain is due on friday and again in Sunday… Those who believe.. please pray.. (You don’t have to say a prayer, Carl…i understand… 🙂 ) Best!motsfo

        • For the rest…

          Mots is trying to gently push me back into the fold, and I remain a happy heathen.
          We often debate this in private in an amicable way, that is what grown ups do, discuss things in a grown up way with respect. 🙂

          So, out of the stochastic cloud of uncertainty I hope rain will come for Mots. 😉

          • I do not think she needs what is heading your way. May be a bit too much of a good thing.

          • Oh come now… it is not uncommon for these thing to park and drop a foot of rain.

            Besides, even one of our prognosticators is thinking that it might do a hard right turn up through Geogia ranter that coming here.

            As my cousin up in North Carolina stated to me on SMS, “Storm preps are like being stalked by a turtle.”

            And now I am AFK for a bit. Wife sez I have to cut the grass.

          • “Dont’ cut it while it’s hot, I worry about you!!”

            Okay, but she better be happy with the strange cut pattern., Dark is difficult to do. Only major reference points were available.

          • Since both of us has had the same medical issue, blood pressure and heat is not a good combo. Better with odd cut pattern.

          • It was a actually quite fun. Especially when I found out the headlamps the mower were out.

            … go straight, miss the chair. Hard right, accelerate, count 3 hard right, aim for the tree…

  15. Fortunately the Stromboli PF went the other way. If it hit the city it would have been catastrophic. How unusual are eruptions like this at Stromboli?
    Is the volcano changing it’s behavior (for the worse)? The villages on the island will have to be abandoned for a time if this kind of thing goes on. Not to mention a exclusion zone for ships near the scarp. Maybe an article with some historical information about past episodes of increased violence.

    • It is a good idea to make an article, we will though have to see when we can get around to it.

    • It seems to me that the scarp, or the Sciara del Fuoco as it’s known, channels the pyroclastic flows to the sea. A VEI-4/5 eruption could probably send PFs down the other flanks outside the Sciara del Fuoco, There do not seem to be any eruptions exceeding a VEI of 3 in recorded history since Greek or Etruscan times.

      The biggest potential danger is another flank collapse not unlike what formed the Sciara del Fuoco over 5,000 years ago. This could send seriously damaging tsunamis all along the coasts of southern France, Corsica, the west coast of Italy, including Sardinia and the north coast of Sicily. A rise in the sea level due to global warming could cause an increased risk of a sector collapse. Many such major collapses including those in Hawaii appear to have occurred during times of elevated sea levels during past interglacials and probably also warmer period of the Holocene.

  16. I’m not sure its wise to assume that there can be no eruptions >3 because none have been recorded since 2000BC or so. Does anyone know what the plumbing is here? It would be a really nasty place to do a Thera

    • One should never say never around volcanoes, they tend to change their behaviour over time.

      And a funny thing, for this particular volcano it depends quite a bit from where you count the start of the eruption.
      Let us take the current batch as an example. Up to the first big paroxysm we had business as usual, and all of a sudden Stromboli went mental (for being Stromboli that is, for let us say Grimsvötn this would have constituted as a wet fart).
      If we would count the first mental paroxysm up until now today, then we get the funky thing that it is probably not that far of from a small VEI-3, a couple of more mental paroxysms and we are definitely there.

      And here is the thing, when volcanoes change they can go in any direction. Stromboli is as likely to go back to small farts again, or even take a decade long nap. But, it could also continue like this, or even increase in eruptive strength.

      If it was me, I would not go back up and sit and drink beer next to the volcano again.

      • Well, that should pretty well cover all eventualities, I guess .

        No, I wouldn’t sit and have a drink near the volcano again. Etna is massive so its not likely to go in a single puff, but smaller volcanoes could and sometimes do.

      • The magma supply to stromboli is very constant: basicaly a viscous steady state basalt magma influx. The supply to stromboli cannot be very large… since its not very productive
        Carl, Albert ;Boris anyone here what is strombolis yearly supply in cubic meters ?
        It cannot be very large…this volcano produces only small stones everyday.

        But Basaltic Vulcanian eruptions can be a new pattern when water rich blobs of fresh magma enters the system.
        Most of the tiny Island is 300 000 years old so it have not been very productive.

        • I do not know the yearly influx rate.

          A point here Jesper, yes the Island is mostly just 300 000 years old, at least the parts we can sample. But, it has wasted away a few times in large collapses.
          So, it is in fact as small as one might think.

  17. Hi. long time lurker.not good in com.
    Is Iceland asking for att. ?
    No sci behind me but, i realy like this blog.
    Hafnarfj. Iceland.

    • Hello Gudmundur!
      If you are talking about the earthquake swarm out at Geirfugladrangur at Reykjanes Ridge, it is a regular thing happening. It is a volcano, but mostly the swarms are tectonic. That being said, sooner or later it will erupt, question is if it happens next week or in a hundred years.

  18. https://www.youtube.com/watch?v=g28O5-X-2vU
    Carl look here…. here you haves a video of the active gas free ryholite -obsidian flow that was produced just after the gas rich plinian phase of 2011 Caulle eruption. It emerged from the 2011 vent after the violent phase. It advances like stiff -paste buldoozer its completely covered by a thick caparce crust.
    Blocks tumbles down the flow front.. and gets overunned by the front itself.
    The glassy rubble masks a 900 c orange interior

      • Nope these where links to papers on that flow
        And the reads are very intresting.
        This is the first video I posted here

  19. I like the article Carl and the pictures of Hekla in action. I imagine she looked pretty wicked to the farmer who had taken them.

  20. If we use the volume as the main factor for calculating VEI, Caulle and Chaitén were estimated roughly in 1 km3, but in the case of Caulle they assigned about 0.75 km3 to tephra and the remaining to lava. Despite this, Chaitén has been always cited as VEI 4 and Caulle as VEI 5. That always has looked weird to me.

    About the ash going around the globe, that was true. Here is a satellite animation:

    • And that is cheating.
      Grimsvötn 2011 was 0.8km3 tephra and 1.2-1.5km3 of lava. Still it is only a VEI-4.

      • These 2011 Subglacial lake floor lavas was far from calm pillow lavas….
        Instead it flowed like hells flood underwater… too fast flow rates for pillow lavas.
        Souch fast submarine lake Grimsvötn lavas are called “submarine sheet basalt flows”

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