The Great American Volcano – Aniakchak

Photograph from New York Times. In the image we see the massive crater wall and two of the rebulding vents.

Photograph from New York Times. In the image we see the massive crater wall and two of the rebulding vents.

The Caribou was standing on the plains 30 kilometers away from the mountain; it had not fled the roaring mountain more than that. After all, the ash was driven by the fierce wind to the north, and where it stood to the west in the early summer morning it was only a spectacular view. It was still trotting together with its heard slowly further west, but with the constant stops to graze it took time.

Image from Wikimedia Commons. This revolving 3D image clearly shows the scale of the lateral blasts.

Image from Wikimedia Commons. This revolving 3D image clearly shows the scale of the lateral blasts.

By now the eruption had gone on for two days and it had reached the VEI-6 mark. Due to convective air currents and strong northerly winds the ash columns from the active vents had only reached a height of 23 kilometers.

The 3 000 (10 000ft) meter high mountain had first opened one vent, then others had followed and radial fissures had quickly opened. Still the pressure increased and finally the eastern and western sides of the mountain were blasted out sideways in two immense lateral blasts dwarfing the 1980 Mount St Helens eruption. The Caribou and the heard were obliterated a few moments later as a surge of blasted rocks, ash and pyroclastic flows overtook them.

By now the mountain was doomed, too much material had left the magmatic reservoir and the mountain started to fall down into the partially empty void. As the cold rocks hit the hot gas and water rich magma a tremendous explosion occurred, and 2 kilometers of old lava and a one kilometer layer of even older sedimentary rock was blasted upwards in a final cataclysmic explosion.

A late descendant to the ill fated Caribou in my narration. One should remember that the area is inundated by Caribou, so quite a lot of them was most likely killed by both the explosion and the tsunami that followed.

A late descendant to the ill fated Caribou in my narration. One should remember that the area is inundated by Caribou, so quite a lot of them was most likely killed by both the explosion and the tsunami that followed.

Due to the inverted layer of air above Aniakchak the column rebounded and turned into a large base surge powering in all directions from the former mountain. The base surge travelled more than 50 kilometers in all directions depositing ash layers more than 100 meters in places, and in the south it hit the Pacific Ocean at Kujulik Bay and continued outwards causing a small tsunami. To reach Kujulik Bay the surge travelled over a small mountain chain.

Image from the Wikimedia Commons. Notice the Peninsula that juts out into the Bay above Aniakchak. The entire Peninsula was inundated under the tsunami.

Image from the Wikimedia Commons. Notice the Peninsula that juts out into the Bay above Aniakchak. The entire Peninsula was inundated under the tsunami.

The base surges effect was worse northwards, there it hit the Bristol Bay with tremendous force causing a large tsunami that rapidly powered over the Bristol Bay and hit the northern parts of the bay. As it made landfall it inundated the land and ripped up the peat and created a deep layer of peat and pumicious gravel and ash. It inundated the entire Nushagak Peninsula with decimeter thick layers of the mixture. Later the tsunami debris was covered with a thick layer of ash that fell down during the next hours.

The ash cloud continued to deposit large amounts of ash as it continued towards the northern shores of Alaska. As Alaska gave way to the Arctic Ocean it still left behind a layer of ash several centimeters thick, and by air currents it was carried across the northern hemisphere being deposited everywhere. The ash is still clearly visible on every known northern Glacier that has been stable enough to leave long lasting records.

By now, for all points and purposes the largest North American eruption since de-glaciation was over, it would though take 3 500 years before people understood how large the eruption had been, and how massive the impact was. Nature itself had pulled a prank to cover the effects due to another volcano erupting massively the same exact year.


Across the globe and through a complete coincidence another large eruption was taking place that were going to grab the center of attention, the 1628BC eruption of Thira in the Greek Archipelago. We know that date with such an accuracy due to a very well preserved dendrochronological (counting tree rings) record.

Photograph from the Wikimedia Commons showing the location of the volcanic vents and the size and depth of the Caldera.

Photograph from the Wikimedia Commons showing the location of the volcanic vents and the size and depth of the Caldera.

The Minoan eruption was a 60 cubic kilometer eruption making it into a very large VEI-6, or a very small VEI-7 on the Volcanic Explosivity Index. The eruption at Aniakchak was even larger with a size exceeding the 100 cubic kilometer mark. We know that the eruptions happened the same year since the ashes found in glaciers are intermingled with each other in the same layer. Roughly 70 percent of the ashes in the glacial layers are believed to come from the Aniakchak eruption, and the ashes are sufficiently different to be fairly easy to tell apart.

Mount Aniakchaks eruption created two large lateral blasts, a caldera that is 6 by 10 kilometers wide, and blasted away a multi vent stratovolcano that was in excess of 3 000 meters. The eruption was powerful enough to blast everything on top of the magmatic reservoir leaving the floor of the new caldera down at the oceanic level. The caldera floor has later risen to a height of 300 meters (1 000ft) due to dome resurgence and magma layering from the 3 active vents.


Image by the Alaskan Volcanic Observatory.

Image by the Alaskan Volcanic Observatory.

What is interesting with the Aniakchak eruption is how different it behaved in comparison with other large eruptions. The behavior is closer to what we could expect from a super eruption than your average garden variety VEI-6 eruption like Pinatubo. The complexity of the eruption with lateral blasts, tsunamis, base surges of pyroclastic material, the total destruction of both the edifice of the mountain all the way down to the magma reservoir, makes it into an interesting subject to study if one wants to understand supervolcanoes.

And there is a stark lesson to be learned here for other volcanoes of similar type that are close to populated areas. It teaches us that the destruction would be massive even if the eruption is just a small VEI-7.

If an eruption on the same scale happened at for instance Campi Flegrei we can easily see that it would kill everyone within a circle reaching 50 kilometers out from ground zero, and that we could expect mortality rates up towards 50 percent for the next 50 kilometers. We also learn that the climatic effects would be comparatively minor. No big famine is recorded happening after the double eruption of both Thira and Aniakchak.

Will Aniakchak suffer a large eruption in the near future? No it will not. It still needs to spend thousands of years rebuilding both its edifice and the magmatic reservoir. There are though other volcanoes up in Alaska that resembles what Aniakchak did before it blew out. I will get back to those further down the line in this series.

Aniakchak last erupted in 1931 in an ash explosion that probably was just a large phreatic event, but it has suffered numerous magmatic eruptions in the last 3500 years. Currently the risk associated with an eruption is ash causing problems for the local air traffic.

Aniakchak Mountain is today a national park, and is famed for being the least visited national park in the US. This is rather incredible since it is the volcano responsible for the largest Holocene eruption in Northern America and this regardless of its remote location.


185 thoughts on “The Great American Volcano – Aniakchak

  1. It is starting to look like there might actually have been an earthquake at Laki, the signals are though intermingled with the much more powerfull event at Hámarinn. The signal reads as a double-event of 2 M1.4 events at Laki separated by 8 seconds.
    If it will ever be possible to get it sorted out is another thing. First of all the signal is weak, there was a more powerful signal disturbing the event, and ontop of that the Laki area is a really bad spot to pinpoint seismic signals in.
    The event up in Hámarinn also seems to have been unusually noisy due to a magmatic intrusion occuring. I would not want to try to pinpoint the Laki event…

    • As I check the Vonarskard SIL it looks like there might even have been a small eruption or a phreatic detonation at the same time as the Earthquake at Hámarinn.

    • And IMO is done with the quakes. They seem to have given up on the Laki quake, probably just to weird to get heads or tails out of. I am though fairly certain that it did happen.

      28.10.2013 12:08:16 64.482 -17.730 7.6 km 2.5 99.0 3.8 km E of Hamarinn
      28.10.2013 12:08:14 64.029 -18.343 1.1 km 1.4 41.89 7.0 km SW of Laki
      28.10.2013 12:08:05 64.476 -17.742 4.6 km 2.6 99.0 3.4 km ESE of Hamarinn

  2. Nice article.
    Lately, it seems that mother nature is teasing us: Etna, Sakura-Jima, the Kamchatkan volcanoes, … and now Laki.

    Also the storm that hit UK last night, Belgium this morning (only 80-100km/h here) developed a clear eye above the Wadden Sea around noon and is now hitting Denmark with Hurricane force with gusts up to 200 km/h. North of the Netherlands is in troubles with uprooted trees and damage everywhere. I hope the Danes have everything tied up very well,storms of that calibre are very rare in this part of the world.

    • Here in utrecht it was allright. 50 km off the coast and just down south of the path. I did measure 80 kph on my roof. but we misted the brunt. Still quite some trees that toppled over and very limitted train service.

      • Here was it also just a really windy day, but nothing special. The biggest problem was that a lot of trees still had there leaves. Funny enough was yesterday nearly as windy as today and it caused in this part of Belgium more troubles with the trees. This morning the leaves were already blow of by the hard wind of yesterday.

        • Yeah same problem here. Lots of rain in the last week, saturated soil and very high temperatures the last two weeks. So trees started shedding too late, and this storm was early. Most damage here was from falling trees. bad timing…

  3. Hi Carl

    Very good article on a volcano which is not well known. It is interesting to note that the eruption year was the same as Santorini. However, the Thira eruption destroyed the minoan civilisation but also had some deep impact on nearby civilisations (Egypt at least I think) so maybe the conjuction of the two events did have a effect on the climate.

    • One should remember that the Thiran eruption caused a minor tsunami, and a large ash flow that dumped down on the surrounding islands.
      But, and this is a big but… What actually made the Minoan culture to diminish is contested today in archaeology. It did not just die out from an eruption like previously believed, instead there are quite a lot of remnants from after 1628BC. Probably loosing a stronghold like Santorini was a blow, but also other cultures pushing in and a growing power in the greek mainland citystates caused more important problems for them.
      There is also no sign of grain diminishing in the years that followed, and that is known from the infamous linear-A clay tablets.

      I am more and more convinced that the large explosive eruptions causes far less climatic impact than previously believed. The de-bunking of the Toba Bottleneck is a large clue in that direction.

      • Some religious studies claim that the Egyptian story of Moses was linked to Thera, saying that the crops failed for seven years before the final explosion, and that Moses followed a column of ash by day and of fire by night, crossing the Reed Sea when the waters rushed into the caldera as it formed leaving the seabed exposed, and that chariots have been found on the seabed that might have been pursuing them, so it is said…

        Who knows? Seems fairly logical and close enough to the projected time scale for the OT stories.

        My imagination is off wandering in other directions too…

        The cliff which rose suddenly, in the previous thread, put me in mind of the Cliffs of Moher, west of Ireland, County Clare. I searched for a time scale for when they might have risen sheer, all of a sudden, but all the info seems to be about the sedimentary layers exposed on them. If one looks at a map of Ireland, at a stretch of the imagination it could resemble the impact effects on the coast of Mexico re the extinction event that happened off the coast there. The lakes inland in Ireland are semi-circular.

        With 2 massive volcanic events occurring in the same year, plus the flooding of the Black Sea basin, following Thera, I just wonder if we should be looking for an impact somewhere in the Atlantic to the west of Ireland.

        • Well, let us put the religious stories to rest, there was no eruptions before the Thira eruption that would have caused famine, nor are there any archaeological evidence for it, quite the opposite. Religious sources are notoriously bad sources.

          • Apologies for digressing – point in question being whether Thera might have been erupting for a long time before it went caldera…

            • There is no evidence of that having happened. Remember that it is a small Island, and the residents did not start to evacuate untill right the eruption started. We know that from written records.

  4. Good article. I have said for a long time that the VEI-6 that’s listed for Aniakchak was almost certainly under-representing the size of the actual eruption.

    VEI-6 eruptions don’t form 6×10 km calderas. Heck, most of the VEI-7 eruptions that have happened in the last 10,000 years left smaller calderas than the one seen at Aniakchak. That leaves only two options. Either the caldera was the product of a previous older eruption, or the caldera was initially smaller, but grew as multiple eruptions expanded it’s size (ala Katla).

    Since this was a full-on stratovolcano before this eruption, the caldera formed from a singular event, giving us another VEI-7 in the last 10,000 years.

    • Another interesting anecdote is that Veniaminof blew up at a very similar time period that Aniakchak did. Veniaminof may have been larger as well, as it’s represented by a larger 8×11 km caldera.

      Also – going further down the line in the Aleutians, I may have found one of the eruptions that contributed the the huge spikes in So2 the occurred towards the end of glaciation.

      “The 11 x 18 km Fisher caldera on western Unimak Island NE of Westdahl volcano is one of the largest calderas in the Aleutian arc. The caldera, which is elongated in a NE direction, formed around 9400 years ago, accompanied by emission of large-volume, mobile pyroclastic flows that reached the Bering Sea and the Pacific Ocean”

      It would seem to be large enough – 11 x 18 is huge, and the timing of 9400 years ago certainly doesn’t hurt.

      • Let us just say that Alaska is filled with several very large volcanoes, and there are certainly still volcanoes in the region capable of throwing eruption of that size. But I will return to those in time.

    • The interesting thing is that around 8 000 years ago Aniakchak suffered a more normal VEI-6 eruption somewhere in the size of the Katmai-complex. So, before these volcanoes can go off with a mega-colossal eruption they probably will suffer 1 or more colossal eruptions.

      I am starting to believe that the VEI-7 eruptions are far more common than the previously believed 1 per 1 000 years. I think we can safely assume that a more realistic number would be 1 per 500 years.

      • Totally agree on the frequency thing there. There have just been so many biggies in the last 10 000 years.
        Let’s list all eruptions that have erupted 50km^3 or more in the Holocene:

        Lombok (?)
        Kurile Caldera
        Crater Lake
        Fisher Caldera (Unimak Island)
        Macauley Island, Kermadecs
        Black Peak, Alaska

        and maybe:
        Long Island
        plus all the big effusive eruptions as well.

        what have I missed? There must be more in South America and Central America and Indonesia is totally under-represented. I bet the real number is a fair bit higher. And if you extend the window a bit further you get some real monsters: Aira, Taupo, Witori, Campi Flegrei,

        • Before people get all excited, I guess I should point out that even 1000 years is a verrrrrry long time in human terms.

        • I would personally be extremely interested in an analysis of the economic impact of a Tambora sized eruption at various areas in the world. IE – what would be the global impact of Tambora’s eruption if it were to erupt now instead of the early 1800’s?

          One interesting aspect of the Japanese Tsunami was the global impact on the economy. There was a legitimate ripple effect from that event, and even where I live in the american midwest, there was notable changes in the economic climate in a few ways.

          -I know the Japanese auto industry was hurt greatly by this throughout much of 2011.
          -One of my good friends is a material science engineer, and he works on metals that are used for microchips and such. He mentioned that the tsunami had a huge impact on the microchip industry suppliers.

          With that said, what would the impact of a Tambora sized event be if it were to happen now? While I don’t think climatic impacts are huge as Carl said, there would 100% be a bottleneck in the food supply if we saw a similar cold summer as was seen after the Tambora eruption. That bottleneck may be extremely small, but it may also be larger than we expect as we’ve grown accustomed to not having to deal with food shortages in the first world. We’ve never experienced a similar cold snap like that in modern times, so how impactful would this be with a worldwide population that’s many many times greater than it was during the early 1800’s? Would modern farming equipment and technology be able to shrug off a much colder summer? How would the disruption of air-traffic affect things? How would industries that are globally dependent on business in the vicinity of the eruption adapt? How would this affect global shipping & logistics?

          Naturally, the closer said large eruption is to a very populated area, the more likely it would be to cause extreme economic disruption. Any plinian eruption in the Naples area regardless of what volcano it comes from would likely have worldwide economic implications. The same is also true for many of the Japanese volcanoes. On the other hand, a VEI-7 in the Aleutian Islands or Kamchatka peninsula would likely have some small, but relatively insignificant affects on a global scale.

          • I would say that the effect would be drastically dependant on where it happens. A VEI-7 close to the poles would be having less effects on the climate and crops. But the largest impact would be if it happened in an area with a large population like Aira, parts of Indonesia and Phillipines or in Italy. I would say that the worst thing that could happen is Campi Flegrei, followed by Aira or some such. Campi Flegrei would bancrupt Italy withing minutes, with tremendous effects on the Euro-zone, and with global impact on a massive scale. And the cost for rebuilding a large part of southern Italy… It would be bad.

            • I couldn’t agree more. Campi Flegei would be bad and end of the euro-zone as we know it. Aira on the otherhand, well, i can’t explain it but japan seems to survive anything.The dept, the quakes, the sunami and fukushima.
              It all doesn’t seem to matter.

            • If Aira were to put up a VEI-7 again, there is no “surviving that”. You either get out of Kyushu before it happens, or you pray you can find a far corner of the island that you can wait things out in. The tsunami from that eruption alone would dwarf the fukushima tsunami (at least in the kagoshima bay area). Oh, and there are also nuclear power plants in the area that would be wiped out by pyroclastic flows.

              The only area I think could be potentially worse for a VEI-7 would be naples, but I would think they’re pretty even overall.

            • The difference being that the Japanese are better prepaired.
              And especially the difference is that the Japanese population would leave if they where told to leave. The Italians would just put their five fingers up in the air and tell the volcano to stuff it…
              INGV are good, but then comes 69 levels of politicians, Mafia, and all the other stuff that will be sure to kill a lot of people in Italy regardless of how good INGV are.

  5. I would also like to point out that the 1931 eruption was magmatic. The crater at the bottom of the last image was the 1931 crater. There is some lava in that crater.

    • Actually I could not find any reference for lava being emitted during the last eruption. But, the one at the bottom is a frequent erupter, and several of the eruptions out of that crater have been magmatic.

      • From AVO:

        “Father Hubbard flew over the volcano on June 10, while the eruption was still in progress. His party first hiked to the caldera on June 13 and discovered moving, blocky lava flows at the bottom of two new explosion pits [see figs. 6A, B in original text]. A third small lava flow issued from a knob slightly above the base of the west caldera wall [see fig. 6C in original text]. Steam explosions had reamed a shallow pit in coarse ash and lapilli that blanketed a lava-flow field inside Half Cone [see fig. 6D in original text]. Although accumulation of fallout was heaviest in the western and northwestern parts of the caldera, nearly all vegetation inside the caldera was destroyed or buried. Three small lakes in the western part of the caldera (Knappen, 1929) were filled completely with ash and lapilli, and Surprise Lake was cloudy with suspended ash. Hubbard also reported dead birds, presumably killed by carbon dioxide that had accumulated in low areas near the vent. The north rim of Vent Mountain’s summit crater reportedly was steaming (Regan, 1987).”

        This is from the Historical report of the volcano’s eruption.

        • Ah, missed that one. But then I mainly went for scientific journals on this one since I needed data on the mega colossal eruption.

            • That depends on what you are writing about. I was not per se writing about the latter stages of small eruptions, I was writing about the large 1628BC eruption. So, therefore I needed the Scientific Journals, not short paragraphs from various pages that are not peer reviewed. Of course I could have written down a list of papers, but I tend to not do that since this is a blog and not a scientific journal in itself.

            • And we all love the word FREE since we read so many papers.
              I have been pondering the small fact that volcanologists are probably writing the most well read papers of all of the sciences. I would guess my papers have had about 5 to 10 readers, but you have hundreds reading yours.

      • It is definitely capable of producing plinian eruptions. But, there is though a very large diffenrece between a Plinian VEI-4, an Ulta-Plinian VEI-5, a Colossal VEI-6 or the Mega-Colossal VEI-7. In reallity the VEI-7 eruption I described is about 1 000 times larger than the highly common VEI 4.

        It is though fun to notice that we seem to be getting 1 VEI-4 per year, 1 VEI-5 per decade, 1 VEI-6 per 50 years, and 1 VEI-7 per 500 years. There though seems to be a very large step to the VEI-8 with 1 about every 100 000 years or so. Apparantly the amount of volcanic eruptions seem to follow a fairly common statistical curve up to the VEI-7, and above that the statistics fall off sharply.

        • We haven’t had a VEI 5 in 2 decades. When was the last time we had an Explosive VEI-4?Chatien? I think that we have had plenty of VEI-7s, but it think it is somewhere between 500 and 1000 years of occurrence.

          • Explosive VEI-4? In 2012 and 2013 there has not been any (so far), but in 2010 we had Eujafjallajökull and Merapi. 2011 gave us Grimsvötn, Puyehue-Cordón Caulle and Nabro. There was also a probable VEI-5 or even VEI-6 in a sub-aquatic caldera north of New Zeeland causing the largest recorded pumice raft.

            One must remember that we are talking about averages here. There could be a century without anything larger than a VEI-4, and then we get two VEI-7s in the same year… One must always remember that we are talking about averages, and short term timespans are insignificant and useless to draw conclusions from.

  6. @ Bobbi and Geolurking, from the previous thread:
    This is the paper by S.F.L. Watt et. al. from 2012 on the previous studies around Montserrat with an exact map of the area:
    “Widespread and progressive seafloor-sediment failure following volcanic debris
    avalanche emplacement: Landslide dynamics and timing offshore Montserrat,
    Lesser Antilles”

    I have to read it yet but from the introduction it sounds very interesting.

    Now on to Carl’s article, looks like a fascinating read. Thanks for your work!

  7. Great read again !
    After reading the article i started fiddling around with google earth. I managed to pull this screen shot from google earth.

    Very close to the first picture in the article
    If you go to these coordinates in google earth:
    56°55’27.67″ N 158°07’07.94″ W
    It should you get to within a kilometer of that spot. Do look around, it’s an amazing place.
    Scary how accurate free download google earth is. This is one of the more remote places on earth. There is a much bigger cone in that caldera, but still these relatively small features show up quite accurately in hight and shape. Imagen the amount of measurements it takes to do this for the whole planet, mind boggling..

    • Google earth is still my favorite tool for the amateur volcanophile. Make sure to download the GVP’s overlay that marks annotations of each volcano where you can read the overall summary.

      As for Mdact’s thoughts earlier about submerged calderas – If you go through google earth, most of the island arc areas such as the Kermadec ridge, or even some of the arcs that are around Japan, you can see quite a few unlabeled structures that are likely calderas of some sort. I would personally imagine most of these form in eruptions that never really reach the surface (ala havre). It’s also relevant to know that the google earth ocean bed isn’t 100% accurate however.

      I know from some of the research I did on the Kagoshima Graben that there are likely a few more large caldera structures in the sea just south of japan similar to Kikai, it’s just very difficult to map these, and probably not worth the funding to study them.

  8. Thank you Carl, it is in der Tat one of the most gruesome and mindboggling places of the world.

    Just take that first photo, open it in full screen and look around you.
    There are the up to 1000m high caldera walls, the tops disappearing in the wafting clouds. The cones in the middle are mere up to 300m; imagine someone standing beside one of them – he would be only a tiny dot in the calderascape! Now zoom in and the cones grow to some size. You realize that 300m *is* a mountain if you are in front of it… it bearly bears thinking of the 1000m cliffs around it all. You can now explore the strange ground under your feet, there is no road, no path, only bumpy lava, mosses and lichens. You feel a faint trembling – oh, yes, I am in an active volcano… Suddenly the air becomes colder, and thicker, more clouds are descending the now menacingly glaring at you cliffs, you are aware beeing cought in a humonguous bowl, you want out! Well, click on the back button and you’re back in the volcano cafe, exploring Aniakchak from your living room. 🙂

    • I loved your narration 🙂
      What surprised me was that the entire mountain was so completely destroyed, 3 kilometers of mountain height was just gone after an eruptive phase lasting for just a few minutes. The scale of power is purely mind-boggling. The caldera wall was just one third of the original edifice where it peaked.

      • Thanks! Where did I read that the walls are presently still 1000m high in places, can’t remember now. If they are, the hole after the eruption must have been a good deal deeper than that, because during 3500 years afterwards lava/tephra and sediments must have built up considerably on the caldera floor. Imagine a HUGE hole 1500m deep! 😯

        • It has built up about 300 meters, mostly due to uplift. But then we have these nice little cones sticking up. The hole is huge however one counts it.

  9. Halloween is coming. So I drag out the standard Michael Jackson video clip… from a time before he actually had body parts falling off and he was quite entertaining. Oddly enough, the make-up and special effects crew turned him into a Scottish Terrier rather than a Were Wolf.

      • 5″ 54. Nice shot!

        Trivia question… what does the “54” mean?

        And for those that are easily amused, the tradition of “Counting Coup” is still alive…

        “Risk of injury or death was required to count coup.”

            • Ref the Naval gunfire… one thing they have been kicking around are ratt rounds. rocket assisted projectiles. Another program that I heard about several years ago, was the idea of adjusting the trajectory by having the round pivot about a point on it’s body.

            • Putting an GPS (steering) into it works nicely too, small rocket engine or solid booster, small fins popping out, that way you can spend government funds much, much quicker!
              “Calibre” is inside diameter of barrel (or dia of projectile)

            • Not in this case. Naval guns are measured differently. Caliber indicates the barrel length… it’s a multiple of the diameter. The Iowa Class BBs used 16 in /50s

              “In some contexts, e.g. guns aboard a warship, “caliber” is used to describe the barrel length as multiples of the bore diameter. A “5-inch 50 calibre” gun has a bore diameter of 5 inches (12.7 cm) and a barrel length of 50 times 5 inches = 250 inches (6.35 m).”

            • Whenever you hear that your government is planning to start using GPS controlled munition and the Archer platform (Lurkings favourite new Vehicle), send a thought of thanks to Sweden for developing it.
              The reason for us developing ultra-long shot insanely accurate shells is that we have 5 soldiers in total, so we had to make damn sure that every shell hits the target further away than anyone else can fire…
              We used to have a large army with moderately high tech level. Now we have a miniature army with all the goodies… From one extreme to another. Last number I saw was that we had 2000 soldiers or something such. Sigh…

            • Thanks to Bofors, certainly, for the bits that go bang and the metal that holds it all together, but I think the clever bit of how to guide artillery using GPS is US technology.
              Having said that, arguably the cleverest bit is down to a small company (now a tiny division of a US giant) based in Devon who cracked how to make an inertial measurement unit small enough to fit in the fuze cap of an artillery round, but ‘gun-hard’ enough to withstand the launch forces. Oh yes, and incorporate a GPS receiver too!

            • Yepp, definitly DOD and Raytheon responsible for the GPS. But they didn’t put it in an artillery shell.

  10. Great article Carl, just one small caution:

    “Due to the inverted layer of air above Aniakchak the column rebounded and turned into a large base surge powering in all directions from the former mountain.”

    Any kind of eruption column will just punch through any atmospheric inversion like it wasn’t there, until it finally runs out of energy, perhaps as high as the stratopause.

    That kind of behaviour, weakish column with a lot of boil-over PFs and base surges, is a characteristic of an eruption with a large, wide-open vent – Lammington-style, as opposed to the classical Plinian style, which shoots material to a great altitude from a narrower vent, like from the barrel of a gun.

    Or so I was taught…

    • Hello Mike!
      You are probably right you know. I was actually thinking that it felt a bit odd when I read that. The figures is taken out of a paper, but irritatingly enough they had no basis for the calculation, nor a reference for it. So, I used it even though I would have loved to know how they came up with the number.
      We know that the wind was blowing hard during the eruption towards the north, but the only explanation I can come up with is that the boundary to the troposphere was low during the eruption and had an unusually hard boundary. But, I can’t get it really to pan out. Such a low boundary are only there during the winter, and we know it did not happen during the winter. On top of that you only get a hard boundary during winter.
      I think they just punched in the figures they had available (winter) into the computer and got a winter model.

      More likely would be a 35 km ash column Lammington-Style or not.

      Sometimes papers have these glaring holes in them… Sigh…

      • To continue, I have noticed that errors like this crop up quite often when scientists who are not natives do the calculations. They in theory know the gigantic differences between winter and summer, but it is not “in their bones”, so they tend to forget them now and then.
        I most probably do the same mistakes on occation when writing about certain southern conditions.

  11. @GeoLurking – you were asking about the size of the “crazy” rocks. Go to and then scroll down to Recent Photos. Click on “Dive Highlights October 27, 2013”. The very last photo shows the ROV hovering over one of the rocks. Click on it to enlarge. That ROV is 11 ft long, 6 ft wide and 7.5 ft’ tall. It normally maintains a distance of about 3 meters above the bottom. The photo was taken from the other ROV that takes all the movement of the ship and allows the one on the bottom to be stable by using a 90 ft flexible tether.

  12. Great post, Carl. I love the Alaskan volcanoes. So beautiful and yet so remote that most of us will only see pictures of them.

  13. SakuraJima has been quiet so far today – The last few times it sat quiet, it came out with larger sized eruptions after it’s quiescence. I guess we’ll see how long she remains calm for and if that theory will hold true.

  14. Better a couple of posts late than never about Yellowstone hazards.
    “The pervasive hazard in Yellowstone is earthquakes,” said Robert Smith, a seismologist at the University of Utah. “They are the killer events.”

    The above article links up with this old news, below, but still good news: About the Yellowstone plume.

  15. Good morning VC!
    Did you know, there is a species of huge snow owl watching over the volcanoes in Kamchatka,
    Filin custos vulcanae avachinskiensis?
    (in plain English: the owl of Avachinsky guarding the volcanoes) 😉

  16. Great article Carl. That top photo is just stunning, and is the new desktop wallpaper on my Linux box.

    I was just stunned by the description of a mountain that tall vanishing in a matter of minutes, and you can really get a sense of the power that must have been expended in a short amount of time by looking at that image with a 300 metre cone dwarfed by the caldera walls.

  17. Interesting article, Carl! Gives the reader the feeling of being there when it happens, without being in any danger. How immense must this eruption have been!
    Enjoy the way the eruption could be dated so precisely.

      • ROFL!!!

        No, it is dated 3 ways.
        1. C14-dating, they have dug up wood that was covered by the eruption. That gave cirka 1650BC.
        2. They know exactly when Santorini erupted due to the immense and very accurate record of tree rings that have been dated all the way back. Then they dug up a tree on Santorini, and compared the age of that tree and when it died. 1628BC is the date of the Thira eruption.
        3. In ice-cores from Alaskan and Greenland glaciers they have counted icelayers and found a layer that hold ash from the Santorini eruption. That ash we have a date for, namely the same tree ring age from 2, namely 1628BC. And here comes the big hoot, that ash is intermingled with the ash of Aniakchak. And since ice is building in yearly layers we know that Aniakchack happened the same year as the well dated Thira eruption.

        Case closed 😉

      • I’m sticking with the coprolite theory. When something something that large goes off, everyone is gonna dump a load.

        Interspersed in the tephra bedding, will be a layer of hastily deposited fecal matter. It may have even had time to coalesce into rivulets of hot steaming goo. This is probably where the idea of “sh%% river” comes from… just make sure to bring a paddle.

        • The problem is that the only thing dumping would have been the Caribous 😉
          The coprolites would make a good sample for C14 dating, but in this case the dendrochronological material mixed with ice core sampling would make this into one of the best dated early eruptions we have.

        • And Lurkings method implies that we first have to wait until the Caribou droppings (if still well preserved) have turned into fossils, which will take a lot of time.

  18. A webcam picture from last nights Sakurajima eruption. Does anybody have an idea what the light stuff on the foreground is? It suddenly appeared at the edge of the crater and was only visible for short time. It looked liquid and went downhill, like a little waterfall.

    Image and video hosting by TinyPic

    • Probably dust / ash mobilized by the shockwave of the blast. You can see this at a lot of volcanoes during an initial explosion.

    • I think this has been posted before. Here you can actually see the shockwave:

      And this shows another explosion with your “white stuff” swirling over the rim, which I believe is very fine ash with steam condensed on the particles, so a steamy muddy mixture, wich will be dry dust in a whiffy again as the water evaporates.

      (on YouTube by photovolcanica)

      • There are a couple of recent examples of this phenomenon but I must admit, sometimes it’s hard to know when it is the pressure wave and when it is the fallout from volcanic bombs. Look at these

        Popo (shockwave at a guess):

        Shinmoedake (fallout, at a less confident guess):

        • Bruce, you cannot confuse a shockwave and tephra fallout, they are two different things. The shockwave occurs with the detonation, before (!) the column starts rising, and lasts only a second (!) or so. It is air becoming visible by normal humidity moisture suddenly condensing, caused by the high pressure. You see it rising upwards (!) throughout the whole picture, like a lens put over shortly and removed again. A shockwave is very clearly visible in your first video (Popo) at 00:05 but I could not make one out in your second video.

          So anything that happens after the column began rising, lasts longer then a second and moves downwards has nothing to do with a shockwave. I am trying to find where I read the explanation.

          • I know exactly what you mean Graniya, it is all about the timing. In your video of Sakurajima the column is already a couple of hundred meters tall before the flank of the volcano takes on the fuzzy appearance from disturbed ash which would indicate it was fall out more than shockwave. (That was kind of what I was trying to say).

  19. Farther down the Aleutian chain / Alaska Peninsula is Okmok, a circular caldera some 6 mi (9.8km across). Last VEI 6 was 400 BC. Last eruption was 2008.

    North and East of Aniakchak is Chiginagak, which had a partial crater collapse dump the contents of a highly acidic and metals rich crater lake downstream into part of the Bristol Bay salmon fishery May 2005. There was no eruption associated with the collapse.

    Interesting description of the damage to Bristol Bay and surrounding region via ash fall and tsunami. I knew the area got regularly dusted, but didn’t know it was buried and suffered a volcanic caused tsunami.

    Currently, a bunch of the locals (along with most of the national environmental groups and organizations) are fighting a proposed large copper – gold – silver mine called Pebble that will sit north of Lake Iliamna. Current arguments all are based on some variation on the theme that the mine will instantly and completely destroy the Bristol Bay fishery should any acid or metals leach downstream. Appears that the local volcanoes do that sort of thing on a not so irregular basis and the salmon do just fine, which means they are well adapted to the local environment and its hazards.

    Thanks for the additional info. It will be helpful. Cheers –

    • The largest environmental disaster is most likely that acidic lake going downhill… It took out rivers, lakes, everything. And in some of them the fish never returned due to the acidity remaining to low to this day.
      The difference between a volcano and an improperly run mine is that the mine can polute for decades and even a big eruption is over fairly rapidly.
      I would though like to say that a well run mine that is supervised thoroughly is not going to cause a problem (most likely). People look at old mines or mines in China and scream to high heavens. Modern mines are totally different than those. Instead people want everything to be mined in China where the pollution will be enormous and where thousands of people die every year so that they can have their iCrap thingies and cars. I just do not get them…
      But, then I am partially paid for by the mining industry (should say that so everyone knows) so my opinion is almost all pro-mining (as long as it is done responsibly).

        • Problem is that their reported reserves are all lies.
          China used to boast that they had 100 years of reserves on REM and Tungsten (among others). One year ago they after hard pressure admited that it was not true. They then reported 20 years of reserves. A more correct figure would be 5 to 15 years depending on the mineral in question.
          When those deposits run dry we are pretty much in deep creek since we have shut down mines, or not opened new due to iCrap carrying people who do not want mines outside of China.
          Just think about it… 85 percent of all Tungsten is produced in China today, when that is finnished all those machining tools and drill bits that the world requires to function will not be possible to make. Same goes for all consumer electronics…

            • Link #3 kicks arse!

              And for a glimpse at what it’s all about…

              Some of the ideas frighten me… mainly in how TPTB will go about trying to implement the ideas. Not a lot of them are very bright, or care about civil liberties. Many just want to carve out a mondo slice of the pie of whatever funding gets thrown about.

              I like Barnett’s lectures. He got into this grind by working with Cantor Fitzgerald about what Y2K could entail should it go bad.

              From the lecture:

              “Gonna make an argument about shifting to the second book about the scene between War and Peace, which is hard to explain to Americans, because we like to declare war on everything. We can’t get an erection, we declare war on it. We get a bald spot, we declare ware on it. If we’ve got a disposable income, we declare war on it. We declare war on everything in America and we treat everything like war, football, sex, business, whatever, except actually war which we, you know, commercialize and put in video games.”

            • Ref Human Augmentation.

              I’m sure that you have seen the Alien’s movie where the heroine is tromping around in an exo-suit… that version is well on the way.


              I play a lot of online “combat” games, and in a few of them, there is a “Max” or “Brute” soldier class. The implementation of the logic behind these classes is that of an exo-suit. It’s used to mount heavy amounts of firepower (though somewhat futuristic) and provides an additional amount of resiliancy in the armor that it provides. Many of the games make this class slower and more lumbering than normal players, which is a nod to how the reality of how this sort of equipment would fit in if it existed.

              As for Ghost in the Shell, I rank that series along the lines of Phillip K Dicks, “Do Androids Dream of Electric Sheep?” and the movie that came from it, “Blade Runner.” At what point of automation does an android achieve consciousness? The Nexus Six of Blade Runner, as portrayed, were quite close. Then you have to ask other more bizzare questions… Why does Motoko Kutsanagi prefer to keep a female chasis? The character Batou is always querying her about that choice.

              I think I can answer that from two points of view. 1, her original human form was female before she became a Cyborg. If this were real, that would probably be the only reason. A persons sense of self is very important. It’s who they are. It defines them. The other reason comes from my experience in gaming. The female form is smaller, lighter, and harder to hit. In several clan based skirmishes, we had run across another clan that ran nothing but female avatars. And yes, they were harder to hit and maneuvered quite well. Another human trait is that one would tend to pause for a second if you caught sight of one running up the stairs… and that hesitation was usually enough to get you taken out. Male instinct is male instinct.

              One thing that I have always been fascinated with, is how life imitates art. Many of the things that we see in science fiction have either come to pass, or someone is working on it. Many years ago, Star Trek had Spock fiddling around with some crystals that were holographic memory units. Much work has been done to make that a reality. Photoreactive crystals were able to be written to using differing wavelengths of laser light in a page by page format. They even had a unit about the size of a 1980s VCR that was fully functional. The issue (I think) is that over time, the crystal would begin to cloud and turn opaque and useless. But, the idea of using CDs and DVDs.. and then BlueRay has stuck around and is viable. Take the communicator from Star Trek… essentially, is is functionally, a cell phone. The “Star Wars” Strategic Defense Initiative did have a few things that came to fruition. The Boeing YAL-1 Airborne Laser Testbed is totally functional… it just lost favor with the powers that be. Can’t be shooting anyones ICBMs down now can we? Rail Guns and directed energy weapons are in progress and will be coming out sometime in future. Hell, many missile illuminators are effectively directed energy weapons if you are too close to the antenna when they go in to CWI mode. I know of one that can fry your private parts at 1200 feet. (And this is not the Vulcan Phalanx CIWS in the training facility up in Great Lakes that they used to track people’s belt buckles with as they walked down the sidewalk. Imagine what some software changes could turn that thing into.)

              Wrote that last bit and forgot what my point was. Anyway, one of the recurring bad guys in GITS was the Laughing Man. Similar to that, the Anonymous “group” has a single icon… a Guy Fawkes mask. The only common thread. Laughing Man was supposed to be able to infiltrate any and all camera systems that could observe him, which I think is beyond what Anonymous can do. So, their appearance is heavily staged with a controlled shooting of any statement that they make. Not necessarily “life imitating art”, but mimicking it.

            • Reply to GL about GITS. Last reply and sorry for the big OT.

              Arise is out. Volume 2 is due in a few weeks. 🙂 First one was great.

              Loved Laughing Man, all three of the series was great. Ghost in the Shell: S.A.C. 2nd GIG,

              That was based on the March 15 rebellion in Japan-1932.

              Zaibatsu, Sakurakai and Co did a number on the government then.

              Kingoro Hashimoto be the charter base for Kazundo Goda.

              Tokyo earthquake 1923 in real life would equal the role of “The People” in the show.

              That’s one of my takes on that series. 

              Thanks GL for putting keys to blogs

        • Yeah, but you can almost bet your ass that we won’t try to get them. “No Blood for REE!” and all that horseshit. Even in Iraq, the international concerns went after the oil. I personally think that there should be renumeration for the effort. Hell, even Syria is a friken set-up. They declined the pipeline deal with Saudi and Qatari interests. Can’t have someone infringing on Gazprom’s monopoly ya know. (The European Market is one fat juicy plum) That’s why Saudi Arabia and Qatar want him ousted. They coudln’t care less about the people. Hell, I’ve even heard rumor that the chemical munitions were provided by Qatar and that since instructions for their use were not provided, the “rebels” managed to gas themselves when they started fiddling with it.

          Ref the video… that’s something best handled with a 2 x 4. You won’t be a macho badass, flinging your belt around while you are trying to find your jaw.

          Personally, I’m just out and out disgusted. I don’t think I have ever had such a desire to urinate on someones grave as I do right now. I overheard a tax clerk talking to someone on the phone… clerk says When it comes to loosing your house, I’m sure that you can come up with $2500.00 Yeah, I’ll bet. How much are kidneys going for now? Maybe turn a few tricks on the weekend, you’ll make it up in no time. No, she didn’t make the statements in black text, but that is what I inferred from her tone of voice. Maybe breaking into the clerks house and stealing the silver? That might pay the bill. Short of actually being able to FIND a decent job, what are the options?

  20. The Jebel Zubair eruption 2013 is no longer submarine:
    Image and video hosting by TinyPic

    I made this animated gif from Landsat L8 images from August 20, 2013 and October 23, 2013. Images by NASA.

    • Here we can see clearly that the distance between the lava flow / bombs and the driving cars (crossing bridge) is much bigger than it seems on the nightly video above.

  21. Ride em Cowboy!

    Friends… Texas is gonna get horked. As is part of Oklahoma. Before I tell you why, let me ask you a question. Have you ever drunken through a straw? If you have, you have experienced what I’m going to say, through you may not know it yet. The liquid in your drink climbs up the inside of the straw because of the vacuum, or lower pressure that you place on the top of the straw. If you didn’t place a vacuum on the straw, the liquid would just sit there at the bottom of it, maybe crawling up a bit due to the wetting action of the fluid on the surface of the straw.

    The venturi effect is when the pressure of a fluid drops due to it’s higher speed. A similar effect, the Bernoulli’s principle, is used to lift aircraft off of the ground due to the higher speed of air traveling across the top of the wing as opposed to air passing underneath it.

    Now… something different. Warm-Moist air carries potential energy. This energy is manifested by rising, condensing into clouds, and raining. The Convective Available Potential Energy (CAPE) is a measure of just how ripe the atmosphere is to doing this. In high CAPE conditions, you can easily get thunderstorms. Combine a high speed wind field at the top of where the storms are at, and you increase the ferocity of the air moving up the storm. In other words, the vacuum at the top from the high winds can make the storms much stronger.

    Another measure is the helicity of the atmosphere. This is simply the tendency of the rising air to twist as it ascends. In areas of high helicity, coupled with strong storms, you can get tornado activity.

    Well… right now West Texas and Oklahoma are sitting pretty, if you want the nasty of the nasty weather… I’m not a meteorologist (as well as not being a geologist, marsupial, or purveyor of fine merkins) but it seems to me, they may be poised for an outbreak. This doesn’t mean that it’s gonna happen, but the forces at work are pretty close to being lined up for it.

    Note: TGMcCoy should be versed enough to tell me I’m a barking loon or not. He deals with “air stuff” in his normal line of business. For him it’s a safety issue.

    Images come from the model run images hosted at the University of Dupage.


    250mb winds


    • Yes, Lurk they have a pretty good chance of severe weather.
      This time of year can get some big storms in that region.
      Bet there is a tornado box put up…

  22. I always thought it was spelt “mirkin”…but i googled and you are right… it is infact “merkin”. Interesting that there is a wikipedia entry on it 🙂

    • Somewhere in the world there is bound to be a collector of merkins. Probably more than one, and those probably have merkin conventions where they gather trade merkins between them and famous merkin makers hold lectures. I can even imagine them singing “What a Merkinful world…”

    • Could someone who is more intelligent than me explain this…
      When the eruption finnished the depth of the summit was 114 meters. Now it is 87 meters. Between those two measurments there have been no eruption according to the authorities.
      I could buy that further inflation had done that, but not here since there is no chamber under the volcano that could inflate, the chamber is in under Tanganasoga….
      I could only understand it if there has been a couple of small eruptions during the “no eruption” period. But then I am not that particularly bright… 🙂

      • I think it is only a question of date. This is the very last bathymetry of the volcano. The value of around 90 m has been already given several times in the past (and I think also when they gave out some underwater videos). There is also the fact that there was some heavy degassing at some time and that probably did not help with the bathymetry data acquisition.

        • Yes, but the 90 meters was before the collapse, after the collapse it was 114 and the eruption had ended…
          I guess the answer is that the reports are not entirelly that well written really, and ontop of that it is always different authorities making the reports.
          To be honest, I would not rule out a small eruption having occured after the end of eruptions as reported by the powers that be.

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