The Great American Volcano

The Bona-Churchill Massif with the Klutlan Glacier flowing out. Photograph by George Herben.

The Bona-Churchill Massif with the Klutlan Glacier flowing out. Photograph by George Herben.

Few countries on the planet suffer from such a varied set of volcanic features as the United States of America. On the western seaboard you have subduction volcanism ranging from long dormant volcanoes to active volcanoes close to cities. As you come up around the tectonic bend into Alaska you get large subduction volcanoes capable of VEI-6 (Volcanic Explosivity Index) eruptions like Katmai (Novarupta) and Churchill. As you continue further along the Ring of Fire you have the ever erupting Aleutian Arc, a chain of volcanic islands that continue all the way over to Kamchatka in Russia.

Old Faithfull in Yellowstone National Park painted by Albert Bierstadt in 1881. Wikimedia Commons.

Old Faithfull in Yellowstone National Park painted by Albert Bierstadt in 1881. Wikimedia Commons.

Out in the Pacific Ocean at the end of the Emperor Seamount you have the largest active volcanoes on the planet, created as a large hotspot pushes never ending flows of basalt out thru the volcanoes on the Islands of Hawai’i and Maui.

If we move back to the continental US we find yet another hotspot volcanic feature, the Snake River Plain volcanic zone. It is a great U-shaped feature where a stationary hotspot has blasted a sequence of calderas and volcanoes as the US continent did a U-turn as plate tectonics moved the continent around. First the continent moved to the east, then turned and started moving west. I will get back to this trajectory in a later article.

At the end of Snake River Plain we find Yellowstone National Park, a set of at least 3 nested calderas. Yellowstone has been made famous in a rather hyperbolic TV show by BBC/Discovery Channel where it was dubbed with the nowadays popular term “Supervolcano”.

In reality it is an active volcanic system that might still produce normal sized volcanic eruptions; it is though highly debated if it still has the capacity for anything larger.

We will get back to Yellowstone sooner or later, but let us leave Yogi Bear and Old Faithful for now.

A new series of articles should start off with a bang, and especially a series about American volcanism. After all, it would be rather un-American if it was not the “Largest and most bad ass eruption in history”. So, welcome all to the largest American eruption since the last Ice age.

Mount Churchill

USGS team investigating the caldera rim of Mount Churchill. The rocks they are climbing on top of is consistent with the later White River Ash deposit. Image from Wikimedia Commons.

USGS team investigating the caldera rim of Mount Churchill. The rocks they are climbing on top of is consistent with the later White River Ash deposit. Image from Wikimedia Commons.

Up in Alaska you have some of the largest volcanoes in the United States, several of them capable of having eruption well into the VEI-6 range (plus 10 cubic kilometers of magma erupted in one explosive eruption). The last of the Alaskan volcanoes to produce a VEI-6 was the Novarupta eruption of Katmai out in the southwestern part of Alaska. During the 60 hour long eruption 14 cubic kilometers (3.3 cubic miles) of magma was expelled, making this the largest eruption since Krakatau, Indonesia, in 1883. Or, in other terms, Katmai was the size of 30 Mount St Helens eruptions stacked on top of each other.

If you instead move toward the eastern end of Alaska you come to the Elias Mountains and the Wrangell Volcanic Field you will find the Churchill-Bona Massif consisting of two very large strato-volcanoes. Mount Bona is named after the yacht Bona owned by Prince Luigi Amadeo, Duke of Abruzzi in 1897. Even though Mount Bona is the tallest volcano in the US, he would probably have used the name on Mount Churchill if he had only known about its fiery past. Mount Churchill ranks in as the fourth tallest volcano in the United States, so it is by no means a small volcano either.

The White River Ash

One funny little detail is that the White Wiver Ash is so starch white. Photograph showing the ash layer by P. Sinclair.

One funny little detail is that the White Wiver Ash is so starch white. Photograph showing the ash layer by P. Sinclair.

The White River Ash is actually consisting of two large deposits of ash; the older one is called the Northern lobe and stretches about 400 km (250 miles) to the north. It originated from a VEI-6 eruption in 150AD (+/-100 years) estimated to have ejected 15 to 20 cubic kilometers (3.4 to 4.5 cubic miles) of magma in the form of ash and tephra. The origin of this eruption is not conclusive, but it might have been from Mount Churchill.

The second White River Ash is called the Eastern lobe and stretches 800 kilometers (500 miles) and erupted at 803AD*. Current estimates put this eruption at 30 cubic kilometers (6.8 cubic miles) of magma erupted in the form of ash and tephra. As such it is twice the size of Katmai, roughly equivalent to 60 Mount St Helens, and the largest known Holocene eruption in the North America.

For a long time the origin was unknown and highly debated. In the beginning the eruption was believed to have originated from the nearby White River Volcano (Mt Natazhat) that is lurking in the hinterlands of the Alaska-Yukon border.

In the 1960s volcanologists started to backtrack the ash and ended up in the Wrangell Volcanic Fields with a hypothetical point of origin placed somewhere under the Klutlan Glacier which originates in the Bona-Churchill Massif.

During the 1990s researchers at the USGS used aerial photographs and found a 4.2 x 2.7 km oval caldera east of the summit of Mount Churchill.

During a field trip the USGS found pumice and lithic fragments at the caldera rim that is consistent with the Eastern lobe of the White River Ash.**

Sociological effects

Among other things the White River Ash is coveted by potterers for its high quility.

Among other things the White River Ash is coveted by potterers for its high quility.

Very few historical eruptions in the United States have had any effect other than locally, not even the Mount St Helens eruption caused any effects beyond the regional level.

The Novarupta eruption of Katmai caused slight climatic effects in the northern hemisphere, but nothing that would be considered worse than any old rainy and cold summer.

The same was probably true for the 803AD Medium-sized VEI-6 eruption that caused the second White River Ash deposit. The effects on the regional scale was though staggering since a 340 000 square kilometers (130 000 sq. miles) was covered with an average of 0.6 meters (2 feet) of ash.

This radically altered the history of the United States since the local inhabitants had their main means of sustenance removed. This caused an exodus as the Athapaskans wandered eastward into the Mackenzie Valley and to the south where they formed the Pacific Athapaskan community and into the southwestern United States where they formed the Apache and Navajo.

As such the ramifications on the sociological scale far supersede any global climatic effects of the White River Ash eruptions.  The eruption left such an impact that the story is still retold in the verbal accounts of the various Native American nations.


*Most reference literature state that the eruption took place in 720AD +/- 80 years. About a week ago Assistant Professor Erik Klemetti wrote a short article in Wired on a different subject where he mentioned the White River Ash, and there gave the rather precise dating of 803AD. The only way to get such a precise dating is through dendro-chronology, or in other words, counting tree-rings. My guess is that Klemetti has access to unpublished data of that kind, so I am graciously using the same date he provided.

**In the same short popular science article (referenced below) Klemetti also noted that the origin of the White River Ash was in dispute. He did not though specifically say that it was the Eastern lobe that was in dispute, so my guess is that he meant the older Northern lobe. Anyhow, I am going with the standard interpretation until further scientific evidence emerges.

155 thoughts on “The Great American Volcano

  1. When the U.S.A. exceeds the debt ceiling at the forthcoming 17 October, it will default and will be unable to pay the government loans back. The debt-bubble will explode and it will have catastrophic consequences for the world economy and the financial and monetary system could collapse. Banks will collapse, debt-laden Eurozone countries like Greece, Spain and Italy will also default. Even the Credit Default Swaps and derivatives could collapse. This will be a catastrophic financial eruption with huge financial pyroclastic flows and caldera collapse. Which V.E.I. number would these financial events have on the V.E.I. scale?

    DragonEdit: This has allready been debated a lot in here. Unless the economic crisis in the US will create further cutbacks for the USGS I suggest we leave it be. At least untill there is another Friday thread. 🙂

    • I have my own catastrophic viewpoints on this but defer to the elder dragons.

      … hell, I just took a 30 minute nap in a rest area just so that I could drive into the sun’s glare. Some nitwit (elsewhere) had mentioned that there was an abnormal feature in the sky just after sunset and I wanted to see for myself. Got a glorious view of Saturn, Mercury, and Venus. And one serious headache while waiting for it, navigating in and around the tractor trailer rigs and highway patrol. The fun part was watching the zippy zippy cars blowing by, then sneaking a peak around the rig to see them all bottlenecked behind the state trooper that was out in front.

  2. Here is a still the top view of the recent TFZ earthquake swarm (color) together with all earthquakes 1.5+ from 1995 to present. These are the data from the listi files and represent only 99% quality, manually revised events. There are now about 1140 listed for the last 20 days.
    Image and video hosting by TinyPic

    And here is the view from South. The swarm stayed relatively deep in comparison to previous swarms it seems.
    Image and video hosting by TinyPic

    The gold layer is the presumed Moho from and the coastline is from NOAA.

    If anyone wonders why the axis labels are mirrored, these are snapshots from a rotating 3D plot. I am just short of time to do the whole animation procedure right now, but I think the two images show the essence anyways.

    • Thank you Cryphia!
      That would mean that almost all earthquakes have been manually checked by now. Someone has put in the extra mile at IMO.

      • Thanks! The grey dots are transparent (alpha 0.5) and the colored dots have priority of visibility. There are also many below magnitude 1.5 which would appear between the older grey events.

            • I was scratching my head on those ones to… But I guess it would be almost impossible to find them and separate them from other activity. Or at least a horribly gigantic and time-consuming project.

            • Might be that the coast is not all that important.
              I think the wedge is the Holy Grail (Holy Handgranade), but that might just be me… 🙂

          • You are right, your plot had a better resolution and not so much clutter. The smaller earthquakes don´t stand out so well in my plot, but they are the guide to see the wedge shape (checked it by removing the older eqs).

  3. Nice article Carl! Am I the only one who sometimes starts off through these articles and wonders who the author is? Normally Carl’s journalistic “voice” is so unique it is easy to spot. But in the meantime so many people here have raised the bar, sometimes it is kind of hard to know who the author is till you get to the end. A good thing and good for the blog.

    I was also wondering if anyone was going to do an article on the Samalas 1285 eruption that Erik featured in that article (or Rinjani – that is the volcano we know though technically it is just an Anak Samalas). Kind of amazing that it took that long to identify. There is obviously a heap of work out there to be done (any budding young volcanologists here?)

    • Interesting, I have never really thought about that.

      Samalas is a hard one, not much is known except what Erik just wrote about, so I am a bit reticent to write about it since I feel that I can’t really add anything to the picture. But, there is probably those who can. 🙂

      There are a great deal of large volcanoes that very little is known about, or in some cases, that are known to be highly active, dangerous, and still are unmonitored. We are going to come back to those in the end with a bang of our own hopefully 😉

    • Nice introduction Carl and some good points raised Bruce! Another point to consider when selecting material is the complexity of the subject. Just take a look at the Three Sisters Area which also includes at least three medium-sized shield volcanoes, some as recent as under 10,000 years of age, and a couple of stratovolcanoes plus a goodly number of cones and buttes. How do you bring order to that inside the scope of an article?

      • I have been trying to bring som semblance of order unto Icelands volcanoes for the last 3 years. It has gotten me nowhere really. Every time I turn around another volcano that I never heard of Pops up. I am still shtumped that I had missed what just has to be Icelands largest volcano.
        Conclusion. Order is over-rated. Come over to the Dark Side – We have cookies.

      • The three sisters are is also interesting as it has erupted high-silica rhyolite. It is also somewhat similar to pre-caldera-Mazama as it is coalescing chain of stratovolcanoes.

            • If i had to guess, I would say volcanoes like these are all fed from a similar “deep spot” magma chamber or feeder system. The only difference is that the shallow magma chambers differentiate, creating separate volcanic edifices. I think some of these could potentially indicate a precursor to a large caldera-forming eruption, or on the other hand, be somma volcanoes sitting around a since buried and unknown caldera.

            • Fourpeaked looks very similar to Mt Washington if you’ll allow for the two John Cleeses leading the expedition to the two Kilimanjaros. In the case of Mt Washington, it’s the result of glacial (ice age) erosion where the peak is a volcanic plug that has withstood erosion.

              Mt Washington

  4. Great Article Carl. I flew past the Wrangells on a fire call to the interior of AK.Kind
    of humbling when you know that mass of rock and Ice are a volcanic range…
    When I was in anchorage this spring I got a copy of a picture of redoubt erupting some years back. Here in the American west you cannot ignore the Volcanic

    • I also remember someone in Vancouver talking of their knickers getting eaten away by the sulfuric acid (from Redoubt?) while hanging on the washing line. That is what I call a tangible impact.

      • err.. I mean the knickers were hanging on the line, not the person wearing the knickers… grief. syntax. it can kill.

        • I liked the original version. It would have to be a very persistant Volcanophile to hang oneself on a clothesline wearing only knickers to firsthand watch how the sulphuric compounds dissolved ones item of clothing.

    • “Here in the American west you cannot ignore the Volcanic past.”

      Sure you can! Any number of congress critters whose driver should have to carry this in the vehicle to meet DOT safety guidelines for the transport of hazardous material should they have an accident, could care less!

  5. Thanks Carl for this exciting post. Leaves one thinking that these eruptions which caused nations to migrate were in a not so distant past.

  6. Magmatic again?
    07.10.2013 15:25:04 66.277 -18.556 13.1 km 1.4 99.0 17.4 km NW of Gjögurtá
    07.10.2013 13:47:12 66.256 -18.454 8.1 km 1.5 99.0 12.5 km NW of Gjögurtá
    07.10.2013 13:07:13 66.260 -18.454 10.0 km 1.4 99.0 12.8 km NW of Gjögurtá

  7. May I introduce you to Mrs Sill

    TFZ zoom

    Herr Dyke is also there

    DragonEdit: Tried to save the picture… But nope, it is just not working.

    An alternate Dragon takes a stab at it… Check it closely, I may have stabbed my foot. 😀

    DragonEdit: Those that start with anything but tinypic are for code integration I think. Could you upload again?

    Mrs Sills is getting larger

    DragonEdit: Happy Dragon see now can 🙂

    • What is interesting is the stack of larger ones going down. The fracture surface is probably large enough for to have created a conduit. Then Herr Dyke got into existance, and when the Dyke was full it seems to have gushed off into Mrs Sills.
      Now I just wonder if that will hit an old emplacement (which we know have happened since there is a hydrothermal field), or if another wadd of magma will go up shorthly. Or if this will continue to climb for a while and get stuck, or if it will come out.

      • sorry, this is a mistake from me( mea maxima culpa). The large ones, are the magnitude scale (but they are lost in the Moho) – I will correct this for the next plot. So that there is not that many quakes in the nether parts. Herr Dykes is a tendril going up.

        • Dfm, could you post first to our facebook page as tinypics has this irritating feature that when you click to see a larger version of your pic, you do not get it but some tinypic ad bullcrap? Please?

  8. One of my daily check-in websites is emsc for the European quake patterns, watching how the bigger picture bends and flows. Recently in the news we have been told how climate change is caused by human activity. I am of the view that responsibility for pollution and damage to the environment can usually be laid at our door, but that climate is probably a bit bigger than us.

    Vukcevic on chiefio’s wordpress page appears to be looking at the bigger picture still, measuring correlations between weather and changes in geomagnetism. I only have a simplistic grasp of what he is proposing but it would seem to have a basis in evidence from what is written here:

  9. I’m glad to see that some earthquakes are starting back up at Vatnajokull. Carl were you talking about flooding in the glacier yesterday? I read but didn’t post anything.

    • It is remarkable what a change it was when they redid the entire list.
      As the center of attention moved about it was interesting how it created upward dykes (counted 3) and also how it formed a Sill.
      I am so curious what this will lead up too.

      • Ya know… if I ever get my head back I might run one of those Heat3D™ simulations on it. Right now I’m still trying to decompress from driving down there, pugging in the monitor, and having it come right up. (allegedly is was dead)

        I drug it back here and threw it on the bench and am doing a “burn in” test to see if it has a heat issue. Four hours is the magic point. It reportedly went that long and then shut down.

        Here is TZDV (GeoLoco might like it…)

          • No… just keep it dry.

            I seem to be getting more and more non work related requests to replace phone or laptop screens.

            The record is my grandkid who lost his phone at a party. He had a friend call it and the fire started ringing. Singed the case a bit. I’ve done that phone about three times for screen work.

            • Grandkid is in luck.
              In need of iphone repair = Granddad
              In need of fishing = Granddad
              In need of cool things to go “boom” = Granddad has the largest colletction of them

            • Ref: “Boom” Well, I used to. I got highly pissed off at him when he was living here and managed to get himself into probation. I couldn’t have any firearms around or else he would have been in violation of probation and eligible for full on prosecution. At the time, his uncle (my stepson) was also living here and had to move all of his firearms to his sister’s house. I imagine it was quite a site seeing us walking several shotguns and ammo boxes out to her truck.

              I stopped building remote actuation devices many years ago before I went into the military. The spookiest one triggered whenever it was exposed to light.

            • I kind of meant the never ending list of cool volcanoes… But explosives would work I guess 🙂

            • The problem with the cool volcanic boom booms is that you have to have an appreciation of the size of the energy release.

              I’ve been around large ordinance releases, and it’s difficult to relate that to a young one.

    • What I am really looking forward to is what Erik is going to write about the White River Ash, he seems like he has something up his sleeve. I wonder what he has found out that the USGS missed. One should though know that the Wrangell Volcanic Field is his Universities Homefield. Most of the Mountains in the area was first climbed by expeditions from the University. So I would not be surprised really if he had a mighty Ace tucked away somewhere.
      I started to read up and scetch this piece (together with a few more American pieces) about a month ago, and then on the home stretch Erik got up like the man from U.N.C.L.E and starting saying things that made me jump. I still decided to finnish writing the piece, but something tells me that I will have to get back to this one again.

  10. I have a few comments – first off, in Erik’s article on Samalas, he mentioned that the white river ash was the largest eruption in the last 10,000 years. Either this is a typo, or what we supposedly knew about the white river ash deposit is dramatically wrong. Considering he mentions it multiple times in the article that the white river ash is likely in the VEI-7 range, I highly doubt it was any type of typo.

    To quote Erik ( )

    “This is similar to one eruption I’ve been working on, the White River Tephra in Alaska, where a massive eruption in 803 A.D. that spread ash across much of eastern Alaska and the Yukon (and is claimed to be the largest plinian eruption of the last 10,000 years) is still not conclusively matched to a source vent. ”
    If this was the largest volcanic eruption of the last 10,000 years, then this eruption didn’t come form the source of the recent caldera discovered beneath the glacier. And on that note…

    From the article above –

    “Our drill site was so close to the crater of Mount Churchill that if it had erupted in 803 A.D., then ash would have been preserved somewhere in our record in the core,” explained Tracy Mashiotta, a research associate with the Byrd Polar Research Center.

    “We drilled all the way through the glacier to the bedrock below and didn’t find any ash.”

    “Without a visible ash layer in the core, we don’t believe that Mount Churchill could have been the source for that deposit.” explained Lonnie Thompson, professor of geological sciences and researcher with the Byrd Polar Research Center.”

    So as a relevant addendum, the white river ash deposit is still a mystery ash deposit without an associated volcano (from what we currently know at least).

    • 1210 years later. The ash could have been washed / eroded off the glacier by summer rainfall or wind. Or fallen on a different side of the crater.

    • The only time I have seen it referensed as a VEI-7 was by Erik, and it does not match up with the amount of DRE, even by a longshot. But, once again, that is Eriks home turf.

      And regarding the drill core, all it would have taken was a piece of glacier, or a swift water run-off and it would have swept the slate clean. It is mentioned in other places that the ash deposits are in some places spotty. The northern regions have a tendency to do stuff with stratigraphic layers. My opinion would be to go with Churchill up untill someone comes up with something better. So far there are more pointing towards Churchill, than against. And, judging from the spread patterns it had to be mighty close.
      Also, it is bloody hard to argue with the rim leftovers. You kind of have to explain those away.

      • Just reread the article. They drilled between Bona and Churchill and are surprised that they did not find any ash. Hm, they seem to have forgotten that any ash would by now be carted off by the Klutlan Glacier, and the Klutlan Glacier that existed 803AD has melted away at the bottom long ago. The ash they wanted to find is nowadays at the bottom in the two deposit piles that form those pumice terraces in the pdf Cryphia linked to.

        • Yeah, I’m not sure, but I wouldn’t argue with the guy from which this article came from. He’s one of the foremost experts in the world in ice core dating and climatology. I would have a hard time believing he would gloss over something that simple, I would imagine he’s well aware of where the glacier would or wouldn’t have gone when proposing this theory.

          As for Erik’s comments, I have a hard time believing he would mention something like that without being nearly 100% confident in what he’s said. Considering how anti-sensationalist he is, and the fact that he loathes innacuracy in reporting, I would have a hard time believing he would mention something like that without having some legitimate data and evidence to back it up.

          • Me to, that is why I am so curious about what he will come with.
            I am still though not entirely convinced about the ice core samples, there are a few things that strikes me as odd in the write up about it. I will try to track down a paper, if they wrote one. If needs be I I’ll go and bug the glaciologists here at the University, we have the majority of the bigwhigs in that particular subject right here in town. They probably have a good inkling at what and why this happend.
            What I have a bigger problem with is those pebbles.

            But, heck, in the end Erik might be laughing all the way to the bank because he has found the volcano with conclusive evidence.

            Please do note that I wrote above what is “The Standard Version” according to the USGS, and I would be very happy if it was another volcano in the end. For all we know it could be ash number 1 that caused the caldera, and ash number two came blasting out from something else close by. What would surprise me enormously is if it came from something far away.

            • About the “missing” ash.

              One thing we always kick about are the lahars. If the eruption was large, a significant part of the ice cap (that feeds the glacier) would have been flash melted. Much of it would have contributed to the column, but a part of it could have rushed down the glacier. Either on top of, or lubricated the bottom and eased the friction, allowing it to slip down the channel much more quickly than normal.

            • I was seeing some references to the water getting into the picture of the eruption making it more explosive.
              I would definitly not count out a lahar dragging it all down to the bottom, or one of those creapy moments where ash flow faster over water and thusly left a smaller track.
              Another thing that sticks out if this glacier behaved anything like the european glaciers it would have been melting fast during that time period, and only have started to grow later. I am not impressed that they found later sulphates in the ice, they should really be there anyhow.
              Ontop of that, I would love to have the flow rates for that particular glacier, the lower parts seems to be pretty fast, but the top is normally much slower. My point is, if the flow rate is low, let us say 4 meters per year, then the topmost part would be 5 km down by now, probably further still since pace tend to pick up further down.
              After all ice is by no means stationary.

            • Um …… don’t forget that glaciers, themselves, flow downhill. So the glacier would have moved any ash from the original deposition site.

              The best place to look for ash would be on the crater floor.

  11. With that said, it wouldn’t be the first time a very smart person has been wrong.

    I think one possibility is that there is an older deposit in the holocene that’s potentially larger than the two deposits that are mentioned in this post. I gotta imagine the

    • Well, as I have said, I just wrote what is “the standard model”. I would be seriously surprised if Erik would be far off if he has an Ace up his sleave.
      I am going to try to dig up some maps and a few sat images tomorrow and see if I can back track an idea I have.

  12. Still, “the largest plinian eruption in the last 10,000 years” is really saying something. That means it would beat Santorini, Changbaishan, Taupo, the Sandy Bay Tephra, Ambrym, Tambora, Kikai, Kurile, Karymsky, Mazama, Aniakchak… to name just a few… or does largest plinian exclude ultra-plinian eruptions?

    • Nah, he meant in the North America. Same as I meant in this article.
      It would perhaps meet the criteria for becoming one of the top ten for the last 2000 years globaly, but not more than that.

      • Are you sure about that?

        This is another quote from Dr. Klemetti in the same article.

        “Put that all together, and it appears Samalas is the source of the 1257 eruption — one that was very sulfur rich and possibly close to the size of the Tambora eruption. Looking at deposits, total volume of magma erupted close to 35-40 km3, making it roughly a magnitude 7 (correlates to ~VEI 7) — definitely putting it in the same class as Tambora, Crater Lake, White River, Taupo.”

        He’s comparing it to the largest VEI-7 eruptions in the last 10,000 years. If the only reference he made to it was that it was the largest plinian eruption of the last 10,000 years maybe he would be referring exclusively to north america.

        But even then, that still puts it larger than Mt. Mazama, which puts it well above the VEI-6 range where it’s currently thought to be. I think there is something more to this that we don’t know about given the information currently available to us.

        • So sayeth CVO:
          A total of approximately 51-59 cubic kilometers of magma was ejected in the precursory and climactic eruptions, and approximately 40-52 cubic kilometers of Mount Mazama was lost by caldera formation. The spectacular compositional zonation shown by the climactic ejecta — rhyodacite followed by subordinate andesite and mafic andesite — reflects partial emptying of a zoned system, halted when the crystal-rich magma became too viscous for explosive fragmentation. ” Less than Mazama.

    • Even if he was just referring to this as the largest eruption of last 10,000 years in North America, that still makes it larger than the eruption that turned Mt. Mazama into crater lake.

    • Although he does not say so – explicitly he said “and is claimed to be the largest plinian eruption of the last 10,000 years” – he must have meant in North America or he’s got his marbles seriously scrambled. For a starter, the greatest plinian eruption of the past 10,000 years globally has to be the ultra plinian Hatepe Eruption at Taupo at ~180AD – VEI 7 with an estimated 120 km3 (29 cu mi) of which 30 km3 (7.2 cu mi) was ejected in the space of a few minutes. The last part, 30 km3 in a few minutes, equals the entire White River ash eruption provided the figures for the Hatepe eruption are DRE.

    • Well… an oscillation is a sympathetic vibration throughout the length of the resonator.

      How tightly the resonator is peaked on it’s characteristic frequency, it measured as it’s “Q”. This gives it’s frequency response.

      Q = Pstored/Pdissipated = I2X/I2R
      Q = X/R
      where: X = Capacitive or Inductive reactance at resonance
      R = Series resistance.

      Note: this is for a tank circuit. At the peak frequency, Xr = Xc.

      For the transients. reactance is “opposition to current flow.” Specifically for an AC circuit. This is similar to the definition for resistance, but since the current and voltage phase angles change depending on frequency, you can not use resistance as a correct term. The math can get funky, with the introduction of the “j” operator. Essentially ir boils down to Pythagorean math as you try to sum up the different reactances.

      Purely inductive – (ELI) Voltage leads current.
      Purely capacitive – (ICE) Current leads Voltage.

      mnemonic → “Eli the Ice Man”

      This frequency dependance issue is why a reconnection events in the magnetosphere can wipe out power substations. They are designed for either 50 or 60 hz. (depending on country) and the currents induced by the magnetic field pulse are at essentially a lower frequency. (though the pulse may only be part of a full cycle) This can load the windings on transformers and push them outside their design criteria.

      Side note for the easily amused. A “Tank Circuit” is a combination of reactive components that alternately feed energy back and forth to each other. At resonance with positive feedback, you get an oscillator. Capacitance and Inductance in parallel is one pretty simple configuration. The inductor builds up a magnetic field, when it collapses it pushes electrons into the cacpacitor, which charges up. With no more “push” it then discharges through the inductor, the flowing electrons building up another magnetic field. The cycle repeats.

      In the field that I worked in, the preselector circuit was literally a cylindrical metal tank, complete with a tuning plunger. Part of my maintenance checks were to make sure that the frequency of the tank matched what the system was ordering it to via syncros and servos. One vexing problem was when a gear came off of a freq indicator servo pot. The tank slewed to one end and hit the stops, and the frequency indicator free spun like there was no tomorrow. The only way to fix it was to hoist the 150 pound display unit up so that the back of it sat on it’s rails in the track, and lashing the business end to the overhead. It was the only way that you could get at the gear and torque it back onto it’s shaft. Oh, and the system had to be “hot” when you did it so that you at least had it close to the correct frequency. Having 3600 volt CRT drive voltages present in the back of the unit tended to make you a bit nervous. Problem #2… we were underway and rocking. Yee Haw :D.

      I had an assistant specifically stationed nearby with a wooden pole whose instructions were to pry me off of the gear if I got hooked up. No passing of tools, no talking. Just get my ass off of it if I get in trouble.

        • That I’m half crazy?

          …ummm…. “yup.”

          In my defense… that piece of gear had to be up and running. CASREPing the gear would have meant that the ship could not meet the mission requirements that it had at the time.

          The standard rule of thumb is the NEVER work on energized equipment unless it is called for as a maintenance procedure. (such as alignments). Even those can be quite spooky. Before I continue. An inductor stores energy by generating a magnetic field. When the current that made the field goes away, the magnetic field collapses and continues to push electrons along the same direction that the original current was flowing. In this instance, it acts like a battery, of sorts… until the field completely collapses. In this particular piece of gear, there were “saturable” reactors. (a type of transformer) The tertiary (3rd) winding of it was used to change the hystorisis (response) curve of the reactor’s core. Using these devices, a high current AC voltage could drive the antenna motors at varying speeds. In actuality, they were high powered servo motors, and the thing was used to amplify the rather small servo signal to drive them. Now.. why was this thing spooky? Well, when you have a reactor (transformer) under full current, and with a fully formed magnetic field… and for some reason the circuit that you are driving develops an open… that current is going to go somewhere when that magnetic field collapses.

          Ohms law → E=IxR. Voltage equals current times resistance.

          For example, suppose you have 10 amps of current flowing though a 10 ohm load. Thats 100 volts. Now as the circuit opens… say up to 100 ohms, that same 10 amps will generate 1000 volts. Now increase the resistance to 1000 ohms… 10000 volts. Fully open? Potentially infinity voltage. (It will never get there, but it will damned sure try.) At some point the voltage will be high enough to cause the air to achieve dielectric breakdown and you will have an arc. IF your hands are inside the box when that happens.. you become part of the circuit if your antenna drive circuit inadvertently goes to an open condition.

          We affectionately referred to this box as the “snake pit”, and standard precautionary measures were to use two pair of high voltage gloves when attaching the test leads. And again, have someone standing by with a pole to knock you off the gear if you hook up… just in case.

          Back in school, we had a piece of gear that had a test point that you had to measure and set to 450 VDC. The problem was that ground floated at 10,000 volts relative to the chassis. The way you measure it is you disable the high voltage floating ground, and take the measurements. In order to do this, you had to switch three or four interlocks on the power supply (disabling it) and then short the capacitors in the bottom of the unit to bleed off any dangerous voltages. This was done with a shorting probe. It’s a two foot piece of clear Lexan with a brass rod attached to a large braided (And insulated) cable that you attach to the chassis.

          One of my classmates was happily blowing sparks out of one of the lab units and gleefully stated how good it was that he was shorting the charges on the caps out. The instructor became livid. My classmate had not disabled the high voltage subsystem. After remediation he was allowed to finish the lab and he eventually graduated. According to the instructor, he would have figured out the problem himself when he ran out of brass rod. Essentially he was doing a welding operation.

          I myself had my own issues in lab. In an antenna lab my probe slipped and momentarily arced across the main power relay, fusing it in the “on” condition. At that moment we were presented with a directable antenna slowly spinning it’s way up to about 300 rpm without a radome on it. The spooky part of that was that this was a back to back collinear antenna with lots of scary looking protrusions. The only way to remove the probe was to secure power to three classrooms so that the system would spin down to a stop. A bit of wiggling of the probe and it popped loose. Like my classmate, I had to repeat that lab. No harm, no foul, just scared the shit out of everybody.

          • That antenna was my only screw up. It went to full power (and tried to do the 300 rpm thing), nothing was damaged, and no one was hurt. Startled, hell yes. It’s not like I got a buffer stuck under a horizon tracking antenna (different class)… or fell out of a tree on a date next to a high security area. (room mate) I was a well mannered student… and even left the CT’s alone. (no weekend brawling in the berthing quad for me)

            I spent most of my time oogling “Holly,” a mutual friend of one of the guys in my company. “Built for speed” is the best description I can give you. She had a much higher moral integrity that many girls with her features. (I was a sailor… what do you expect. I tried.)

    • Exactly.

      Magma supply goes away, the volcano shuts down.

      So, why would a magma supply go away? Because the conditions that caused it to form went away.

      The Cascade volcanoes are fed by the same process that feeds the volcanoes in South America or in Mexico. As the descending plate crosses through about 110 to 125 km depth, it begins to melt, mostly due to the melt point of the rock being lowered by the presence of water both in the minuscule cracks and by the water taken up in the chemistry of the rock. In Mexico, you can see a general trace of the 110 km or so depth curve by connecting all of the active volcanoes. In the US, you can see it in the locations of the Cadade range volcanoes.

      At one time, the Farallon plate was pushing under the North American plate. The dormant volcanoes of the Sierra Nevada mountain range were fed by that subduction zone. Eventually, about 20 or so million years ago, the Farallon fully subducted, and that zone became a transform fault. Today, we call it the San Andreas. The portion of the Farallon on the east side of the oceanic ridge detached and dropped down into the mantle. Some turbidity currents from that event caused additional volcanism, but for the most part, the Sierra Nevada volcanoes shut down. Why? No more melt was being generated to feed them. Some of those turbidity currents may have instigated the formation of the Basin and Range province. In locations where the crust has thinned enough, decompression melting has formed some volcanic structures in that area.

      In places where decompression melting is not occurring, the volcanism tends to come to a stop.

      Other than that, it’ s a matter of upwelling mantle material.

    • I’m not an expert, but I believe these are a few ways.

      1 – the magma upwelling from the mantle boundary finds a different path to the surface. Keep in mind, magma welling up from depth starts at depths greater than 100 km beneath the surface. 100 kilometers is a very long distance, and it’s not difficult to believe that magma could easily “Find a new path” to the surface. This would dry up the input source for the current volcano, and reactivate an old volcano, or create a new edifice.

      2 – Subduction stops. In a subduction volcano, if subduction completes or halts, volcanism will halt as there will be no means to produce fresh magma.

      3 – Rifting halts. In rifting (decompression melting) volcanoes, if the spreading of the surface of the earth stops, volcanism will typically stop along with it as the low pressures required to melt the mantle are no longer present.

      4 – A subduction zone starts to subduct at an angle too shallow to create magma. If the subducting plate never reaches deep enough (usually below 100km) in it’s subduction, you may get a “dead” zone in arc volcanism as the plate never gets hot enough to produce magma. This can be seen most readily in the Andes volcanic arc. Volcanism can start up again if the subducting slab starts to bend down at a greater angle.

      • Mexicos Popocatépetl is about 210 miles from the SZ that feeds the plate providing melt, Mt Hood, about 186 miles… South Sister, 178 miles.

        Many times I have read that Mexico is an example of “Flat Slab” subduction. But it’s not all smooth going. Colima is about 101 miles from the segment of the SZ that feeds it.

        In my opinion, the subducting plate has a tendency to “pleat” as it goes down, folding back upon itself much like a girls skirt.

        I’ve seen this on some plots of Benioff zone quakes.

        A few iterations of the Eruptions blog ago, I used to mince words with a poster named “Passerby.” One of the things that he derived from my plots was evidence of a slab hitting a desity level that caused it to start folding back upon itself much like hot taffy hitting the bottom of a pan.

        Given that subduction slabs tend to pleat, it makes sense that they would to other things once they got really deep… near the slab graveyard. I imagine that it is even possible for the ultra deep quakes to be collisions of slabs as the settle down and wait for the big melt.

      • One word Cbus – water.

        The main reason for subduction driven volcanism is the water contained in the subducted plate. It acts as a flux which once it reaches a critical temperature quickly melts the subducted plate and as the “bubble” of melt formed has both less density and higher temperature, it rises upwards. As long as the subducted plate contains enough water, the process continues at more or less the same location as melting depends on the temperature gradient hitting the critical flux melt temperature. Once the water supply is exhausted, temporarily or permanently, flux melting of the subducted plate stops as does the volcanism once the last bubble has reached the surface.

        • Yeah, this is most definitely true. With that said, if a subduction slab stays in motion, it should have a pretty constant supply of water as new oceanic crust reaches that 100km depth area where melt forms due to water saturation. Of course, some areas of the slab may be more saturated than others, so it’s definitely possible to “dry up”.

    • You guys forgot Hotspot volcanism.
      Normally that is much lest deep than CBUSes 100ish km (that is true for most subduction cases), as the continent moves over the hotspot sooner or later the hotspot will be at another place and the connection is permanently severed.

  13. The eruption of Novarupta was fantastic, produced a new baby volcano, caldera collapse at Katmai, which then extruded a lava dome, produced the VTTS.

    The really incredible thing about the Katmai volcanic area, is that all the volcanoes are magmatically connected. It is thought Novarupta got most of its magma from Katmai, which in turn got its magma from Trident.

  14. When in doubt, go grab a second opinion.
    I my case I went to the Arctic Research Center and found a professor to bribe with lunch. The cool thing with people when they get as far as they ever gonna go is that they tend to be amused and helpfull when an idiot shows up with questions relating to their field. It is the mid people who are a pain in the neck. So, always go for the big Kahuna.

    So after being regaled with stories about trekking Beerenburg and Erebus I sneaked in my question. Where did the ash go from Klutlan. Here is the gist of it.

    1. Hot ash on glacier would work like oil in a hot frying pan, it would slide down very fast. The term in translation from Swedish would be “glacial mirror” effect. So, the wast bulk would have slid down to what then was the bottom of the glacier (it can be seen in the Cryphia pdf). The boundary was closer up then, see 3. So, there would have been a dusting of ash on top of the glacier, much thinner than at other places..
    2. Here it goes hysterical. There should have been a sulphatic boundary at Klutlan even if it was a volcano upwind. At those release rates the sulphates travel several laps around the globe and should therefore be in every known glacier even one a few tens of kilometers upwind from the source. Reasons for them not being there is 3 and 4.
    3. The interglacial discontinuity. Between the years 600 and the little ice age the glacial melt rate was the highest after the ice age. Every layer between those dates would be melted together in a lump, or plain just have melted away. So, the glacier was much smaller than today, and it moved at higher speeds. That is why you have a problem finding old drill core residues even in the vastly larger Vatnajökull that is stable and does not surge in the middle.
    4. Glacial surge, even if 3 had not happened glacial surges would by now have deposited any findings down towards the middle of the glacier, or at the bottom.

    In short, his comment was that they had found what should be there, and had not found what should not be there.

    Over to the stones/pebbles. As being the result of ice age glacial movement they would be deposited under the glacier and function as ball bearings. Any ash deposited would be deposited above the ice, therefore the pebbles themselves would never be in contact with the ash. So, the pebbles found without ash is not a problem.

    A friendly tip, if you go and bug a senior professor, read the basic book on the subject. I took glaciology 101 way back when, and I speed read the damn book during the wee hours. Otherwise I would have been sitting going “meh?” all the time. In the end I struck gold, the book was written by that same dude.

    Release rate? Best fit model is a 45 km high ash column hit by a 10 meter per second westerly wind.

    • And just to be exact here.
      I wrote about the standard model in this article up above. I am sure that if anyone is going to say that the White River Ash did not come from Churchill they will have found the actual crater or caldera that released the ash, and have corroborative petrochemical analysis to prove that.
      Nobody would be happier than me if that happened 🙂

      • In other words, if your a naysayer bringing up a problem, you had better do it the right way.

        A Senior Chief that I used to work for had the philosophy that he didn’t want you to bring him problems… he wanted you to bring solutions to problems. If he had to figure out the solution to your problem, you may not like the result.

        I used that a couple of times with my sailors and it is a great professional development tool. Ernie was one smart cookie.

        • I was more talking in relative science terms. It is damned easy to go about and find one detail that is troublesome for a standard model in a complex science such as vulcanology. Does this detail put the standard model out of work? No, it is just a pointer that more research is needed.
          A real honking dealbreaker instead is finding a more fitting caldera with physical corroborating evidance.

          My point was more about Eriks highly hypothetical find. He has after all not said that he actually have a new solution. But, I bet that if he does, then it is going to come complete with a caldera and petro-chemical evidence. Erik is a rather smart cookie, so he would, I know I would if I was him.

          I agree though, I used to be a get me a solution not a problem type of guy. Problem is to know whom you want coming with the solution, and whom you never want to come with a “solution”.

  15. couple of quakes south of Hekla.
    08.10.2013 04:59:11 63.913 -19.666 4.8 km 0.3 57.87 8.7 km S of Hekla

    08.10.2013 04:48:40 63.910 -19.665 3.0 km 2.0 90.03 9.1 km S of Hekla

    • Tyler, neither of them are actual Hekla quakes. The higher probability one is at Vatnafjöll, a completely different volcano, and the other one is, if real, over beyond Búrfell.
      Hekla quakes are really close to Hekla.

      • And here is a dream plot for me…
        Vatnafjöll is having way more earthquakes than Hekla. About one every week or so. So, a well defined plot would be gold 🙂
        Remember, we are talking about a large volcano that is long dormant. So it would be fun to watch what she is up with those steady ticking earthquakes.

        • revised now : note the depth (close to the hot stuff?)
          08.10.2013 04:59:11 63,909 -19,672 5,8 km 0,8 99,0 9,2 km S af Heklu
          08.10.2013 04:48:41 63,913 -19,659 7,3 km 1,9 99,0 8,8 km S af Heklu

    • I’m not gonna sign up, but would maybe like to check the page now and again, is it possible to make it public access?
      I notice that some new and returning commentators are making their way here from the factbook page, which is nice 🙂
      100ish members is not bad going…

      • It is public to read, but not comment. To be able to comment you need to be a member. Might though be that you have to be logged in on FB…
        Yes, it worked as I hoped it would with oldies returning 🙂

            • I guess Nevermind is a translation of the actual name…
              I’ve heard of a mountain called Your Finger, You Fool…

            • Dragonlance (Hickman & Weiss):

              Mount Nevermind

              The home city of the gnomes, is actually a dormant volcano. Its naming involved a time when the Knights of Solamnia originally landed on Sancrist. The gnomes attempted to hide their mountain from the knights, who they believed were planning to steal their mountain. However, a gnomish guild thought that it would look suspicious if an entire mountain, the tallest on the island disappeared. This prompted an argument between two opposing sides of gnomes, meanwhile, another gnome set the device off anyway which, as with most gnome inventions, malfunctioned and did nothing more than cover the island with the smell of rotten eggs. Then the gnomes were forced to leave the mountain from the stench and meet the knights. When an elder asked the Gnomes what the mountain was named, an incredibly long, complicated explanation of the mountain’s nature (functioning as its name) was given, spoken in the incredibly quick way of expression of the Gnomes. The elder said “Nevermind”, and the Gnomes took the name as a stroke of genius.

              Mount Nevermind has an incredibly “sophisticated” transportation system. Many gnomes considered that stairs were outdated, useless, and “primitive”. Their method of traveling to different floors within the mountain involves “gnomeflingers”. On the ground are many catapults of varying design. The gnome gets on one of them, and then a bell rings on the floor that the gnome intends to go to, letting the inhabitants of that floor know about an arrival. The catapult then launches the gnome upwards. When the gnome reaches that floor, a net is supposed to roll out and catch the gnome. If it fails, then a net on the floor below it opens. If all the nets on all the floors miss the gnome, sponges are deployed on the ground floor to help clean up the mess.

              During the Chaos War, the gnomes were forced to abandon Mount Nevermind. With the help of some turned Knights of Takhisis, they fled their longtime mountain home (one major reason why they left was that they thought that the journey would be interesting).

        • I have the same problem. Like I sais I can go to the avcan page (even if I can only read), but I would need to connect to get access to the FB page.

          • Problem is that Avcan was created before FB changed things. Nowadays we would need to remove every safety setting to get the “Avcan-effect”. Sorry.

        • I have been here since the beginning, lately just lurking in the shadows 😉 The Fb page seems nice additon, at least we get more nice pics of volcanoes 😛

  16. Ever heard about these guys “Hekla-Empfangskomitee – Initiative für mehr gesellschaftliche Eruptionen”?
    In English that would be “Hekla Reception Committee – Initiative for More Social Eruptions”. No? Neither had I before today, of all things hidden behind that name is a German terror-group that hates among other things rail-roads.
    They are though far less proficient than their namesake at getting things to actually burn down. 17 incendiary devices have been planted. Only two went off, none have been hurt, and only superficial damage was done.

    • It’s a matter of funding. Yellowstone Park staff have better funding and can menace people much more effectively.

      “Vaillancourt was one of thousands of people who found themselves in a national park as the federal government shutdown went into effect on Oct. 1. For many hours her tour group, which included senior citizen visitors from Japan, Australia, Canada and the United States, were locked in a Yellowstone National Park hotel under armed guard.

      The tourists were treated harshly by armed park employees, she said, so much so that some of the foreign tourists with limited English skills thought they were under arrest.

      – See more at:

      And in keeping with the age that he depicts… our “President” sends a very clear message. MINE! MINE! MINE!

      All departments are funded and operated as directed by the Office of Management and Budget… which falls under the executive branch. What gets opened and what gets closed is their call. In all the budget melee, they did find room to purchase a mechanical bull though.

      “GSA reported the National Guard of Utah requested a mechanical bull for messaging and recruitment” ($47,174) I guess they are gonna need it since the Feds decided to delay death benefits for the families of service members killed in the line of duty. The message; Here, “ride the bull!”

      This video parodies a few things things using the BF2 game engine. The opening sequence is a play on the tendency of players to crowd the helo pad waiting to get the helo when it spawns in.

      And for those of you unfamiliar with gaming… a game is limited to the 3D engine and graphics package that is used to represent the real world. Physics and gameplay tried to represent the real world, but never can quite get it all correct. If you see something that doesn’t make sense in the real world… that’s okay. It’s a game engine. Physics can be a bit odd. Mostly it’s governed by “hit boxes” or collision meshes. In a previous version of this game engine, the BF1942 edition with the DC mod, you can see some stuff done with an MI-24 Hind helo that isn’t really possible. I used to fly low enough to put the gunners perspective under the terrain.

      • Heh… they do capture some of the more “ehh?” moments.

        DICE and mainly EA have pretty much sealed their fate with our Clan. Most of them originated in Tribes when they formed up. They went through the whole squeezing blood from a rock bit of that franchise. They were in Jumpgate by the time I joined up with them. Off and on, we tried to find something that we can all rally around, but everything tends to fall way too short. When Tribes Ascend came out, there were high hopes, but it too also failed. EA and DICE got pretty pissed off when the DC mod for BF1942 came out. It made the game last well beyond their intentions and they couldn’t make any money off of it. So they gobbled up the DC development group and their IP, then locked down the game so that it couldn’t be hosted on private equipment with all of their new releases. In other words, they became money hungry and pissed a lot of people off. EA can pack sand for all I care. About the only development company that is more inept is Hammerpoint Interactive with their WarZ title. They did manage to get into a legal fight over the name and had to change the name of it. It had potential, but the twitch kiddies ruined that one. If I want to do nothing but FPS, I’ll go to a game designed for FPS where you spawn in with what you need to survive. In WarZ you spawn in un-armed and are pretty much immediately ganked by the time you find any resources. Screw that.

    • The Kyoto university cam pointing right at the Showa crater is showing nothing. I´d say moon or city lights.

      • City is the other side so not city lights; and, the Kyoto University cam is real time so won’t show something that happened earlier.

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