TVZ Part II -Taupo Volcano

Volvo A40F dump truck

This is a Swedish dump truck. A very good Swedish dump truck. It can carry a load of 39,000 kg – let’s be generous. Let’s say 40 tons. It makes the maths easier.

Now imagine 192,500 of these dump trucks passing your door. That’s right 192,500. Every second. Oh, and they must be going at a speed high enough to shoot 50 km into the air. (I’ll let someone else do the calculation on that one). But they are very fast dump trucks.

Got the picture?
No, well I haven’t either. Let’s try ships:

Sabrina I cargo ship from Wikipedia

This one here can carry 40,000 tons. That’s handy. Right, imagine 192 of these passing your door every second. OK, now we are getting somewhere. I can almost imagine that. 192 very fast ships, every second. Well, this is the eruption rate of the most powerful unit of the most recent major Taupo eruption, the Hatepe eruption in 181 CE (or 233 CE, according to radio carbon dating by Sparks).

In fact, I am wildly underestimating the volumes involved, because those dump trucks are not filled up with dense rock (magma equivalent), but light, aerated pumice. Lowenstern (or somebody else) from the Yellowstone Volcano Observatory once said rhyolitic magma can expand by up to a factor of 630 due to the exsolution of volcanic gases. I don’t know how many dump trucks you need to carry 40 tons of pumice, but it’s a lot. Same goes for ships.

We have entered a sphere that is simply inconceivable. We are in the domain of the mega-scary.

Here a list of some more stats, the bulk of which are taken from assorted papers published by C.J.N. Wilson:

The Hatepe eruption was the most violent Plinian eruption in the last little while. You probably have to go back 5,000 years to find anything with a bigger bang, although over the last couple of years I have come to doubt the veracity of this claim. Tambora, Krakatoa, Baekdu/Changbaishan were also pretty big eruptions, but possibly they just took a couple of hours to do what Taupo did in a few minutes.

In sum it is likely that up to 120 km³ of magma was erupted in the Hatepe eruption over the full course of the episode. Of that total, approximately 35 km³ seemed to go up in the space of just a few minutes (the bit I tried to describe above). Imagine this volume suddenly getting shunted up to an altitude of 50 km. That’s right, 50 km. About one third of the way to low-earth orbit. Higher than Felix Baumgartner.

Think how much energy a space shuttle needs to shunt a couple of tons that high and you start to get the idea of how powerful this eruption was.

But what goes up, comes down. And this one came down with a wallop. The ensuing pyroclastic flow is thought to have been 1.5 km high and travelling close to the speed of sound. It surmounted Ruapehu, 65 km to the southwest and at least 2100 m higher in altitude than the vent.

Pyroclastic flow at Pinatubo

The force of this catastrophic event is also recorded in the nature of the deposits: the ashfall from earlier parts in the sequence blankets 30,000 km² east of the vent with 10 cm of ash but the ignimbrite left behind by the final pyroclastic flow is laid out in an almost perfect circle, extending 80 km from the vent in all directions and covering 20,000 km².

Oh, and this is nothing. Oruanui at 26 kA was at least five times bigger (c. 530 km3 magma). And Whakamaru, north of Taupo (approx 340 kA) was much bigger again (1500 km3 though possibly in two or more eruptions).

Quite simply, we do not want something like this to happen in our lifetimes. Or our children’s lifetimes. Or our children’s children’s.. but one day it will. And, let’s face it. Humanity will survive it. Maybe not in New Zealand, but somewhere else for sure. Maybe Iceland. Or Alpha Centauri ;-).

When we grew up, the northern horizon was dominated by the distant and majestic cones of Taranaki (we called it Egmont back then) and Ruapehu. I remember seeing the eruption cloud from Ruapehu while driving down to my grandparents’ place on the beach, miles to the south. What’s more, back in the sixties and well into the seventies, Ngauruhoe erupted in regular Strombolian bursts. For us, these were our volcanoes and Taupo was well, just known as “The Lake”. You could still be forgiven for overlooking it as a volcano because it simply isn’t there. Just a ruddy great hole in the ground full of gloriously clean water and rainbow trout.

It’s not even round, like a crater, but totally irregular in shape. And it’s a big lake, stretching 46 km on its longest axis and 33 km in breadth.

Sure, some people told us Taupo was an even bigger volcano than Ruapehu but this sounded like legend or some fact of the long distant past because it obviously wasn’t anything like Ruapheu now. It was only later, that I started to read up about volcanology that I realized how wrong our impressions had been. Not only was Taupo never ever a nice big mountain, but, paradoxically, it is way bigger than Ruapehu in terms of volume of erupted tephra. It is also very, very active, still today and makes Ruapheu look positively gentle.

A nice and gentle eruption from Ruhapeu

So, just how big is this hole in the ground we call Taupo?

The current Taupo caldera takes an oblong shape, which is kind of interesting as Okataina displays the same rectangular shape. More on the significance of this later. The actual caldera basin is, logically, much smaller than the lake but is still quite sizeable:

Bouguer gravity anomaly

This hole in the ground has produced 28 eruptions in the last 26,000 years following the massive Oruanui eruption (although eruptive activity actually goes back about 300,000 years). And, precisely because the Oruanui eruption reset the system, most of those eruptions were in the latter half of those 26kA. Thankfully most of them were small. But at least four of them were scary humdingers and two of them were off the scale. Moreover, its eruptions appear chaotic with no discernible pattern in the size or the repose time between eruptions. Look at the chart of recent eruptions to the left. See any patterns?

fig 5 from GNS siteYeah, all well and good, but why? Why is Taupo so prolific? Why is there no pattern in the repose time? Why is it so violent? Why is it even there? What makes it different from any other subduction scenario around the world? I’ll try to answer these questions in the next installment.

Bruce Stout

The 26.5 ka Oruanui Eruption, Wilson, Blake, Charlier and Sutton 2005
Development of a Volcanic Hazard Model for New Zealand Stirling and Wilson, 2002
The Taupo Eruption, New Zealand, I. General Aspects, Wilson and Walker, 1985
Taupo Field Guides


190 thoughts on “TVZ Part II -Taupo Volcano

  1. Whoops, I see I made a bit of a mistake in the text (why does one only see these things when the page is made public??)
    In the very last paragraph, the bit that says “Look at this: Yeah, all well and good…”

    This should be changed to read:

    Look at the chart of recent eruptions to the left. See any patterns?
    {paragraph break}
    Yeah, all well and good..

    usw. Sorry!! (Don’t throw the croissant at me, Spica, please!!)

    • Hey, i like my croissant, and i am glad other people also only notice their mistakes once they are online, not only me. I feel i am in good company now. And sorry overslept and will leave the comment new post is up on the last chapter right now.

        • OooO dont start with that on a sunday morning! We had received an apricot jam last year with an amount of alcohol in it that was not to be underestimated. If you had a few croisants with that really jummy thing, you could start feeling a tiny bit tipsy.

          • Mmmmm… sounds yummy and a nice black expresso coffee please!

            Another great post, Bruce – you bring it all to life and it sure brings it home why New Zealand was uninhabited when the Maoris arrived!

  2. PS… @ everyone.. I hope people realize I was joking about our survival chances in NZ. Despite the violence of this eruption, NZ is a pretty big place and everyone outside of a critical radius would have survived. Volcanoes aren’t quite as deadly as popular fiction leads us to believe.

    • They leave a legacy of disruption to flora and fauna though, so it would be reasonable to expect that survivors would have great difficulty finding or growing food, especially on an island far from other land masses.

    • Sure glad I’m not the only one with only 1 piddly point! Like Lurking, I think I got mine quite by a wild, accidental guess. Congrats to the winners. Am really enjoying your Taupo posts, Bruce.

  3. The outset of this post posits a scenario and asks about the speed of the material coming out of the ground… in other words, the ejection velocity.

    The USGS has a program availible for download called Eject v 1.4 by Larry G. Mastin, 2001, “A Simple Calculator of Ballistic Trajectories for Blocks Ejected during Volcanic Eruptions”

    Using the data for the initial scenario, a spherical 40 metric tonne mass at 2700kg/m³ density, has a diameter of 3.05 meters. Choosing an angle of 89°, and slowly working my way up through the velocities… the program craps out much above about 1800 m/s.

    Taking and recording a few lower speed launches, then fitting a curve to them, I get about 1903 m/s needed to loft a 40 tonne spherical mass 50 km into the air.

    Think about that for a moment. 1903 m/s.

    The Barrett M82 is a premier long range sniper rifle. It fires a .50 caliber round and can accurately hit targets at an insane distance. (and punch though engine blocks) It doesn’t have the highest muzzle velocity, but it makes up for it with the massive size of the round. The Wikipedia listed muzzle velocity is 2,799 ft/s, or 853 m/s.

    (Note: I have seen videos of this weapon shooting through a masonry wall to hit its target)

    An even faster high powered rifle round, the .257 Wby. Mag. (87 SP) (150 Sp), when fired has a muzzle velocity of 3700 ft/s, of 1128 m/s.

    And the Hatepe eruption launched material out of its crater at 1903 m/s.

    Yep… that was one nasty eruption. Oh.. did you know that the speed of sound at sea level is 340.29 m/s?

  4. ” And this one came down with a wallop. The ensuing pyroclastic flow is thought to have been 1.5 km high and travelling close to the speed of sound.”

    On this scale of physics… things start to blend together and get fuzzy. It is very possible that the flow could have exceeded the normal speed of sound. In nuclear blasts, the precursor wave appears to travel faster than sound because the air is instantly superheated, raising the speed of sound. With an eruptive column of this size, it is not out of the question that the pressure front could have heated the air directly in front of the flow.

    Dunno for sure… but it seems plausible to me.

  5. I have been busy as ..,but there is a volcanic eruption in progress in Indonesia, Mount Rokatenda in Sikka regency, East Nusa Tenggara (NTT), continues to spout volcanic ash. Residents living around the volcano have reportedly been evacuated…article from Fri, 16 Nov 2012 08:51 CST, found at and here a bid of info from USGS
    Paluweh – Indonesia
    Subregion Name: Lesser Sunda Islands (Indonesia)
    Volcano Number: 0604-15=
    Volcano Type: Stratovolcano
    Volcano Status: Historical
    Last Known Eruption: 1985
    Summit Elevation: 875 m 2,871 feet
    Latitude: 8.32°S 8°19’0″S
    Longitude: 121.708°E 121°42’30″E

    Paluweh volcano, also known as Rokatenda, forms the 8-km-wide island of Paluweh north of the volcanic arc that cuts across Flores Island. Although the volcano rises about 3000 m above the sea floor, its summit reaches only 875 m above sea level. The broad irregular summit region contains overlapping craters up to 900 m wide and several lava domes. Several flank vents occur along a NW-trending fissure. The largest historical eruption of Paluweh occurred in 1928, when a strong explosive eruption was accompanied by landslide-induced tsunamis and lava dome emplacement.

  6. Just…. “wow.”

    Using the Mastin et al formula… the 50 km plume height of Hatepe eruption, that works out to about 631,802 m³/s (500,980 m³/s for the Sparks equation)

    (2.2 km³ per hour)

  7. The miscellaneous riddles page was updated too, and i decided to claim the Olympus Mons point i jokingly won, because when i am editing and posting the riddles i get the answers sent in advance often ( not always!) so there is a slim chance i can join the riddling fun in the future.

    When updating i noticed we don´t have a post on the Laki eruption. We really need one, i think. Anyone up for that task? There are some really good documentaries out there on this one.

    • I have not updated Alans riddle page because he said a Talla-i-fic Ding but i did not get what he ment exactly and if some points are still to be grabbed. ( i think there are)

    • Dunno… but “The Dead Zone” covers why the dead zone may be so quiet.

      I’m still fiddling around with MMI curves and have one set of parameters that may allow a better guesstimate at the size of the initialing quakes. Personally, I think that since Laki is in some peoples back yard, and that there is more data available to some one who can read the language… that it might be better suited to someone who can actually read the accounts….

      Not trying to draft anyone, just adding my 2 cents.

  8. Ah! What Bliss! An absolutely brilliantly illustrated post by Bruce. The comparisons of the eruption to things I can comprhend rather than pure numbers (which I have great difficulty with) sets the scene perfectly. A monster indeed!
    Then closely followed by Lurking’s genius with physics and numbers and more comparisons so even I actually now understand the enormity of these eruptions.
    Bruce never worry about the mistakes/ typing erros etc. I always see one as you and Spica says after the post or comment. Thank you these Taupo posts are excellent! I am enjoying them.
    The ,to put the snow on top of a perfect volcanic cone ( or to put the icing on the cake!) a coversation about croissants and jam. MMMMmmmmmm !. Another international coup for VC now entering his/her 2nd year.
    What a wonderful Sunday this is. Cold but beautiful sunshine making the frost glisten,. Meg the Puppy is asleep, curled up on husband’s feet on the bed ( A brave puppy indeed). She appears pretty well house trained already, so I am leaving her and Husband to have a well deserved lie- in.
    Nearly time for coffee #2. I have so enjoyed this quiet me time in VC this morning.
    I hear a patter of paws coming down so I must go to open back door. I will be back later to comment on a query I have.
    Must hurry! Meg looks a bit desperate >>>>>>>>>>>>>>

  9. Nothing like waking up in a frigid tropical morning and have the pleasure to read a brilliant and interesting post like this: dump trucks and freight ships flying out of a lake in front of you at the speed of sound.
    And of course, rainbow trouts – a pity that Bruce didn’t describe his weird “fishing methods”, but I leave that for him to tell it later.
    Am I too late for the croissant?
    Thanks, Bruce: you did it again!

  10. MMM!
    So far only 1 ding for Talla for correctly spotting Roach Stone Bed, Portlandian Stage
    Sissel has spotted one of my ‘bed mates’, Titanites
    But; who am I? Read the question carefully and look at fossil lists!
    Another bed mate is be a bit ‘horsey’!!

    • What about the horse carved into the hill at Osmington. There are fossils of Trigoniidae to be found close by? or has the Lulworth crumple i Stair Holed got anything to do with it? Very rushed guess though, this riddle solving is beginning to annoy my other half quite severly…I may have to ‘retire’ Kelda for a while, at least until he goes back offshore.

  11. Thanks for a great post Bruce; looking forward to the next. 😀

    And I now have a lovely image of Spica enjoying tipsy croissants. 😉

    • I seems that he can’t maintain them now that he has moved to Denmark, and the donations from the blog will no doubt have dried up since the number of visits to the blog imploded. It is such a shame, as the people who caused all the trouble that heralded the downfall of the blog never seemed to have visited again. Here people feel comfortable to talk about things OT , but snap into serious mode when something noteworthy is happening. That is its great strength. Long may it continue 🙂

      • So the priests of seriousness have not been the ones to put the bet on? What’s wrong with these unfunny people? Never happy. They achieve what they want, but then, like rats, don’t stay on the ship…
        Why would I never try to build my foundations one something internet-based? Why the hell do I smile even when I use my brain? I still have so much to “learn” until I am like the “serious” people…

  12. Belemnites 😕 and all the fossils I could find for Purbeck:

    “The Purbeckian equivalents of Spilsby and Speeton are in the zone of Belemnites lateralis. Other marine fossils are Hemicidaris purbeckensis and Ostrea distonta, the latter being abundant in the Cinder bed of the Middle Purbeck. The fresh-water mollusca include Viviparus (Paludina), Planorbis, Melanopsis, Unio, Cyrena. A large number of insect genera has been found in the Middle and Lower Purbeck Group.

    Dinosaurs (Owenodon, Echinodon [known from “Isolated skull elements of at least [three] individuals.”[6]]), crocodylians (Goniopholis, Petrosuchus), Cimoliosaurus, the plesiosaurs and the chelonians (Chelone, Pleurosternum) are representative reptiles. The mammals, mostly determined from lower jaws, found in the beds mentioned above include Plagiaulax, Amblothenium, Stylodon, Dorsetodon, Triconodon, Spalacothenium and several others. The isopod crustacean Archeoniscus brodei is very common in the Purbeck of the Vale of Wardour.

    The silicified stumps and trunks of cycads and coniferous trees, often surrounded by great masses of calcareous concretions (burrs), are very noticeable in the dirt beds of Portland and near Lulworth. Chara is found in the fresh-water cherts of the Middle Purbeck.” Source:

    • But nothing horsy in that list. Hmmm …. :ponders:

      BTW limestone folding image found during my tour of Southern England:

  13. Thank you, Bruce, for a most entertaining and informative post again! 🙂

    And to you, Renato, for this wonderfull Hekla picture – Icelandic winter light – I just love it!

  14. Some potential bedmates: The gastropod Aptyxiella portlandica and trigoniid bivalves. Laevitrigonia (“Trigonia”), Isognomon, Aptyxiella and Solenopora (a red alga). Sowerbya dukei and rare Buccinum naticoides. Laevitrigonia gibbosa, Lucina portlandica, Camptonectes lamellosus, Ostrea expansa, Natica elegans. Large cockle: Protocardia dissimilis, small euryhaline cockle: Protocardia purbeckensis.
    But horses….. not yet….

  15. Thanks Bruce for another ‘Wow!’ of a post. As everyone has already said: the forces are almost unimaginable. How wonderful it would be to see such an explosion (making sure that everyone, including all pets, livestock and wildlife where possible, was safely evacuated). I look forward to part III. 🙂

    • It would not be possible I think to evacuate people and livestock in time for an eruption of such dimensions (a mountain 2100 m high overrun by pyroclastic flow in a distance of 69 km!!) – better not wish to see anything like that, would be a death trap for too many! Otherwise they would have to evacuate the whole of NZ and in which time span?? 😯

      • And I don’t know how many years of volcanic winter an eruption column of 50 km would mean (GeoLurking?) – in any case too many! I start freezing just by the thought of it.

          • The most likely volcano is Karthala, according to GVP it did a VEI-2 from 2007 Jan 12 through the 15th.

            Also interesting in the video, is that there are two really persistent sulphate plumes in Africa. Doing a screen grab and syncing the image up in Google Earth shows the two clusters of likely volcanoes.

            White particles represent sulphate.

        • Inge B.

          And I don’t know how many years of volcanic winter an eruption column of 50 km would mean (GeoLurking?) – in any case too many! I start freezing just by the thought of it.

          The Hatepe eruption (Taupo) is dated to around the year 180 CE.

          It has been noted that the SO2 signature from it is … missing. That is if it existed at all.

          Note: The Note that says the X-scale is 1000 years per division is wrong, I zoomed in on the period of interest.

          Of course, this is the Northern Hemisphere. It might show up in Antartica, but I haven’t looked the plot yet.

          Possibly tomorrow. (well, my tomorrow, most of you are already there)

  16. Excellent couple of articles Bruce! Well played.

    I’m now living within 300km of the Taupo ‘red zone’; if anything does kick off I’ll be sure to report it. If you ever fancied visiting NZ… wait long enough; one day NZ will visit *you* 🙂

    Right now I’m more interested in Tongariro; after the phreatic blast a few months ago, things seem to have gone into slow motion. It’s had an unusually long repose period, so things might be more interesting than average when it does kick off again. NZ volcanoes in general have been atypically inactive the last few decades; one wonders where all the energy/magma has been going…


  17. Ow!
    I’ve been rumbled!!
    I’m Aptyxiella portlandica, the Portland Screw . Y’ see y’d have a job to turn me into wood!!!
    My bed mates, cos they can be found in the Roach, are ‘osses ‘eds, and Titanites – I’ve seen one 6ft/2m across!! You could have had saurian footprints as well here !
    Ding count
    Sissel 2

    Evil enough? 🙂

    • Unbelieveable evil! All the time I thought of “turn into” as “change into”, so it made no sense to me at all. Great fun when one finds out!

    • Very evil! But the best kind of riddle as it makes perfect sense when you get the answer! I’ve never been to Portland – though I have “done” Charmouth beach and Chessil beach. One day I will get there – and I will remember that it is so devilishly unlucky to mention rabbits that the Wallace and Grommit film “Curse of the Wererabbit” had to have a name change before it was shown there! 😀

    • Just to compare the Titanites. Here is the biggest ammonite found in the Netherlands, between 60 and 70 cm across. The text says that the worlds biggest ammonite is 3x as big – they mean 3x as wide so that would be the one Alan saw.

    • Lots of chocolate; no Nobel Prize in the bag or on the horizon; just a bigger waist line 😀

      What sort of chocolate do the Swedes eat?

    • Also for Sweden, Austria, Denmark, Norway, UK and Germany. the less chocolate you eat the more Nobel prizes.

      Any one want any volunteers for more research 😉

    • I hated some “importers of knowledge” I use that term since I don’t know if he was a teacher/instructor/professor. But even though you don’t like someone, that doesn’t mean that you can’t learn from them. A couple of terms that I picked up from him, was socio-enculturalization. That’s the process where an individual learns the folkway-mores-laws of the society in which they dwell. Each person is unique in how they learn this, but in the long run, they have a common set that they operate off of. As a group, they make up a culture.

      Where the problem arises, is when one culture is at odds or misunderstanding of another culture. In this case, each will tend to favor that which it is most familiar with.

      “Subjectivity refers to individual interpretations of experiences consisting of emotional, intellectual, and spiritual perceptions and misperceptions.” In all cases, the award of a Nobel prize is done by committee… in other words, a group of people. Normal bias dictates that they will award the prize to those with whom they know about, and in all likelihood, most familiar with. Though it was intended to be awarded to those making the greatest strives in whatever field, that measure of worth is still determined by committee.

      Again, a subjective determination.

      After chocolate was “discovered” (by Europe) it mushroomed into a major industry. It became a staple product for some countries, and the general focus was in the same area where the focus of the societal bubble of the Nobel committee resided. It is not to far of a reach to see why there may be a correlation between prizes awarded and chocolate eaten.

      Remember, correlation does not equal causation.

      Note: Chocolate is produced from Cacao tree (Theobroma cacao). Cocaine, another brain affecting substance, comes from the Coca plant (Erythroxylaceae family). Coffee is from plants in the Rubiaceae family… and if you didn’t have any of those around, the caffeine could be obtained from the toasted leaves of the Yaupon Holly (South Eastern US)

      • Nothing wrong with that. Actually.. no excuse is really required. 😀

        (Unless you are working at a medical station in a shipyard and the chocolate doesn’t belong to you…. see my 22:15 below)

        This Chocolate article is a good example of what sort of nefarious things you can do with statistics.

        “Lies, Damn Lies, and Statistics”

    • Of course, the sovereign country with the highest ratio of Nobel prize-winners to population is …. Iceland! (the Faroe Islands would win if they were independent)
      OK, there was only one (the extremely wonderful, supremely readable and massively recommended Halldór Laxness) but he sounds like the kind of guy who would have eaten chocolate.

      • That reminds me of a prank (payback) that a Nurse at a Shipyard once played.

        It seems that someone kept pilfering food and snacks from the medical station’s community refrigerator. Said nurse was also skilled at making candies and chocolates. Taking a mold of a common candy, the nurse then melted down some chocolate and Exlax and poured out the mix into the mold, making a pretty good representation indistinguishable from the original.

        The pilfering stopped.

        So if you worked at Avondale Shipyards in the medical staff during the 1950’s and had an unfortunate experience during your shift… that involved you blowing up a toilet. Now you know what happened.

        • During my studies I lived in a student accomodation where 12 international students lived in single appartments, but shared a large kitchen. One of my neighbours was a Chinese girl, who was an excellent cook. At some point the food from the fridges started disappearing, in particular butter and some other cheese bread spreads and similar and we couldn’t find out who was taking it. So the Chinese girl used your nurse’s method and added some Chinese laxative plants into a tasty herby cheese bread spread. Needless to say that was the last bit of food that disappeared for a long time. True story. 😀

      • @Ukviggen. I am sure, Halldór Laxness liked chocolate – as the good life in general.

        I like his books – and I always liked his car , saw it rather often for some time when driving by his (former) house in Mosfellsbaer which now is a museum and literature center with public readings of well known Icelandic authors on each of the 4 Sundays before Christmas. For free, and mostly very recommendable, heard eg. once Jón Kalman Stefánsson and Vigdís Grímsdóttir (both very good authors, too). 🙂

    • Yes, I agree. Didn’t manage to get to it earlier today, but I really enjoyed your writing style – a treat for Sunday night!

  18. Hi all. The weekend’s sport is out of the way (round ball: Saturday, oval ball: Sunday) and it has been a FANTASTIC weekend all round, for various reasons.
    What could make it better? Having time to finally read Bruce’s second brilliant post – loving this series!

  19. I love this post! Thank you!
    And talking about dinosaurs, one often finds them depicted with active volcanoes in the background (check google image search). In pre-VC times this let me falsely (?) conclude that volcanism was happening at a much larger scale during prehistoric times. As if most volcanoes nowadays were extinct.
    Let´s hope that Taupo et al will give some timely hints before going caldera again.

    • Well – that was a marathon… interesting though, and as usual left me thinking of other ways to address the evidence!

      The bit on Mars losing its magnetic field near the beginning intrigued me, and I wasn’t convinced by the hypothesis of Mars just losing its heat. I also have a hunch that moons play a role in sustaining the dynamic of the core, though that is a bit hazy…

      There was no mention of Mars’s moons in the program, yet our moon controls our tides, and Mars has lost its water. Phobos may be small but it is very close to the planet, and I’m still not convinced it was so long ago as 4,000,000 years ago that Mars lost its magnetic field and its water. I think the 2 things are linked in some way, I also think the gash along the southern half of Mars was an impact of immense proportion.

      The measurement of the 2 impact craters which were without electro-magnetism may have indicated that Mars had lost its field, or I wonder, may suggest that an impact might have neutralised the field in some way.

      • More food for thought…

        Moving electric charges generate a magnetic field. Re-stated… an electric charge that is moving generates a magnetic field.

        When a lightning bold strikes a nearby house/tree/cow/golfer, an intense magnetic field is set up as millions of amps of current go streaming down the ionized channel. This magnetic field can then impart current flow on other conductors, because a changing magnetic field will induce current flow… or a moving electric charge.

        Items that are susceptible to squiring a magnetic field, things that are ferromagnetic, such as iron, can become magnetized by a magnetic field. This comes from the alignment of the magnetic domains in the structure of the material. This also works in reverse, An opposing magnetic field can “un-align” these domains and remove the magnetism that they have. (this one pisses me off to no end because I travel far enough that my screwdriver bit keeps loosing it’s magnetism over time as I cross back and forth over the field lines of the Earth, so I have to re-magnetize it periodically or else spend a half hour chasing a screw around inside the chassis of what ever I’m working on)

        Anyway… back to the moving charges. Being Nickel-Iron, the core of the Earth is conductive, both electrically. As the molten/plastic outer core moves around… eddy currents etc, it drags electric charges with it. These induce magnetic fields, which cna then induce additional current flow… which induces a magnetic field.. which induces current flow… etc. Another interesting thing… the Nickel-Iron core acts to concentrate magnetic fields also.

        Something you may or may not know… transformers typically have a core placed inside of the windings in order to enhance their ability to use the magnetic field of one coil to induce current flow in the other coil. It increased their efficiency by concentrating magnetic lines of force. What are transformer cores made of? Typically a ferrite material… predominantly iron. (“ferrite” as used in electronics industry, dunno if it’s related to the actual chemical structure) So… not only does the Earths moving core drag and conduct electric charges around, it’s ideally suited for passing magnetic lines of flux.

        Mars had a magnetic field at one time. If the core cooled and stopped dragging charges around, then that field would be frozen into what ever orientation it was in as a residual charge. Could a large impactor disrupt the flow and change the field? Yeah. But it would also induce energy into the system and keep the system liquid longer… if the impact was large enough to disrupt the flow and field in the first place.

        About the only way I can logically see an impactor shutting off Mars’ field, is if it excavated a sizable chunk of the core and distributed it up into the upper layers of the crust. But that’s a lot of energy… and most of that material would wind up being molten… which would then settle out in according to density… much like it probably did when Earth got whacked… hard. Most of the Nickel-Iron settled to the deeper depths, and that material that was blasted outside the Roche limit coalesced into what we now call the Moon.

      • Note: GeoLoco later in this thread -> November 19, 2012 at 08:41

        Posted a link to an Impact Effects Program. You can run through different sizes of impactors and have it calculate the effects of that impact and get a reasonable look at what sort of damage it would cause.

        Using this, and then backing out by a factor of about two, you can get into the ballpark for what would have happened to Mars in a similar scenario.

    • The magnetic field reversals seem to be conserved in all the existing lava fields. In Iceland, for example, it is not very recommendable to use magnetic compasses in a lot of regions, because they just get confused – and so you may get confused yourself, better use GPS. I tested this by myself, on some places up on Hellisheidi (Hengill and Brennisteinsfjöll volcanic system regions) the needle is just working itself up in sort of a frenzy. 😉

      • This has nothing to do with the reversal of the magnetic field. But when i was in Tenerife this September i had a bag with me on the beach which has a magnetic clip and this looked like a sea urchin after contact with the black sand. I tried magnets on all black sand of the Canary Islands that i have ( Teneriffe and Lanzarote). Same affect. That no tourist ever noticed this, is beyond me.
        Yeah i know volcanic ash can contain a lot of iron. Obviously the case here.

        And as for the magnetic orientation. Every object which is heated up above 1000 degrees looses it magnetic properties and when it cools down it stores the momentary magnetic field of the earth, not only in orientation but in strength also. They can measure the strength of the magnetic field with glass and ceramics ( measuring the orientation does not make much sense with moveable objects), but measuring the orientation and strength is possible with places where huge fires burnt or lava flows. Orientation as where is north and where is south ( Reversal) and also where the north pole was at that time because it is moving even if it is not reversing.

      • Haraldur Sigurðsson, an Icelandic geologist whose blog (in Icelandic) I mentioned sometimes, also wrote an article about the magnetic field and the probable pole shift found out by other scientists. Acc. to him, in Reykjavík at the moment of the entry (in 2011), the deflection of the magnetic from the geographic north pole was of around 16°. And it seems that the north pole is moving a lot faster than the south pole (north pole: 64 km/year, south pole: just 5 km/year).

        In the film was mentioned how the sea faring navigators had to take these defletions into their account. Today this also plays a role in aviation as Haraldur mentions. So that the numbers on the landing runways – reflecting the degrees – will have to change soon. One commentator (Þorkell) mentions an airfield in Skagafjördur region (Saudárkrókur) which at the time of building was 20° east, would now have another location of 25° so that it would be necessary to change the writing on the runway accordingly.

  20. Re Ruapehu: just got a nice little bit of insider information from my best mate in New Zealand:

    “My mother happened to do a scenic flight over Ruapehu a couple of weeks ago with a scientist on board the plane. He was monitoring discolouration in the lake to try to get an indication of any developments. His comment was that he won’t be doing many more flights if things continue as they are.”

    I should add that his mother is very same woman who was doing the Tongariro crossing in 1975 when Ngauruhoe blew. She has POWERS. 😉

    • Yin and Yang. There are two sides.

      There are two ways to read that statement.

      “He won’t be doing many flights” because there will be nothing to see?


      “He won’t be doing many flights” because it will be too dangerous?

    • I just saw the video by Geoff Mackley how he and a mate were airlifted off Ruapehu by copter when the ’95/96 eruption started. Quite spectacular. Make me wonder if your mom flew the copter back in ’95? 😉
      Once again, what a nice piece you wrote Bruce, danke schön!

      • Great video. Thank you. 🙂
        And I’d say, it is well to be seen that the eruption started with an phreatomagmatic phase, because of the lots of Rooster Tails. This would also get well together with the existence of a lake within the summit crater.

  21. Wow, missed a lot.
    Bruce, all has been said. Great job. Again, what a man.
    Chocolate: my contribution to the average chocolate consumption in my country is undeniable. We’ll talk about the Nobel Prize when I’m much older. I mean, things take time… 😉
    I don’t know how you possibly couln’t like chocolate. It exists in so many variations and covers so many tastes that I’m sure everyone could find one (s)he likes. Dark chocolate with pieces of sea-salt. With all kinds of chunks in it. Flavoured with flowers, chili, fruit. Classic milk, with nuts or caramelized almonds. It’s a tasty madness even sillier than coffee. All this stuff where you start with one “original” component, and can decline it to a rainbow of possibilities… When you say wine some think of deep dark red, others of Passito di Pantelleria… Never forget our basics: shelter and food. Then health and love. Wow, that already makes quite a lot. Just wonder why so many people polute their minds with money, power, fame… Could it be they are having some trouble with priorities? Hmm…
    Have a nice start into the new week.

    • aww Geo, I love it when you go all philosophical on us first thing on Monday morning. Your weekend must have been a real bender!! Here’s one for you:

      • My weekend was great. Fully loaded and time went by incredibly fast. Sunday morning I was back on ice-skates after 17 years… Sonnnnnn of one of the interstellar powers… Gravity and time play a bad game with us humans… 🙂 And what’s more: you have to look solid enough to inspire your kids some confidence and make them honestly believe this is fun… My oh my…

    • It seems to be pretty version of

      I have been referencing this site for years when ever the media starts jumping up and down over a rock. It’s handy for beating on catastrophists.

      But, there is nothing wrong with getting the data out there… and they did cite Robert Marcus, H. Jay Melosh, and Gareth Collins.

      My only issue is when fancy web crap is plastered onto an other wise highly useful if not pretty web interface. Such as the USGS screwing up their website and making it a chore to dig through the pretty shit to get to the data.

    • I’m in the phase where my emotions about his long absence follow a sinus-curve: he’s absent because something good is happening to him – he’s absent because something bad is happening to him – good – bad – good – bad – good…
      That’s where in real life you just walk out the door and physically go check your friend. If he’s well you drink a coffee and go home waiting for him to have time again, and if he’s bad you stretch your hand towards him and look if there’s a way to pull him out of the shit.
      But we’re in virtual mode, and he’s free of obligations concerning us in here. So he’s like an icelandic volcano, and all we can do is wait and see…
      That sucks.

  22. SO2… that has come up a bit.

    Turns out the the tephra from the Hatepe eruptive sequences had a sulphur content below detection thresholds…. less than 200 ppm. And they looked for it along with the other volitiles.

    Additionally, the magma was pretty homogenous in chemical make-up. From start to finish.

    More later… and a paper link. I’m typing from a phone.

    • Cool! I remember that coming up the last time we discussed this but I found it really hard to find (or better, get my head around) the information on it. The homogenous thing is from Colin Wilson. In fact, I don’t think I did this enough justice in part 3. Maybe I did, let’s see when Spica publishes it. I might surprise myself yet.

      • Yes, but I’d say the “blanket of ash” is the trace of a lahar from the summit crater lake. As far as I remember, Ruapehu is also known for producing lahars.

        • Ha Inge, that reminds me of this (page 202 of Lockwood and Hazlett – a must-have for anyone volcanophile) .. I’ll type it in here and hope the authors forgive any copyright infringement but it’s an absolute classic:
          “Renewed eruptive activity beneath these crater lakes can violently eject their waters in a Surtseyan maner, as New Zealand geologist Peter Otway and a colleague discovered on snow-covered Ruapehu volcano in 1971. Ruapehu is a dangerous volcano, with a summit crater lake known for a history of hydrovolcanic explosions accompanied by destructive lahars. Their team had been dropped off by helicopter near the summit to monitor activity, and were routinely surveying when part way throught their work they noticed puffs of steam rising from the middle of the grayish-green, sulfurous lake. The steaming patch suddenly exploded, and jets of black ash steam and large angular blocks shot upwards. Peter, who was on the snow-covered rim of the crater, pulled out his camera to take a snapshot, when suddenly the explosions increased in violence; Ruapehu’s crater lake had begun a serious of violent hydrovolcanic explosions, and the New Zealanders were directly in the path of the ejecta. Each had only a few seconds to grab ice axes and dig in, lying flat to the ground and holding on for dear life. A torrent of muddy water cascaded down, mixed with angular blocks that made sharp thuds as they impacted nearby. The water was unfortunately not scalding and neither man was swept away during their three minutes of terror…”
          Buy the book for the pictures 🙂

      • “Mount Ruapehu, which also erupted in June 1996, sent plumes of steam, ash and debris into the sky which towered an estimated eight miles above its crater”

        That’s about 2268 m³/s of DRE according to the Mastin et al formula.

        • Oooh….

          That could be fun to play with! It should be possible to calculate a range of resonant cavities that fit those frequencies. But I have to work.

          Any idea what the depth of the 7hz source is?

          • Ha, I see another email to GNS in the making.. they are going to hate me soon, but they’re the only ones who could answer that question.

          • Possibly it’s 130 m (depending on the depth of the lake when this graphic was made, which I don’t even know) If that 1000m scale is accurate, it looks to be in the 150 to 200m range. I’m intrigued as to what kind of resonant cavity that could be when it is directly under the lake!

          • @Hae Bruce! Just as you have email to GNS in the making, could you ask them if that is a lava dome or a spatter cone in the making at Tongariro (acc. webcam)? 🙂

          • Inge, I saw you mention that before. Do you have a screen shot or something? I would be highly surprised to see a cone forming at Tongariro as that eruption was merely a steam driven eruption without any juvenile material in it. I just checked the webcams and all I can see is steady steaming from the new Te Mari craters and the usual steam from the Ketetahi hot springs.

  23. Okay, so I’m just mooning around today…

    First of all – the moon’s orbit has a wobble, like the earth ‘Longitudinal libration, due to elliptical orbit of the moon about the Earth, is 7.7 deg. From the point of view of an observer on the moon, that makes Earth rock back and forth in the sky, east to west.
    Latitudinal libration, due to the tilt of the moon’s axis with respect to the ecliptic, will cause the Earth to oscillate north and south by 6.7 deg each way.’

    Then – wondering about the apogee and the perigee – it seems the moon was at its furthest away this weekend.

    Thirdly – for all kinds of orbital calculations: or in my case lots of pretty pictures….

    And then Mars: ‘Mars’ moons are probably not native to Mars. Most likely, they are asteroids that were captured by Mars’ gravity, and could not escape. The largest reason behind this hypothesis is their small sizes.’ I really am a picture thinker, and this is a pretty clear explanation here:

    If I had a brain the size of a planet I might be able to put together a hypothesis out of this lot…..

    • Sorry – I should have put this under the documentary linked by Ursh – thanks Ursh – as it got me ruminating about Mars and moons, so should be up there with my first post today….

    • So – the next stage of my monologue – water: ‘Water is miscible with many liquids, such as ethanol, in all proportions, forming a single homogeneous liquid. On the other hand, water and most oils are immiscible, usually forming layers according to increasing density from the top.
      As a gas, water vapor is completely miscible with air.
      Water forms an azeotrope with many other solvents.
      Water can be split by electrolysis into hydrogen and oxygen.
      As an oxide of hydrogen, water is formed when hydrogen or hydrogen-containing compounds burn or react with oxygen or oxygen-containing compounds. Water is not a fuel, it is an end-product of the combustion of hydrogen. The energy required to split water into hydrogen and oxygen by electrolysis or any other means is greater than the energy that can be collected when the hydrogen and oxygen recombine.’
      Thank you wiki:

      There is a theory in this somewhere, I think. Does water need to have an electro-magnetic field? Raindrops are after all round. Its fluidity I once read is due to the 2 hydrogen atoms being able to move between the oxygen atoms, swapping places, and not being fixed. (New Scientist a few years ago)

      • @ alyson
        I Think the theory you are looking for is polarity. The watermolcule is slightly angular. This means that it has a slight positive charge at the hydrogen “end” and a similar negative charge at the oxygen end. This is the reason why water dissolves for instance alcohol, which is also a polar substance, and not oils who are apolar in Nature.
        Magnetism does not influence drop formation. The most important factor here is surface tension, which is an effect of the polarity of watermolecules.
        Just a short amateur explanation. Hope It’s adequate

    • 0.3% odds of total devastation (M 9 quake) in the Pacific NW per year? Last one was 1700…That gives me the creeps in retrospective. I lived in Seattle for two years right after the Nisqually quake (“only” M 6.8). At that time I thought I was rather safe because tension had just been relieved. There were cracks in the walls of the building I was working in. Now I would be more than uneasy to move there again, with kids probably I wouldn´t. It´s so sad, it´s such a beautiful place.

      • I know most volcanologists and scientists hate the term “overdue”, mostly due to how often it’s misused by the media. That being said, there is *some* truth to something being overdue (generally speaking) at least.

        If we were to take a balloon, and slowly fill it with air at a constant rate, eventually that balloon is going to pop. While you can look at the statistics of 300 balloons and suggest that in “any given time period there is a .3 percent change of it popping” that doesn’t really tell the story very accurately. The odds of said balloon popping increases at a rate proportional with the amount of pressure built up within the balloon.

        This can be roughly translated to earthquakes and volcanoes as well (with a big emphasis on the “roughly part). The odds of seeing a “big one” increases significantly if said fault hasn’t done a thing for over 300 years, or if volcano “x” hasn’t done anything for a while.

        This can be used as a very very rough guestimation of how things work, but the problem when applying said reasoning to an actual prediction or model, is we’re assuming the energy input into said system has remained constant. In our balloon model, it’s easy to assume all energy (air) is being placed directly into said balloon at a constant rate.

        If we were applying this to volcanology per say, there are a lot of other factors that account for the cumulative pressure inside a volcano as well.

        -Has the magmatic input into the chamber remained constant? (this is a factor which has shown capability of changing wildly as seen in the Puyehue eruption of 2011, or being incredibly predictable like etna)

        -Has the chemistry of the lava changed or evolved (thus changing the gas composition, and pressure inside the chamber)?

        -Has the volcano had any minor eruptions in recent time (thus relieving pressure)

        While I’m not quite as familiar with earthquakes, it would be pretty safe to assume a similar case scenario, where you can’t predict a rupture, but you can at least gauge that there is a higher chance of “x” event happening each year as more and more pressure builds. The good thing for us, is that the Cascades megathrust earthquake typically appears with a repose time averaging around 450 years, with the lowest repose time between major quakes in the last 2500 years being 390 years apart. We’re currently only 312 years out from the last megathrust in the cascades, so the odds are still pretty low that it will happen soon.

        • Given the uncertainty of the estimated dates of the last 7 megathrust quakes the intervals are less well defined. The average of the average date intervals yield 491 ± 242 (sd) years, but calculating the maximal and minimal intervals based on the uncertainty range one can get from 130 to 930 years.
          I fear we don´t know enough yet to say the odds are low.

        • …but you can at least gauge that there is a higher chance of “x” event happening each year as more and more pressure builds.

          The only problem is that probability is not cumulative… at least not with a volcano.

          You can judge the cumulative probability as the likelihood of having had an eruption occur over some interval, but you can’t sum the probability and state that any specific day is more likely of having a greater chance of an eruption than any other day. You’ve touched on the reasons for that already.

          Here is an example. This is the normal distribution for Katla over about a 8000 year history.

          If you will note, there are a few instances where the repose interval is outside of would ordinarily be indicated. Intervals greater than 209.3 years should be quite rare with something on the order of 0.1% chance of occurring. Yet that one instance out of 130 is 0.77 %. Events longer than 2 sigma (161 years) should be 2.2%, yet those seven events outside of 2 sigma tally up to 5.4%.

          I’ve done this with other volcanoes, and even tried a Poisson distribution.

          In a nutshell, volcanoes don’t follow a schedule… but they are quite fond of blowing statistical theories out of the water.

          • Which is why I stated specifically that there are way too many other variables that account for the slew of variations in volcanoes, not limited to magmatic input from depth, water input, changes in magma composition, interactions of different types of magma in the conduits and chambers, whether small eruptions have occurred, and even something such as the external strength of the rock surrounding the magma chamber (ability to withstand high pressure from below essentially).

            Volcanoes definitely don’t follow a schedule, but if (emphasize on the if) we were to assume all other things being constant in a volcanic system, we could generally assume that eruption probability increases the longer the repose time.

            The problem with that is that there are too many variables that do not follow constant rates.

            One interesting facet however I do feel is worth noting, is that volcanic arcs that are subducting at a much higher rate, have traditionally been much more active than volcanic systems that are subducting at a slow rate.

            Long story short, there IS a relationship between magmatic input and eruptions (as one would expect), but it’s only one of many factors that can be used to determine a potential probability scale for an eruption.

          • I agree.

            Where the problem lies is with the Media and Reporters. They will jump all over the “overdue” stats but will turn a blind eye towards glaring statistical anomalies… ones that go against common sense. They are all about the Red Herrings.

          • The other variable with volcanoes is that the longer the repose time, the cooler the chamber becomes, unless constantly replenished from below. Yet this feeder mechanism seems to be highly variable itself in most cases.
            I guess with earthquakes aseismic creep would be the corrollary to cooling off of a magma chamber.

          • And, from that paper that I have linked in about two or three places here…

            The incarnation of the “chamber” that spawned the Hatepe eruption was believed to have a high state of mixing. Though the feed is the subducting plate, the eruption was almost completely rhyolitic. The paper mentions that the heat was likely from andesitic underplating off of the melt zone, which then heated the greywacke to a high melt percentage…. maintaining enough heat to keep the material well mixed.

            According to the paper, they could not come up with anything to dictate the changes in eruptive style from when it went off until it finished… other than modification of the size of the vent. Towards the later stage, lithic emplacements were found in the ignimbrite, which to me could indicate that the vent eroded the sides and chunks came out… decreasing the velocity of the column and then moving into the collapse state with the ensuing monster pyroclastic flow.

            The one real oddity that perks my ears up… is that the trace elements matched that of the ryholite part of the Novarupta eruption (1912), and that of Mt Mazama (5,677 BC). Though they are separated by thousands of miles and hundreds of years… that might indicate some common feature of the nasty eruptions… or it could just be a coincidence.

            The water percentage didn’t seem to be a major player in the overall intensity of the eruption… at least according to the paper… and sulfur was below detection thresholds. (200 ppm)

            So… what give? What made it as nasty as it was?

      • I’ve commented here and on Erik Klemmenti’s Blog that I moved from Coos Bay, and the Coast in general because of my ongoing unease with living with the Juan De Fuca and its
        potential especially living in a very vulnerable area. I have a little block of Basalt (a little column) in our garden I live in the Grande Ronde Valley of NE Oregon while there can be quakes here, there are no Tsunamis and no potential for a 8-9 mag quake…

      • Interesting concept may have some bearing on theory…
        Not fond of Jello however,Wife has a old ad for Jello framed in our
        kitchen-vintage 1920’s shows Mama bear serving Jello to Papa and
        Baby. Papa has a look of “Where IS my honeycake?” Baby is howling
        and-not- happy… I am much the same….

  24. Hi

    Here is the update for Earthquake animation for Iceland TF zone from 12 to 19 November 2012.

    In the first part of the video, colorbar is according to elevation (0-top). Moho is shown.”Active earthquake is in red and its size is not related to magnitude.

    Dot size for the older EQs is proportional to Earthquake magnitude.

    In the second part of the video, Dot color is according to date (see colorbar, axis for it is the days’ number)

    What I find interesting in the second part is that you can very well see that the earthquakes are moving about and do not stay in the same zone but appear to happen in a zone in a short time sequence. I wonder what could be an explanation for this phenomenon ?

    • Take two irregular surfaces… say, a broken brick, and try to jockey it back and forth until the two sides fit again. You will notice that if you are close… but not quite, different parts of the brick will grind against the other side at somewhat random points where the high spots on each side happen to touch…

      That’s pretty much what you have going on here.

  25. Bruce Stout… a seriously evil critter on a par with Allen.

    One word… “Whakamaru

    I don’t know what the actual translation is, but piecing together a couple of bits

    1. (particle) to cause something to happen

    2. (noun) shadow, shelter, shade, power, authority.

    I think that is an appropriate fit…

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