Eruptions

Quick update for 2/23/2010

Posts might be a little sparse for the next few days – I’m recovering from a rather nasty bout with a flu-type thing, so I’m fallen behind in pretty much everything. I’ll try to get back up to speed here in a few days, but if you run across any fascinating volcano news, feel free to post it here.

Comments

  1. #1 Kver
    February 23, 2010

    Get well soon!

  2. #2 Randall Nix
    February 23, 2010

    Hope you feel better. Here is something:
    Can volcanoes trigger ice ages?
    http://environmentalresearchweb.org/blog/2010/02/can-volcanoes-trigger-ice-ages.html

  3. #4 mots
    February 23, 2010

    Up Your vit D.
    what did You expect from a grandma?
    Take care on the rebound.
    Best!motsfo

  4. #5 EKoh
    February 23, 2010

    Gee Erik, flu is 2009 ;)

    Things are relatively quiet or unchanged volcanowise. There is an interesting little blurb on Ritter Island on GVP.

  5. #6 Henrik
    February 23, 2010

    Hope you recover quickly Dr Klemetti! Isn’t it funny (funny-peculiar) how an infection such as the flu mimics plate-tectonic driven volcanism?

  6. #7 doug mcl
    February 23, 2010

    when the body gets infected with flu virus, part of the host response function is to heat up (fever) which weakens the virus so that it can be destroyed by other processes.

    Does this sound a bit like global warming?

  7. #8 Diane
    February 23, 2010

    I hope it isn’t the “green around the edges turkey trot, Erik. That one isn’t any more fun than the chills, achy, fever kind.

    Hope you feel better soon!

    On the volcano front, there still is some activity, slow activity, at Mammoth. Seems like they get a quake there every day or so. All small so nothing much is really happening as yet. And, of course, probably nothing will.

    Hey, Boris, what is Etna doing right now? Just curious.

    Popo is covered in snow and steaming as usual. The Halema’uma’u crater was showing a nice red glow this morning and the deep part of the crater was looking rather interesting. They might be coming out with some more pics or even a video as a day or so ago it looked like it could have been splattering in one area. We will see what happens there. One morning, I actually saw someone at the center at about 6:30am THEIR time! That was surprising.

    Iceland seems to be calming down for the moment, too. Still shaking, but not as much. We will see what that does, too.

    Take care y’all. ^_^

  8. #9 Diane
    February 23, 2010

    Well, I just checked Iceland and they are having another swarm SW of Bassar (SP?) with 92 quakes right now. So they seem to be having swarms from one place to another. May mean something and may not. We will see.

  9. #10 Stefan Kuettel
    February 24, 2010

    In Iceland, I already saw a lot of swarm (e.g. Askja region) but most of them stopped without a visible eruption. However, as Boris already said earlier, I also wouldn’t be surprised to see an eruption this year. If I remember right, they have statistically seen an eruption every five years or so and there wasn’t one for a while…
    At the same time, there are no news yet in the Icelandic press like http://www.mbl.is. So it’s probably still one of those normal swarms and nothing to worry about. We will see if Katla is going to change that or not.

  10. #11 aldo piombino
    February 24, 2010

    hi erik
    get well and return quikly…
    volcanos are sill erupting without your comments….

  11. #12 mjkbk
    February 24, 2010

    Erik came down with a mysterious flu-type thing. The brand-spanking-new camera on the caldera rim of Chaiten quit working.

    Coincidence? I think not. :-D

  12. #13 Diane
    February 24, 2010

    I guess we will have to do our own commenting for a while. I haven’t seen any new pics of the lava flows or the Halema’uma’u crater activity yet. I suppose they will post something soon if it gets intereting. The last people to be living just on top of the pali will probably be moving soon if the flows come much closer to them. I have no idea how they get in and out of there except by helicopter, if they have one. It sure doesn’t look like they have a way out of there any other way.

    I hope we can get back to pics of different volcanoes to guess where or what they are. That was fun, but some people here are sooooo good at knowing what they are looking at. This summer I will have to get a better picture of what I sent Erik, but I think he thought it wasn’t either a good enough resolution, or it was too remote. Maybe one day he will post it just for interest sake. I can tell you it is a weird crater. And that is all I’m gonna tell ya. ;-D

  13. #14 Passerby
    February 24, 2010

    Our virtual host didn’t come with any old ‘flu-thing’. He came down with THE flu, 2009 H1N1 (SOIV).

    Colleges See Rise in H1N1 Swine Flu. WebMED Feb 24 2010.
    http://www.webmd.com/cold-and-flu/news/20100224/colleges_see_rise-in_h1n1-swine-flu

    US DOD also reported an modest uptick in H1N1 among military personnel last week.

    I had this virus in May, while recovering from chemical-induced asthma. Not fun. First and only flu attack in almost 20 yrs.

    Get some rest if you can, Erik.

  14. #15 Randall Nix
    February 24, 2010

    It’s kind of a slow volcano day so I am posting this:
    Study reveals ancient rocks linked to old Earth’s crust
    http://www.physorg.com/news186221373.html
    It is geology related;)

  15. #16 Randall Nix
    February 24, 2010

    This one is volcano related:
    ‘Pompeii-like’ excavations tell us more about Toba super-eruption
    http://www.physorg.com/news186223140.html

    Hope you get to feeling better Erik.

  16. #17 Randall Nix
    February 24, 2010

    Anyone have a guess as to which megavolcano could have gone off about 1.2 million years ago?

    Humans were once an endangered species
    http://www.physorg.com/news183278038.html

    If not a megavolcano then maybe an impact event?

  17. #18 Fitz
    February 24, 2010

    Doctor – heal thyself …. except I dont suppose you have a Volcano-related illness. Everyones a Specialist these days.
    Get well soon.

  18. #19 doug mcl
    February 25, 2010

    This New York Times article on the risk posed to mega-cities in earthquake zones is very interesting, and also has a very effective graphic for illustrating how earthquake likelihood, citie size and construction standards stack up (or fall down).

    http://www.nytimes.com/2010/02/25/science/earth/25quake.html?em
    Note that Port au Prince wasn’t the highest risk point on their scale.

    Has anyone seen an analogous “global view” illustration for volcano hazards? There might be some useful “how big is the dot and what color is it” comparisons between Campi Flegrei, Mexico City, and various other places where large populations reside within the prospective red zone of nearby volcanoes. This gets to Dr. Benke’s point about being able to concentrate science and policy efforts on the places where we can accomplish things that help people.

  19. #20 Henrik
    February 25, 2010

    “Has anyone seen an analogous “global view” illustration for volcano hazards?”

    Shall we start our own? 1) Laacher See, 2) Campi Flegrei, 3) Aira/Sakurajima.

  20. #21 Passerby
    February 25, 2010
  21. #22 Gijs de Reijke
    February 25, 2010

    @ Henrik: seen the current activity in the Eifel region, I would definately not give the area around Laacher See a high ‘at risk’ rating. Seen from the point of statistics it’s far more likely for the Eifel to see the formation of a new scoria cone or a maar. And if a big eruption (VEI-5 for example) would happen there, there’s no way to tell right now if it’s going to happen at the Laacher See caldera. The East Eifel Volcanic Field has around 100 volcanoes, the West Eifel Volcanic Field around 240. Almost all of them are monogenetic (the type of volcano that has only one period of activity), and only three of those have been identifeid as calderas. So maybe we’re going to see the formation of a new caldera. Maybe in the ‘Pellenz Verbandsgemeinde’? That is IF something like that is going to happen again, although I think there’s a pretty high probability of that. Since volcanic acivity started in the EEVF around 650.000 years ago, several calderas have formed. The Rieden volcano, the ‘Wehrer Kessel’ and after that the Laacher See caldera. Other pumice layers have been identified, but no craters have been found so far (although I’m not really sure about the Kempenicher tuffring), like at the presumed ‘Frauenkirch Bimsvulkan’. Both the Rieden volcano and the Wehrer Kessel erupted more than once, so maybe something is going to happen at Laacher See… or maybe at Wehrer Kessel again? Hard to say, which is exactly my point: compared to other volcanic areas around the world, the EEVF is not an immediate threat because of it’s current activity. Campi Flegrei? I wouldn’t want to live anywhere near that place (and that doesn’t have to do completely with volcanism and earthquakes :P )

  22. #23 doug mcl
    February 25, 2010

    @passerby, thank you for the link. Very interesting

  23. #24 Henrik
    February 26, 2010

    Gijs!

    A region where in excess of 50 million people live within 100 miles/160 km of a hotspot that has, in geological terms, recently produced a VEI 6 eruption and where an eruption of similar magnitude would incidentally have extremely severe consequences for the world’s second largest economy as well as Belgium, the Netherlands, Luxembourg and Eastern France has to be rated a high RISK even if, in human terms, another VEI 6 may be highly unlikely within our “lifetime”, ie the next 25-50 years.

  24. #25 Gijs de Reijke
    February 26, 2010

    There’s not enough data available to be able to tell if there’s something like a Laacher See like event going to happen again at all. You mentioned Campi Flegrei, where activity appears to be much higher, where a lot more (unprepared!) people live in the immediate vicinity (in the caldera itself that is) and where even a VEI-7 is one of the probabilities. Even if we don’t look at the very remote probability of something like a big caldera forming eruption happening at one of those places in our lifetime, I still wouldn’t worry too much about the EEVF. The amount of volcanism related activity is just not worth preparing a lot of Germans (and people from France, Belgium and the Netherlands) for something that’s very likely not going to happen during their lifetimes, maybe not at all. The economic damage would not justify ‘better safe than sorry’ when there are no signs of impending volcanic danger. Especially in an area where people haven’t seen eruptions in their lifetimes, and where hundreds of generations haven’t seen any volcanic activity.

    But I definately think that more attention should be paid to what’s going on around Laacher See, mainly from a scientific point of view, but also to let (local, regional, national and international) authorities get a picture of what can happen and what they should do when something might happen. Anything else would only cause more harm than good.

    Unless people would focus on what is, from a statistic point of view, more likely to happen: the formation of a new scoria cone. Let’s take the West Eifel for example. A small eruption there would be harmful on a local scale, but for the relatively poor economy of the Eifel it would be good because of an increase in tourism. It would definately outweigh the damage done from an economic point of view.

    Apart from that: the Eifel is not really part of a hot spot system, because the plume shaped anomaly below the area isn’t a ‘classic hot spot’, but probably an accumulation of more fluid material caused by pressure relief in the Earth’s mantle. But the effects at the surface are the same I guess.

  25. #26 bruce stout
    February 26, 2010

    I’m in full agreement with Gijs. I just don’t see the necessary combination of frequency, severity and population exposure to classify the Eifel so high on the list. There are many more cities around the world (the decade volcanos are a good place to start) where the population stands at a much higher risk from volcanic activity than the Eifel. Italy has both Campi Flegri AND Colli Albani, not to mention Etna.. then there are places like Taal on the doorstep of Manila and any number of volcanoes in Indonesia and elsewhere on the Pacific rim. I am not saying the Eifel is negligible, it’s not, and it certainly warrants adequate funding to keep it closely monitored, and then again, as Boris has often pointed out the next big eruption could easily be from some place nobody has ever thought of.

    @Gijs, do you know anything about the Auckland volcanic field? The only information I have found also states that there is a plume under the city causing the volcanism but I have my doubts that it is a classic hot-spot. There doesn’t seem to be any ponding of magma at depth, just rapid ascent of mafic magmas causing very similar maars and monogenetic cones to those in the Eifel. (this would be another interesting feature for Erik hint, hint). In the Eifel there is a bit of extension going on isn’t there? This would facilitate the rise of magma but I don’t know of any similar structural weakness at Auckland. All quite puzzling.

  26. #27 Gijs de Reijke
    February 26, 2010

    @ Bruce: I don’t really know a lot about the Auckland volcanic field, but I can guess. It’s close to the subduction zone that has caused the much larger volcanoes of New Zealand to form, but the materials (alkali basalt to basanite) are pretty typical for intraplate volcanism. My guess is that the Auckland field, as well as the Whangarei field and the Kaikohe-Bay of Islands field have formed due to pressure relief caused by nearby subduction zone.

    It might by the same thing for the Eifel, although research has shown that there’s definately a plume-like structure under the Rhenish Massif, on which the Eifel is located. What’s interesting is that the Eifel plume probably doesn’t go deeper than the low velocity zone at 660 km depth, which makes it only a shallow plume. Such an anomaly could be caused by extension around an area where orogeny takes place. And ofcourse the Eifel is not the only place in Central Europe where volcanism has occurred since the Alps started to form. Stuttgart is on the northwestern edge of the so called ‘Swäbische Vulkan’, a Tertiary volcanic field. Relatively close to that area are the Hegau and Kaiserstuhl. And east of the Eifel there are the Siebengebirge, Westerwald, Vogelsberg, Hessischen Senke, Rhön and Heldburger Gangschar. In France lies the enormous Massif Central. All of these areas are in places that have seen extension because of upheaval, but for some of them I don’t really know how much they’re directly related to the Alpine orogeny (are they enormous anticlines, or maybe partially, or not at all?), the Eifel being one of them.

  27. #28 bruce stout
    February 26, 2010

    damn inability to delete or edit posts.. ;-) .. sorry Henrik if that sounded too harsh.. given that no one knows where the next eruptions will be, yeah, why not add Eifel to the list. I still think it is unlikely to produce another Laacher See type eruption so soon but what would I know? Maybe the Laacher See eruption is a sign of a fundamental change in nature of volcanism in the Eifel which would be a bit of a worry.

  28. #29 bruce stout
    February 26, 2010

    @Gijs. Thanks for that.. It still is quite puzzling for me.. I mean these are mafic magmas so we are not talking about continential lithosphere. That means that the mantle must rise up high enough for the drop in pressure to lead to magma genesis. Supposedly there is a nascent rift valley forming from Norway down through the Rhine Valley to the Massif Central but I suspect this is probably unrelated to crustal tension caused by the Alpine orogeny. Case in point: the Himalayas haven’t produced any volcanism (yet) or at least none that I know of.

    The Auckland field is a bit more bizarre as it is quite far removed from the extension and crustal tension going on the TVZ and Havre Trough. There is an ancient volcanic massif to the west of the city and Coromandel to the East is covered with ignimbrite. Maybe it is just a pocket of mantle left over from earlier tectonic movements that is high enough to lead to pockets of melt suddenly rising.

    What puzzles me about this though is that there are no major fault systems to fascilitate the rise of the magma so why doesn’t it just pond under the continental lithosphere and spend the rest of its days there?

  29. #30 Henrik
    February 26, 2010

    Bruce! Since my field is history, not vulcanology, I’m grateful for your answers! To paraphraze – if you do not heed history, you are doomed to repeat it. What I see from the information available is, relatively speaking, “minor” volcanism over 650,000 years followed by a large VEI 6 as recently as some 13,000 years ago. Something has changed, no? The last eruption dammed the Rhine and when the colossal dam was breached, everything below was inundated. With signs of magma degassing, not only under Laacher See, but also the Rhine itself, what consequences would a “modest” VEI 5, perhaps under the Rhine itself, have in an area where more than 50 million would be affected some way or the other? Even if there is a risk that a geologically speaking imminent eruption of Campi Flegrei potentially could kill many more outright, I see the impact on human affairs of an Eiffel event as far greater. If I am wrong, please tell me so and don’t worry about sounding too harsh! I’m grateful for the knowledge and insights!

  30. #31 bruce stout
    February 26, 2010

    Hi Henrik, thanks for your openness. If you are interested in the Eifel take a look at this feature Erik did on it:

    http://scienceblogs.com/eruptions/2010/02/laacher_see_the_caldera_in_the.php

    You’ll see there are a lot of far more expert people here to tell you if you are wrong or not than me!! (hint: Gijs is one of them)

  31. #32 Henrik
    February 26, 2010

    Thank you Bruce! That is indeed where my read-up on Laacher See in earnest started. Pity there is no reliable guide to the thickness of the pumice layers as they give the impression of being close to 30 meters (100ft) thick, very local I presume.

  32. #33 Henrik
    February 26, 2010

    Gijs! Thank you for your informative replies which will take me some time to digest. Also, I found this paper: “Structure and Dynamics of the Laacher See Magma Chamber (Eifel, Germany) from Major and Trace Element Zoning in Sanidine: a Cathodoluminescence and Electron Microprobe Study” by CATHERINE GINIBRE*, GERHARD WÖRNER and ANDREAS KRONZ.

    [url]http://petrology.oxfordjournals.org/cgi/content/full/45/11/2197[/url]

  33. #34 Gijs de Reijke
    February 26, 2010

    Thanks Bruce and Henrik ^_^ !

    The Laacher See eruption (with around 6.3 km3 of ejecta (dense-rock equivalent) a VEI-5) wasn’t the only VEI-5 eruption that happened in the Eifel.

    * There were three VEI-5 eruptions between 440.000 and 390.000 years ago, each about 1 km3 in size, at the Rieden volcano (also a caldera, even larger in size than the Laacher caldera), which lies about 3 kilometers west-southwest of the Laacher See caldera.

    * Around 215.000 years ago the Wehrer Kessel caldera formed immediately north-northwest of Laacher See. That eruption produced the 2 km3 ‘Hüttenberg Tephra’. The Wehrer Kessel had at least one other large eruption, which was the ‘Glees Tephra’ producing eruption, 150.000 years BP. That was a VEI-4, with an estimated 0.4 km3 of ejecta.

    * 115.000 years BP the Dümpelmaar formed around 5 kilometers north of where Laacher See is today, with an eruption that produced around 0.5 km3.

    * Around 12.900 years BP Laacher See had it’s big eruption.

    During the history of the EEVF several other vents that produced pumice eruptions formed, but most of them have disappeared due to erosion or to covering by other volcanic deposits. These (small?) vents are presumed to have erupted a lot less ejecta than the other volcanoes I just mentioned. All of the major eruptions were phonolitic in nature, the Rieden volcano produced leucitic phonolite and the Wehrer Kessel, Dümpelmaar and Laacher See produced plagioclase-phonolite.

    It shows that the EEVF has a violent history. Still, at this moment there’s no way of telling what kind of eruption is going to happen in the future (if any more eruptions are going to happen at all, but I’m betting on it). There are a lot of scoria cones in the area, so we might see something like a very small mafic eruption. Maybe the EEVF is not the first of the Eifel volcanic fields to produce a new eruption, but is the West Eifel Volcanic Field going to do it.

    The activity in the WEVF is almost nil right now: every once in a while a small earthquake (usually no more than 2.0 MMS) and steady degassing of cooling magma chambers (a whole bunch of ‘mofetten’ can be found there, of which the one in Wallenborn is the most impressive).

    The EEVF has some more activity. Also some mofetten (like at the eastern shore of Laacher See and in the Rhine near Andernach), but so far the gas mixtures show nothing that’s reason for a lot of concern (unlike the Vogtland area near the German-Czech border, where the some of the highest amounts of helium in Europe come out of the ground, only second to Etna). The earthquake activity in the EEVF is a lot higher than in the WEVF though, expecially between Mendig, Plaidt and Ochtendung. Earthquakes there sometimes get over 4.0 MMS, and apart from the intensity of the quakes the frequency is also a lot higher than in the West Eifel. The quakes are shallow though and tectonic in nature and/or caused by hydrothermal activity.

    However, for as far as I know there’s not a good view on what exactly is causing those quakes, mainly because there aren’t a lot (i.e. ‘enough’?) of seismometers around. It’s also difficult to keep a good track of the changes in gas emissions, because there are no permanently installed installations in the area to do that. My point is that first things should come first. I don’t know if the Eifel is being monitored enough as it is, but my bet is that it isn’t. There’s no use in speculating purely based on what has happened in the past, although I agree on that’s it’s a good point to start with when we talk about extra monitoring of the area.

    An extra thing that I want to add is that the amount of people living in the direct vicinity of the area that has the highest potential for new eruptions (big and small) is high, but not enormous. Not when we compare it to the situations, for example, at some of the decade volcanoes. We’re talking about a few hundred-thousand (Koblenz and surrounding towns and villages) that live close enough to get hit by pyroclastic flows and extremely heavy tephra fallout. Settlements down the Rhine river (Bonn, Köln, Düsseldorf etc.) might get hit by lahars, but probably only partially.

    The economies of Germany and the surrounding countries will have to deal with a considerable blow by a big eruption anyway, whether we start taking precautionary measures prematurely or we let the infrastructure and industries in this part of Europe get hit hard by the eruption itself.

    In my opinion: authorities on all levels should gain more knowledge to prepare for a possible volcanic event (through funding of more research), but shouldn’t look at such a scenario (yet) as if the public should be on a high alert.

    ==========================

    @ Bruce: magma chambers tend to solidify within tens of thousands of years, depending on their size. Volcanic fields usually have a lot of small chambers, so I don’t think there was any magma left that could have become unstable and made it’s way to the surface under what became the Auckland field. But like I said, I don’t really know anything more about that area than what I’ve seen from the Global Volcanism Program.

  34. #35 Henrik
    February 27, 2010

    This is exactly what’s been missing, putting things into a proper perspective, thank you! It is the same phenomenon at work as when “The Truth” became “Yellowstone is long overdue a VEI 8!!!!!!!!!!!!!!!!!” – not painting a comprehesive picture/history that focuses only on big eruptions in order to generate public interest. Unfortunately, vulcanologists seem to have to perform the same trick themselves in order to get funding for research. “We would like €1,000,000 in order to investigate the EEVF because we know little about it” is far less likely to get the grant than “Sir, based on our current understanding, the EEVF could produce a VEI 6, possible even a VEI 7, that would kill upwards of 10 million Germans, Belgians, Frenchmen and Dutch and we need to monitor it closely”. I know it’s an exaggeration, but I’m out to illustrate the principle. Likewise, I would not have been told as much had I not “Painted Satan on the wall” (Swedish expression)

    The article I referred to has several interesting pieces of information, the most to my mind is the one where the authors point out that the Basanite intrusion was so rapid that it may not have occurred until after the eruption had started, ie was not the cause but an effect of the eruption. The reverse of that coin is that when the intrusion occurred, eruption rapidly followed. Would a correct deduction be that if similar conditions exist today, there is a possibility that there might be very little warning before an eruption?

    I agree completely, we need to know more and here, sites such as Dr Klemetti’s and the scientists that willingly contribute is extremely important! Unfortunately, it seems that the only way to generate enough public interest for funds to be allocated is sensationalism.

  35. #36 bruce stout
    February 27, 2010

    @Henrik,

    the whole issue of magma ascent really fascinates me as this will also govern the amount of warning we get before an eruption. The geonet site for NZ volcanoes has this to say on the Auckland field (which bears some similarities to the Eifel):

    The Auckland volcanic field owes its origin to the presence of a region of hot rock known as a hot spot or plume located about 100km beneath the city. …The melt.. has a low viscosity (flows easily) so that it can force its way through the overlying crust quite quickly (speeds of 5 kilometres per hour have been estimated). Each volcano in the Auckland volcanic field has been fed from a deep source and each time there has been an eruption it has been of a new batch of basalt magma.

    /end quote

    If you want some more information on the Eifel I heartily recommend Schmicke “Volcanism”. Chapter 7 is about intraplate volcanism and has a lot of detail on the Eifel… (in fact I’m off to reread it right now!).

  36. #37 bruce stout
    February 27, 2010

    sorry, bit of a typo there. His name is Schmincke.

  37. #38 Henrik
    February 27, 2010

    Just had a look at the list of the Decade Volcanoes mentioned above and it reads like a list determined by what lobbyists could push through rather than one based on vulcanologist exertise? Certainly, the underlying ideas are magnificent and funding to further knowledge cannot be said to be anything but most welcome. But where are some of the really dangerous volcanic systems that meet most of the criteria such as Rabaul, a town built in a rather active, mostly submarine, caldera with three active stratovolcanoes and several pyroclastic cones, a town that has had to be temporarily abandoned after eruptions in 1994? Btw Bruce, apart from Auckland, aren’t there another two New Zealand towns that are built within active hydrothermal/volcanic systems(Rotorua and Reporoa)?

  38. #39 bruce stout
    February 27, 2010

    Hi Henrik,

    I think the whole idea behind the decade volcanoes program was to try and assess the highest exposures to risk so this includes aspects like 1) frequency of eruption, 2) severity of eruption and 3) size of the population at risk. Maybe that is why places like Rabaul are not on it because the population is not big enough? (The list does seem kind of arbitrary!)

    You are right about NZ. Nobody in Auckland is perturbed about the volcanic threat as everyone feels there will be enough warning to move away and the eruption is likely to be small scale. Moreover, it’s a bit of a lottery, no one can tell where exactly the next one will pop up, let alone when.

    As far as the Taupo Volcanic Zone is concerned (which runs from Ruapehu at the south through to White Island offshore) there are plenty of small towns that could be at immediate risk of an eruption, but again these towns are small. I think the biggest risk in terms of combining likelihood and severity would be a minor eruption in Lake Taupo causing a tidal surge across the lake and resulting flood down the Waikato River which has a number of hydroelectric dams on it. This could cause pretty severe damage all the way down river.

    I know Reporoa has been mentioned a few times recently on this site but I don’t think it is anywhere near the risk that Taupo or Okataina represent. Or to put it another way: the entire mid-section of the TVZ from Taupo to Okataina should be viewed as one hotbed of caldera volcanism. The next one could be anywhere in this zone, let’s just hope it is not too soon!!! The system is deemed to be chaotic so there is really no telling when the next one will be but, that said, it has pumped out an awful lot of ejecta in the last 30k years, so let’s hope it takes a breather for a while.

    Finally, even a big eruption from the TVZ is unlikely to put a large population at risk unless you got rare wind patterns or it hit VEI 6+, so generally, there is no risk in NZ comparable to what you get overseas at places like Taal or Merapi, Galeras, Colima etc.

    Then again, just about everything I have posted on this forum has been proven wrong, so .. um what does that tell us?

  39. #40 Henrik
    February 27, 2010

    Thanks for the NZ info! To return to the peculiar “Decade Volcano” list – what is Rainier doing on it? It’s at least half a million years old and apparently the greatest devastation caused was from a summit collapse avalanche 5000 years ago. The size of the population at risk – mainly from lahars – seems to be moderate: “According to USGS, about 150,000 people live on top of old lahar deposits of Rainier.” Could it be that the proximity to Redmond, the headquarters of Microsoft Corporation, influenced the choice? Wouldn’t the money have been better spent on understanding the change in behaviour of the Long Valley caldera if it had to be a US location? And how can Santorini be construed to be a greater risk to humans than Campi Flegrei? Santorini with a 2001 census population of 13,670 seems to be on the small side of the 4 million at risk in the Naples area. Furthermore, the greater part of the Flegrei Caldera is submarine and I’d lay bets on a) that a Flegrei eruption has the potential to cause at least as devastating a tsunami as a Santorini one, and b) the threat is more imminent. Is it because Italy already had two on the list?

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