Mayon – Or what is a deadly volcano?

Photograph by Sinjin Pindeda. The photograph is taken from a hill at the outskirts of Legaspi City. Note the lava flow that is hardly even covered by greenery. A couple of more kilometers of lava flow and Legaspi would have been gone.

Photograph by Sinjin Pindeda. The photograph is taken from a hill at the outskirts of Legaspi City. Note the lava flow that is hardly even covered by greenery. A couple of more kilometers of lava flow and Legaspi would have been gone.

A few days ago Spica wrote a post asking us for our most dangerous volcanoes since she is going to give a speech at Ars Electronica in Linz. Normally I try to stay away from discussing megadeath volcanoes since the subject is fairly gruesome. But, I got intrigued by the notion and started thinking about what would be the most dangerous volcano on the planet.

First I had to think up a set of requirements to judge it by. The premiere one would have to be a lot of nearby residents. The second requirement would be that it has a history of frequent medium sized eruptions (VEI-3 to VEI-5). The third requirement is that it should have an eruptive style that poses a large threat to the residents. The fourth requirement is that it should be a known killer volcano, and the fifth one is that it should have the capacity for a large scale eruption (VEI-6 to VEI-7). For those who know the history of volcanic eruptions will know that this is a true recipe for disaster. With this list of requirements in the back of my head I compared it to the list of volcanoes known to me. It was surprising how many well known bad boys in the world that did not meet these requirements. In the end it was though one that climbed out on top of all the others by virtue of being in the top 3 in all of the categories.

Mount Mayon was the top contender, locally known as Bulkang Mayon after the heroine Daragang Magayon (Beautiful Lady in the local language). For those who love stories of love that end badly, read this one.

First, let us go through the list of requirements and see how Mayon fares. The volcano is encircled by eight cities and numerous villages. The combined population of the cities are 736 000 people, with an additional half a million living in the villages. All of these people are within a striking distance for a VEI-4 sized eruption. Almost all parts of this area has either been previously covered in up to 15 meters of ash, and/or been overrun by pyroclastic surges or lahars.

The ruins of a village that contained 1 200 people. Only the burnt husk of the church remained after the village being covered in 9 meters of pyroclastic material. Photograph by Anne Jimenez.

The ruins of a village that contained 1 200 people. Only the burnt husk of the church remained after the village being covered in 9 meters of pyroclastic material. Photograph by Anne Jimenez.

According to the Global Volcanism Program Mount Mayon has suffered 14 VEI-3 eruptions and 2 VEI-4 eruptions since 1616. That gives an average of one medium sized eruption every 25 years. This is a very high number if one sets it into relation with the high number of potential victims.

Mount Mayon has a very perfect and steep cone built out of alternating layers of ash, lava and pyroclastic deposits. This makes it into a very unstable volcano with a highly varied arsenal of deadly expressions. The number one historical killer has been lahars. Secondly comes the pyroclastic flows. The rest of the list covers suffocation due to ash and gas, rockslides, and incandescent bombs. The volcano also frequently suffers from unexpected phreatic detonations that occur without warning. Mount Mayon last killed people in May when climbers that had sneaked inside the 6km permanent danger zone got blasted by a phreatic detonation.

A realistic death toll for Mayon is about 50 000 people since 1616. This number has been achieved without any episode where a city has been hit directly. The highest known death toll for one single eruption is 2 200 people that died from lahars, suffocation, and ash fall. If there had been a lahar or pyroclastic surge hitting one of the cities the number would have been much higher.

Due to the shape and height of Mayon the aperture of the volcanic crater has grown increasingly narrow. This increases the pressure inside the system during an eruption. One could compare this with a rifle that has a barrel that is getting narrower over time. As one fires the rifle the bullet will be squeezed harder and harder for every shot with an increase in gas pressure behind the bullet. One day the rifle barrel will rupture, and the same goes for Mayon.

Basically this gives the same basic setting as for Pinatubo, as a large eruption happens the volcanic aperture cannot withstand the pressure and an explosive widening of the crater occurs. The other thing that could happen is that Mount Mayon will suffer a flank collapse like the one that happened at Mount St Helens. This is though unlikely since Mount Mayon erupts so frequently that the volcanic tubing is in a state of being semi-open all the time. A flank collapse requires a lot of pressure building up prior to an eruption, but in the case of Mount Mayon that would cause a normal eruption to occur at an earlier stage.

Due to the mountains height it exerts a tremendous downward strain on the underlying bedrock. At the same time magmatic intrusions lift the mountain upwards as the volcano inflates. The highest downward pressure is in the center of the volcano, and the maximum upwards push is at the outer edges of the volcanic system. This over time creates a ring fault running around the volcano. This is a permanent weakness and as the systemic pressure increases over time as the crater aperture diminishes more and more stress will happen at the ring fault line. And when the pressure becomes too high a flank vent eruption will occur somewhere along the ring fault line.

Photograph by NASA. The almost perfect shape of Mayon. With Legaspi marked.

Photograph by NASA. The almost perfect shape of Mayon. With Legaspi marked.

I think I should explain how high the volcano is compared to its prominence. The volcano is 2 463 meters high above oceanic level. That does not sound much compared to some Andean giants. But here is the thing. If you measure from the bottom of the volcano to the top (prominence) it is 2 447 meters high. Or in other words, the volcano rises from a height of only 16 meters above sea level. This gives the volcano an ample supply of water to drive explosive eruptions.

Sooner or later the volcano will start to have predominantly flank vent eruptions until the ring fault gives way and the volcano goes down in the middle and the entire ring fault line erupts and the ring fault is almost down at sea level giving the flank eruptions a higher explosive force due to available water. This is your basic somma caldera formation. Mount Mayon is quite near this stage, but near means within geological time. Due to the number of flank vent eruptions we do know that Mayon is about as close to this happening as is possible, but it will most likely take a long time from a human perspective. It could though occur if a larger than normal eruption took place, say for instance during a Pinatubo style widening of the crater aperture.

Mount Mayon is my candidate for deadliest volcano around since it could quite easily kill more than 100 000 people during a medium sized eruption that takes a bad route and also since it could have a VEI-6 to VEI-7 eruption that would directly kill between 1 000 000 to 5 000 000 people in the initial stages. She is equally beautiful as deadly.


133 thoughts on “Mayon – Or what is a deadly volcano?

  1. Excellent article *as usual* 🙂
    BTW, Etna was moved to Iceland area for test purposes a few days ago.
    I have not seen it (but it migh still be here, we just do not have visibilty to check) so it must have been returned to Sicily.

    Explaining the rain thing, It has rained twice in Iceland this summer – first for 24 days and then 45 days …

    • HAHA!!!
      They are apparantly so used to doing Icelandic volcano tests that any volcano is in Iceland nowadays.

    • Yup, it seems, but I can not tell if Etna is there beside Hekla today… as you see “nothing”, thats the wet thing, RAIN !
      Mayon in Phillipeans *article does not say*

    • LOL! That’s what comes of not checking something before you post it! Sorry to hear about your rain – we had that last year. This year Britain is having a proper summer with lots of sunshine and heat! 🙂

      • Indeed, and buring airliners at Heathrow probably add to the “heat”, or did your summer ignite “the Plastic plane” 😉 But its good knowing the summer is somewhere and not “missing” hoping for it spreading here before winter sets in … (here it rained all summer 1995 … and it happens here too every ten years or so …)

  2. Thanks for the post – Mayon does look unnaturally steep. One can only hope for good evacuation plans and expert volcanologists.

    • PHIVOLCS are actually very good, as long as their equipment does not grow legs and wander off. And they have good evacuation plans too, but… Problem is that it takes time to evacuate the 80 thousand people that live in the first 8km exclusion zone. And if it is judged necessary to move even more people… Well, problems.

  3. An excellent exotic article Carl. The pictures are stunning. Nice strato. Makes one want to buy a plane ticket (sigh)….

  4. “She is equally beautiful as deadly.” – Definitely, a treacherous killer.
    I remember watching a TV show, some ten years ago, even before my interest about volcanoes had increased, in which they pointed Mayon as the deadliest volcano in the world. In 2009, when it threatened to erupt again, I stumbled into Erik’s blog and soon thereafter, came Eyjafjallajökul – reason why I have been around ever since.
    It’s a pity – she’s definitely one of the most peaceful looking and beautiful volcanoes in the world!
    Thanks for the post! 🙂

  5. Ahh Saturday. Making breakfast… walking around the house with a dog stuck up my arse.

    Ya see, this dog does not like thunder and lightning. And a storm has formed directly over my house. The dog seeks shelter. Dunno how my arse can act as shelter from thunder and lighting…. but the dog seems to think its a safe place to be.

    • Now I am having the disconcerting image of a 6 legged human-dog Kentaur running around making breakfast. Perhaps it would be a Lupaur, I am not sure about the semantics…

    • He’s hiding under the couch now. He pissed me off and I elicited omega behavior from him. I had let him out to go do his thing, he only did part of it. The thunder scared him back inside where he did the rest.

      I don’t put up with that. I snarled at him and whacked a box with a stick. He got the message and retreated.

      Now that my wife is up and about, he decided that she is safer. (from the thunder and from me)

    • And you have an answer.

      It is a very good paper, but it does not cover all forms of caldera formation.

      Lurking asked about the depth of the magma chamber… I guessed the top would be at 5 km. It seemed like I was prophetic again. I got hold of a meeting synopsis giving the depth, and we have yet another volcano with more than one chamber, but it seems to be an internally connected magmatic complex moving magma back and forth. Lurking is going to have a field day with this. Well, anyhow the system is running between 5 km down to 11,5km

      Click to access SVC050-15_E.pdf

      • And some evidence of a 1.95 km intrusion…

        Click to access doi10.10292000GL012656.pdf

        Edit Add.

        Just read your link. {shudder} Another multi chamber system that keeps pushing magma from one area to another. Unlike Hekla… mostly vertical movements. This critter seems to be quite prone to fractioning and stashing the different magmas at varying levels. Get a hot fresh injection of basalt rich magma into the wrong chamber and it could get dicey when it remobilizes that mush.

        *Opinion of a non geologist only. Do not pass Go, do not collect $200.

          • Oops…

            We have a width of the magmatic system (please note, this is note the same thing as the size of the magmatic chamber), it is a whopping 8 km radius from the center of the volcano.

            The intrusions mentioned by Lurking are not that small… not piddly at all…
            “The characteristics obtained for the intrusion are: a depth of 1.95 km below the base of the volcano, 0.21 kbar pressure, a radius of 1.65 km, and 0.474 MU for mass (1 MU = 1 Mass Unit = 1012 kg) for epoch 4-1; and a depth of 1.82 km, 0.31 kbar pressure, a radius of 1.71 km, and 0.841 MU for mass for epoch 5-1.”

  6. Fe-Mg diffusion modelling in pyroxenes suggests timescales of
    less than 10 years between mafic injection and subsequent eruption.
    Preliminary volatile data from melt inclusions in tephra fall deposits
    of the 2000 eruption yield source depths of about 9km. Additional
    volatile analyses of different Mayon eruption deposits are underway
    to further characterise the inner workings of the volcano.

    Click to access Goldschmidt2012_Conference_Abstracts_C.pdf

  7. Great writeup. My only comment is that I don’t think pinatubo is a great comparison since pinatubo had very little activity until it blew its top. The difference being pinatubo is dacitic, thus it clogged itself preventing minor eruptions.

    Mayon i believe is andesitic to basaltic, which lends to more frequent small scale eruptions, and less clogging overall. That doesnt mean it cant form big eruptions, but it requires a larger buildup of the edifice prior to forming a very large eruption.

    • I know, I just used Pinatubo since it is a fairly well known example.

      My point was that the buildup is substantial at Mayon. At over 2400 meter straight up it is a very tall and extremely top heavy volcanic edifice. One should remember that the andean giants are placed ontop of plateaus, Mayon is at the sea level and very high as andesitic single vent cones go.
      If we compare with Mt Cameroon it is a more baseline basaltic volcano with several vents. And Cameroon is higher, but much broader over the shoulders so to speak. Another difference is that Cameroon is not sitting atop the primary magmatic chamber, it only has a small depot chamber connected in turn to a very massive chamber situated another further 8 km inland under an ancient supervolcanic caldera.

      Mayon of course follows a completely different road to large scale eruptions. It has almost continous inflative periods leading to numerous eruptions, a process that over time enlarges the magmatic system untill it grows to large to be able to hold back the weight of the edifice above. As such it is very near to critical failure (geologically speaking).
      My ultimate point with the post was not to write a “it will go big” post. I just wanted to point towards what constitutes a truly dangerous volcano. Even a medium sized eruption can have truly horrific effects at Mayon.

      By the way, how about you write a post about the japanese caldera volcanoes? You always write very informed comments about them so I would be very interested in reading a full post on one of them by you? Please 🙂

  8. Hmm…. there’s a familiar shape.

    This is Mount Iriga, also known as Mount Asog. It’s an active volcano. From it’s appearance, it seems to have had a lateral flank blast/collapse eruption at sometime in it’s past.

    It’s also a neighbor to Mayon… about 32 km away. Fed by the same subduction generated magma process that feeds Mayon and it’s siblings.

    This sort of thing could make Mayon not form a caldera… though it would be devastating in it’s own right.

    • Yepp, and that is why I hedged the bet with mentioning a flank collapse. I still think it is a bit unlikely since Mayon is so active. But, if it happened it would assuredly be very gruesome. It would be like Mount St Helens blasting away surrounded by cities.

    • I also feel if you go a bit further south, you get Bulusan in the same volcanic arc. Bulusan is a somma volcano that sits in a very large caldera (roughly 13km circular). I’d imagine both are highly likely.

  9. Great post, Carl. Thank you. 🙂

    OT-ish. Is the lava dome on Mt St Helen’s larger, or does it just look that way becaue I now know what it is 😕

    • Karen I think it is not any larger but just the fact that it is a bit more exposed than normal due to our overall lack of snow cover this year…
      Waiting for the fire horn to go off here in NE Oregon will be working for a Operator that does fire patrol air attack and heavy lift Helo work (for now I will be flying crews and mechanics..)
      My tanker job is on hold…

  10. KarenZ, what have you done to deserve the dungeon? Returning from my Eifel vacation with un-spamming you ;-).

    We saw loads and loads of volcanoes and several Maars, I would already begin to be on cold turkey was it not for the nice posts to catch up with 🙂

    Mayon´s slope indeed looks insanely steep, you could almost align an exponential curve to it.

    • Karen has for reasons totally unknown been thrown time and again into the Dungeon for days now. We try to release Karen as quickly as possible, so it is good you are back.
      We are hoping that Akizmet will learn, but it goes insanely slow for it to learn, much slower than normal.

  11. OT: The Epitome of Stupid.

    SSH is an encryption protocol that establishes a very secure communications channel among two systems. Stuff passing along this channel are virtually impossible to aquire… unless you have a monstrous data acquisition infrastructure and the cryptologic horsepower to break the encryption key… such as the NSA does. For the run of the mill intruder, it’s generally beyond their capability. So.. one thing that is always guarded, are the encryption keys. You don’t pass them around, and you don’t arbitrarily include them in a firmware fix.

    Several models of Emergency Alert System decoders, used to break into TV and radio broadcasts to announce public safety warnings, have vulnerabilities that would allow hackers to hijack them and deliver fake messages to the public, according to an announcement by a security firm on Monday.

    The vulnerabilities included a private root SSH key that was distributed in publicly available firmware images that would have allowed an attacker with SSH access to a device to log in with root privileges and issue fake alerts or disable the system.

    The stupid! It burns!

  12. And another OT

    Post Office admits computer system at centre of sub-postmaster prosecutions had bugs

    Read more:

    I don’t deal with the software side of things a lot…. but some of these interconnected accounting systems can be a real pain in the ass. One application that I know of, has a tendency to wipe out local configurations when the server side pushes out a software update. Occasionally, Staff at the outlying offices are presented with an inoperable system on Monday morning with unhappy customers lined up at the door. I blame unsupervised code writers and little to no error checking.

    • I was just looking at that. My personal opinion is that they are having problems with the sensor.

      released by dfm

      • I would have thought that too if it wasn’t for the timing of the quake with the activity showing up on CHIE. That is what caught my attention. Could be a coincidence or?

  13. KarenZ – Thanks for the overnight bag, please fetch more biscuits next time 😀

    released by dfm – it seems that even mentioning the name of Karen sent you to the dungeon.

  14. Thanks for the Mayon Post Carl.
    Glad you got intrigued about the idea of that talk. The subtitle, the most dangerous volcanoes of the world was not chosen by me but by people who just want a header which could draw more people.
    The visitors who will be at the talk, will most likely know Zero about volcanoes. I will most likely have to address, what a volcano is at all. Not a mountain spitting ” fire”.
    Thats also why i plan to continue the series on volcanic hazards very soon.
    I am really glad about all the assumptions which came from the blog, though i might mention many of them with only the name and a pic and concentrate on a few, with which there is a certain possibility, people may have heard at least the name of the nearby town before.
    I agree with most here, the most dangerous volcano is probably one which was inactive or neglected or forgoten over the years and suddenly stirs. In case it does it Chaiten style… this is a dangerous scenario. If this happens over longer periods of time.. there would be a longer period when people can be warned what could be happening.
    One problem with volcano warning though… if people get told to evacuate and nothing happens.. they wont go next time.
    Oh well, expect more ruminations by me on the topic in the coming weeks.

    • Not sure that it is true that people won’t evacuate next time, provided a hazard awareness programme has been put in place after the first alarm.

  15. Come up with this whilst “visiting old saved favourites”, pity Carl is on train today but hope this does not derail anybody.
    This shows hefty uplift in last our-to-six weeks or so. I think 30 mm can be regarded such, and over total of 80 mm since early year 2010. (Note this is detrended format so should be very accurate.) Enta and nearby Entujökull is N or NW “corner” of Katla Caldera, so this begs the question: Will this “develop into a situation”? It can bring heavy flooding to Markarfljót etc.
    *not expert*

  16. Interesting, this is Eldgigur.

    14.07.2013 10:37:29 64.183 -17.461 15.7 km 0.9 99.0 26.2 km SSW of Grímsfjall
    14.07.2013 10:37:16 64.189 -17.434 17.8 km 0.7 99.0 25.1 km SSW of Grímsfjall

    • yes, we are certain of this and that connect, eventually 😉
      *forecast for “next days” in geological time for area is increased rifting and occational “showers” or “drifting” pumice & tephra*

      • Again spoke too soon! & back in the dungeon. Alison has finished off the remains of the biscuits. Please send more 😀

          • While you are testing, some choccy biscuits and a cup of tea would be welcome 😉

            GL Released

        • The problem seems to be related to the IP range you share with Alison. Then the NtV competition probably gave you a bad score with Akismet which probably tries to prevent high volume of comments per IP in a short space of time. Hopefully repeated un-spamming will help after a while.

          Biscuits are refilled btw.

          • I think the amount of comments per IP would have landed me in the spambox a very long time ago… *ashamed*
            I temporarilly dragonized Karen so she can release herself when needs be. And, I also suspect Dragons are better treated by Akizmet…

            I will though continue to look as often as I can since also Alison is in trouble.

        • Oh no, stuck in here again and there’s no biscuits and I can hear something moving in the dark …..Help!!!!!!

          Rescued in the nick of time by Kilgharrah

    • They have pyroclastic and lava flow, lahar and ash fall hazard maps, but no lateral blast hazard maps.

      • I imagine that would be pretty hard to produce. It depends on what side the volcano fails. If you use Mt St Helens as a guide or example, figure an arc a few degrees wide out to several kilometers. Pick a bearing.

        • If you draw an 18 km circle around Mayon, then anything along a few degree arc from the summit could be considered a hazard area for a lateral flank blast of roughly St Helens size.

          But.. remember, St Helens had this “bulge” that represented a crypto dome up inside the edifice. When the landslide occured, it released the pressure holding the vapor in the rhyolitic mush in solution. When that happened, you had violent degassing.

    • I think of it as akin to a tea kettle. The higher the pitch, the higher the pressure. (or the gradual closing of an orifice or the thickening of a fluid)

      (Not a Geologist, just some poor sap cruising the board at midnight, really jonesing for some ginger tea.)

      • A Gurgle translated portion of the article.

        According to reports received from the National Secretariat for Risk Management (SNGR) volcano watchers volunteers, staff and community IGEPN (especially social networking) ashfall was recorded associated with the activity of the volcano Tungurahua in the provinces of Tungurahua, Chimborazo, Bolivar, Los Rios, Manabi and Guayas.

        The explosion of 06:47 (local time) and emission tremor that lasted until 08:40 (local time) today, July 14, column generated a high emission of ash falling rubble caused (fragments of slag) of 5 Chacauco centimeter diameter and 4 cm in diameter in Bilbao. Meanwhile Huambaló sector was affected by falling rubble black and pink color. Were affected by a major ashfall thick black Bilbao sectors, Chacauco, Cahuají, Choglontus, El Manzano, Puela, Penipe Shrine Sabañag, Hualcanga, Quero and Mocha. According to the report of the Tungurahua SNGR, Cotaló was affected by mild to moderate drop of thick ash and small gravel.

        The Canton Ambato was affected with a thin layer of coarse ash black. In this county were affected the central and southern part of the city, Quisapincha, Raisin, San Fernando and Pilahuín. Other sectors affected with ash medium to fine, black, were Pelileo, Cevallos, Riobamba, Penipe, Guano, Colt, Guanujo, Guaranda, Echeandía and various sectors of the provinces of Los Rios, Manabi and Guayas, including Quevedo , Porto Viejo, Buena Fe, Valencia, Quinsaloma, Mocache and The Junction.

        Dragon Note: As of 0507 UTC, no KarenZ posts were spotted in the dungeon. Just a few cookie crumbs from the last occupant. You guys really need to watch the food droppings, we don’t need any vermin down there. I damned near got my leg taken off the other night.

        There are what appear to be two bona fide SPAM critters in the que. I poked at em with a stick for a few minutes, but was unsure if I should summarily whack them. (just on the oft chance that they were innocent. ) I’ll leave that determination to the more SPAM savvy Dragons.

        • Think you released the last one from me yesterday evening 😀

  17. This is an unsolicited advertisement. In other words, no one contacted me and asked me to put something up about it. I just through that I would pass it along. If you like it, cool, if not, please ignore.

    I subscribe to a free newsletter called Explorator. It’s put out about once a week by David Meadows and covers stuff about the Humanities. The newsletter does not include images or scripts, it’s just a quick summary plain text with raw links to the stories. In other words, it’s pretty safe from a vulnerability point of view.

    In the about section:

    EXPLORATOR is a free weekly newsletter bringing you the latest
    news of archaeological finds, historical research and the like.
    Various on-line news and magazine sources are scoured for news of
    the ‘ancient world’ (broadly construed: practically anything relating
    to archaeology or history up to World War II or so is fair
    game) and every Sunday they are delivered to your mailbox free of

    I first subscribed to it about 1998 or so. I find it handy to be alerted to new findings or news about Neanderthals, Ancient Rome, Clovis people, or whatever happens to come up during the week.

    It’s pretty handy when you start thinking about historical volcanic activity and it’s effects on cultures. And if you have pet oddball theories it can come in handy also. (personally, I’m a follower of the “Clovis First” idea)

    If you are intersted,

    To subscribe to Explorator, send a blank email message to:

  18. Excellent article Carl,

    very much enjoyed it. Funny how the Philippines seem to be such a focus of deadly volcanic risks when other countries, like Indonesia, have more potentially deadly volcanoes and arguably greater population exposure. But I agree about Mayon and for me the second contender would be Taal, also in the Philippines which is kind of like putting a temperamental volcano like Taupo in spitting distance of a megacity, in this case, Manila. Worse, just look at Google Earth and imagine trying to evacuate Manila if it were about to get 20 cm of ash dumped on it. It’s an absolute bottleneck. The chance of people getting away in time should be a bit higher at Mayon but it’s all relative. Moreover, Taal has had numerous magma intrusions recently so the system is probably pretty hot.

    The other thing that keeps ringing like a little alarm bell in the back of my mind is, before the final cataclysmic stages of a large eruption, there is not very much available to warn us in advance that an eruption is about to ramp up and go all catastrophic on us. In the Hatepe eruption of Taupo there were a number of different phases in the eruption before it went ultra-plinian and none of them were necessarily a sure-sign that the final unit of the eruption (Y7) was going to be so catastrophic. This is why even small eruptions need to be given due respect. You just never really know what they might trigger.

  19. Post request!

    I am not that savvy with Tungurahua, could someone write a post on it? If you wish to do that and are not a Dragon, just shout tell us and we will help with editing it in.

    Kindest Regards!
    Carl and all the other readers of VC

  20. Hey! That is a high plume. I wonder if we can tell by the shape if it has reached above stratosphere… According to the numbers given by Pyter’s link above the column reached a height of over 8 km. Plus the 5 km of the edifice, it would sum up to 13 km. That is not enough to reach the stratosphere, is it? Yet that shape…
    Lurking, what is your take on this?

    • Wikipedia: “The troposphere extends upwards from right above the boundary layer, and ranges in height from an average of 9 km (5.6 mi; 30,000 ft) at the poles, to 17 km (11 mi; 56,000 ft) at the Equator.” … Humm…

    • Unlikely… based on average height at that latitude. Average elevations derived from Giovanni. I don’t have real time tropopause data, so it’s always possible that there is a divot there and it made it above that…. but it’s still quite unlikely.

      HOWEVER…. the general trend of atmospheric circulation in this area is upwards towards the tropopause. That means that even if the plume peters out a bit short of it, SO2 and other sulfur compounds don’t have much further to go to make it there as part of the normal circulation. It just won’t be as forceful as a direct injection.

      Analyses and visualizations used in this plot were produced with the Giovanni online data system, developed and maintained by the NASA GES DISC.

      (boiler plate acknowlegement recommended by Giovanni)

      FVXX20 KNES 141342
      DTG: 20130714/1342Z


      PSN: S0128 W07826


      SUMMIT ELEV: 16480 FT (5023 M)

      ADVISORY NR: 2013/166



      OBS VA DTG: 14/1315Z

  21. No ruminations this morning. I might make coffee #2 before husband and I head North. We are off for a couple of days courtesy of a voucher given to him for his birthday from his Sister. It will be good not to have to cook for a day or two :). Please don’t panic though ! I will be back for Friday’s riddle solving . 😀
    Thanks Carl for another very readable post. No volcanoes where I am going, just sedimentary. Mostly Carboniferous limestone.
    See you all later in the week.

  22. Any volunteers ready to try this out over on Hekla?

    She documented the rising tremor frequency, starting at about one hertz (or cycle per second) and gliding upward to about 30 hertz. In humans, the audible frequency range starts at about 20 hertz, but a person lying on the ground directly above the magma conduit might be able to hear the harmonic tremor when it reaches its highest point (it is not an activity she would advise, since the tremor is closely followed by an explosion).

    The source article

  23. OT but I want to go here for my next holiday:

    “The planet’s atmosphere is scorching with a temperature of over 1000 degrees Celsius, and it rains glass, sideways, in howling 7000 kilometre-per-hour winds.”

    NASA Hubble Finds a True Blue Planet

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