The Ruminarian, again

By GeoLurking, January 8, 2014 (republished)

Photograph by Tom Murphy, Yellowstone in Winter

Curmudgeon “an ill-tempered person full of stubborn ideas or opinions”

Well, if the shoe fits, I guess I’ll wear it. But… I don’t come about it lightly. To me, stuff has to make sense. One thing I abhor is mindless ranting that is specifically intended to scare people. What is even worse is when sound science and research is twisted to fit this purpose. Usually you see this as “Argumentum ab auctoritate.” One of the more popular tactics is to roll out someone carrying credentials and point at them as justification for the fear mongering because something they have said supports your alarmist claim… even if it doesn’t. Recently commenter Robin Hull Pointed out a fresh new article by titled “Risk of supervolcano eruption big enough to ‘affect the world’ far greater than thought, say scientists.” Yeah, like we haven’t heard that before. (yawn). Before I continue, many thanks to Robin for bringing it up. At the time I was freaking out by the actions of my dogs and needed the distraction so that I could get my mind off of what it was they were alerting on. (I had already checked the yard). Reading the article, this is what I found. “The eruption of a “supervolcano” hundreds of times more powerful than conventional volcanoes” Really? Okay, lets go with that.

First of all, the term “supervolcano” is a media construct. Before they started flailing about, wildly chanting the term, it didn’t exist. It’s purpose, like all alarmism, was to get attention. Since the article is about the old standard “spook everyone” subject of Yellowstone, that means that it is a product of the Yellowstone hotspot… because that is what feeds the system. Just in case you are new to this, the entirety of the Snake River Plain was formed by periodic Large Caldera Events and Volcanic Fields that leveled any mountains that were in the way, leaving a relatively flat plain in it’s path. Since the heavy work was done, the Snake River had a pretty easy path to form in as a drainage path for the surrounding watershed. Now, referring back to the independent article. “…they have been responsible in the past for mass extinctions, long-term changes to the climate and shorter-term “volcanic winters” caused by volcanic ash cutting out the sunlight.” Um… the jury is still out on that. The BBC, who ran their own version of the supervolcano article, had this linked as a related article: “Toba super-volcano catastrophe idea ‘dismissed”. In that article, they look at research centered around Toba, a system that has at times been claimed to have nearly wiped out mankind about 75,000 years ago. From the BBC version, which is a bit less alarmist: “”We think Yellowstone currently has 10-30% partial melt, and for the overpressure to be high enough to erupt would take about 50%.” Now lets take a look at those numbers and see how they square with the Independent’s statement of “it would take at least a decade or so for the magma pressure within a caldera to build up to a point where an eruption is likely.”

The last eruption was 600,000 years ago. In that time, Yellowstone has accumulated “10 to 30% partial melt.” (ignoring the numerous caldera filling resurgent activity eruptions, so that adds a quite bit of uncertainty). 30% in 600kyr yields about 1% additional melt for every 20,000 years. In order to get to the 50% melt accumulation where the authors believe that the pressures would be high enough to be in danger of erupting, we need another 20%. At the 20kyr per 1% rate, that’s an additional 400,000 years. If you assume that the 10% current melt is correct, you get 60,000 years for a 1% increase. To get to 50%, you need another 2,400,000 years.

Hmm…. One of the more common statements is that Yellowstone is “overdue” since the spacing on the last three or so eruptions is about 600,000 years. One thing I have found is that volcanoes don’t play the stats game very well at all. If your prognostication uses only 3 events, your stats are worth crap. Taking the eruption dates from a larger history of the hotspot reveals that the average interval is actually about 500,000 years. Worse eh? Not so. That list includes many caldera filling eruptions. The only criteria is that it made a tuff deposit somewhere. Since it is composed of 31 data points it is a bit more robust. The one sigma (standard deviation) is 648,588 years. The 95% confidence interval is 271,684 to 728,316 years. If you want to be more realistic, and only use honkingly huge events, the average gets closer to 5.4 million years or so, but that is from looking at it a few months ago and is from memory.

Caveat: I am not a geologist, nor am I a statistician. My stats experience is from failure analysis and process control of electronic equipment. If you think you can do a better job, by all means, please do. Even if your numbers are different than mine, at least you are using your own mind and looking at the data for yourself. Fair warning, not only do volcanoes not care about the Gaussian distribution, they don’t care much for Poisson distributions either. Hekla and Katla showed me that.

In keeping with the apparent tradition of articles about the Yellowstone Supervolcano… the obligatory picture of Grand Prismatic Spring.

Image source: Wikimedia Commons

Pretty isn’t it? I think that’s the reason most of them use it. This is not the yellowstone caldera. This pool is about 26 meters by 96 meters. The actual Caldera of Yellowstone is several orders of magnitude larger. In my opinion, this spring/pool formed from a maar like explosion. It’s also what I expect to occur again at Yellowstone should activity actually begin creeping upwards. About 160,000 years ago, a maar like detonation formed West Thumb. Yet one more event in the many that filled in the ancient collapse caldera. Magma + Water below the supercritical pressure = boom.


The track of the Yellowstone hot spot: Volcanism, faulting, and uplift 

Pierce and Morgan (1992) Geological Society of America, Memoir 179

Supervolcano eruption mystery solved James Morgan BBC News.

Risk of supervolcano eruption big enough to ‘affect the world’ far greater than thought, say scientists Steve Connor The Independent.


This is still as true as it was several years ago. The story that Yellowstone could build up to an eruption fast still runs today. And it is still used every year as the volcano that sells papers threatens a super eruption. But it threatens nothing of the sort. In fact, the chances are that it will never have another major eruption. The hot spot moves on, and at some time will make an attempt further east. Or perhaps, as we don’t really understand where the hot spot came from, we don’t understand how it will end either. Perhaps it will just peter out. No, the real dangers are elsewhere.

We have had a VEI7 about once every 300 years. But they don’t happen to schedule, and the risk doesn’t depend on when the last one was. We can say that there is a 0.3% chance of a VEI7 each year. But even though we haven’t had one for 200 years, the chance remains 0.3% per year. That is high enough that risk analysis should take it into account, but without panic. VEI6’s are more common and there is a 1-2% chance of one during the next year. Bigger than an ordinary VEI7? A Toba-like eruption, perhaps once very 100,000 years – 0.001% per year. A flood basalt eruption? Once every 10 million years – 100 times less likely.

Now changes to the Earth may play a role: where major ice caps are melting, the chances of a large eruption increase. It is quite plausible that Vatnajokull will be the site of a large eruption within the next 200 years, once the ice has gone. But not certain, and Iceland does not do VEI7’s. Never has. Now Antarctica may be a different beast, once it’s ice has gone. But until this happens, Geolurking remains a more reliable source of information than the Express. Albert

And finally, a movie of all USGS recorded earthquakes since 2000. Spot the Bardarbunga eruption, when Iceland flickers.

227 thoughts on “The Ruminarian, again

  1. Thanks Albert! I totally agree about the last part regarding Geolurking vs the Express 😉

    Right now there is an ongoing swarm outside Selfoss in southern Iceland. A couple of M3.4 so far. May well have been the main event, but could also be foreshocks for something a bit bigger in the SISZ.

    • Make that one M3.4. I think the list briefly included both the automatic and manually checked versions of the same event. Or one of the events was downgraded.

    • I’m not familiar with this view of the summit close up, it’s always cloudy, but seems to be a rock fall or some disturbance centre left.

      • I’m not entirely certain, but I don’t think there’s anything going on. That feature was certainly there yesterday.As for before that? I would have to compare it with older photos.

          • Something seems to be going on. The sharp brittle fracture quakes have dropped off, but there seems to be an increase in low-level background noise. I don’t think it’s wind – only 16 km/h at present.

  2. This was such a good one I have moved it to the post itself: see above. A movie by the Pacific tsunami centre, of all earthquakes of the millennium. The disco Earth.

  3. Is the change in the seismo for Agung now showing harmonic tremor? If so I have never seen it last so long on that seismo since I first started checking it.

    • I’ve been wondering about the comings and goings of the base line noise. Current view is very clear so weather does not appear to be the culprit. I do notice that the increase is post the outages and artifact noise between 6-9am so maybe a change in sensitivity/scale is a possibility?

  4. Now I know it’s getting dark, so the shadow will be on the underside of the cloud/plume making it look darker, and there has been no obvious explosive event.. but I’ve just spent 15 mins or so watching that plume, and to me, that is no longer just steam. That’s smoke . There are moments when you can see BOTH steam and the darker material.

    • Yes Neil, I have been wondering if that was smoke too for the very reason you outlined, white steam but darker material at the same time? Obviously it goes without saying, I am just a watcher and have no expertise at all.

      • I have been watching for 30 minutes now and am becoming convinced this is smoke not steam, it is far darker than the odd cloud that drifts past.

        • I’m going to stick my neck out and agree with you. It’s looking to me like there are 2 separate emission sources.
          What convinces me is that the dark material looked dark regardless of how it presented to the sunlight.

          • Perhaps it may be confirmed tomorrow if the clouds don’t get in the way, it’s been remarkably clear there today but with the rainy season coming on I doubt we can be so lucky two days in a row. Now back to watching the Beach cam in Bognor, high tide in an hour and very rough already.

          • I’d still go with how the steam plume is presenting with respect to the setting sun, just looked back through the last 2 hours available on that feed. The clear dark emissions from about 90 mins ago are located in the same spot as the denser steam (bright white) emissions that preceded them 30 mins earlier. The darkness does not linger in the plume either, something that i would assume to see if it were ash. I’d add that that i’m no expert either so could easily be wrong.

            I would say that the steam does seem to be very active and pulsing to some extent but not sure how this compares to previous days, every time i normally check it’s cloudy!

            The one thing i do notice is the the shake on the camera – suggests that it is rather windy so maybe that could be the reason for the increased background noise on the seismogram?

          • Swebby, time will hopefully tell. But whatever any of us saw, it certainly wasn’t breaking any records as eruptive events go !
            What I think I saw were a couple of occasions when there was white steam both behind AND in front of a small, dense plume of dark smoke.
            I’m not surprised by the steam and a possible source of smoke being close together. The hottest part of the crater is probably the part most likely to create both steam and smoke, if the components are present

  5. Well, daylight is back and whether it is steam or smoke I am still uncertain! It certainly appears to be an increase in activity though. However definitely not yet a proper eruption.

  6. DOH! Covered in cloud now! Interesting seismo though.

    So far unable to find a source for the larger quake at 2:31 ish, local time. Perhaps a larger quake further afield but I haven’t yet found a source for it.

    • So far the plume, small as it is, definitely looks more smokey than steamy. Still we shall see what ones more expert than me think as the day goes on. I am off to bed soon.

        • From “Le Chaudron”, via google translate.

          “A surveillance drone detected Thursday that the fracture in the crater of Mount Agung had widened since the last satellite image on Wednesday.
          The spokesman of the National Agency for Disaster Mitigation (BNPB), Sutopo Purwo Nugroho, said the fracture was on the east side of the volcano. “The sulfuric gases emanating from the fracture are also denser than before,” he said in a statement Friday.”

    • I’m assuming that constant low tremor is the wind? Is that likely to be right?

  7. Looking at the seismograph, interesting to see some tremor (no wind) and tornillos the last few hours. Looks like fluid movements.

  8. Sutopo Purwo Nugroho, Head of Information, Data, and Public Relations of at the National Disaster Management Agency (BNPB), Sutopo Purwo Nugroho, said the sulfuric steam generated at the Mount Agung crater has fluctuated. Rumbles can be heard at the crater, and the smell of sulfur is very strong.

    Sutopo said the conditions indicate that the magma has reached the surface.…s.sulfuric.steam.fluctuates

    • Looking at the seismographs, I can see what he means. There appears to be low level tremor and small pulses of fluid movements. The 1963 eruption started with a magma / lave outpouring that was slow and unspectacular. Are we seeing the same here? A throat clearing of old, remobilised lave being oozed out of the tubes?

      Total speculation. Please start lobbing your Andesite chunks at me….!

      • Argh “lava”! “Lave” – good grief. Makes it seem like a car wash. A volcano wash…

  9. Agung is possibly on the brink of an eruption (but NOT this month yet); magma is probably very thick and slow moving. It will probably erupt but it will take some days to some more weeks perhaps.

    It reminds me a bit of Mt St Helens eruption.

    St Helens 1980: Following weeks of intense earthquake activity, small phreatic explosions occurred, with steam/ash columns up to 2km high, and a crack widening and developing in the top of the mountain and a bulge increasing over the period of one month. A section of it was sliding down gradually. Then, one day, seconds after a major earthquake, the whole thing erupted violently, as we know it.

    Pinatubo (1991) also developed this way. For 3 months it experienced earthquakes and small phreatic explosions over a widening fissure. Then magmatic eruptions occurred for two weeks as a large lava dome increased in size at the summit, until the final VEI6 eruption.

    Maybe Agung will follow a similar pattern.
    Let´s see if a lava dome appears at the summit.
    The fissure might point to that

    Note: phreatic means its not new magma erupting but its heat causing water at the summit to explode portions of rock upwards

    • I’ve been trying to learn as much as possible by watching this situation develop from the first time it went to the high alert, and I’ll keep watching until it resolves in whatever way it does… You may have noticed I’ve pitched several questions about it over recent weeks.
      I’ve also, when time permits, looked online for reference material, both on this particular volcano, basics of the scientific observation such as how to read a drumplot (which at times doesn’t seem “basic” in the slightest), and looking at histories of other eruptions.
      So please forgive me if my questions seem basic.
      Anyway, I was meaning to say, although the scale of any eruption would likely be somewhat smaller, it seems to me that Pinatubo is (so far) a fairly good fit for the chain of events.

  10. if i remember correctly, (haha) this particular volcano starts with just a magma emission and later follows with a more explosive event…… we aren’t out of the woods yet. Best!motsfo

  11. Despite of decrease seismic activity, today in the mornig the white plume is significant.

      • the closer view is now running again. It is now very clear that this is more than just steam. There are occasions when black, not dark or shaded, but black components are in the cloud. A few moments ago I also saw what MIGHT be a small explosive event at the base of the plume… A small phreatic event?
        To me, this is stepping up quite considerably.

        • Another consideration for occasional dark clouds are rock slides kicking up dust, Carl suggested that some of the long period episodes seen on the seismo were the results of rockfall. If however the dark clouds appear from the exact same point as the steam plume then that would be a bit of a coincidence.

          Neil, i’m sure that buried somewhere on this site, or maybe the old one, there was an excellent beginners guide to reading drum plots. If i have time i’ll see if i can locate it – it showed the differences between EQ’s, tremor, weather, rockfalls, traffic and even stampeding animals!

          • Thank you Swebby…. Happy to parade my ignorance in the quest for further enlightenment.

        • I haven’t seen the images of the dark clouds. Bur do be aware that water clouds can look very dark when they are in shadow, especially with a bright background. To the eye, light grey can look dark , because they detect contrast rather than brightness.

          In the image above, squares A and B have the same brightness. If you don’t believe this, try to cover up everything on the image apart from the centres of the two squares. Your eye looks at the contrast with the neighbouring squares when assigning brightness. A bright object suppresses the response of the rods and cones next to it in the eye.

          • I stand to be corrected, but.. A couple of days ago I think it was definitely open to debate. But since the last dawn in Bali, there were times when it seemed clear. Not just based on the colour, but also based on the movement.
            It is still difficult, because it’s not exactly a Grimsvotn plume , but there were at least 2 moments when I was fairly sure I could see (very small) explosive events at the base of the plume.
            It would be interesting if they were able to get that drone up to the crater again. That’s probably the only way we’ll know for sure…. Until something bigger happens.

  12. If it is “oozing” old magma out… the thick stuff, keep an eye for when the less thick material is no longer being held back sufficiently. That’s when it could become energetic quite fast. While the ascent is slowed down by old thick material, the newer magma can degas in a sedate manner. When it’s confining pressure starts to drop at a spectacular rate, it can degas at the accelerated rate… possibly transitioning to nucleating bubbles. When that happens, it becomes a similar dynamic to a well getting difficult to handle when gas bubbles begin pushing up through and displacing drilling mud, lessening the pressure holding it back. Volcanoes don’t have blow-out preventors, but it does conjure up a pretty extreme idea. How would you even begin to design something like that? To what and how would you attach it? There would be virtually no way to get a seal… and the material that it is affixed to could easily deteriorate and become part of the erupted ash… taking the necessarily huge gizmo with it. Might make an interesting Sci-Fi tale if done right.

    Note to any would be authors. The pressures in play are measured in MegaPascals. Levels that can fracture solid rock as the dike moves to the surface.

    Also, if you approach an actual geologist with this idea in order to get some solid science behind the scenario for the story, be fully prepared to be laughed at. Not only would the gear have to be phenomenally tough and huge, it would need to be able to remain fully anchored and withstand temps easily passing 1100°C if it came into contact with actual magma. Tungsten can deal with the heat, and is quite tough, but it’s also gonna be very very pricey, especially for the amount that would be needed… and it’s very very difficult to work with. Usually sintering is the process that is used to fabricate stuff out of it since it’s melting point is so high. (3422 °C) As for price, current spot price is over $25.5 USD per kg… and the device would easily exceed several tonnes. That’s an awful lot of money for a gizmo that will just have the edifice collapse out from under it as the magma takes an easier path and makes a side vent. Hmm… there’s your crisis for the story 😀 It almost writes itself.

    • Okay, I’ll help you along. Assume that the bankroll for The Project is unlimited, and the materials are available and can be fashioned into some megascale gizmo. The very action of fastening it to the mountain top will weaken the rock it is bolted to. The anchoring devices would have to latch onto enough material that there is no risk of the thing being blown off the top. So, it’s gonna have to be really really huge. Tungsten is not light. It is about the same density as gold. As big as this thing would need to be, it’s gonna have an effect on the ground that it is placed on. Crustal deformation is a real possibility… on a mountain with potential to erupt. (got to pick one that motivates the building of the thing) How it would effect that mountain is a large unknown variable. Calderas form when the underlying rock can no longer support it’s own mass. Drop a ridiculously large chunk of tungsten on it… good luck puzzling out how that will effect things. It might provoke early formation of caldera if the magma finds another way out of the chamber. (Magma will do that if the pressure is high enough)

      • Ok so…. letting the “silly play out…and why not… It’s going to have to be a giant upturned tungsten colander, big enough to cover the entire edifice right down to the base, thus spreading the load, and with enough vent holes to release the pressure safely whilst also dissipating the force of the larger blasts.
        And if cost is no problem, why not rig the entire outer surface, and particularly the vents with an extensive network of powerful sprinklers, to calm down even the most enthusiastic of pyroclastic flows.

        I think we have this one covered….so to speak.

      • I like you guys. Let your imagination run free. Just remember to add in possible detractors so that the budding author who takes this on can have some guidance on things they need to address.

  13. Note for anyone reading my last two comments. It’s an exercise in silly. No plausible idea is being suggested. It is just me mulling over a stupid thing that I alluded to while thinking about what Agung could do.

    An actual Volcanologist (Sparks) has noted that some volcanoes exhibit what could be phenomena resembling a sigmoid function as the nucleating bubbles in mama cause the overlying magma to push out of the way, lessening the confining pressure and cascading into more energetic events. (This was in a preface that he had authored for a collection of several papers)

    Now, the thing about sigmoids. The curve describes a system (or some variable in the system) That slowly approaches a tipping point and then the system rapidly shifts to another state. The cool bit, is that sigmoid curves show up in a lot of natural systems. Everything from neuron behavior to public opinions on something.

    • Not denying that comment. But it looks like sporadic traces then. Dunno how this system behaves in a saturated signal environment, but I expected it to swamp when the actual tremor started, not start dropping out erratically. I can’t really say one way or the other, but I’m leaning towards component failure. (it’s what I do, assume the equipment went kaput) BUT, that does not mean that it hasn’t started. Even with my biased opinion, Marek still has a plausible interpretation.

  14. I’m a long time reader/follower/fellow volcanoholic and I’m definitely not an expert like some of you here. But I just arrived on the island of Gili Trawangan a few days ago, which is approx. 60 km away from Mount Agung. So if anything is going on there, I might become an eye witness.
    We can not always see Agung from Trawangan, but I was able to catch a glimpse this afternoon and there is definitely steam coming out of the crater. I couldn’t judge if it was just steam or smoke as well. But as for the background noise – it has indeed been super windy here the last few days and the waves are pretty high too.
    I’m really curious and excited about what’s going on, and it’s also a little bit scary, but I guess that’s what people have to deal with when traveling to Indonesia and the ring of fire…

    • Envious of your cat bird seat. Great score! Far enough away to be highly survivable and still see what’s going on.

      Some terminology. Smoke – sooty result of a fire. Ash – ground up and fractured rock dust from a vokcano. Smoke has little effect on a jet engine, ash can clog it up and make it inoperable. Keep that in mind when you read news paper and online articles. I can almost guarantee that some author or editor will hose that up.

    • The gnomes spin the Wheel of Moral Tetpitude to find the correct avatar.

      • i came in early and it knew i was a little old round grandma with glasses…. mine really looks like me….even has my positive attitude…. Best!motsfo

  15. Early morning at Gunang Agung and a significant increase in the amount of steam coming from the volcano since the last time I saw it 2 days ago! Interesting!

    • This is no longer a wisp of steam where one thinks, “Did I see it or not” This is “Oh my goodness, that steam is covering a third of the mountaintop area!” Wondering if this is just an anomaly or if it will last all day? I am off to bed soon so I must leave it to other watchers now. Goodnight fellow volcano watchers.

  16. Looking right now and maybe some rocks sliding down the left side of the volcano

  17. It might be… Or it might be just the tremor made by people doing their daylight activities. Look back and you’ll see the pattern. And it’s been quite windy of late.
    But it might also be harmonic tremor.

    • Except (“repent at leisure, having checked the cams) it doesn’t seem at all windy there right now… And that’s quite a lot of tremor.

    • Hi Neil, yes I have noticed before the increase during daylight hour but this time the line is far thicker with more small peaks in it too. It started to increase at 15:30 but by 15:40 is noticeably thicker than I have ever seen it before. Then the seismograph stopped updating! GRR. On past form it takes a few hours to update once it stops.

      • Yes, I notice that it seemed to be gradually, fairly evenly intensifying. It’s another “Wait and see” situation. I’m trying to find the best cam, and at the moment it seems to be this one.

        • Doesn’t seem to be steaming as heavily as yesterday but it has always been pulsing. Don’t have time to watch it now. 🙁

  18. I’d err towards weather related signal noise. Like you Frances, I’ve also noticed that over the past few days the background noise seems to pick up during daylight/afternoon then dies down overnight, this does make me think wind is the culprit. There is also a decent bit of shake on the web cam and the clouds on the cameras at the mo are certainly motoring a bit. Talking of clouds, Bali is not the sunny paradise i’d imagined – looks more like Manchester most of the time.

    Weather is also another factor to consider with judging the apparent strength of the steam plumes, what may look like increased activity could simply be that the water vapour/humidity already present in the atmosphere makes the plumes look more impressive. This however cuts both ways, increased venting of gases could be hidden if the weather is not so conducive to cloud formation. Think airplane contrails – sometimes long streaks all the way across the sky, other times they dissipate within seconds.

    • Even given my limited knowledge I’m finding it difficult to read at the moment. Some cams are showing strong wind, and yet this one is clearly working but shows none.
      It seems you need a great deal of patience in this game.

      • Monitoring of the Last 6 Hours, Great Mountain Activities Declining-

      • Yes, weather is looking very localised to what side of the mountain you are viewing and i’m not sure where the G Agung seismo is actually located? On this cam it has been looking very inclement over the past hour, with the smoke from the fires that seem to be constantly burning being blown about a good bit. A definite uptick on the background noise as Luisport has pointed out.

        • Yes, as I pointed out further up the page, it is a shame the seismograph is now down as we can’t know how long that increased background noise has lasted. If it was still high in a few hours when the seismograph gets going again then I would definitely wonder what was going on.

          • That other cam I linked to a while back seems to have a live feed from a seismograph. I don’t know where they’re getting the feed from, but it appears to be working, and continues to show that noise.
            It was this cam.

  19. Blimey – big event on the seismo – local or a very big quake in the region?

  20. M6.7 under the Flores sea about 100 km east of Bali, registered as quite a bang.

    • Suspect there will also be a few aftershocks now showing up on the Agung seismo.

      • Yes, that will likely confuse the issue still further as to what is happening at Agung.

        • I don’t think so, the M6.7 quake was at over 500km depth – so unlikely to show aftershock activity.

  21. Tuesday
    24.10.2017 14:18:32 64.520 -17.410 4.4 km 4.0 50.5 14.4 km NNW of Grímsfjall

    • Tuesday
      24.10.2017 14:18:30 64.621 -17.443 6.5 km 4.1 99.0 4.6 km ESE of Bárðarbunga

    • Is there volcanic tremor there now? The signal looks tremor ish to this noob.

      • Yes there seems to be some tremor going on.

        This is quite important. Because it points to magmatic movements and a change. An eruption could follow, or a minor flood. Or perhaps a strong swarm will begin. Despite the fact that the IM commented that no tremor was detected, which is false.

        Tremor is detected in several stations across Vatnajokull.

        • Correction. Tremor is not visible in low frequency plots
          Seems to be just a lot of minor earthquake activity. I think it still means a change happened in Bardarbunga with some magmatic movement going on. Let´s wait and see.

          • At least there is no storm out in the sea around Iceland or anything like that. This is clearly activity detected around Vatnajokull. Could be water movement also, or just geothermal.

          • Some nearest drumplots in the vicinity:

            Only SKR (SKRO) show similar pattern,

          • Hmmm, the timing makes me wonder if this is a katabatic wind effect? This is something that has caught me out before when seeing periodic noise on Icelandic plots. With high pressure over iceland and low/no wind as the forecast i would immediately discount weather as a possibility when seeing noise. However, looking at data from the actual wesather stations in the valleys around the ice caps, there were repeatedly very localised winds well in excess of 30mph during night time hours, presumably as the result of dense cold air running off the glaciers.

            In this case, the nearest station to Von and Skr is Hágöngur and it shows a definite increase in wind 3-7am

            It’s not an exact match so tremor or something else is still an option.

          • Replying to Swebby’s point re: localised winds.
            I had been wondering about this. Surfers talk about “The evening glass-off”. This is the same effect, I believe. The difference in temperatures between land and sea changes dramatically in the evening as the land cools, and this sometimes causes an onshore wind to turn into a gentle offshore breeze, helping the waves to hold up just a little taller, and smoothing out the chop on the water.
            A simple change in local temperatures can cause all sorts of effects.

          • Look for the noise on the line to become thicker. With these traces, I expect that like to grow thicker until it begins clipping. That will appear as a solid line the traces will not exceed and make them appear to be far solid lines. If you see graboils on the plot… run.

  22. One more: Tuesday
    24.10.2017 14:54:36 64.621 -17.430 1.4 km 3.4 99.0 5.1 km ESE of Bárðarbunga

    • The first two are the same quake, the last one is the same location but shallower.

    • Well, yet another ‘normal’ day at Agung and those poor evacuees are still displaced in refugee centres. I feel so sorry for them! If it was me I would be desperate for it all to be over and to return to my home. They must be so homesick! 🙁

      • Daylight hours. Human activity builds, and the noise picks up again. There’s that pattern, right on cue.
        Let’s see if it intensifies to the same level as yesterday.
        Anyone know if they’re having a clog dancing convention nearby?

        • Haha, Neil you made me splutter scone all over the keyboard.
          You are correct, it IS right on cue, as soon as it begins to get light, people are up and about and making noise on the seismo.

    • Even with scenario #1, how would that stack up for all the altered rock on the summit of Rainer?

      For others; Altered Rock is rock that has been subjected to years of percolating SO2 and water from rainfall/snow that acts to form H2SO4 and weaken the rock, making it have the consistency of firm clay. Clay is not known for it’s cohesiveness under shaking. This is one of the stronger potential sources for a Lahar threat… something you can get even if a volcano is seemingly quiet. As far as I know, there is an extensive warning network for the municipalities that can be effected. If you live there and are in a threat zone, your best bet is to learn what local policies are and which way is the quickest evacuation route. Know it by heart. You may not have time to stop and think about it.

      When it comes to avoiding being hurt by a volcano, my motto has always been “Don’t be there.” But if you have to live there, always know the way to safety. Lahars can move quite rapidly. If you aren’t already on your way to safety by the time you hear it, you may not make it. (The same thing sort of applies to Hekla eruptions. IF you are standing at the summit and feel the ground tremble, you probably won’t make it off the mountain in time. The Hekla 2000 eruption tremor was only discernible by human senses about 15 minutes prior to it going off. That’s why Hekla is so spooky.)

      • Speaking of spooky and Halloween is near, here is a tale about a “hag.” Personally, I think she got some bad press, and may have been somewhat justified in her anger. The guy she killed probably had to deal with parasites quite a lot and she was angry that he effectively ruined an piece of difficult to acquire clothing that she owned. I’m not saying that Bardi had lice, but the era of the events occurred is about correct. Parasites would have been a concern then. Her only “crime” before killing Barði, was being large and ill tempered… and a pagan. Personally, I would avoid large angry people as well, but that doesn’t make them a Hag. She couldn’t have been extremely bad mannered, she was employed by the Abbot.

        Picture this. The soon to be dead Bardi madly dashing about the fields searching for sheep, while wearing womans clothing.

      • I started studying the Cascadia years ago and decided as soon as I could,
        to go back to NE Oregon, and put three Mountain ranges and gigatons of
        Basalt between my family, and the ‘Ol demon that lives in the cold water..

  23. Regarding the discussion on the seismograph readings and tremor….

    This human activity is something we have become used to with Icelandic seismographs. However, in the earlier days of watching the Agung seismograph I do not recall seeing these increasing / decreasing tremor patterns. I think we would have noticed them and commented on them, like I was watching for tornillos (which have become more apparent).

    This could mean two things: the seismograph sensitivity has been dialled up so human activity has now become apparent, or there really are increased periods of tremor and some of them coincide with human active times.

    If the readings are increased in sensitivity, then I pose the question: why are the brittle fractures generally no larger than they were before?

    Perhaps we need an expert like Geolurking to cast his eye over things and see if chart sensitivity has been altered? I don’t know enough about seismographs to be able to tell if MAGMA team changed the parameters of the equipment.

    • Or perhaps serendipity could intervene…. An intense and prolonged period of noise at around 2 am local time…. Although for the benefit of Frances I might postulate that such a thing might be caused by large numbers of somnambulant clog dancers !
      Or an unusually quiet period in the afternoon.
      It’s the repetition at the times of peak human activity which currently persuades me, although it did seem unusually intense yesterday.

    • Hi Clive

      For yesterdays noise (late afternoon local time), I’d certainly err towards weather as being the culprit. At the time, satellite/radar showed there were some rather hefty storms building up in the area and the weather on this cam looked filthy. It was definitely showing strong winds despite the general forecast for the airport saying winds of only 3-4kts.

      In general however, i do agree that this increase/decrease in noise is something that has only become apparent recently. Is it however a case that we are now seeing quiet periods that were not showing in previous weeks?

      • The ‘noise’ between about 0730-0830 local time today had a number of those sharp spikes which usually indicate lightning, so maybe a thunderstorm?

      • The wizard factor, in the land of the blind the one eyed man is king.

    • This is the first of two things. Seismogram is in sensitive mode now. When a lot of quakes emerge, sensitive is decreased for better visibility.

      “why are the brittle fractures generally no larger than they were before?”
      Because their energy decreased.

    • There were two quakes about M5.0 in the same area about 250km SW of Bali over the past few hours. The long tail on the seismograph from these is normal, it’s not “wet looking” but relatively long duration and low frequency shaking tapering off from a reasonably large but distant quake. If the signal wasn’t clipping, then you’d probably be able to see more clearly the arrival times of the P and S waves. Should be about 30 seconds apart – which if you look at the chart, you can make out despite the clipping.

      I don’t think I saw the daily variation of background noise before.
      For a graphic example of this see the NZ Geonet SSAM charts:
      In some cases (Auckland drum) then it’s clearly traffic – there’s less on weekends and on a public holiday last Monday 23rd. But there’s no traffic on the Kermadec drum, the daily variation must be weather.

      • Thanks Oranui.
        It may appear slow, but I’m learning. Hopefully there are plenty who can learn by reading these.
        I said a few days ago that I would parade my ignorance… by which I meant that I wouldn’t filter my posts too much…Some , yeh.. but I’m deliberately sticking my neck out when I think I’ve worked something out…Thinking out loud, if you like.
        To be clear, I am not merely using everyone here as my teachers. I’m reading as much as I can, when I get time. I hope it’s not too burdensome.

        • That is absolutely fine, Neil, nothing to apologize for. We all learn together and you contribute a lot. In the mean time Agung is still deciding what to do next and will have more surprises. The area is tectonically active. One way to check for long-duration shaking from distant earthquakes is through the USGS at (need to ‘zoom’ to the world view)

  24. Some of you have asked what the tremor will look like on the drum plots when it becomes “showtime.” I tried to describe it earlier, so here is a graphical representation. TOTALLY FAKE, it only serves to illustrate how the trace will probably appear when it starts.

    There may be a large quake at the outset, but the tremor line will ramp up to a higher level, and then begin clipping based on what we have seen of the drum plots behavior.

    And just in case anyone missed it, THIS IS NOT A PLOT OF ANYTHING FROM THE REAL WORLD. I made it here in about 10 minutes of fiddling around in order to illustrate a point.

    • Hi Lurk, All these drumplots, We are trying to interpret them by looking at them when actually they are soundwaves and we, humans, are much better equiped to LISTEN to those if they are within appropriate wavelentgth range. Would it not be interesting to transfer them to audiofiles and listen for signatures? Scientist looking for bats ar doing this. With some software they can pitch down the bat calls so that they can be heard by human ears and doing so the bat scientists now can find and study bats just by listening to them. SImilarly, I am working with DNA technlogy and about 15-20 years ago a crazy guy tried to transfer DNA sequence to audiofiles. Funny enough, it was very easy to recognize signatures representing various DNA- sequence features!
      Maybe this has been done allready for seismograms? Would be interesting to listen through a build up to and an eruption! If many drumlots are around they can be given different voices. Maybe up to a whole symphony !!??

      • Very interesting !
        I do a lot of home recording, so I have the software to hand if there is a sound recording I can play with. I could try different transpositions… different octaves… and find the best fit.
        If I had a raw recording to work from it would only take a few minutes.

        • First problem is to get the drumplot data into an audiofile. I am sure softwear that can do this already exists!

          • Busy with a recording project at the moment, but it’s a really interesting idea, so once I’m done ( a few days) I’ll have a look around. I think I may know a way anyway….sort of cut and paste onto an autotune grid, and as long as I know the pitch of at least one fixed point (as a datum point) the rest should be easy.

        • Thank you, that was extremely interesting. In fact , very interesting indeed for someone working with sound transients as wave forms. Now I’m back to my recording project…looking at the drumbeats which would be anything with vibrato…and finger picked acoustic guitar (volcanic scream) and rockslides (snare drum).
          Those are all pretty good fits for those patterns of attack ,sustain, and decay of a signal. Now I must get back and put each track through a high pass filter, to get rid of the noise on the original recordings.
          Weird just how transferable this knowledge is.

          • Example. 2.46 local time on the Agung plot.
            That’s a crash cymbal, all day long. Instant attack and long concave decay.
            Long period low tremor is the sound of a large gong, coming to its “blossoming”…That “breaking wave ” effect.
            I don’t have any of my gongs here with me, nor do I have a recording of just a gong blossoming to hand, but a year or so back I did an experimental recording to see if I could use a gong to smooth out radical changes of dynamic in a piece of music…and in the graphic, you can see the tremor building out of the African drum sound..which will substitute for noise for this purpose.
            Don’t bother with the other recordings. I write and arrange for others…I’m no singer ! And I use this account for rough ideas, as I don’t read or write music very well (“nothing to see there…move along now” 😀 )

          • Really interesting Neil. Ever thought of writing a volcanic symphony? I am serious when I say this as what you are describing could I think transfer well to music. I know next to nothing about music but my son, who is also brilliant at maths, absolutely loves the mathematical precision of music and consequently taught himself music to express some of his ideas. He has written quite a bit of music but is at the age where he enjoys dissonance in music, not something I as an oldie am so keen on.

          • Frances,
            I haven’t… but I sort of have…In a sense.
            Whilst I work with bands of a particular style, I also have interests in sound as forms of expression outside of the areas that most in the UK think about when they hear the word “Music”.
            One such is the Saami style known as Joik/Yoik. It was explained to me a Saami musician as a very direct expression of a thing…any thing. It could be a person, a moment, a place. She said that in effect you could “Yoik” a person. If you were to do so, you could use any reasonable means to express that. It may have words..or just vocal sounds. She said that these days you could also use any form of instrument, although traditionally there are instruments which were preferred.
            So I tested it, and I recorded a yoik on the subject of the evening and place we met. She heard it and said that , yes, it worked as a yoik. I recorded the music thinking about the landscape and particularly the breeze in that place.
            To do the same with a volcano, I think you would have to know it very well.
            As for recording a piece using volcanic sounds? I think , given that I’m old fashioned, and I prefer real instruments and real recordings to the electronic realms, I think I would find it exceptionally difficult. I’m narcoleptic, and if it ever got to a section which was tiresome to work on (which it would), I would hit a brick wall and start passing out. I avoid such situations.

          • Neil; times like this I’msad that John Peel is no longer with us The Agung seismogram transferred to record would have been right up his street

          • Perhaps you misunderstood me Neil, I was interested in you suggesting that certain seismic forms would suggest certain instrument, as for instance your suggestion of cymbals for one. That really resonated with me, (No pun intended. 🙂 ) as I could see exactly what you were meaning even though I have almost zilch knowledge of music. The fist musical instrument I experienced at age 4 was the cymbals, I don’t think anyone was impressed. 🙂

          • Sorry to hear about your narcolepsy Neil, I have a friend who suffers with it, when we go on a bus I am always ready to stop her falling on the floor when the driver corners sharply. She will literally fall asleep at the drop of a hat, often over dinner.

          • Isn’t it fascinating. You realise of course, that you could turn this around. If I were to take the soundfiles I’ve been working on these last few days, all you would have to do would be to stick them all onto one continuous line (rather than each instrument having its own line), and the rhythmic nature of the piece removed, there are people on this blog who could give you a seismic interpretation of what you were looking at? Because they would look just like drumplots, particularly before I “clean them up” and remove the noise.
            I know gamelan, although I don’t ( yet) understand it, having never worked with it. But when it comes to music I’m something of a sponge. I want to soak it ALL up. I have particular skills in particular styles based on my experience of life, and personal preferences, but I find I always need new stimulus.. new paradigms to explore, new instruments, sounds and techniques.
            Agung would need my large gong, some small chimes, a rainstick, an African balafon ( I have one), a Russian overtone flute…and probably several other things I haven’t thought of yet. Overall it may well sound something like gamelan.

            John Peel… A DJ beloved and sorely missed by every musician I know. I agree, he would have gone for it.

            Frances, thank you for that. The condition is the reason I now run a shop rather than working with tribunal law. Whilst it unfortunately renders me pretty unemployable by most, as long as I can run my own workload and therefore maintain my interest, most days I’m fine until I get home. So I don’t have it as badly as some. But I’d make a very bad diplomat. If I get bored, I pass out, and I can’t fake it ! But believe it or not, it’s not all bad. Lucid dreams on demand is a pretty cool thing to have access to, for example. My father is now in his 80s and is much more severely afflicted, but he’s also one of the most highly qualified psychotherapists in the world, and a published author on the subject. And he’s still working , despite his age. As I say, it’s not all bad news. It’s just a bloody nuisance.

        • That was fun indeed! Thanks! not surprised that this was done already!

    • nope…. don’t know how to do that…. but down on that page there is a good example of Augustive puffing ash in short durations which look very much like Lurk’s example..

      • Well,I’m no specialist by any means. But in my mind’s eye, the show is over. Seismic activity has dropped precipitously, and the only things now showing up are weather related or distant events. Clearly a dud. The “brittle fracture” lookalike signal is the mountain settling back down after what was quite a hefty bout of intrusion.

        Agung just went Fizzle on us…. Dreadful for the refugees who were displaced and live in dreary conditions for weeks, for nothing. Don’t tell me I’m badmouthing VSI, they did the right thing, if it had gone out of hand their quick acting would have saved thousands of lives.

        But with the volcano playing cat and mouse with them just to fall back into slumber, is the worst thing a disaster prévention team may be faced with….

        Held for approval by our filter. Future comments should appear without delay – admin

        • Hi Alcide,

          There has been a big drop off in activity since the 20th but we do still have volcanic and harmonic events way above background levels so i think it’s way to early to draw a conclusion one way or the other.

          The best indicator would be the actions of VSI – e.g lifting the exclusion zone. I do not envy the person(s) that have to make that call – rock and a hard place springs to mind!

        • My own non-expert view is that it’s way too early to write this off as a dud. Seismicity has dropped, but I was reading a couple of days back that the competent authority had stated that magma had reached the surface. The drone overflight revealed a new crack open in the crater.
          It may well return to a (more fitful) slumber until the next intrusion, or it may have become quieter because it has done most of the required rock cracking (as per Hekla?)
          But it’s still steaming like a train at this moment, so there is certainly significant heat in the crater.
          I don’t know which way it’s going to go, but I do remember that a month ago, people here who know better than I do were saying that the likely sequence of events would be exactly what we have seen thus far.
          In the case of this particular volcano, I too would be happy to see it quit its rumblings. It isn’t miles out in the middle of nowhere. This has, as you say, already hampered the lives of many thousands of people.
          But even if it does settle, it will do so in a more pressurised state than previously. Perhaps it will have a shorter fuse at the next intrusion (?). If that’s correct, that would make it much more dangerous.

  25. volcanoes don’t just “erupt once and done” they continue for some time destroying lives and homes and food sources esp in this area. i for one will be relieved if this just goes away (and stays away). VSI did great but will probably be on the rack for a while.
    1am here… so tired, loopy.
    Best! to the rest of You…. motsfo

  26. I don’t know about Agung slowing down – I have my doubts. Between 11:00am and 12:00pm (Bali time) this past day there were some very interesting readings on the seismograph. I’m not any expert, but could they have been drumbeats? Either that or a guy with a jackhammer on the road down form the Mountain Observation Post!

    I feel things appear quieter because the rock-cracking is done. All we wait for now is a pulse of magma from below and away she goes. I think Agung is in the “the lull before the storm phase…” Still very dangerous unless we’re told otherwise by MAGMA.

      • Haha, and at 23:30 local time the somnambulist clog dancers start too! 🙂 Sadly they weren’t as fit as earlier in the day so only managed a 7 minute routine!

    • Definitely a decline in activity, which points at a failed eruption (or, as Mike would say, a successful intrusion). It is not all over though. The 2009 Harrat Lunayyir intrusion comes to mind, where earthquake activity ceased for 9 months before the real intrusion began – although it was still halted 2 km below the surface. Or Montserrat: large earthquake swarm was in June 1994, but the eruption did not begin (feebly at first) until July 1995, and the main eruption began in early 1996. There is now a pause, but whether it will be days or years before re-ignition is up in the air.

    • this video suggests significant drop off in overall activity – then haphazard quakes (which would seem to fit the current pattern – but I’m no expert) then becoming drumbeats is likely in progression toward eruption

      • Thank you very much for posting that video Edward, I found it extremely interesting. The older I get the more I find pictorial scenarios, along with vocal interpretation, to be a far easier way of learning. Eyesight not as good as it was for deeper reading and concentration not so good. However that video explained things in a manner even a newcomer to the subject could easily understand.

      • If you look at Pu‘u ‘Ō‘ō (POC) tilt it also had a large shift on the 24th. The update page states this.

        Puʻu ʻŌʻō Observations: In the past day, seismic activity has continued at normal, background rates. The tiltmeter on Puʻu ʻŌʻō cone recorded a slight deflationary trend in the past day; a sharp inflationary tilt signal 24-36 hours ago was related to very heavy rainfall.

        I wonder whey the UWE Kīlauea did not take as much of a hit like the other two?


        • From the various plots, it seems that this quake released some of the stress at the summit that had build up over the past months, as the mountain expanded.The plots had shown a jump late September which has now reversed.

  27. All the EQ activity reminded me of North America’s largest in Alaska 1964. I had read from LiveScience, under facts about the 1964 Alaska EQ, the tallest out of the tsunami wave height it created was 219ft/67m. Such a terrible disaster had helped scientists understand many things for future EQs. Video from USGS.

    • Hubby blames his little brother for the ’64 quake… their mom came into the room and said “Turn that TV off, we should be praying or in church.” (because it was Good Friday) but he snipped at her:”Oh, mom, that was 2000 years ago; it doesn’t matter today….” AND the earthquake hit, tv smashed on the floor and they road the quake out for 5 minutes on the couch….slamming into opposite ends of the room as the floor rolled like the sea below them…. Dh says he didn’t think he was going to die, he knew he was going to die. Everyday since then is gift. And every Good Friday the little brother is in church… drunk or sober…. in church. Best!motsfo

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