Kawah Ijen and Active Mitigation

The famous burning sulphur of Kawaj Ijen. Photo by Seshadri K.S., taken from Wikimedia Commons.

The famous burning sulphur of Kawaj Ijen. Photo by Seshadri K.S., taken from Wikimedia Commons.

Imagine that you are Gunung Merapi and that nobody cares about you since there is much more famous volcano named Gunung Merapi. And to make things worse it is also located in Java, Indonesia. So, you think long and hard and through a few well placed eruptions you create a side vent with a very special feature. And once more you are neglected since everybody knows your nice new side-vent and forget about you even more.


Kendeng Caldera with known volcanic features. Image from Global Volcanism Program.

Kendeng Caldera with known volcanic features. Image from Global Volcanism Program.

Kawah Ijen is located inside the Kendeng Caldera (sometimes called Ijen Caldera). Kendeng has no less than 4 ring-fault volcanoes that are known as Ringgih, Merapi, Ranteh and Jampit. There are two extra caldera volcanoes, Suket and Raung and to top it off there are 13 intra-caldera volcanoes and vents. One of those intra-caldera vents is the side vent of Merapi that we are going to talk about today.

It is the spectacularly well known Kawah Ijen, most famous for its blue flames burning in the night and the sulphur mining that is being done there. The last part is probably the most dangerous line of work on the planet.

It is though the least well known feature that we are going to talk about today. Inside the crater is a 1000 by 700 meters baby blue lake. Normally amateur poets would descend on such a lake to write bad poetry, but in this instance that will not happen since we are talking about one of the world’s largest potential natural disasters.

Anyone who has ever gotten a drop of car battery acid on their hands knows how acidic that is. A car battery has a ph around 1. Kawah Ijen has 0.2 in ph, and it contains 31.5 million cubic meters of acidic brine caused by sulphuric gases being scrubbed in the rain-water filled lake.

So, basically what looks like water is sulphuric acid that is diluted by salt water and particulate matter that is suspended in the mix. In this case 1 liter of water contains a whopping 100 grams of particulate matter. The amount of sulphur is so high in the water that large rafts of sulphur float on top of the water. And to compound the problem even further, the water is high in heavy metal content.

The lake is kept intact by a natural dam that has been reinforced due to structural weakness. But, to all points and purposes even a small volcanic event, an ill placed earthquake, or even natural erosion, is all that stands between the nightmare waters of Kawah Ijen and a city of 1.2 million people. And then we have not talked about the effects on the river system that irrigates countless farms in the region. To all points and purposes it would be the largest industrial accident in history, only that it would be nature itself that stands for the devastation.

This has made the Indonesian Government to make a broad call for ideas upon how to actively mitigate the hazard of Kawah Ijen.

Risk of Active Mitigation of Lake Ijen

Lake Ijen, the dam is in the upper left corner. Photograph by Okkisafire by Wikimedia Commons.

Lake Ijen, the dam is in the upper left corner. Photograph by Okkisafire by Wikimedia Commons.

As late as 2012 there was a high degree of unrest in the volcano caused by an intrusion of magma at very shallow depth, probably the intrusion was as shallow as 1.8 kilometers below the volcano. This directly affected the water table below; in turn this caused blasts of acidic water, sub-aquatic emission increase and increased temperature of the lake.

With such a shallow intrusion of magma any lowering of the over-burden pressure causes high risk for an eruption. As such, fast removal of the water would most likely cause the catastrophe you are trying to mitigate.

An outline for active mitigation of Kawah Ijen

As I see it there are 3 ways that you could mitigate the hazard. I will begin with what I perceive as the worst way to try and go about it. And that would be to try and scrub the acidity in situ.

The simplest way would be to use helicopters dropping finely ground calcium hydroxide (slaked lime) into the lake, or pumping a slake lime solution into the lake. This would raise the ph of the lake and increase particulate size sufficiently to remove a lot of particulate matter since gravity would force it down towards the bottom of the lake.

The problem is that this would involve such large volumes of calcium hydroxide that you would quickly raise the level of the lake so that you risk compromising the precarious dam. You also risk clogging up the hydrothermal vent systems in the lake so that pressure rapidly increases and a series of hydrothermal detonations causes an eruption.

In my view this would at best produce a less acidic outburst of water and at worst it would cause the dam to burst before you have gained any effect at all.

Solar powered mitigation

The beginning of the crater wall of Kawah Ijen with Gunung Merapi in the background. Image from Global Volcanism Program.

The beginning of the crater wall of Kawah Ijen with Gunung Merapi in the background. Image from Global Volcanism Program.

In this case you would drill a wide bore non-corrosive tube at an upwards angle into the lake so that the opening is at about 100 meters depth. This would ideally in the end remove 80 percent of the available water over time and greatly reduce the risk of dam failure, or that an earthquake would pierce the crater wall in such a way that water came out. It would also severely decrease the risk of a spill out during an eruption.

If this is done over a prolonged time the risk for a de-pressurization eruption is fairly low, and even if it happened there would inevitably be less water contained in the lake. And in this case every single meter the lake is lowered is a victory. Because, whatever we do the volcano will sooner or later erupt again.

If you increase the rate of removal with ten liters of water per second you would empty out the lake completely in 100 years time. If you aim at removing 80 percent of the water it would take 80 years at this speed. Just remember that every single meter of lowered water level in the lake would be saving lives.

Removing all of the water is in this case pointless, the point is to make the problem manageable and diminish the risk of dam breaching and earthquake spill over. There is also a high risk for local tsunamis caused by crater wall landslides and seiches.

The idea here is that you build a series of meter deep square ponds out of concrete, perhaps 10 by 40 meters and cover them with black roofs. The black roofs would create a warm environment that would increase the rate of H2O loss and in a little while you would get a powdery residue of sulphur, salts and metals.

After enough refills you get a deep layer of residue that you would need to remove. Here you would need to employ quite a bit of cunning since we are talking about highly toxic waste. You would need to find a cheap way of removing the sulphur and sell it to local sugar factories, the metallic salts could be sold for its metal content if you are lucky.

The worst case scenario would obviously be to dig all of it down and cover it up while you wait for the next big eruption.

The advantage is that it would be fairly cheap and create a few jobs locally. But, the problem is that it would be creating a lot of highly hazardous waste, about a kilogram per second if you would be handling the minimum of 10 liters of water per second.

Water treatment mitigation

The lake with the dam to the left. Photograph by Lee Siebert, The Smithsonian.

The lake with the dam to the left. Photograph by Lee Siebert, The Smithsonian.

This is my preferred option. The greatest drawback is that it would cost more than the solar powered version and about the same as the calcium hydroxide injection into the lake. But it would produce dramatically less toxic waste (but the same amount of waste) as the solar powered solution and be far safer than either of the other solutions. It would also create a few local jobs.

It begins with the same wide bore pipe being drilled in as with the solar powered solution. But instead of being dried out by heat you treat it as waste water.

The first step would be treatment with calcium hydroxide to raise the ph-level to the ambient level of the river you will in the end let the water out into. The calcium hydroxide will create larger particles that can be scrubbed out of the water.

Next step is repeated aeration of the water to make the particulate matter buoyant, this makes it easier to sweep it out since it would create foam on top of the water.

The next step is sand filtration passages to remove the last of the particulate matter. By now any particles would either be at the bottom of pools ready to be sucked up and dried, or scrubbed away as foam and dried, or being stuck in the sand filters.

The reason for removing the particulate matter is that it would as the water is released end up in the gills of any fish in the river systems and risk killing them over time.

By now you have ph-neutral water that is low in particulate matter and with a manageable content of heavy metals. Some heavy metals still remain in the form of salts, but there is little you can do about it without incurring massive cost. And remember that these metallic salts would anyway unceremoniously be dumped into the river systems if the dam breached or there was an eruption at Kawah Ijen in far greater amount than from the treated water.

The remaining water would then be allowed to flow down into a river dilution pond where it is diluted with a factor of 1 liter per 100 liters of fresh water before being injected into the river system. Since the water is slowly let out and is far less toxic it would not constitute a health hazard for the population, nor would it endanger the flora and fauna.

The waste would mainly be constituted by various sulphates, carbonatites and silicates. These are fairly inert compared to what the volcano already contains, so they could safely be reinserted into the volcano. This would as it happens lower the de-pressurization with 10 to 20 percent. As such it could help to delay any de-pressurization eruptions from happening, and it would for all points and purposes be a pretty good place to store it in since the volcano either way would have ejected it in a far worse form if it had been left alone.


Active Mitigation of a volcano is at best controversial. At Kelud the lake has been mitigated for a long time, a practice that has saved a lot of lives during the last eruptions. At Kawah Ijen the risks are far greater since the mitigation might produce a premature eruption. But, in the end you are risking to set off prematurely what would have happened anyway. And in the end, even just a few meters of less water height would shore up the dam and produce a significantly diminished acidic lahar.

To me the benefits would be larger than the risks. Here I leave it to the respected readers of Volcanocafé to do what they do best, discuss matters and weigh in. I think that anyone who is really going to do this project could do worse than read the comment field.


91 thoughts on “Kawah Ijen and Active Mitigation

  1. While I do not have the expertise to give an opinion on mitigation strategies, it does strike me that a lake of concentrated sulfuric acid laced with elemental sulfur and heavy metals is not so much ‘toxic waste’ as a chemical industrial feedstock of some considerable value. The problem is getting it from Ijen to a chemical plant far enough distant to be safe from a magmatic event, but close enough that the transport costs are not excessive.

    BTW I wouldn’t call the sulfur extraction at Ijen ‘mining’. Quarrying would be more accurate, surely?

  2. More stuff I didn’t know! Thanks Carl! Great article!

    Why could you not mine the metal salts (via vacuum), not unlike they do with the Sulfur.

    Crud. Just noticed Michael Don said as much the same above.

    Anyway, again, Great Article!

  3. Harvesting the metal salts would be one idea, it all depends on the infra-structure obviously.

  4. Also, with a pH of 0.2, what kind of hydro-thermal and chemically altered rock makes up that edifice? I can see why the locals are worried. A sector collapse and subsequent lahar is bad enough as is, but make it an H2SO4-laden lahar and you have all kinds of different problems on your hands.

    Wow. Just. Wow.

    • That is why the regional government has decided that enough is enough. After all they still suffer the effects of the 1817 eruption when the lake last came barreling down the rivers.

      • Really interesting article. I decided to take a peak at the lake in Google earth (as I usually do) – I noticed that the breach is situated on the side of the caldera, which would likely make it pour out into the caldera itself. Not that this wouldn’t be a large environmental disaster, but wouldn’t this avoid the populated areas quite a bit? I didn’t see any cities or noticeable settlements inside the caldera limits, likely avoiding the 1 million population centers on the eastern coast (I think).

        • The problem is the Banyo Pahit river that goes out of the caldera through a breach. That is what is leading straight into the populated areas.

      • But again, what exactly can you buttress your embankment with when you have a lake of (literal) battery acid behind it and expect it to hold for ANY REASONABLE amount of time?

        A steel-reinforced concrete wouldn’t work as you would only end up with a slurry clay powder and mildly salt-water diluted battery acid. A glass substrate might work a little better, but there isn’t a non-reactive mortar that I am aware of that would be up to the task. Even if you find something, eventually you are going to see the lake eat around the dam or overtop it via landslide/hydrothermal tsunami.

        Anyone have a km3 of lye or chalk laying around that you could FedEx to them?

        • The dam is leaking a lot already. And your points are exactly why I think the only way to not have a dam breach is to lower the level of the water as fast as possible.

  5. Reading this left chills traveling down my spine. Sure glad I don’t live anywhere near that area. Nicely written and thought provoking article.

  6. What are the water and sulphur budgets of the lake? How much rain is added per year, how much evaporates and how much runs off? How much sulphur is added per year, how much is lost?

    The trick is to change small fractions of the lake per year. Evaporation makes things worse so you want to change the balance between run-off and evaporation. Even 5% per year would quite rapidly improve the water quality. The first run-off will the worst, but it sounds like some is escaping now anyway. Of course, if you can catch the run-off and let it evaporate away from the lake, that would be a good solution.

  7. If one tries to deal with the problem in situ, no matter what method is chosen Murphy is guaranteed to strike. IMO the only “safe” way to deal with it is to remove the lake once and for all:

    1. Build a neutralisation and extraction plant at a safe distance (think 100 olympic sized swimming pools to contain the acid water for processing)

    2. Build a canal to lead the crater lake water to said plant

    3. Breach the wall in the correct position incrementally to drain the lake and make sure it stays it breached

  8. There has been a 5.0 mg earthquake in the strait of Gibraltar this morning at 04:40 followed by another 5 earthquakes until now 06:22 .

    Can anyone explain what is happening in this area and what could be the cause and where this is all leading to.

    • The 5.0 was widely felt in Morocco and southern towns on the Costa del Sol.

    • Good morning Jan!
      That earthquake happened in the Alboran volcanic ridge. It is notable for the Alboran Islet volcano.
      It is quite likely that this is volcanic in nature, but the EMSC-CSEM has not divulged any details as of now.

      I have been tracking these earthquakes for some time now, but it is still hard to say if this will stay as an intrusion under the Alboran Ridge, or if there will be an eruption.
      If an eruption occurs it will most likely be a sub-aqueous eruption or surtseyan eruption.
      The only associated risk is flank destabilization of the ridge, any volcanics in and of itself is unlikely to cause harm to humans.

      • Thanks for the clarification Carl – who does the small volcanic island belong to? Is it Morocco or Algeria?

        • Alboran Island belongs to Spain. They took it for El Alboran, a Pirate way back when.

    • Thanks for the explanation I will read up on the Alboran volcanic ridge today .

    • Siphoning sounds good, problem is there is a limit to how much a siphon can suck up above fluid level before dropping down the outlet tube, I think it’s about ten metres?

  9. Can anyone explain why on the linked-to site below, in the left-hand column there are often apparently big noises without a corresponding earthquake? I mean the one at 01.30 today (in red) was huge but there’s nothing on the charts, and no corresponding large earthquake worldwide.


  10. photos I found on the internet of Kawah Ijen

    best view by a dam site:

    wonder what it pays? wonder where your match heads come from?

    family picnic anyone?

    • Great pics – quite useful for illustrating how close the water is to the breach in the crater wall.

      • It is probably not a coincidence that the lake level is so close to the dam. That is the level you expect if inflow on average exceeds evaporation. The best way to mitigate the lake is to reduce evaporation. That will give a bit more overflow, which will carry away more of the lake water with its minerals. The run-off can safely evaporate elsewhere, and the lake will over time become less extreme.

  11. The wife and I visited Bali at the end of January for 6 nights. I soo wanted to take a trip to ijen but the driver we hired said that the approximately 160 mile round trip, a 2 hour adventure on interstates in GA. USA, could take 16 hours due to the roads and traffic. So we only visited Batur and some of the older cones around the Jatiluwih Rice Terraces. Very nice trip.


  12. Bear with me, it’s a halfway stupid question.

    What are the dangers of “lake” overturn? Is the (de facto) acid vat stratified in it’s water content?

    If so, how would this impact attempts to pump the lake? What would be the dangers of aerating it? Is there an alkali sort of gas that could be used to neutralize the water in place without adding to the liquid mass? Failing that, maybe they could try using “water” extracted from it, treat it to an alkali state, then feed it back in? This would work towards controlling the lake level, and neutralizing it at the same time (in a controlled manner)

    I guess the limiting factor is how fast the water can be treated and released outside of the lakes watershed without causing problems from the mass change felt by the crater floor.

    Another idea, (even more stupid), is to manufacture a set of plates suspended from floats and wired to act as a battery. You would get power from the floats, and the action would slowly deplete the electrolyte. Building up a depleted region near the surface would probably not be an issue since the electrolyte changes specific gravity as it becomes depleted. It would self mix. Hardening of the electrodes would be an issue as they are used up. But, re-manufacturing/replacing them could be an industry unto itself, covered by the mitigation budget. Scaled up enough, it might even be a viable psuedo-green energy source. (much “greener” than letting it sit and eventually flood down valley as concentrated acid.) Even the much vaunted acidic soil loving azalea can’t handle pure acid.

    The crater wants to be a battery, help it out.

    Caveat: I have batteries on my mind right now. Just changed out 80 lbs of them arranged in sleeves. Had to drive home with dried acid residue on my hands. (I misplaced my sodium bicarb solution squirt bottle that I usually use when fighting batteries) Odds are, those pants are done.

    • First I would say that the danger of water overturn is rapid release of gas. Think Lake Nyos.
      The battery idea is pretty cool, but the water is just to dirty for it to be working. To much gunk suspended in the water.

  13. So I was doing a bit of reading and noticed something mildly interesting about a very large volcano in Japan. Now, I’m going to preface this with a very large “volcanoes do not follow schedules” type of warning. This somewhat proves that point.

    At this volcano, there have been 14 VEI-4 eruptions in the last 4000 years. All 14 eruptions occurred between 2010 b.c. and 886 a.d., averaging a recurrence interval of close to 200 years for every VEI-4 eruption. Since 886, there hasn’t been a single eruption here, leaving us with over 1100 years of quiescience.

    I Just think it’s interesting how a volcano can seem so “regular” (although interval between eruptions did go as long as 600 years at times) to a much longer period of dormancy.

    • Ooh, right you are. Definitely a poster child for “volcanoes that don’t like stats.”

      Right now, we are at the “has probably already erupted” portion of the curve. In other words (for them that are curious), based on the eruptive history of the system, it should have already gone off by now, yet it hasn’t. Sort of an inverted Black Swan…

    • for a volcano to erupt, it needs to be fed, where does it come from, especially because of its ‘known’ brew, subduction zone not far away, with plenty of water available …..

  14. Yesterday was the Ides of March, traditionally the end of the roman new year celebrations. Today is back to reality. Is that spanish/maroccan/tunisian volcano still planning to erupt?

  15. There’s a bit more earthquake action again on Vatnajokul this morning

    • Yesterday morning another series of deeper quakes just north of Askja.

      Tuesday15.03.2016 07:52:42 65.071 -16.671 18.1 km 0.2 99.0 4.8 km NW of Dreki
      Tuesday15.03.2016 07:50:52 65.074 -16.705 16.5 km 0.4 99.0 6.2 km NW of Dreki
      Tuesday15.03.2016 07:50:25 65.085 -16.677 17.8 km 0.5 99.0 6.2 km NNW of Dreki
      Tuesday15.03.2016 07:49:10 65.091 -16.704 14.9 km 0.0 99.0 7.5 km NW of Dreki
      Tuesday15.03.2016 07:48:27 65.084 -16.708 18.4 km 0.0 99.0 7.0 km NW of Dreki
      Tuesday15.03.2016 07:48:07 65.081 -16.707 16.9 km 0.3 99.0 6.7 km NW of Dreki
      Tuesday15.03.2016 07:47:53 65.078 -16.691 18.7 km 0.1 99.0 6.0 km NW of Dreki
      Tuesday15.03.2016 07:46:55 65.081 -16.732 15.2 km 0.2 99.0 7.6 km NW of Dreki
      Tuesday15.03.2016 07:46:23 65.068 -16.705 15.9 km 0.0 99.0 5.7 km NW of Dreki

      Source IMO

      • These are all very low magnitude quakes – the proverbial “cheeseburger” quake if we’re going off strength, although the depth interests me here.

      • Yeah, go ahead and think that. It keeps the swans alive.

          • Eruption at Bardarbunga does not even qualify for point one of a “black swan” event,as it is an active volcano in a very active volcanic zone,so an eruption from the Calder is not an outlier.No unless something dramatically different starts happening there it’s time to look elsewhere….😊

          • “so an eruption from the Calder is not an outlier”[sic]

            Which is diametrically opposite to the meaning of your 18:41.

            You can not have it both ways. If an eruption from the caldera is “not an outlier” then Bardarbunga can not be logically inferred to be extinct.

            Black Swans come about from the assumption that the lilihood of a hazardous event is effectively zero. Being an assumption, it is a construct of human perception. With no humans, there are no Black Swans. Erroneously assuming a threat of zero and then having it show up anyway, is the core essence of a Black Swan event. In keeping with Taleb’s original idea, the effects of said event have to be profound when they happen.

            Explaining it away after the event is usually part of the process.

            Bardarbunga or Grimsvotn throwing a VEI-4, not a swan. Doing a repeat of the roughly 8000 ybp event… definite swan.

          • Yes but nobody assumes that the possibility a large caldera eruption in Iceland, is zero or close to zero.Now a large eruption occurring in England maybe considered close to zero and if it happened ,explanations for it occurring would be forthcoming as though it should have always been a possibility and the effects would be more extreme than in the much lower population density of Iceland?

          • The movement of that large a mass of magma might be noticeable. New Zealand’s magmatic generation systems might be able to get the mass in place and erupted before any one notices, but England doesn’t really have a source like that.

          • F.a.o our friends at the IMO:

            What are the current odds? Please put me down for a tenner on “within a week”.

          • So much for that Dodo idea…

            16.03.2016 20:54:55 64.149 -18.345 7.2 km 0.7 99.0 10.3 km NNW of Laki

            Hello Veidivötn fissure swarm…

            Hat tip to Carl who noticed it firstest.

            (“firstest” → alleged term coined by Gen Nathan Bedford Forrest as in “get their firstest with the mostest”)

  16. Interesting.

    25 km to the coast. Run two lines. one draining the lake, one replacing the lake water with sea water. A smart engineer could probably figure out how to use the difference in water density and the significant hydraulic head as a tool to help pump the sea water back up. Keep the lake at the level you want and slowly dilute the acid pond by replacing it with sea water.

    The effluent outlet in the ocean would not be a place to go fishing but the dilution factor is enormous and it would be a localized impact only. One way or another that acid lake is going to wind up there someday anyway

      • Nope, but I have seen what happens when you add it to a beaker of powdered sugar. Instant toasted marshmallow. And by toasted I mean BURNT of course.

        The only thing in physical science lab that I found more impressive was when my teacher took one cubic centimeter of pure Na and tossed it into an aquarium, because … reasons? The resultant explosion and ad hoc fireworks display (of flaming Na chunks) was awesome. Both were better than when we burnt through a lab table (and almost the floor) when a smallish pile of powdered Mg accidentally lit when a bunsun burner was knocked over into it.

        …..Man, I miss the 80’s.

    • “significant hydraulic head as a tool to help pump the sea water back up”

      Don’t forget, there is free electrolyte in the form of lake “water.” As for the particulates Carl mentioned, use a resilient nylon mesh seine to collect them for input to a smelting operation for the metals.

    • It might also be possible to convert the lake into a non flowing (slower flowing) jelly like mass with lignosulphates or some other acid resistant gelling agent.

      You have to be mindful of the oxidation byproducts though, some ligninsulfonates turn into vanillin when they oxidize. The whole area could wind up smelling like cookies and burnt matches.

      • Several years ago, I had an Easter egg hunt in my yard for the grandkids. We were quietly chatting away watching the kids go bonkers doing their search. A screech from around the corner of the house got our attention, we looked just in time to see one of them fleeing quite rapidly from what he had found. An egg from the previous year that exploded in a puff of yellow stinky dust when he picked it up.

  17. So, I have a question. It is about dinosaurs and their extinction. There has been some recent research that has put the Chicx impact crater occurring after the K-Pg event. I don’t want to argue that (because I know what I don’t know) but I wonder…. Ir is the marker, it is 30x the background level at that strata boundary, and it is fairly uniform worldwide. And the mid-Atlantic Ridge has been pumping out new sea floor regularly for about 150 million years or so. They even use it for tree rings for pole swaps. Why not count backwards to 65 million years, punch a few cores into the floor and see if the Ir is there? It may not prove it was the cause, but it could prove that it wasn’t. There should be a distinct line of Ir on both sides of the ridge, equidistantly each way. If you don’t get the line until 50 million years, then…. And you can get the age based on the aforementioned pole switch lines by crossing them with the Deccan Traps. Make sense?

    • Yes, it does. But it has to get funding. And someone competent to undertake it.

      One of the beauties of Volcano Cafe, is that occasionally we discuss a topic that sparks curiosity in the casual reader. Some of our ideas would make excellent research projects… if one had the resources to pursue it.

  18. I was thinking. Could the Bolivian supervolcano had a moderate eruption in the beginning of the 19th century? Others said the south of Peru was a possibility for a volcano eruption. Putana was named, Huaynaputina is a possibility but had already a large eruption in 1600. But I think the Bolivian supervolcano is pretty unknown?

    • Which Bolivian supervolcano do you speak of? For sake of clarity, lets not use the word Supervolcano – lets just go with large caldera complex since its a more accurate word that better describes things.

      Do you mean…

      The Los Frailes ignimbrite plateau?
      Pastos Grande Caldera?
      La Pacana Caldera (just south of Bolivia in Chile)?
      Uturuncu (not erupted as a large caldera eruption, but has potential)?

      Or possibly other massive volcanoes in the general area of Bolivia, but not part of Bolivia itself such as the Pastos Grande caldera?

      But to answer your question, its certainly possible one of these massive volcanoes had a small eruption in the 19th century. Many large caldera complexes erupt with a fairly high level of frequency, but only do so in small eruptions. In Bolivia, these volcanoes are very remote, so a small eruption could have gone unnoticed or unrecorded.

      As for eruption frequency of large volcanoes, many “supervolcanoes” erupt quite regularly.

      You can even watch a large caldera erupting fairly regularly here – http://www.opentopia.com/webcam/8683 (Sakurajima for reference). Others such as Lokon-Empung or Soputan (part of the Tondano caldera complex) have been erupting quite regularly throughout modern history.

      Tarawera erupted a VEI-5 eruption in the late 1800’s, which is more or less part of an enormous string of calderas in the Taupo Volcanic Zone (closest to Okataina).

      No idea how you got hung up in the spam-box.

      • Yeah, sorry for mentioning supervolcano. Massive calderacomplex is probably more accurate. Or maybe the hotspot (a volcano in the hotspot (i think volcanism there is created by a hotspot if i’m right?), i don’t know which volcano, but i meant one of those volcanoes there. Is the volcano Putana also a part of that massive caldera complex in Bolivia. I saw it borders Uturuncu.

        • Believe it or not, most of what we would define as “supervolcanoes” do not actually form from hotspot volcanism. There is only one hotspot volcano that we could define as “super” (capable of producing VEI-8 eruptions) in the last 10+ million years ( at least from my knowledge). That volcano of course is Yellowstone.

          The Altiplano area (the region in Bolivia where these enormous caldera eruptions have occurred) is a bit strange in that the calderas and large eruptions don’t seem to follow any real pattern of erupting from a few distinct spots. They seem to kind of just pop up in assorted areas in the region similar to what we see in the Taupo Volcanic Zone in New Zealand.

          One thing worth noting is that the area hasn’t had much major activity in the last million or so years. There were spikes in the large eruptions around 10 million years ago, and another around 4 million years ago. Since then, in terms of large eruptions, there has been one known vei-7 ignimbrite eruption in the last million years, which seems to be roughly around the same size of the Tambora eruption. This area certainly isn’t dead, and it can definitely create large eruptions, but it’s not particularly prolific in the grand scheme of things.

          I would highly recommend loading Google earth, and doing a hover-over of the entire area. It’s a graveyard of volcanic features almost everywhere the eye can see, and due to the lower rate of erosion there, the volcanic features are extremely easy to spot.

  19. And for those dreaming dark dreams about large Icelandic eruptions today was not a good day.
    Nothing overtly volcanian at Bárdarbunga and Askja. Bárdarbunga continues to suffer from settlement earthquakes after Holuhraun and Askja is keeping up the deflation.
    Grimsvötn is perking up, but is still some ways away from an eruption.

    Alboran Ridge is slowly getting there it seems though.

    • Iceland is probably the wrong area in the world for those dreaming dark dreams of big eruptions. Not that it can’t happen, but your odds are much better in other areas than Iceland.

  20. Is it my imagination, or does Iceland’s seismic activity seem to turnover regularly? Almost like it is “breathing”? I pop in to check the charts regularly and there’ll be a couple of days of tremors all over the place, before it goes quiet once again. Set aside wind, sea and traffic events, you’ll get a few days quiet before tremors increase again for a little while.

    OK, thanks for entertaining my dumb thought. I’m getting my coat and am leaving the building… 🙂

    • Sadly missed, and it seems like the last years of his life were stricken with personal sadness. KE made rock seem musically serious to me in my youth, though the antics with the Hammond on some clips look a bit silly to my eyes now. Still, youthful frustration and agression need their outlets.

      Re the clip you’ve posted, I watched it yesterday and couldn’t work out what the link was between the Yamaha keyboard and the synthesiser behind him. Anyone?

      And it’s just over a year since the great Daevid Allen died, founder member of Soft Machine, founder of Gong, and digger of holes in space.

      • I blame Santa Monica. California has a way of sucking the life right out of you.

      • It is the gargantuan Moog behind him that he plays the basline on, the Yamaha keyboard had VC-control of it.

  21. There has been a swarm (quiver?) of earthquakes in the South Sandwich island, with 5-6 M5+ in the past month. Judging from the map, it is somewhere around Zadovosky island, if that means anything to anyone. A highly volcanic region but also tectonic – pick your choice.

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