The Missing Piece Part 1

Big intrusions = Big bangs?

With mafic systems hogging all the attention, as a felsic guy, I feel compelled to represent my magma type. Large felsic systems are a slow burn, they spend plenty of time accumulating magma and give frequent small eruptions before releasing huge amounts of material in one eruption. These systems usually take 10s or 100s of thousands of years to recover from their massive blasts. Felsic systems usually don’t have a large supply. Intrusions do add to the volume but normally at a range smaller than 0.01 km3 a year, nothing compared to caldera-forming eruptions. It is natural to think that bigger intrusions would destabilize silic systems more than smaller ones but looking at one of the largest explosive eruptions in geological history has led me to question this.

Just because a system is experiencing a huge intrusion doesn’t mean you’ll see inflation that’ll represent the scale of the intrusion. Corbetti caldera is a good example of this and is the volcano that brought this idea into my head. This volcano is rising at a rate of 6 cm/year, not bad but something that has been observed before. The magma, chamber, and set up for this volcano, however, is compressible. This hides the scale of the intrusion and after a while, the seismic activity won’t serve as a good representation of the intrusion due to a more open pathway for magma to move through; 1×1011 kg of mafic magma enters this system yearly.

Corbetti is a very close contender to being the number 1 most dangerous volcano on the planet in my opinion. It has a strong chance of producing a caldera-forming eruption, I think it has the potential to produce some extremely intense eruptions, It is surrounded by people, and hosts a myriad of threats. This is just another reason why this volcano needs permanent monitoring.

The volcano is on the East African rift, where Africa is splitting apart, this volcano is somewhat unusual as it is a sillic system on a very healthy and expanding rift. But upon further investigation, this is not the case both in terms of the compressive setup and the size of the intrusion.

A compressive volcanic background is not well studied but I do know of another volcano that has a compressive setup this time on a subduction zone. You’ve heard the name before, Chiles-Cerro negro. During the seismic crisis in 2014-2015 deformation was observed of around 20 cm however it was found that the deformation was tectonic, not volcanic. As such there was no known volcanic deformation during this period of unrest that was caused by magmatic intrusion. However seismic analysis has shown during this period around 0.035 km3 entered the chamber in less than two years. Enough to trigger substantial deformation, as the intrusion at Laguna del Maule is around that volume per year. The compressive setup here is because of regional tectonics and less of the type of rock.

Deformation is not enough to figure out the scale of an intrusion but I don’t have access to technology to find out a past intrusion’s size so I’ll have to rely on deformation. The question is where has an intrusion like this happened before? This is a difficult thing to figure out. As past non-eruptive unrest is a very hard thing to conclusively model. I think the answer to this lies within the phenomena known as resurgent domes. A common feature at calderas, this is the result of magma going to the chamber and displacing rock, this isn’t a sign of an imminent eruption but is fun to look at and a perfect source for scary headlines. There are such domes at the long valley and Yellowstone calderas. These domes are over 500 meters high but only after 600,000 years so deformation of around 0.1 cm/ year is enough to result in these structures.

So let us look at another “Super Volcano”. Plenty enough come to mind but for some reason, my mind is on Kikai. This caldera located in Japan, to the south of the Kyushu island, is famous for producing a VEI 7 eruption around 7.3-6.3 thousand years ago, consisting of 500 km3 DRE of rhyolite magma. It is currently erupting at a subaerial vent known as Satsuma-Iwo Jima.

The caldera is 19 km by 20 km so it’s pretty big, it has a dome rising 600 meters off the caldera floor. After only 7,300 years at the most, it has produced a dome that large?! Yes. Assuming the post-eruption deformation started right after the eruption and didn’t end until now. That means this volcano has risen 8.5 cm/year. At the minimum. The earlier date yields 9.5 cm a year. That’s high but not the rate of Laguna del Maule’s current unrest. The value goes up depending on how long you want to say high levels of unrest last for.

This does not account for the magma erupting through subaerial vents or potential horizontal expansion of the chamber. If the setup at Kikai is compressive like that of Corbetti then you can expect even more magma. The fact that this is a submerged caldera gives it an edge over other volcanoes in terms of compression as this dome rises 600 meters below water. Initially, the dome started using some basic math, with 18 trillion kg of water over it or 385 kg/in2.

Kuchinoerabu-Jima, within the same region, experienced a respectable 0.01 cubic km3/year intrusion for at least 10 years before erupting and only experienced modest deformation.

Now, here’s a question, why are these systems getting these large intrusions and don’t look any closer to erupting? Corbetti may be receiving a large intrusion but everything seems relatively stable in this area. Different volcanoes react to the same things differently but if large magma intrusions cause significant destabilization why is Corbetti only moderately unstable despite this large and protracted intrusion? In fact, why do some intrusions cause smaller eruptions and not bigger ones if the overall processes within the magma chamber are the same? Do volcanoes even need thermal rejuvenation to erupt big? Apparently not. The Wah Wah springs eruption released over 5,000 cubic km DRE of magma so one would expect to find some thermal rejuvenation right? Well not at this volcano and in fact the magma seems to have been in a cool state before erupting. Thermal rejuvenation for sillic systems seems like it’s the most common but not the only cause behind eruptions.

So how in the world could a near solidus magma chamber produce one of the largest known explosive eruptions? The current models of Caldera forming eruptions have an intrusion invigorating the dormant system for the volcano, this phase is universal among countless models. The fact that an intrusion might not be needed for the largest eruptions is such a crazy and outlandish idea that a lot of people shy away from but if the scientists analyzing this eruption are right and I am in no position to assume that they’re wrong, we should investigate this proposition.

All eruptions begin with the movement of magma but what could cause the mobilization of the magma however is a different story, with no thermal rejuvenation something else would have to get things moving. Regional faults and magma chambers have an interesting poorly explained relationship. The local faults of a volcanic system have historically focused magma accumulation into a specific location. The Wah Wah springs eruptions came from highly evolved sources and likely had an extensive regional tectonic setup.

It is a well-known fact that large earthquakes can mobilize and destabilize magma. It would seem crazy however to assume that a tectonic earthquake could mobilize 5,000 km3 of magma and in fact, if the magma chamber wasn’t molten, where’d all that melt come from anyway?

The natural assumption is to think that the erupted products were the 2-10% of melt within the chamber. It would also seem unlikely that all of this melt would find itself in exactly the right spot to erupt within a massive magma chamber. Melt with silicic systems usually take the form of sills within the larger system but in my opinion, it would be too dismissive to write this off as a possibility

It would seem more likely that 1 or more tectonic earthquakes mobilized a significant but relatively small amount of magma compared to the magma released in the eruption. Whereas the force of billions of tons of rising magma against the roof of the magma chamber could generate a lot of pressure that still doesn’t explain two things. If we are to assume that the all of the already small percentage of melt didn’t coalesce into one area then how did they get into the right area for eruption and more importantly where did the heat come from? 100s of cubic km of magma pressing up against a vulnerable setting may be enough to trigger an eruption but the products of the Wah Wah springs eruptions were HOTTER than the Fish Canyon tuff eruption in which the latter received thermal rejuvenation.

Assuming all of the erupted melt didn’t pool into one area, then we have only one other option, the eruption itself rejuvenated the system. That is, without a doubt, one of the craziest ideas I have ever come up with but let’s investigate. How in the world could an eruption make turn mush into magma? This where things get even foggier because in order to really delve into this idea we would need to know the specifics of this eruption which we don’t have. Just like everything else I find interesting! Chiles-Cerro negro, volcanic winter, Tatun Volcanic group, and The other thing I am going to write about!

But I am going to stop whining and do my best to explain this conundrum. An eruption is the result of a system releasing the pressure within itself, the pressure needed to trigger this caldera-forming eruption would be orders of magnitude larger than whatever we have seen historically. This eruption released over 100 times the material of the Mount Tambora eruption. The Tambora eruption released 45 km3 DRE of magma while the Wah Wah Springs eruption released over 5,500 cubic km3 DRE of magma. (I guess this makes Wah Wah springs a VEI 9 in bulk!) So since we don’t have any specifics on the nature of the eruption, let’s use crude math and say that there was a similar difference in pre-eruptive pressure. Which leads to a chamber pressure of 55,000-68,750 Mpa or 7,975,000-10,037,500 psi. I don’t think the chamber pressure rises linearly with volume but it’s the best we can do for now. Funny things could happen with this pressure, the compression or the decompression could bring substantial amounts of heat to the system.

The magma at Wah Wah springs was crystal-rich and water-poor so I think the magma was teetering on the edge of being useless mush but was at its most volatile stage before this transition. Now just like all my other propositions I can’t actually prove it because I don’t have any resources but this does show one thing. We’re missing something on caldera-forming eruptions. If there doesn’t need to be an intrusion or thermal rejuvenation then the 40% molten threshold may be invalid for these eruptions.


97 thoughts on “The Missing Piece Part 1

  1. Corbetti among other East African silicic/bimodal systems are a concern because they are so badly monitored, the few papers I had found on these were quite dated. It doesn’t help that the poverty and warring in the Ethiopia limits outside studies – indeed a civil war started in the north of the county in November.

    We also know that this area is still in a period of active change, with the rifting of the Somali/Rovuma plates likely to continue for at least the next 10MY. One would expect further large eruptions from this area – the old cratonic crust allows for build up of complex magmas over a time period. At least Indonesia & Japan have some sort of monitoring system in place.

    I think it’s a slow burner but one more capable than most.

  2. I do like how this past few months has seen a lot of posts that have deeply questioned the traditional narrative. First a series on how basaltic volcanoes are capable of violent and dangerous activity, and now a series on supervolcanoes erupting at exactly the point we think they should be harmless.

    I dont know if this data is actually recorded but is this site frequented, or at least visited, by any high profile volcanologists? Looking back at the older articles it is a great read but its pretty much just a descriptive text of existing information, now we are at the point of directly questioning the fundamentals with great enthusiasm.

    Perhaps it is time I got involved… 🙂

  3. Sounds sorta ‘thixotropic’. Specifically, a small, local fluidisation progressively destabilise the bulk, which duly ‘Goes Large’…

    Echoes of too many spectacular and oft-fatal ‘failures’ familiar from ‘Landslide Blog’…

    FWIW, such an earthquake-triggered failure mode could have interesting consequences if you consider near-antipodal impactors. Okay, a real planet’s interior is not a mathematician’s neat ‘ringing, singing sphere’, is multi-layered, variously dissipative and ‘blobby’. eg Chix was not as antipodal to Deccan Traps as hoped. And what was antipodal-ish to the Siberian Traps’ Permian hot-spot ??

    Still, such a butt-kick only has to get lucky to remotely ‘frack’ an existing weakness unto ‘spectacular’…

    • The Deccan eruptions started before the impact, so any relation would be hard to argue. None of the major LIPs have been linked to an impact.

    • And what was antipodal-ish to the Siberian Traps’ Permian hot-spot ??

      Wilkes Land crater

      In general, the whole conjecture about Antipodal hotspots is a bit thin. But I am of the opinion that Chixilub’s antipodal nature to the Deccan traps could have set the whole system into overdrive.

      From Wacky Peek at Ya: “Plate reconstructions for the Permian–Triassic boundary place the putative crater directly antipodal to the Siberian Traps, and Frese et al. (2009) use the controversial theory that impacts can trigger massive volcanism at their antipodes to bolster their impact crater theory

      For those wishing a more encompassing discussion on the various hot spot/Mantle Plume ideas:

      • There are numerous more visible examples in outer space than there are on earth. Thing is we’re relying on plate tectonic reconfigurations and precise dating to link antipodal instances. I do believe though that the energy generated from a bolide impact has far more of an affect than we realise and definitely influences volcanic activity.
        Chicxulub was estimated to be a Mag. 11.5 at impact and 9.5 around the world was it not?

  4. How does the buoyancy-driven mechanism of large silicic eruptions factor in here?

    • The buoyancy of the magma would act as the main source of pressure for an eruption. degassing magma would provide too little pressure for the eruption. It has been speculated that instead of intrusions, magma buoyancy provides most of the pressure needed for caldera forming eruptions

  5. I can suggest three (possibly co-operative) mechanisms. All ultimately rely on decompression to trigger gas bubble nucleation that can drive the eruption.

    1. Runaway destabilization. A small eruption lowers the pressure enough to decompress more magma enough for nucleation. More magma erupts, and even more decompresses …

    2. Removing the cork from the champagne bottle. Something nonvolcanic (landslide, quake, ice melt, or even cumulative erosion over enough time) removes overburden until the pressure drop at the top of the magma chamber crosses the nucleation threshold. Boom.

    3. Shaken can of Coke. Here, a quake directly causes nucleation, with the pressure troughs in the P-waves being low enough to cross the nucleation threshold. If that doesn’t directly set it off, it’s now primed. Something pops the tab, such as a landslide (possibly triggered by the same quake), the tiny bubbles expand rapidly, and now you’ve got quite a mess on your desk.

    Dark horse candidates include something that perturbs the chemical composition. This could be an addition (think, Mentos in Coke) — a hydrothermal loop slowly introduces elements into the top of the chamber, which diffuse and percolate further; or assimilation of crustal material at the margins. It could also be a subtraction (think aging dynamite) — it cools enough that one component starts precipitating out. At some point, the capacity to hold gas drops (= nucleation) or a reaction occurs that is strongly exothermic, or something. If the precipitate plus remaining solution occupies significantly less volume than the previous solution, you get decompression, and so forth.

    The aging-dynamite version is rather worrisome, as it suggests every magma chamber with some particular subset of silicic compositions might be a ticking bomb if it’s shallow enough, going through a very unstable phase where it might spontaneously go off, or the removal of even small amounts of overburden could set it off.

    • Just faulting .. no side intrusion, no blocky flow

      Its non volcanic

      • USGS Analyst agrees, just some movement on the fault just to the south of the mountain. Darn it, I almost got excited…

  6. About Corbetti Caldera,,,is it known approximately when it was formed and how much magma it erupted? Did it form during the Holocene? As others have said, I understand there isn’t that much info around regarding that volcanic feature, and Ethiopia’s current situation isn’t helping matters any.

    • The caldera was formed 182,000 years ago with a large VEI 6+ eruption, the larger Awassa caldera is overlapped by this system. My apologies for answering sooner but I’ve had some issues relating to part 2. The volcano is scary there is no information relating to who big the system is but this system has the potential to produce some extremely violent eruptions.

  7. Tallis, I think you’re overthinking this a bit.

    “Whereas the force of billions of tons of rising magma against the roof of the magma chamber could generate a lot of pressure that still doesn’t explain two things. If we are to assume that the all of the already small percentage of melt didn’t coalesce into one area then how did they get into the right area for eruption and more importantly where did the heat come from? …..

    That is, without a doubt, one of the craziest ideas I have ever come up with but let’s investigate. How in the world could an eruption make turn mush into magma? This where things get even foggier because in order to really delve into this idea we would need to know the specifics of this eruption which we don’t have.”

    You’re jumping to the assumption that the pressure required for something like this would need to be equivalent to the pressure released by the eruption itself. Go back to your simple champagne bottle analogy. When you remove a cork, or punch a hole in the cork, is the energy used to punch that hole or remove said cork equivalent to the pressure released? The answer in most of these scenarios is going to be no.

    I think you need to view an eruption as a potentially very fast series of chain reactions.

    – We know that crystallized magma with lots of gas trapped within those crystals is relatively stable when below above a specific pressure / temperature curve. However, the transition from stable to instable can happen very quick upon a rapid drop in the pressure or a rise in temperature.

    – In the scenarios where we do not have heat rejuvenation, the eruption process is just as capable of starting from a decompression event, given that we have enough decompression to cause destabilization & rejuvenation of the molten magma.

    – If we were to get a hypothetical small crack above a very large, mostly molten magma chamber, you may get a small eruption through this new vent / fissure. So if a small portion of the molten magma is rejuvenated and erupted, what then happens to the rest of the crystallized magma that was surrounding the region which just got erupted?

    – The answer is that this could easily destabilize the area surrounding the region in which the magma was initially erupted from, which causes another eruption. The eruptions would potentially increase the size of the vent, which then causes more depressurization.

    – The process theoretically continues until all the magma that is above the heat / pressure gradient curve (relative to the conditions in the erupting chamber) is erupted outward.

    In short, it’s the quintessential example of how a small domino can cause destabilization in a much larger system.

    • Essentially what I am saying that a small domino may have triggered the eruption, I don’t think it setup the eruption.
      That’s the key point, the magma chamber wasn’t mostly molten, it was in a cool, dormant state before erupting. I am arguing that this eruption was started by decompression event but In the eruption still had to heat the magma better than thermal rejuvenation and more importantly, the eruption still had to have significant unrest backing it. I don’t believe that the mechanics behind the eruption was so simple, because if it was there would more caldera forming eruptions without thermal rejuvenation.

  8. Some deep quakes near Pahala.with some apparent tremor.

    2021-01-18 15:10:08 2 33.9
    2021-01-18 14:52:43 2.1 51
    2021-01-18 14:43:05 2.9 45.6
    2021-01-18 14:41:36 2.5 45.3

    • The current Kilauea Inflationrate is steeper than before December 2020. Probably won’t take that long until a new vent opens, the eruption rate increases or an intrusion happens somewhere else.

  9. Thanks Tallis for the time and effort…plus a very interesting topic!
    With all the recent talk/posts regarding magmatic “pressure”, I have a simple question/thought experiment that maybe you could answer….
    Hypothetically, if a hole 100m (arbitrary) in diameter was quickly bored in the middle of a tectonic plate devoid of fissures or subduction to below the MOHO, how high would the magma shoot up in the air?…or would you see nothing but a magmatic lake at the bottom of the hole?
    In other words, does the mantle/magma at depth actually produce a “pressure” on the overlying crust, or are things in a state of “virtual equilibrium”?

    • I don’t think so? While I am not sure, I don’t think that area is molten enough for magma to shoot up like a fountain, The mantle is not very molten relatively speaking.

      • Its only really liquid molten near the most major hotspots and the very fastest of superfast spreading ridges..

        Decompression melting and decompression melting of hot plume heads

      • Thanks. I’ve often wondered if there was anything other than decompression and resultant buoyancy to provide an upward “thrust” of mush into a magma reservoir. I guess in the absence of devolving volatiles or a hot spot, there really isn’t much magmatic pressure coming from below the crust?

        • When the rock in the mantle melts, it expands, and becomes lighter than the surrounding rock. This provides the force for magma to rise upwards towards the surface, even when it is no longer buoyant compared to the rock around it, like basalt rising through the upper continental crust.

          If there was no melt then it wouldn’t come up.

    • You may get a bit of lava coming out if your hole was directly over ascending magma and the drill pulled some up. Any ascending magma would cool on the way up so the hole may self-seal. When they accidentally drilled into magma in Iceland, the lava that came out only rose a few feet.

      OTH if your hole was drilled over the top of a mantle plume was approaching the lower crust, it might get interesting. But not too sure that a mantle plume would reach that high without producing any fissures.

    • If you drill that far down, you reach mantle rock which is much denser than continental rock. It would rise (at that depth it is quite ductile) but only to the level of the ocean floor, several km below sea level. Now add interesting things. If it contains CO2 (assume a partial melt), the CO2 could immediately come out and act like a rocket engine. It would propel some material up at very high speed. This would come out of the hole with explosive force. Stay well away. The ejected volume will be much less than the volume of the hole. You have made a immediate kimberlite eruption. Because you don’t add heat, diamonds will survive the journey and will be scattered around – you would be rich (unless you stayed around in which case you would be dead.) But the sides of a hole this size would collapse fast. This falls down several tens of km and reach high speed (and heat). The rebound would eject rocks at very high speed: this is an implosion. Conservation of energy tells you that you can get speeds much faster than the infall, as long as you accelerate only a small part of the collapse volume. Warn airlines and prepare for litigation.

      • Decompression melting ..

        Take a house sized chunk of the 1320 C soft astenosphere and place it on your backyard

        The glowing mass woud instantly melt to fluid basaltic lava .. and specialy if the mantle was wet.

        Astenosphere is probaly the old remains of what was once an upper mantle magma ocean

        Litosphere slides over the astenosphere

      • Thank you very much for your various insights, folks…especially Albert!
        My question originated during the Holoraun fissure eruption. At one time, it was (or maybe still is) believed that the dike extended below the crust thus allowing some “local” magma to add to the drainage coming down during Bard’s caldera collapse.
        But, when the “piston effect” was first modelled by you, and the eruption tracked your projections perfectly, it was apparent that gravity was the principal force driving the height and volume of the fountaining. If there was any additional pressure coming from below, it must have been minimal/non-existent?

  10. Given this article is about massive rhyolite calderas and supervolcanoes, I think this is somewhat relevant. Not entirely complete but this is a map of all of the Holocene vents in the Taupo Volcanic Zone, it is hard to find exact numbers because in this area the reference timeframe is not usually the Pleistocene-Holocene boundary but the date of the Oruanui eruption, so some young vents are post-Oruanui but still Pleistocene in age, I will in time add to this map all of the post-Oruanui vents.

    One thing that has occurred to me is how linear the zone really is, it is a proper continental rift not just a zone of extension. Only a few of the vents in lake Taupo are actually exactly located so this area can probably be excluded for this, but the other areas still show this very well. I was until now not aware of this situation, especially at Ruapehu-Tongariro which are at the propagating end of the zone and dont display silicic activity but are still rift oriented. One can also see how big the 1886 fissure was.

  11. Looks like 5 more tremor events near Pahala in the last 12 hours, the latest starting at 20:43 UTC
    2021-01-20 20:43:23 2.2 37.5

  12. Etna did some impressive things yesterday. Looks unusually hot.

      • Paroxysm eruptions at Etna erupt at the same temperature as most eruptions in Hawaii, about 1150 C, so the lava is probably turning to.a’a from the high eruption rate and steep slopes, and is also probably rheomorphic spatter fed lava which tends to be a’a. It is very similar to Pu’u O’o in 1985. Etna doesnt have a shallow magma storage area to allow degassing and lava lake activity, which is what would allow pahoehoe to erupt, the eruptions between fountains might not even be new magma it could just be old stuff kept hot by passive degassing.

        There was a video of its eruption in December, because that eruption the fountain was inside a crater it collected the lava better and a fast flowing bright orange lava river was visible flowing out of the crater.

        • Is there any possible conection between high active Etna and a lot of earthquakes in Croatia, Austria….or is this to far.

    • What happened to the image? There was a volcano there yesterday covered in rivers of lava. Today there’s just a grey blurry Lego block. What gives?

      • I linked to a YouTube video. Maybe it got deleted from YouTube.

    • A video of Etna’s paroxysm waxing and then waning, if it was the natural sounds it would have been perfect:

  13. The geothermal supply to Grimsvötn south caldera is very powerful, I read that the geothermal supply for the south caldera is the same or exceeds entire Yellowstone a bit. This is makes sense to keept that subglacial water body liquid. ( a very shallow high magma chamber resides under Grimsvötn)

    • I think it is just very easy to directly see the geothermal heat at these locations, because there is a visual result in the lake being there. But I would expect all large and active volcanoes, especially very active mafic volcanoes, to have a huge heat flow. Etna also has a very high heat flow, and Kilauea was able to keep a lake at almost 80 C for 2 years and that was just a tiny part of its caldera.

      If you remember back to Hectors big basalt blasts series he mentions that at Miyakejima the hydrothermal system was in direct contact with the magma and that allowed for enormous emissions. I suspect Grimsvotn is something similar, there isnt magma above the known chamber and it behaves like a trapdoor caldera.

      • My friend j.s is almost always correct. Grimsvötn is melting alot..but ya know alot about volcanism too..
        Can Chad estimate if the next Grimsvötn eruption..will be any different because of extra accumulating magma?

        • Next Grimsvötn eruption coud be large and long lived
          ( perhaps months at low to medium surtseyan intensity ) and build up a tiny Island in the meltwater lake that then goes effusive lava. There is plenty of accumulated shallow magma now.. when geothermal system is extra hyperactive.

          • Surtseyan activity needs elevated eruption rates, not anything enormous but still much faster than the couple of m3/s that lava lakes run on, underwater volcanoes dont do lava lakes. Trapdoor calderas are not good places for open vents either, Grimsvotn is both of these things…

            I have seen you compare this to the opening of the overlook crater, but Grims has been going like this for months, nearly a year, overlook crater went from fumarole to vent in a week. As I said above probably the hydrothermal system is in contact with the magma. The only way I see a bigger eruption than 2011 is if this hydrothermal system blows up, but that would require a rifting event which are very infrequent in the Grimsvotn system.

          • Wouldn’t the next grimsvotn eruption likely be in conjunction with the draining of the caldera lake? In that case, wouldn’t the pressure release then result in a paroxysmal eruption instead of a slow and sustained pace?

      • Grimsvötn will not do a lava lake.. its not that type of volcano.

        But its probaly almost certainly open conduited and rather heated. The heating been spectacular since 2017

        A long lived Surtsey like event in the caldera is a possibilty. Starts off like 2004 and then evolves into an effusive surtsey like Island. Thats called a glacial table – mountain formation.

        Yes the magma is very shallow in Grimsvötn and maybe in contact with water.. but why does it not blow up in pheratic explosion?

        • Trapdoor volcanoes basically dont do long lived summit eruptions at all, the pressure lifts the caldera until an intrusion goes through the ring fault, usually one edge, and then when it loses enough pressure it drops down and stops abruptly. A table mountain isnt going to form in the caldera, it could form at a flank vent but then it will be monogenetic.

          The hydrothermal system is probably not actually touching the magma completely, there is probably a dry barrier. If the magma drains then it lowers the pressure which allows contact and then you can get a massive explosion, that mechanism is the only way I can see anything a lot bigger than 2011 happening but it would require magma draining. Its exactly as Hector described for Fernandina in 1968.

  14. Lots of volcanic posturing lately…
    Raung, Semeru, Mayon, Merapi.
    That Indo-Philippine corner is busy at the moment. Java especially.

      • Looks like volcanoes around the world waited for 2021 to get here so they can have their turn shining in the spotlight! Now we just need one in the continental US…

    • Looks more like one of them did something and caught attention, then suddenly everyone remembered there are lots of volcanoes in this area…
      I think that there are always at least 10 volcanoes eruption in that part of the world, probably a lot more erupt less often every year. It just that none really do anything so often so we forget they are there. Its like Pu’u O’o and Stromboli, never on anyones mind until fissure 8 opened and Stromboli did a not-so-strombolian eruption…

      I think there is a good chance of a VEI 4 eruption in this part of the world this year though, and possibly a VEI 5, been a while since we had something of that scale in the explosive realm.

  15. The title on Mauna Loa stopped operating, immediately after a rapid (but not large) drop. I am wondering whether to blame the earthquake or the snow.

    • A lot of Tiltmeter started showing strange signals all over the island yesterday because of heavy rain/snow. Especially along the Upper/Mid-eastern riftzone.

  16. Where the hell is Part 2? Or at least some update on the Kilauea lava lake activity or something? This place is starting to collect tumbleweeds.

  17. Saw this video yesterday on cyclic fluctuations at Kilauea’s summit.

  18. Largest Gravity Changes Ever Recorded: 2018 Kīlauea Eruption

    • Very interesting. It points a picture of both lava lakes going a bit stale and degassing in the years before the eruption. The summit and Pu’u’O’o were in hydrostatic equilibrium, but the lava flow was limited.And it is true that the Pu’u’O’o eruption had lost much of its vigour after 2015. I had considered this as a blockage, but this suggest that perhaps deeper rift was opening which bypassed both systems. The Puna eruption developed long before it began.

        • I think that there could also be a bit of an effect of greater pressure at play here. In 2011 maybe only very light gas rich lava could be pushed into the lake, while most of it webt to the rift. In 2018 enough pressure existed to push more dense lava into the overlook crater because less was able to get downrift, or at least less could erupt at Pu’u O’o because there was apparently inflation downrift of Pu’u O’o as early as 2013.

          I winder what the density of todays lake is, I would guess it is pretty close to typical basalt because it is fed out of a vent that isnt underneath it. I think the drowned lower west vent is still open though because the lake subsided a bit during a DI a few days ago, so who knows what could happen in the future.

  19. What is with the cluster of earthquakes at Langjökull? Looks like they are deep to shallow.

    • Is it known whether the EQs in Langjokull and the Reykjanes Peninsula are generated by magma movement or not?

  20. Since January 20th, they recorded over 800 Quakes at Pinatubo , Depth between 15 – 28 Km.
    Phivolcs say, that it is tectonic.
    Any suggestions?????
    The last big bang was almost 30 years back in 1991…….

    • Tectonic? Easily. A lot of stuff is going on there. But don’t forget that it is just outside of the McCleod corridor…. where Taal resides…

      Image hijacked from my “Sleeperfish” post from some time ago.

      Additionally, Pinatubo is likely not sealed up enough to make another large bang.

        • 30 years is nothing in geologic terms. In 300 years perhaps Pinatubo might do a big eruption again.

        • Pinatubo isnt a very active volcano, it tends to go big and not often. Its last eruptive period lasted a while but it was dome building, which hasnt happened in recent years. Probably Pinatubo will do very little else for the rest of the lives of everyone reading this comment. Theres probably some other Pinatubos around the place though, inactive lava domes waiting to destroy themselves, we tend to get hung up on active volcanoes but only mafic volcanoes positively correlate high activity with big eruptions, silicic volcanoes sort of do the opposite.66

    • I have been wondering about Mauna Loa, HVO has done a great new video on it which among other things shows its recent seismic record doesnt look like the run up to 1984, but I do think it might work a bit differently now.

      Before 1975 inflation was only seen for about a year, and it was continuous though reduced up until 1990 or thereabouts, with 1984 being a big drop but not a long term decline. The 90s and early 2000s seem to have been another true dormant period but 2002 saw renewed inflation which has persisted to today with variability. That is a big difference in that there has been 18 years of inflation without an eruption at all.
      I did work out roughly that the supply rate average in these periods is about 30-40 million m3 a year, a lot less than Kilauea but still substantial, and colossal for a mafic volcano that hasnt erupted in that time. Assuming this began in 2002 18 years of that is getting on 0.7 km3, which is more than double a break even with 1984, we are looking at a major eruption in the near future at this rate…

  21. I just noticed that there could be quite a big typo in this article, its not very obvious and probably accidental, but I’m pretty sure that Corbetti caldera doesnt have an anual supply rate of 100 km3, if it did then that part of the earth would be a molten sea of lava and everythign would be extinct… 🙂

      • Yes I see, so if the magma is about 2500 kg/m3 then that is 40 million m3 anually, maybe a bit less as basalt magma is usually a bit denser than that. Much more reasonable for a volcano that is in that setting, in a rift zone, it is similar to the volcanoes of the TVZ.

      • I had to put this through google translate. Which came up with the following english translation:

        Kono arubāto wa nanidesu ka? Watashi no shirīzu no pāto 2 wa doko ni arimasu ka?

        Now English is not my first language so I may be missing something. I may be missing quite a lot..

        Have you submitted part 2 yet?

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