Ten volcanoes with super-eruption potential: Part II

We continue with a list of volcanoes capable of producing a VEI-8 eruption from least to most likely and taking into account the factors that I explained in the previous post, here.

Next volcano capable of a VEI-8 is…

6. Long Valley-Mono (USA)

The volcanism of the western United States can give you a headache in the attempt to understand it: subduction, rifting, a flood basalt, a likely hotspot and volcanoes everywhere, at places where they defy the 3 classical volcanism explanations (including Long Valley). The “weird” volcanoes that are located randomly over the country could mostly be explained by extension and a hot mantle, which are conditions prevailing over much of this area and that create zones of melting. Long Valley Caldera can be grouped with the rest of random volcanoes, it is located along a rift-like feature, Owens Valley, that also includes Big Pine Volcanic Field and the not-yet-caldera Coso Volcanic Field. It’s also a setting with tectonic shearing as shown by the 2019 Ridgecrest Earthquake.

At a smaller scale the Long Valley area is also very complex, with Long Valley, Mammoth Mountain, the Inyo Craters, the Mono Craters and Mono Lake volcanoes.

Basic geology of the Long Valley area. By Roy Bailey from USGS.

Long Valley’s history starts as a broad basalt-andesite field of voluminous plateau flows and shields, 4-2 million years ago, with dacitic eruptions showing up towards the end. This follows a common pattern for most caldera complexes. At 2-1 Ma rhyolite eruptions took place from Glass Mountain at the future east rim of the caldera, these included lava domes and plinian eruptions with some reaching VEI 6. The caldera-formation took place at 760 ka and erupted around 790 km3, falling short of a VEI-8.

Since the caldera, eruptions have taken place from Long Valley but also from the new eruption centres of Mammoth, Inyo, Mono and Mono Lake. First I should say that Mammoth and Long Valley are likely parts of the same system, they are so close to each other it would practically be impossible that their extensive mush systems were not joined at depth, plus their recent unrest also argues in favour of this.

Unrest started in 1978 after a tectonic swarm that included M6 earthquakes. Mammoth Mountain and Long Valley started to inflate at about the same time while long period earthquakes and spasmodic tremors, 10-25 km deep, took place under Mammoth. Together with strong emissions of CO2 this suggested that magma was rising below Mammoth Mountain. There have been some fatalities due to people falling into CO2 filled snow-pits and large areas of forest has been killed. Long Valley has kept inflating ever since. Basaltic eruptions are spread around the central dacites of Mammoth Mountain, this also suggests deep magma rises upwards through here as a feeder conduit and it could be responsible for supplying, heating and inflating the centre of Long Valley. So it would be the Long Valley-Mammoth system.

Further north the Mono Craters form an arcuate structure of domes and tuff rings, possibly representing the ring fault of an independent rhyolite magma chamber that would be in the low-VEI7 size range. Some eruptions from Mono Lake, even further north, may be from a new system, the youngest and northernmost of the group. Eruptions of the Inyo craters suggest that there may be a connection or bodies of melt growing between Long Valley-Mammoth and Mono so that the two could coalesce in the future.


Eruptions and cryptodome uplift took place 200-100 years ago at Mono Lake, while phreatic explosions took place in Mammoth Mountain at 500 years and eruptions from Mono and Inyo around 600 years ago. The last eruption of Mono was around 0.5 km3. With the ongoing uplift at Long Valley the entire group can be considered to be very active.

So regarding the actual potential for a supereruption, what are the chances? Separately Mono and Long Valley have a size where they would most likely result in VEI-7 eruptions if they collapsed. They would be capable of a VEI-8 only if they coalesced into a single melt body. The eruptions taking place at Inyo in between them shows this is possible and perhaps starting. However in their current state it is out of their reach, with the small volume of recent eruptions showing that the amounts of melt assembled are certainly below that needed for a VEI-8. Major changes in their internal structure and a lot of further melting is going to be needed if Long Valley wants to go for the 8.


Inyo Craters that formed around 1350 AD. By C.D. Miller from USGS.



5. Yellowstone (USA)

This one is going to be controversial, I can already feel it. Some are maybe surprised to find it here while other would argue it should be the number 1 (though most of the latter may have been scared away by previous VC posts on this subject). Either way I hope to show that none of this 2 extremes are very accurate.

First of all, plume or no plume? To me Yellowstone shows the characteristics you would expect from a deep-seated mantle plume. A head that impacted against North America in the youngest flood basalt of our Planet, the 17-16 Ma Columbia River Basalt Group. A plume tail that has created a perfectly obvious trail of calderas as the overlying plate moved over it, including at least 11 supereruptions. It is usually active over one location for a certain period then shifts forth to its next location, like oceanic shield volcano trails but with calderas.

Columbia River Basalts thought to have erupted from the head of Yellowstone’s plume and trail of calderas formed from the tail. From USGS.

Lavas of Yellowstone have a high 3He isotopic ratio, rocks with this chemistry are thought to originate from the deep mantle. All of this makes the strongest evidence, I believe, for a continental deep-origin hotspot. But… tomography hasn’t found any deep origin for Yellowstone yet. This opens a window for alternate theories to show up regarding how it formed. There are also a lot of theories as to why tomography hasn’t found it, like resolution being too bad, the Farallon Slab messing with the plume, or maybe it is waning and the deeper parts have already dissipated… I personally think that the techniques used to image the mantle are not precise enough to image narrow plume tails, so I will go with Yellowstone being a deep origin hotspot.

Perhaps as a result of its distinctive origin, Yellowstone has an internal structure that is unusual for large caldera systems. Yellowstone has a Lower Crust body with ~46,000 km3 of basalt crystal mush at only 2% melt, then a second Upper Crust body that contains ~4,000 km3 of rhyolite at an estimated 30% melt. This makes Yellowstone strongly bimodal, it produces basaltic and rhyolitic eruptions but not the stuff in between, excluding a very few exceptions. This contrasts with the Central Andes (and other subduction zone calderas) which typically have a very large andesite mush body and produce a more varied suite of magmas including basalt, andesite, dacite and rhyolite.

Internal plumbing of Yellowstone volcano. From University of Utah.

There is something else that is very distinctive of Yellowstone, apart from the bisons and the bears: there is an abundance of geysers. Here is found the greatest concentration of geysers, mud pots, hot springs and fumaroles on Earth. There are also hydrothermal explosion craters that have ejected rock kilometres away, making them one of the greatest hazards that Yellowstone currently poses. The enormous heat flow (estimated at ~6.5 GW) that is being released by the hydrothermal system is too great to come from its shallow magma reservoir, so it is actually thought to originate from deeper convecting basaltic magmas that also result in a high emission of CO2. Instead rhyolite gives the building material for geysers, the silica precipitates that form conduits which then transport heated water to the surface. So the combination of basalts as the heat source plus rhyolite seems to be what gives Yellowstone its famous geysers.

Map showing active hydrothermal areas, hydrothermal explosion craters and the Yellowstone (Lava Creek) Caldera with its two resurgent domes. From USGS.

This caldera is really interesting for study, that’s for sure, but what about its future? Some have argued that as the thick North American Craton moves over the hotspot it will be the end of it, and I guess that could be true. The thick and cold cratons are practically devoid of volcanism. The thing is that regardless what happens when activity shifts eastwards, now at its current location, Yellowstone can, and probably will, supererupt again.

The caldera last collapsed in the 1000 km3 Lava Creek eruption at 0.6 Ma, but the story doesn’t end there. Lava domes have kept being erupted mostly in 3 pulses: 0.52-0.48, 0.16-0.15 and 0.11-0.07 Ma. The last pulse has involved lava flows erupting along a western ring fault that delineates the Lava Creek eruption caldera. These were HUGE rhyolite eruptions, for example the youngest one, the Pitchstone Plateau flow, had a volume of 70-80 km3. It’s so big that the shallow reservoir of Yellowstone seems to fall short in size to explain them. Consider this, even the largest Icelandic fissure eruptions, 1-25 km3 (like Holuraun or Laki) are only able to reach this size because a caldera collapse takes places that keeps re-pressurizing the magma chamber with each collapse event and keeps the eruption going. Kilauea started to collapse in 2018 when less than 0.1 km3 of magma had been removed from its summit. Yellowstone did these enormous flows without the help of any caldera collapse. I am not aware of any other silicic volcano having done any flow of similar size, the largest lava flows of the Altiplano-Puna only reach to 1/3 the size of Yellowstone’s most voluminous.

“Young” gigantic rhyolite lava flows at Yellowstone. From USGS.

These large effusive eruptions are another oddity of Yellowstone that hasn’t been given much attention by scientists. I think however the explanation may lie in the basalt once again. If the shallow rhyolitic melt bodies are well connected to deeper bodies of molten basalt that are also very voluminous then these could be backing up the shallow chambers with their pressure and making eruptions bigger. This would be my best guess to an unresolved question.

So summing up, Yellowstone has great volumes of melt, including rhyolite, a long history of supereruptions, a large heat flux and a ring-fault full of lava domes. It is looking as if Yellowstone plans to do another supereruption. Its weak spot is that this volcano likes to sleep, in fact it has been dormant for 70,000 years! And for all we know it could go dormant for another 70,000. Paleo-deformation also reveals that the caldera has been predominantly deflating for the last 15,000 years. That is why Yellowstone is not going to erupt any time soon and it will need a great deal of pressurization and re-melting before it does so.

Castle Geysir. Photograph by Arad Mojtahedi, Wikimedia Commons.


4. Taupo-Whakamaru (New Zealand)

The North Island of New Zealand is the scenario to an extraordinary group of calderas (the Taupo Volcanic Zone or TVZ). Its formation is only relatively recent but is in the context of longer changes that have been taking place in this area for the past 16 million years. An ancient arc has migrated towards the trench creating a number of now forgotten calderas and volcanoes. This arc migration must be due to a steepening of subduction and is still ongoing at the southwest end of the island. This is demonstrated by Taranaki where a chain of 3 stratovolcanoes become younger towards the trench. The Central Taupo Zone where the most interesting action is placed became settled at its location around 2 million years ago. However rollback continued to stretch the island and create a rifting arc.

The first large caldera system considered as part of the TVZ was Mangakino which became active around 1.6 million years ago. It produced many large eruptions, including 4 VEI-8 events. However the location of most current calderas was at this time still dominated by andesite volcanism. It wasn’t until 0.9-0.7 Ma that the volcanism became predominantly rhyolitic while rifting also was accelerating.

Most silicic flare-ups are known to be episodic, in a series of steps, and one of the best researched cases is the 350,000-280,000 years old sequence at the TVZ. No less than 7 caldera forming events took place during this period and within 90 km of each other!

The majestic opening was the >2200 km3 eruption of Whakamaru Caldera. A series of VEI-7 eruptions followed. First came 3 collapses at Kaingaroa and 1 at Okataina. At around 300,000 years voluminous lava domes erupting through the west ring fault of Whakamaru Caldera created a natural dam to the Waikato River and turned most of the Central Taupo Zone into a lake (which has been called Lake Huka). Ohakuri and Rotorua calderas then collapsed simultaneously in a rare event. Finally the collapse of Reporoa around 280,000 years ago closed this period of activity and the Taupo Zone sank into a time of relative quiet in which nothing very remarkable happened.

What makes flare-ups be episodic is not exactly known. One possible explanation is that this is due to rifting. Melting of the crust weakens it and makes it easier for rifts to develop. Rifting in turn draws more magma from the mantle and generates more melting, tectonic and magmatic activity are closely related to each other in these settings and are a feedback to each other. Whatever the causes, past activity has been highly variable and evidence suggests that the TVZ may have entered a new period of high activity 55,000 years ago (the best of which could still be to come). This last resurgence has seen very high activity from Okataina volcano to the north and the emergence of a new centre, Taupo, to the south.

Although eruptions had been happening in the Taupo area for a long time, the first ones that can be certainly attributed to Taupo as a separate volcano date back to only 50,000 years. They consisted of several VEI-5 eruptions with a magma chemistry very similar to the later caldera-forming event. There would have also been lava domes and flows, but this is hard to know for sure since they must have been engulfed by the later collapse. At 25,000 years, Taupo produced the youngest VEI-8 of the planet, the Oruanui eruption, with a volume of 1200 km3. Some research has been trying to figure out how long it took for the magma body that fed this eruption to form. Some argue that it took less than 3000 years, after its next oldest eruption. This is because a younger group of zircons (a type of mineral that can be found in magmas) shows in the Oruanui ejecta that wasn’t in the older VEI-5 events. However there were also many zircons similar in age to those of previous eruptions so I don’t think it was so simple. Part of its growth was probably rejuvenation of partially molten mushes belonging to the old Whakamaru system, while new melt intrusions must have been supplied over some tens of thousands of years and finally some last powerful deliveries of melt may have entered Taupo just before Oruanui that introduced the new zircons and expanded the pre-existing melt body.

Lake Taupo fills the Oruanui Caldera.

The speed at which Taupo grew was spectacular and so has been its recovery after the eruption. Studies reveal that Oruanui destroyed the entire shallow magma chamber of Taupo. Yet it has regrown new shallow magma bodies, erupted 25 times in the last 12,000 years and collapsed once again in its ~200 AD eruption.

Even though the volume “only” amounts to a bulk of 45 km3 ,the 200 AD eruption is remarkable for its violence. During one of its phases it produced a 50 km high plume into the atmosphere, inspiring the term ultraplinian. It was immediately followed by an ignimbrite that would have blasted into oblivion anything less than 80 km from the vent (you can imagine all vegetation and animals within this radius perishing under a pyroclastic current, a burning hurricane). The ignimbrite was as far reaching as those of Oruanui. Even though this eruption was technically a VEI-6 it seems to have reached an intensity more becoming of a VEI-8, if it was for a brief time only.

I do wonder if the 200 AD eruption destroyed all of the melt body that had been assembled after Oruanui or not. Once a caldera collapse starts it sustains itself because each collapse event rises the magma chamber pressure so that it often stops only once the entire chamber is destroyed. The 200 AD eruption could have well brought Taupo back to the starting line, to build itself from the mushes. But its small size also opens the possibility that it only evacuated a fraction of the melt down there. Taupo still should need some time to recover before another VEI-8, particularly if the 200 AD eruption evacuated most or all of the magma, but it is also a volcano that can evolve very fast. Melt bodies could form within the neighbouring Whakamaru system as well, but there is nothing to indicate this is happening now.

Taupo remains dangerous for smaller eruptions in the VEI 4-6 range, that are very frequent. I have also wondered about the possibility of floods of water running down Waikato River which drains Lake Taupo. It is densely populated downstream and I don’t know what would happen to the dams in between, whether they could hold or not against potential releases of water or pyroclastic currents.

There has always been an aura of mystery surrounding Taupo. Early volcanologists were perplexed as to why Taupo seemed to be a reverse volcano, a depression that deepened inward into its dark waters, instead of a conical mountains like most other volcanoes. Now we now that volcanoes come in various form, not just cones, but other mysteries remain. Why did the strange 200 AD eruption happened and why was it so powerful? or when and how did Taupo form and how it related to the wider tectonic processes? A lot remains to be known.

Waikato River near Taupo. Thanks to Dharpo32 (Wikimedia).


To be continued…


Information and research

On Long Valley:


On Yellowstone:




Taupo recovers from Oruanui, zircon chronology:


The Taupo Volcanic Zone:



Overview on Taupo:


103 thoughts on “Ten volcanoes with super-eruption potential: Part II

      • Let me add my thanks for this series, Héctor. You have given me a palpable sense of the underpinnings of volcanism, and of the marvelous complexity of the crust, the layers of the mantle, and the percolation of heat from the core/mantle boundary. I especially appreciate your discussions of subduction in all its variations.

  1. We write Yellowstone off you know, because it’s old, it’s overplayed, not showing much signs of activity, entering an old craton.
    In reality it’s still very much capable of simply colossal eruptions, only Wah-Wah Springs & Toba dwarve it among non-Flood Basalt events.
    All it takes is an earthquake, an influx, just that push to bring extra melt into that rhyolite sill and bam! a 500 mile radius gets wiped out.

    Taupo’s the most likely of this series so far to be next though IMO.
    Great read.

    • Not showing much signs of activity?
      Earthquakes swarms, hydrothermal activity and some deformation, it has erupted 1000s of km3 of magma since it’s last caldera eruption just effusively. It’s going to die out eventually and it’s overplayed too death but it’s hasty to dismiss this volcano has contender for a VEI 8..

      • I think a lot of it comes from the Grimsvotn vs Yellowstone article from the early days of this site. It is one of my favorites from that time but it does unfortunately seem to be rather exaggerated. It seems we have been way too dismissive of what is really one of the more impressive volcanoes out there. Remember the old calderas are still active too, their deep basalt mush is what drives the volcanism of the Snake River plain.

        Edited – admin

  2. With regards to Yellowstone it is an amazing place. Below is a picture (if this works) of some of the Rhyolite flows Hector speaks of. These are not bluffs. They are ancient lava flows. Imagine the sight it was when they were active. Probably the most impressive picture of lava flows I have ever seen.

    GL Note: It didn’t work. I had to tweak it.

    Corrected attribution, to Hector – admin

    • Yes imagine that lava front treeless and steaming sligthly in day, and during the night there is orange glow in inumerable tiny spots on the flow edge. Its a magmatic glacier slowly advancing : )

      • The link correction was to dig out the address and find the actual jpeg link. Linking to the website tends to make WP barf on it. By default it strips potentially harmful stuff out of a post. If you can find the URL to the actual image it generally knows how to render that properly.

        Other administrative actions on that comment are not mine.

        • It seems the opening and closing html remarks in the URL is what caused the issue. I wont know for sure until I try it again. That could take a while!! but its all good. Hector fixed it!

  3. Just looking at the map of the massive rhyolite flows at Yellowstone, if even the ‘small’ red flow is about 70 km3, the flow underneath it is an easy 300 km3, there could be almost as much post VEI 8 lava as what erupted in Lava Creek. If you compare that with the 2011 eruption of Cordon Caulle, there was a lot of tephra erupted in that eruption too, so of you scale that to these Yellowstone flows that is a huge number even for an eruption that is still mostly effusive. Considering the volcano has been active for about 2.5 million years and probably behaved the same after the other big eruptions then Yellowstone is probably getting on for 10,000 km3 of erupted material at least. While compared to the 500,000 km3 erupted in Hawaii over that time it isnt that big, the plume is weaker, against pretty much every other continental volcano it is a real monster. The high heat flow would also argue for an open connection to the plume, though maybe not a lot of new magma.

    Thing is that as much as it is sort of a joke today, if Yellowstone behaves the same as Hawaii at a deep level it might not take a huge time period to reactivate, maybe even only a few years. If theres ever a ‘pahala swarm’ at Yellowstone in the future…

    • Yes, more magma has been erupted effusively since the Lava Creek eruption than the magma evacuated in that caldera collapse. The flow underneath you speak of, I think it was multiple eruptions that were spaced closely in time. The youngest lava flow, Pitchstone Plateau, is one of the few largest.

    • If some of these mammoth obsidian flows erupts again it woud be a huge attraction in the park once the start up plinian and pumice fountains stopped. Vistors woud like it alot to see glowing blocks and black steaming glass. The coulee extrusion point glows and hiss like a coal heap with oxygen forced through it

      As you say.. a whole mountain plateau wells up from the Earth over a timespann of just a few years perhaps a decade. Yellowstone obsidian flows are belived to have been erupted with very very high effusion rates, the first days you coud perhaps see the steaming glowing blocks rise from the ground. Souch thick flows woud also take 100 s of years to cool down. The caldera is filled by these flows

    • Shouldn’t forget the ~150 ka VEI-7 that formed West Thumb Caldera! It was about the size of Tambora and half of the 1.3 Ma eruption.

    • When Ryholite forms blocky obsidians kilometers long flows its signs its rather hot ( 1000 C ) Cordon Caulle was over 900 C and was able to flow over the ground slowly. An 1200 C Ryholite obsidian woud perhaps be as mobile as 1100 C Hekla andesites? Some fluid looking light coloured flows in Bora Ale in Afar is ryholite, perhaps heated by rising basalt. The summit haves some light brown pahoehoe if you look at Google Earth.

      The Yellowstone glass flows where perhaps similar in temperature to Caulle 2011 around 900 C / 1000 C. Most Ryholites seems to erupt at 700 to 800 C And forms steep domes. Ryholite lava flows are extremely rare on earths surface, being viscous and difficult to erupt. Dacites and Andesites dominates viscous effusive flows.

    • The Snake River plain basalts from the Yellowstone Plume are impressive as heck for being continetal pahoehoe flows! They are almost as fluid and smooth looking as Hawaii
      Craters of the Moon are rare holocene Thoelitic continetal basalt flows, the lava field is very expansive, and must have lasted for years / decades. Their basalt flows are very oceanic looking, fluid and smooth. This indicates that Yellowstone is a rather hot hotspot with high melt rates. Snake River plain is filled with these pahoehoe basalt flows thats been covered earlier sillic calderas. The morphology of Crater of the Moon basalts suggest well over 1100 C

  4. Consider the scale of the picture I linked. The Teton range in the distance is perhaps 100km distant if not more.

    • The wall is several hundred meters tall at its highest point. But that is not all lava flow. Most of the elevation difference came from the collapse of the low part, as the chamber emptied.

      Yellowstone has not had any volcanic eruption for 70,000 years. It is not extinct but in very very deep sleep. Any other volcano in the world that had been doing nothing for that long would not be high on our list of places of interest. Hector’s case is based on what it could do in the far future, but that might be half a million years from now. What it does now is just an occasional snore. Taupo is a far more immediate threat.

      • We cannot be sure where along the flows this picture was taken but I’m quite sure the caldera is to the left so I don’t understand your comment. As the USGC said “burying the west rim of the Yellowstone caldera” so I don’t think collapse of the caldera increased the relief. If anything you’d think it would decrease it. Besides the caldera collapse occurred well before the these flows were emplaced.

        A correction to a previous post.. Looking at maps the Teton range is more like 60km distant.

        • And yes Yellowstone is in a very deep slumber and we should hope it remains so. One day though well beyond our grand children’s children it will rise again.

        • I think you are right. The caldera wall is some 500 meters high, which is caldera collapse but this happened long before the lava flow. Not sure how deep the lava flow is (100 meter?). That must have come from somewhere and left a sizable hole behind, but probably not right on the edge of the flow!

          • The surprising thing is that there are no holes for any of the recent voluminous lava flows. Presumably the Yellowstone area simply underwent massive widespread deflation without getting to the point of collapse.

            As far as I know, effusive eruptions through the top of a volcano do not release enough pressure to collapse and only remove tiny fractions of the eruptible volume within a volcano, only effusive eruptions through the flanks at low elevations seem to be enough to form a caldera.

          • Hector, it’s not letting me reply to you directly, but that is, er, a rather frightening prospect

          • I measured the lava flow on Google earth to be about 100 meters thick or so, but this is the end of the flow which is a long way from the source at least 15 km, it could be several times thicker there. Also yes this picture is outside the caldera, to the southwest. The mountain in the background is about 30 km away.

            Yellowstone seems to be one of those volcanoes that really does go big or go home. Its erupted a lot more magma in the last million years than most other volcanoes, but probably had a number of eruptions in the single digits in that time…

          • And that is right! Where did it come from?? Such a huge body of magma. Glaciers erased the past perhaps. But its not like if that hole that might have generated this was erased or it wasn’t. We just haven’t found it yet. Many buried flows in the area.

          • There is no hole, the lava erupted out of a vent on the ring fault so there is no gravity involved. There are two options, 1 is that the caldera had inflated and subsided without collapse like a massive version of a trapdoor caldera, but the more likely option is that tens of km3 of magma intruded and displaced the rhyolite, most likely basalt from depth which is denser and cant mix with molten rhyolite so cant erupt itself. The basalt is probably very similar to that erupted at Craters of the Moon, very hot tholeiite basalt. If refill intervals are at tens of millennia then its quite easy to see the refills being of this magnitude, the plume is likely generating magma continuously so doing that for 50,000 years is a big number.

            When you look at at North America as a whole and the direction of the faults and rifts in the basin and range, it really does look like the entire thing is a sort of bow shock in front of the hotspot. It seems the passage over the plume has had a huge effect like its tearing the continent apart in its wake…

  5. I did a bit of research on Long Valley, I was aware of the intrusive episode in the 80s but I didnt know there have been several other similar events including one ongoing as of 2011 at several cm a year of inflation. I have read that there has been at least 0.3 km3 of basaltic magma fed to the system and that feed has been constant this decade, there is probably an open system and that to me says the chance of an eruption this century is rather high, more likely than not.

    • There has also been quite a lot of tectonic activity in that region including the quakes in Nevada (Tonopah region). I have read that the San Andreas is very jammed up around the Tehachapi mountains and some speculate the stress is shifting towards the Owens valley. There is also that spreading center in the Gulf of California. Is this rifting?

      CalTech earthquake monitoring: https://scedc.caltech.edu/recent/Maps/Long_Valley.html

    • With regards to your Yellowstone comment. Your first hypothesis seems the most likely to me. It would explain the vast effusive eruptions without an additional caldera collapse beyond that had happened 600000 years ago. This is is not long in geological time. But long in most vulcanological minds. Mine included or any human.

  6. Earthquake underneath Mauna Loa with a depth of more than 80 km! It seems plausible that the depth will be re-assessed. The seismic signal looks quite messy.

    • At that depth its perhaps
      1600 C and molten mess … cannot quake in a major mantle plume

      Only cold subduction can yeild quakes at 100 s of kilometers depth

    • There was a quake at 75 km a few weeks ago, and that one was within the boundary of Mokuaweoweo… they are rare, maybe 1 or 2 a month, and seem to ignore the volcanism and just happen.

      • Maybe it is fragments of ancient slabs stuck in the mantle transition zone.
        I do recall a theory on this website that the Hawaii plume was birthed at the site of an R-R-R spreading ridge or a slab graveyard.

        • These slabs remains are well heated after soo long near Hawaii

      • I think its just a case of that one very unlikely event that happens anyway. The occasional mantle quake is to be expected. Its not likely the pipe is exactly vertical, it isnt at Kilauea the pipe there begins at a location that is underneath the upper east rift where some recent deep quakes happened. Mauna Loa is deeper still so could be sourced at a location that is underneath a point on the surface that is quite far from Mokuaweoweo.

        Probably these deep quakes are a response to the weight of the island.

  7. Hello, great article. I’ve had to deal with my wife having a stroke and she just passed on Nov.25th. Miss her. she’d been in extended care fora year and a half. Still miss her.quite a woman like no other I know.
    That said I really enjoyed the Yellowstone portion. being surrounded by the Columbia River Basalt and various remnant calderas of that Galloping hot spot..

    • That’s bad news. Sorry for your loss. I hope you will have good memories, to soften your missing a bit. Also hoping VC can provide you some distraction in difficult times.
      All the best.

    • I am very sorry to hear this. We treasure the memories of those who have passed on but they can never replace the real person.

    • My deepest sympathies. After a long illness, my wife passed in 2017 due ‘resistant’ pneumonia and ‘multiple complications’ following a ‘minor’ fall. Am still rebuilding many aspects of my bereft life. The cats have *just about* forgiven me for ‘misplacing’ their favourite knee-person…

      Yellowstone and the ‘Snake River’ complex, however you call it, remains fascinating. Where did it come from ? Perhaps a stray fragment of plate subducted by coastal pile-up ??

      Hidden in the area’s snarl of accreted terrains and subducting plates, is there any hint of an off-shore track ??

      I ask because, the more ‘deep data’ comes in, the more Yellowstone’s roots resemble Iceland’s. That ‘hot-spot’ may have tracked SE from Canadian High Arctic for ~130 MYr, diagonally scarring Greenland in passing.
      Other workers have warily back-tracked it across pole from Permian Siberia ~350 MYr.

      Whatever, Iceland’s roots now *seem* to be extending a tendril Eastwards towards Northern UK waters and the strong, old Skand craton.

      Hmm: Should Iceland’s ‘surface expression’ shift Eastwards by a ‘Snake River’ hop, would that diminish Mid-Atlantic spreading, perhaps synergising the currently minor subduction arcs plus the ‘possible incipient’ off Gibraltar ??

      Likewise, looking at the ‘Snake River’ dates, Yellowstone seems overdue a hop Eastwards, but not just yet…

    • My condolences.

      Whenever I write of the CSZ I have you in mind. One of the few smart people of the Pac Northwest.

  8. Sorry for your loss. It is difficult as I know. Take care of yourself. Try to surround yourself with family and friends. It will help you get through it.

  9. Well, here we go. Little late to the party here, but while i await the top 3, i guess it’s my turn to analyze today’s contestants. Pardon if this gets a bit long.

    I think i’ll talk on the one that’s getting a little less attention. Long Valley/mono-inyo complex. This is a bizarre one, as these are two large volcanic systems in very close proximity. Disclaimer, most of my knowledge of underground plumbing systems comes from studying geysers. Still though. Large systems such as these in proximity as close as this should be expected to have a substantial effect on each other. Now with volcanoes, most of the time by virtue of being farther apart when one looses pressure via eruption, another looses pressure from the squeeze, lessening the probability of further eruption, but these are a lot closer, so I want to reference another possibility.

    In some geysers, major eruptions are in concert with another. these systems have connect plumbing at depth, but volcanoes are playing with enough pressure to deform the land. There for, as opposed to the geyser concert which is caused by decompressive evaporation, is it possible that the eruption of one or the other in a moderate to large eruption could lower the pressure on the other enough to trigger substantial decompression melt, triggering the the second volcano to erupt sympathetically in a buoyancy triggered eruption? just thinking out loud, but it could be an effective way to suddenly and effectively mobilize large quantities of previously low-melt rhyolite.

    • That’s an interesting possibility I shall keep in mind. Another way decompression could work to “awaken” a nearby volcano would be by prompting gas bubbles to grow in the neighbouring magma chamber which could raise its pressure.

      • The only issue I see with that is that the pressures are still going to be incredibly high down there. But that possibility did cross my thoughts, yes.

  10. There was just another swarm of small quakes at Kilauea again, but this time the tilt has gone flat. Its getting pretty unstable there now, if those deep quakes are magmatic (dont know what they would otherwise be) then at about the end of the year there should be a lot of new magma arriving and another swarm like the one last week, or perhaps an eruption.

    I do hope something happens somewhere soon…

  11. http://tboeckel.de/

    Liquid Nephelinite sloshing around at Nyiragongo, Nyiragongo haves the lowest sillica content of all sillicate volcanoes on the planet! As of 2020 its the largest lava lake on the planet and the only active erupting Nephelinite volcano. Nyiragongos lava lake haves a iconic look with small crustal plates and lots of water rich degassing. The viscosity is extremely low, but perhaps not lower than a really hot plume basalt

  12. Incapillo
    Nevados Ojos del Salado
    Long Valley

    I’d say
    1. Somewhere in the Altiplano-Puna (Uturuncu?)
    2. Somewhere in Indonesia
    3. Not really sure about this, not sure anywhere in Japan/Philippines/Tonga is capable.
    Kamchatka or Alaska maybe? Or the East African Rift volcanoes?
    Could throw in a googly with a basaltic VEI8 volcano

    • 3: Uturuncu or Laguna del Maule, either one.

      2: Valles caldera

      1… Puyehue-Cordon Caulle.

      I will be honest, I thought number 1 would be Taupo, so when that isnt even in the top 3 it is difficult… I believe I might also be the only person who is willing to put a currently active volcano on this list as a first place… I am looking forward to the real list

      • Thought Valles caldera was all but dead? The Socorro magma body could throw up something 100,000 years from now.

        Agree about Taupo, reckon there’ll be another VEI8 from there before the year 3000.

        • As I said, my number 1 is number 4 on this list, so I really have no idea what part of the Earth is more likely to do a VEI 8 than Taupo, I just looked at rhyolitic volcanoes with big calderas and large magma volumes. I actually dont think in hindsight that PCC is a supervolcano progenitor, but being that it is a rhyolitic complex that has actually erupted more than once in the last century (3 possibly 4 times) and each eruption has been of moderate to large scale, its got potential.

          I have read Valles goes into very deep sleep like Yellowstone, only even more so, so its probably not dead but also not a good second pick, but who knows.

        • Socorro is one to keep an eye on, in the distant future. My top bet for one in the next 100,000 years is Antarctica though.

          • @albert

            Now that is something I would be strongly interested in learning more about. Always been curious about Antarctic volcanism…

      • hmm… alright, i’ll take a shot i guess. This is not my specialty, so forgive me for not naming specific volcanoes.

        3. The volcanic fields of Washington. (long shot, i know)

        2. maybe something in japan. likely Aira, but potentially Aso (not sold here myself, but it came to mind)

        1. Mexican or central american complex. Either one of the volcanic fields, Atitlan, or Amatitlan

        Other things that come to mind are alaska and that russian peninsula that i don’t feel like trying to spell. Antarctica, as albert said, should also be considered as the monitoring down there is, let’s just say, sub par. the final area to watch may indeed be africa? those are usually basalt though, iirc, so they may not be what we’re after.

        • Africa has got a lot of gigantic calderas, it is very much like at Yellowstone where you have very hot plume basalt melting the crust, making bimodal basaltic rhyolitic volcanoes. At least one is a VEI 8, Awasa, about a million years ago. Most certainly there is the potential for another.

          Kamchatka has the Klyuchevskaya group, but that is a basaltic complex for the most part. Alaska seems very prominent to do sizable VEI 7s but also seems to not go above, and provably that recent study is hyperbole to describe a situation of volcanoes sharing a common deep source, which happens often in such arcs. Really it seems that normal arcs are actually not very good places to make supervolcanoes.

        • Actually i have never thought about supervolcanoes in Antarctica, but if there us anywhere where it wouldnt have a disastrous impact its there. I have no idea how to detect such volcanoes though, the area is so frozen that there are volcanoes which have been extinct since the Pliocene that are still largely uneroded, like Mt Sidley. As interesting as the possibility is its just way too poorly known to make any sort of reasonable assumption.

          It will be interesting the effects of rapid deglaciation, the ice will melt but at least initially be replaced with shallow sea, and a lot of that sea wont go away after rebound. I dont think theres a comparable volcanic environment with big calderas today, no VEI 8s in Iceland and Alaska is too mountainous.

          • The icelandic crust is too thin to support the evolution of a chamber that large, i believe. and alaska is showing mostly normal chain activity with a bit of decompression melt. Antarctica, well, i don’t how the plates are behaving. are there smaller scale grabens? is roleback happening anywhere? it’s unfairly hard to know.

          • Icelands crust is very thick, underplating by a very powerful hotspot
            Icelands crust is 50 kilometers thcik below Vatnajökull, but lacks a litopshere beacuse its spreading boundary

  13. Something for you all to concider… Large Caldera Formation (I detest the media hype “Stuper Volcano” term) is not something that is an all or nothing affair. Caldera’s DO NOT have to be the source of the actual eruption. Noverupta and Katmai in Alaska are a good example, as is BardaBunga-Holuhrain in Iceland. Neither one of those erupted at the main volcano yet both acted to cause caldera/crater formation/expansion at another volcano by evacuating magma from under the edifice. In fact, by tracking Bardarbunga’s plug decent, Albert was able to predict the cessation of activity at Holuhraun within about 6 hours accuracy by carefully watching the rate of decent of Bardarbunga’s crater floor. The curve of that drop was quite similar to a decay curve and indicated a flattening that Albert was able to use to estimate Holuhraun stopping.

    As for Taupo, there are a couple of interesting features that have shown up in papers on the subject. I am not entirely sure if they are specifically about the last eruption, but it has exhibited “trap-door” failure of the caldera floor, and on at least one eruption, has shown via geochemistry, that the entire eruption occurred as one event with little to no variation of the ejecta. In other words, the entire mass of tephra did not show geochemical changes from the start to the finish. This hints that it was well mixed before the eruption. Given that in 1886 nearby Mount Tarawera erupted after about 4 to 6 hours after seismic activity started… this adds a significant “spooky” factor to Taupo and systems associated with it. Either a shallow magma chamber became active, or a dike had to propagate from the 110 km contour in roughly 6 hours, an approx 18 kph ascent rate. The fact that the pink and white terraces were in place and geothermally active, the idea of a shallow chamber source is likely.

    • Very well said and yes spooky!! They might be sharing the same magma chamber to my insipient vulcanological mind

    • Taupo is one i’d definitely consider quite haunting. Among the VEI8+ environments, it seems like the one that’d require the least run-up. I mean, it’d still have a run-up, but the onset of activity could be a lot more sudden, i’d think.

    • From what I saw in the post I read, looks like it’s considered around the size of the Japanese VEI7 systems.

  14. I have a nice sleeper candidate that I don’t think will be included here, but fits well with Hector’s general guidelines.


    “Chacana is a massive, eroded caldera complex of Pliocene-Holocene age that forms one of the largest rhyolitic centers of the northern Andes. The caldera is 32 km long in the N-S direction and 18-24 km wide… Dacitic lava flows were erupted from caldera-floor fissures between about 30,000 and 21,000 years ago. Numerous lava domes were constructed within the caldera, which has been the source of frequent explosive eruptions throughout the Holocene as well as historical lava flows during the 18th century. ”

    Good overview of the region can be found here –

    • yeah, i doubt its conclusion, but if some info comes out, i wouldn’t be adverse to a VC article about the region

    • Yeah, I agree that it probably won’t make it in. I wouldn’t be adverse to seeing a more in-depth look into the region though.

  15. Kilauea seems to be going strong and Etna’s burp was different. We might have more to watch at those two locations.

    • Etna is probably a good bet for the next big basaltic eruption, something like Holuhraun. The last half century has seen a lot of lava, easily over 1 km3, erupted out of summit vents, if I was to guess some point this century we see a similar eruption as 1669.

      Kilauea is going to erupt in the next year 🙂

    • Sadly no information about the strongest earthquakes before the eruption 4480 years ago…

      Source: https://www.volcanodiscovery.com/mauna-kea/news/116406/Mauna-Kea-volcano-Hawai-i-strong-earthquake-on-NW-flank-greater-than-M-4.html

      “The Hawaiian Volcano Observatory (HVO) reported that the seismic network recorded a volcano-tectonic earthquake with magnitude M 4.4 at 25 km depth beneath the northwest flank of the volcano starting around 09:27 local time on 14 Dec morning. The earthquake was centered about 20 km southeast of Waimea.
      Strong shaking, with maximum intensity of VI, has been reported across the Island of Hawai‘i. The earthquake was reported felt over most of the Island of Hawai‘i. The northwest flank of Mauna Kea has experienced only 9 earthquakes greater than magnitude-4.0, within the past 60 years.
      According to HVO acting Scientist-in-Charge David Phillips, “This earthquake was widely felt across the Island of Hawai‘i, and even as far away as O‘ahu.“
      Source: Hawaiian Volcano Observatory volcano activity update 15 December 2020”

      • Probably very fast and violent earthquake swarm, there isnt any shallow magma at under 3 km deep but there is the massive deep system that is still active.

        Mauna Kea has massive eruptions, based on my rough estimations, the Laupahoehoe point lava flow is probably over 3 km3, and the cone it was erupted from is big enough to have been at least a VEI 4. It would have been a rather impressive event, a subplinian lava fountain probably similar to the tallest fountains from Pu’u O’o but much more ashy, and with a massive fast moving a’a flow. Mauna Kea is the type location for Hawaiite, which is sort of alkali basaltic andesite, its pretty similar to what Hekla erupts. Its also the same magma erupted on Heimay in 1973.

  16. Looking around the volcanoes that had VEI8’s in the past, they seem to share thinning crust in behind the main volcanic front in subduction zones and melting of the lower crust, including Yellowstone (subduction of the Farallon Plate, with or without the possible mantle plume). Melting of the lower crust gives the dacite or rhyolites needed. Toba is slightly anomalous because it is close to the Sumatra Volcanic Front and the descending slab is thought to break apart under Sumatra. The next VEI8 is likely to come from similar settings.

    • Its gigantic .. it will take a few years to melt competely?

      My name here spelled correct
      The other post wont appear

    • This is distressing. S Georgia’s numerous and various wildlife will be in bad shape if this thing grounds there.

    • Its unclear to me. The damage is if it grounds on the coast and blocks access to the sea. They now seem to be talking about it grounding on the 200m depth which will not do this, although it may reduce the amount of food that can be returned.

      • Yesterday I learned that due to the lowering of the salt in the water they expect some blooming effect, enriching the food chain and by that the local populations might not be affected that much. Also, the ice sheet seems now turning as well due to currents and might miss the island in the end…

      • Antartica ocean is extremely fertile and productive, cold and green, stormy full of nutrients.
        The biodiversity is low in the cold oceans, but the biomass and producitivity is enromous.
        Tens of millions of penguins and seals, and fish swarms and krill that numbers in their trillions. Cold seas contains alot of more nutrients than warm.

        Hawaii is a clear blue watery desert compared to South Gerogia richness

    • https://icelandgeology.net/

      On here it says a week ago there was deep quake activity at brennisteinfjoll volcano which is the most eastern Reykjanes volcano abd where your article said a volcanic episode would probably begin. Its also the system that Thrynukagigur is part of, the volcano that you can go inside of 🙂

      I dont know how long this stuff has been going on prior to this year with the magma at þorhjorn and Grindavik but it looks like an eruption is an inevitability, just when exactly is not known. This year though has been pretty constant swarms so lots of magma being fed, probably in the next few years something will happen.

      • With the current lock-down due Covid19 and total ban of fireworks in several countries around the world a nice show at the end of this year might be appreciated as well…

      • Don’t hold your breath… Keep in mind that this is a very tectonically active area. Medium sized earthquakes and earthquake swarms are frequent in the area even without magma accumulation. It might take decades before anything happens.

        • How large can earthquakes get at a divergent boundary?
          I appreciate there’s some strike-slip points at times along the MAR.
          You would think it would be relatively smooth.

          • The Reykjanes peninsula can do a low M6. That is considered one of the risks of this year-long swarm, that it triggers such an event along the fault.

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