2 years ago, I wrote an article detailing my selections for the most likely CFE candidates and a lot has changed. My opinion on Katla has changed and I do think an eruption in the near future more likely than not thanks to recent information from recent studies. We’ve gained insight into the magmatic structure of Chiles-Cerro Negro and Ioto is not looking good at all. I will once again indulge these 3 and my unhealthy obsession.

These are my favorite 3 volcanoes to track but I’ve invested too much time on these ladies. I am not joking when I say I’ve got 4 or 5 unfinished drafts that have nothing to do with my treasured 3. Not to mention that I was trying to write 2 different piece on 2 other volcanoes that I find absolutely amazing which actually inspired this banzai here.  So I invested a month’s worth of thought into dealing those pesky thoughts that regularly enter my mind and dealing with rabid desires for a volcanic apocalypse. This is more for me than anything, I want these 3 out of my thoughts so I can fully indulge in the diverse world of volcanoes. I’ve got 8-10 other volcanoes that I find very fascinating with some them being considerable hazards I don’t want to write anything else on my trio until they erupt.

Empress of Iceland: The Quantum Volcano

In my previous piece on the volcano, I discussed the current situation and my unhealthy obsession with Katla. I’d brought up a hypothetical worst-case scenario, the possibility that Katla’s been charging it’s largest ever eruption but I didn’t go into much detail about what that would actually look like and why I even considered this notion. I didn’t and still don’t believe that we will see this scenario come to fruition but some interesting new studies have been published with some very interesting implications that have ever so slightly increased the likelihood of a possible large eruption at Katla. First off, Katla has had the most consistently impressive eruptive record in Iceland of the last 10,000 years. More VEI 4s and 5s than any other Icelandic volcano, 8 fissure eruptions(More than Grimsvotn), 2 of them being large. It also boasts the largest caldera of the country.

Thanks to recent studies, Katla is all but confirmed to have a deep chamber and is not fed by a feeder dike. Katla’s 2 chambers have supplied 2 different eruption styles, the tiny (10-20 km3) shallow chamber is where the silicic magma is born and has sourced all of Katla’s felsic eruption and the basaltic deep reservoir is where the bulk of the basaltic eruptions are sourced. Now what does this mean for Katla? It means that we’re probably not looking for a recharge of the shallow system but the deeper chamber will be the most likely source of any future eruption at Katla. As I’ve said in my previous piece on Katla, Deep volcanic unrest is notoriously hard to quantify and monitor. This does, however, put the recent unrest at Katla into context. The Shallow chamber seems to be very passive as of late, yet there has been pulses of high volcanic activity indicative of magma. So much so that small subglacial eruptions may have happened in 2011 and 2017. It would seem odd then that there doesn’t seem to be anything major happening with the shallow chamber in conjunction with this. Quick failed magma intrusions from the deep reservoir could explain these pulses. Being an highly active volcano, the deep reservoir is likely to have active sills and dikes extending out from it that don’t make it to the shallow chamber as time passes some of these bodies could serve as launch point for failed intrusions that bring heat and gas to the shallow magma and hydrothermal system in turn leading to strong glacial quakes and/or small eruptions. If this proposition holds true than that would mean that it’s likely a real eruption is building at Katla, as we know that the deeper chamber is currently under magma intrusion and these pulses of activity are likely the result of failed magma intrusion from the deeper chamber. The lack of a large shallow chamber despite Katla’s age and activity is evidence that the tectonic system is hostile to magma ascent. A process that is supported by a recent unpublished study. Other volcanoes that have proven hostile setups such as Chiles-Cerro Negro and Cordon Caulle, have no or small shallow systems.

This is all nice and dandy but this just means there is a logical pathway for Katla to erupt soon and not that’s it about to go ham. There is nothing solid that point to a catastrophic build-up of magma preceding an Icelandic armageddon so this worst-case scenario is pure speculation. Nevertheless, I am obsessed with this volcano and I can’t help but find this notion fascinating so let me know what you think of it. The question that probably came to your mind is if Katla has even recovered from its Eldja eruption? The answer to that is possibly. After Eldja, Katla had only done 3 eruptions in 200 years and it would take another 180 years to do a major eruption. This is where things get a bit tricky as just because this volcano did a major eruption after 380 years doesn’t definitively mean that this eruption marked its complete recovery but it’s not beyond reason. Katla recovering from Eldja in 380 years would give it a yearly supply rate of 0.05 km3 which is a reasonable figure. It’s harder for deep chambers to erupt and for the deep system to produce 17 VEI 4+ eruption in less than 700 years on hostile grounds is indicative of some high supply. If we were to use this number than that would mean that the volcano is not erupting anything close to the amount of magma that it’s receives regular which means Katla should have a large magma chamber.

Once again, we’ve got no solid numbers on how big Katla’s deep chamber is, all we know is that it’s probably 15 km thick. Using the caldera as a proxy for the chambers dimensions we’ d get a deep magma chamber with 1,500 km3 of magma(a minimal figure in my opinion) It would take over 30,000 years of high supply to produce such a body. However Katla is over 800,000 years old, so whatever deep system that system has is likely to be old as well and to be frank that figure is not that impressive for volcanoes of this age. Throwing out numbers for the dimension of the deeper chamber is beyond pointless but I am going to do it anyway. It could be as big as the glacier that buries most of Katla or the size of the whole volcano itself. Giving a slew of potential volumes up to 10,000 km3. Again this doesn’t even mean anything as things change with volcanoes and the fact that it might’ve had lackluster supply before doesn’t mean it couldn’t get a high supply rate in the last 10,000 years.

Another potential supporting fact is that Katla is a massive source of CO2 emissions, producing 4% of non-eruption volcanic emissions, around 12-24 kiloton/day. We don’t know if this is normal for Katla or not. The source of these emissions is likely to be the deep chamber as the shallow reservoir is too small to support these emissions without consistent supply which it doesn’t have right now. Those who found this out crunched the numbers and found that 0.18-1.8 km3/year of magma could fuel this degassing. It’s essentially impossible that the reservoir could ever passively degassing that amount of magma over a significant amount of time without a massive amount of supply. Katla might regularly release more CO2 than Kilauea and Nyiragongo combined despite having a far inferior shallow system and being dormant.

Now these numbers are a bit too high in my opinion but 0.1 km3 would still be high enough. Some may take these CO2 emissions to mean that the magma reservoir is melting carbon-rich rocks, a patch of coal perhaps? Coal has the most CO2 out any type of rock other than diamond. If coal is unfeasible than all other CO2 rocks become unfeasible also. This would have to mean that this volcano has been doing this for years. Completely ignoring the chemical analysis of Katla’s erupted magma which hasn’t suggested this process. How much coal would it take to produce Katla’s CO2 emissions over 100,000 years? The average CO2 emission rate is around 12-24 kilotons/day so we will use 18 kilotons. Over 100,000 years that gives us 657 billion tons of C02 emitted. Coal produces twice as much CO2 than it’s mass when it’s burned which leaves us 328 billion tons of coal. This is hilariously impossible. Even if we use oil, it’s still impossible. Let’s not forget that most coal isn’t even found at depths that deep and the coal that forms there would be formed at those depths would be the rarest and cleanest. It’s extremely unlikely that 100 km3 of the rarest form of coal would be present at Katla Even if we were to use 10,000 years, then this would still be practically impossible and despite INTENSE geological study has found only one oil prospect and pathetic lignite that’s even weaker than it’s European counterpart. There is a small chance that an intrusion hit a patch of CO2 rich rocks but this also extremely unlikely due to the same limitations mentioned above combined with Katla’s age. Hell, the mafic volcanism preceding the formation of the volcano should’ve burnt away any of these rocks. And again, the chemical compositions of Katla’s historical products don’t show any amount of CO2-rich rocks or materials. Making this option exceptionally unlikely. The Eyjafjallajökull eruption released about 4.5 million tons of CO2 which is close to normal. Since Katla and Eyjafjallajökull are built on the same source with similar but still different magmas, it just makes it more unlikely for the eruptions at it’s neighbor to have normal eruptive CO2 emissions in comparison to it’s neighbor if the cause was the melting or heating of CO2 rich rocks from the deeper chamber.

There is a significant amount of evidence of course pointing to Katla having large amounts of magma with a high average supply rate but how large is the question. 0.02 km3/yr would still be a relatively high supply rate but that would mean that it has just recently recovered. 0.01km3/yr is pretty decent as well and with that number Katla is a bit more than halfway finished recovering. Who knows what’s going on cause I don’t. The current magma supply could reach 0.1-0.18 km3/yr of magma which really isn’t that crazy for the most productive, biggest volcano in Iceland. For reference, both Grimvotn and Bardarbunga has done 0.05 km3/yr and 0.07 km3 recently. If you take away the rift eruptions Katla has still erupted more magma than both these volcanoes combined over the last 2000 yrs. The worst-case scenario for Katla would be if it has been receiving a 0.05+ km3 average supply since the Eldja eruption with a recent increase in the last 14 years. In this scenario, Katla would’ve accumulated over 47 km3 magma in the last 1100 years, more than a recovery. Under this scenario, another massive fissure eruption would be a solid possibility, the chamber would not only have more magma and pressure , it might’ve had enough time to build the strain needed. The recent eruption pause helping very much in this regard. An interesting range of scenarios exist with Katla all hinging on what exactly has happened in the last 107 years. Did the volcano slumber for 90 years and has only now returned with fury or has it been building up something crazy? Only by peering into the volcano will we know.

Chiles-Cerro Negro: Queen of Intrigue
CCN has been another obsession of mine over the last 5 going on 6 years, most of my articles include it and as such I won’t spend much time discussing the reservoir or large intrusion, instead we will shift focus into the arguably the most crucial factor that I must admit that I neglected. For this segment, we won’t be talking much about the volcano’s chances at producing a caldera-forming eruption though I am still on that train. Instead we will talk about the substantial earthquake risk. This volcano doesn’t need to erupt to cause a catastrophe. Chiles-Cerro Negro has been associated with 2 damaging earthquakes both of with same magnitude of 5.7, associated with the failure of 2 relatively minor ruptures. There has been a known yet mysterious strong relationship with whatever is going on with the magma chamber and the tectonic systems. In fact this volcano could be heralding a massive earthquake but first some history.

On what seemed to be an innocent summers day in the city of El Angel, a large M6.3 earthquake took place. Leveling the city and nearby villages to the ground, and there was no reprieve for the next day M6.7 earthquake took place in the province of Imbabura causing further damage and death with Ibarra being essentially destroyed as well, all in all killing over 70,000 people. The tremors brought so much terror that citizens of Ibarra didn’t return to the city for 4 years and still to this day an annual festival is held commemorating the return on April 26 1872.

The faults that caused the earthquakes are unknown although they are part of the extremely extensive El angel fault system. It’s unknown if these quakes had anything to do with the CCN-Potrerillos-Chalpatan complex but these quakes were within the range of this massive volcanoes influence. Regional tectonics play a crucial role in controlling local stress and will inhibit or enhance magma ascent. As Chiles-Cerro Negro has no/or extremely pitiful shallow magma systems but a massive deep chamber then it would rational to assume that the regional tectonic setup doesn’t favor magma ascent or shallow magma accumulation. It can’t be stressed enough that this system is over 2 million years old but probably erupted less or a comparable amount of magma to Klyuchevskaya. It’s pitiful in it’s erupted progress. The previously discussed Katla has similar issues but its supply is so large that its borderline doesn’t even matter. The 2 geological forces have long been thought to be allies but they can be enemies and like in all battles, barring miracles or magic, the superior force wins out in the end. Up until now the superior force has been the tectonic system. But as magma is just 4km away from the surface and still trying to rise through a massive intrusion, something has clearly changed. As some of these faults fail, their inhibitive effect could weaken and promote volcanic unrest but large volcanic systems can disrupt regional faults through their unrest so which is it? Which force holds the lion’s share of responsibility for the current situation at Chiles-Cerro Negro, the volcanic force or the tectonic force?

My Answer (volcanic origin)
I believe that the situation within the magmatic system has reached critical levels and is starting to completely overwhelm the inhibitive tectonic system. Let’s not forget that all of this didn’t start with a tectonic earthquake but volcanic quakes a full year before any tectonic event happened. The uplift that we see currently is not the result of magma going directly into the magma chamber but magma going into a massive intrusion. According to a very detailed study, a crack 18 km long and 4-6 km wide rising 4-8 km high away from the main reservoir giving it a total volume of 324-648 km3 of magma. This feature or anything remotely similar to it is EXTREMELY unusual. Intrusions that don’t erupt usual die quickly unless the volcano has a high supply rate like Ioto for example. The solution for this feature could be explained by inhibitive force of the tectonic system. You see, deep chambers don’t usually do big eruptions directly, if allowed they’d traditionally relieve pressure by causing an “active period” consisting of larger then normal and/or more frequent eruptions. Deep chambers have a hard time erupting directly and usually just opt to fuel a shallow chamber where the volcano erupts. However this setup is so damn hostile volcanic eruptions and any form of magma ascent, from the tectonic system, to the mafic seal, and ductile compressive crust that it would be unreasonably hard to erupt. The deep chamber could never completely stabilize. With the pressure gradually rising over thousands of years and melt constantly accumulating, this huge crack developed. It cannot be overstated how overpressurized this system would need to be to rupture an 18kmx5km segment of a 10-14 km deep reservoir. This feature is big enough to seriously disrupt any regional fault in it’s vicinity.

All of the tectonic quakes that have happened with this volcano had occurred during the peak of the seismic crisis and would herald the beginning of the end of the swarms. Following every single swarm, escalation in volcanic unrest would be noted and despite the first swarm being the strongest a very clear upwards trend in volcanic activity has been noted. More magma movement, more intense deformation, magnetic anomalies, and more consistently high seismic activity. The failure of these 2 faults likely improved the regional setup in the long-term and promoted volcanic unrest. It is completely impossible to prove if this volcano had anything to do with the great earthquakes of 1868 but the volcano is capable of being the progenitor of a similar event. Of course, there is an alternative option, there is a way for the Chiles-Cerro Negro’s unrest being caused by tectonic forces. If you subscribe to my school of thought that this volcano is a serious risk for a caldera-forming eruption then the volcanic origin would be the scariest however if you don’t and believe that this volcano can’t do it then the tectonic origin would be the scariest option. Before we discuss that option we must establish the tectonic system,

The Tectonic System of Chiles-Cerro Negro and current situation
This portion of the region is poorly researched but it includes a large number of dangerous active faults and an unknown number of undiscovered faults. These faults include the Chiles-Cumbal fault, Mayasquer fault, Chiles-Cerro Negro Fault, Cerro Negro-Nasate Fault, Chiles-South fault, Chiles-North Fault, and others, all in all totaling 12 faults all capable of a M5+ just within the northern portion of the system! The southern portion has a lot of faults but the exact number is unknown. The volcanic uplift and associated changes to the stress field has put these faults under stress. These faults can be likened to a stack of dominoes, a single push could throw the whole thing into chaos. In the same vein though it could also temporarily kill the volcano as well. The !868 quakes have been hypothesized to close conduits within Cerro Payurco portion of the system and 2014 quake is thought to have caused compressional deformation with the 2022 quake being the only recent event that probably definitively helped the volcano out. Some of these faults are long enough to produce a magnitude 6.6+ quake that could kill dozens or maybe even hundreds of people. None of the big faults have ruptured in the last 150 years and their current status is unknown.

As you know the most recent swarm has seen a lot of shallow VLPs from 2024 up until now, the hydrothermal has seen zero big changes and no degassing has been observed so this is unlikely to be magma. As such the cause of this phenomenon is likely the hydrothermal system but not as a result of an increase of magmatic gas or heat, serious changes with one of the nearby faults is the likely culprit. The complete cessation of uplift at Laguna Verdes and observed tectonic quakes at the Chiles-Cerro Negro fault likely being indicative of an incoming earthquake.

Tectonic Origin for the current situation and the biggest caveat
One interesting thing is that Cumbal’s hydro-thermal system magically reactivated in 2009 with declining magmatic input and has stayed pretty much at the exact same level of unrest for 16 years now. The Hydro-thermal system at Cumbal is likely regulated by regional faults and potentially the same thing causing the hydro-thermal activity at Cumbal could be responsible for the activity at Chiles-Cerro Negro. The Magma Chamber for Chiles-Cerro Negro and it’s many surrounding neighbors is likely 30-50 km wide and is far larger for any single fault in the region to control, except one. The mysterious Pulli-Calacali fault and I am going to be honest, there is essentially no study into this feature but this baby is well over 100 km long and hasn’t produced a major quake in centuries. It runs through both Cumbal and Chiles-Cerro Negro and hypothetically could be the progenitor for volcanic unrest through whatever changes it’s going through messing with the stress field of the volcano. This fault is big enough to cause a M7+ earthquake.

Unfortunately, there is genuinely almost no meaningful information that would be helpful concerning the current status of the faults, on ascertaining what exactly is going on and what will come next. The Convoluted regional tectonic setup and it’s effects, a large magma intrusion, and deep reservoir makes this volcano a pain to think about on all fronts. Regardless, something significant is on the horizon, if volcanic forces have triumphed over the Tectonic setup then a large eruption and/or is likely. How long it would take to get there is a different story. However if a unstable tectonic system or the Pulli-Calacali fault is allowing volcanic unrest to take place then a large earthquake could be coming but again how long that would take to pan out is a different story. For all we know it could be a mixture of both ideas, the volcano might’ve reached a critical level of instability in conjunction with a primed tectonic setup. The issue is, of course, that we don’t know. Chiles-Cerro Negro has earned the title “queen of intrigue”

Ioto: The Once and Future King.
What makes a true King? Authority is one but it’s often not that simple to enforce, many kings and other holders of authority have their position sidestepped, used, or ignored as if their authority was non-existent. One of the qualities is that their position is not questioned and the further they’re tested, the more they reinforce their position. When it comes to psychos like me who desire to see the brutal chaos that mother nature can dish, Ioto stands at the top of most lists. It may not be the volcano that we’d personally like to see deliver carnage but it’s the most likely one pretty objectively. Anyone who knows anything about this blog is aware of this fact so I won’t bore you by going over old details. Being the confident obsessive caldera-crazy, I’ve decided to try and anticipate how this volcano will have it’s caldera-forming eruption. A task that won’t be easy due to the ridiculous lack of study into the finer details of this system! Chiles-Cerro Negro has been the frustrating volcano to think about but this volcano has been the most frustrating volcano to study.

Located in the very much underrated Izu-Osagwara arc, Ioto or Iwo-jima is a very fam-Blah Blah Blah Go read the other 4-6 other articles if you want a refresher on the general details. Before I even try to attempt to figure out how this lovely monster will be cut loose, I first must ask the question: is that even possible? How deep is the magma chamber? Don’t know. How big is it? Don’t know. How much magma is in the cone-sheet intrusion? Don’t know! What is it’s supply rate? DON’T KNOW! So little information exists for the volcano that I was tempted to give up entirely but I decided to extrapolate more than I ever extrapolated before. In order to predict Ioto’s coming climax we must first understand the mechanism of the current unrest and how that could escalate to an eruption. It was thanks to Hector’s hypothesis that I believe I figured out the current unrest’s mechanism and how exactly it will escalate into an eruption. So thank you to Hector, and to show my gratitude I will graciously steal refer back to his piece.

And it’s these eruptions that make up the second main trait of Ioto. Frequent phreatic eruptions, tens of them have taken place over the last decades all across the island, though concentrated in a ring inside the caldera, around the center of Motoyama. This is very weird. Other shallow silicic magma chambers tend to build pressure and culminate in spectacular eruptions; for example, Cordon Caulle, Chaiten, Rabaul, or Havre will, when opening a vent, produce enormous plinian rhyolite eruptions or vast lava flows. But Ioto erupts tiny. Even when trachyte finally reached the surface in 2023, the ensuing eruption was minuscule, so tiny as to not even make a dent in the inflation trend of the volcano. This minor distributed activity all around the resurgent dome is the other strange characteristic of Ioto.
In my head, to my bewilderment, Ioto is not a volcano building pressure for a massive explosion, nor is it a volcano preparing the ground for a ring fault that suddenly unzips into a ring dike and empties the volcano. It’s a magma chamber growing slowly, but consistently, UP, throwing small intrusions through the sides that build an expanding bowl of magma, until the chamber eventually reaches the surface. My perception is that the volcano is not going to need excessive pressure or a massive intrusion to collapse, but that eventually the very magma chamber is going to come up to the surface, through the edges of the caldera structure, and destroy itself. It’s like a train heading towards a cliff with no brakes. It will caldera-collapse, I just don’t know how much track lies ahead. I find it possible that this eruption could be the final drop that overflows the vase, but also that years or decades are left. Though I doubt it could be much more than that, given the extraordinary pattern of deformation and how the situation has been rapidly evolving these past few years

.I don’t agree with the conclusion of Ioto lacking a highly pressurized magma chamber or the average supply rate but I will agree to almost everything else. The moment I read this, I mentally threw the sill theory out the window because it just didn’t make any sense to me but with Hector’s model of an ascending magma chamber we must question how this could even happen. This is NOT normal behavior for a volcano. Magnetic Anomalies support this structure

I believe the driving force behind this is the ring-fault interaction with a massive supply and an EXTREMELY overpressurized system akin to CCN. Hector surmised that Ioto had higher end VEI 6-low end VEI 7, 2800 yrs ago and immediately began rapidly inflating, experiencing 500 m of uplift since it’s eruption. It’s uncommon for an explosive system to have no reprieve after a caldera-forming eruption. After less than 3,000 years it look like its going to get another go! This has led to the whole island being an extremely hot spot(Pun intended), heat makes crust more ductile and elastic thus making it harder for the volcano to break the rock that inhibits it’s innards from being let loose. This setup promotes magma expansion and pressurization. As the magma chamber recovered from it’s eruption, the crust continued to build heat and developed a new and expansive hydrothermal chamber.

The ring-fault served as an area of weakness but not for magma initially, heat instead permeated the fault, priming it over the years for the current phase but by the point the magma chamber was being rapidly fed magma and was doing it’s intra-caldera eruptions. These eruptions weren’t it’s usual Trachyte but it was basalt-basalt andesite, likely magma directly sourced from the massive supply. These eruptions would eventually create the Motoyama block and plug the system. The magma chamber became overpressurized and would eventually lead to the creation of the cone-sheet. I am of the opinion that this volcano has had supply rates ranging from 0.05-0.12 km3/year, however the one thing that kept me skeptical of my figure was the question of how could this volcano maintain such a high supply rate while going over in 1,300 years.without an eruption. The answer lies in this GPS data.

Do you see it? The difference of uplift between the J604 and J605 stations is stark, one rises by meters and the other by centimeters. This trend has been universal, the area that J605 station occupies did not submerge after the 2800 BP eruption and as seen much smaller deformation than Motoyama, it is not part of the caldera. Because of the immediate recharge following the formation of the caldera, the block that collapsed into the chamber didn’t settle into the volcano and rapidly began to inflate again. The block would be more sensitive to changes within the chamber and inflate faster than the other portions of the volcano. Compared to extreme uplift of the rest of the volcano, the Chidoghara peninsula hasn’t uplifted as fast but compared to other volcanoes the uplift speed is still striking! Rising 2.4 meters in 11 years, an annual uplift rate of 21.8 cm/year in comparison to the caldera’s 10-15 m of uplift or 1-1.5m/yr. If we were to assume that the ration has been the same for the last 800 and 2800 yrs respectively, we get the values 23 and 96 meters. This is still a massive number and beats almost every other volcano on the planet, for reference Campi Flegeri (a very active caldera) has “only” risen 60 m in the last 5,000 years!
This gives us 2 facts first off as the J605 station is outside the range of the cone-sheet intrusion, it’s inflation likely the result of the chamber directly. With the station being 6-8 km away from the center of the caldera, thus giving the magma chamber a minimal width of around 12-16 km. Another thing that you will notice is that it’s southward displacement is far faster than the vertical movements, we deal with that later but first will continue with the results of the vertical displacement. Due to the caldera-block being pushed up by far faster rate than the rest of the volcano, a void was created and that void would be filled with magma. Even with generous estimates this magma body would only be 0.4 km high, hard to reconcile since the cone-sheet intrusion is at least 0.8 km high. This structure could be considered to be a psuedo-sill. The difference in vertical deformation planted the seeds but it’s not what grew them.

The ring-fault was an area of weakness after the main vents were plugged or maybe even during the early eruptions, magma began to move into the ring-fault. Saturated by heat, the area was primed for magma and nothing major broke and it began to accumulate. This would trigger an extremely unique phenomena, the magma began to push the caldera-block away from the rest of the volcano, this is again seen in figures above where you can clearly see J605-J604 stations rapidly pulling away from each other. The ring-fault was being split open to allow the magma to enter. Hector had questioned how the Ioto could have a ring-fault with no CLVD quakes; the answer is that the ring-fault is being destroyed and intrusion has acted as a barrier that kept the block from interacting from the rest of the volcano. The chamber couldn’t erupt thanks to this unique setup on top of extreme heat of overlying rock.

Now we must answer how much magma is in that cone-sheet and with that we can figure the long-term and short term supply rates of the volcano.The main reservoir is at a depth 2-10 km, the cone-sheet intrusion is at 1.2 km depth so needless to say that this ridiculous large spread. I personally refuse to believe that this chamber is any deeper than 6 km as anything above that would break my suspension of disbelief for acceptable ranges of magma supply. So we will only be using the values of 2-6km for chamber depth. In the same vein area the cone-sheet intrusion occupies is large, enough to facilitate 30-50 km2 of uplift. These numbers are NOWHERE as solid as I want but it’s the best we got.

	10 km2	20 km2	30 km2	40 km2	50 km2
0.8 km	8 km3	16 km3	24 km3	32 km3	40 km3
1.8 km	18 km3	36 km3	54 km3	72 km3	90 km3
2.8 km	28 km3	56 km3	84 km3	112 km3	140 km3
3.8 km	38 km3	76 km3	114 km3	152 km3	190 km3
4.8 km	48 km3	96 km3	144 km3	192 km3	240 km3

An absolutely acceptable spread if I do say so myself. The minimal and maximum figure on this table are extremely unlikely to pan out in my opinion, I personally think the 20-40 km2 and 1.8-3.8 km ranges are more acceptable nonetheless we will calculate the full range. The resurgent dome has a volume of 34 km3 which is another minimal figure for the amount of magma that entered the system so far. In any case, simple math rules. 0.019-0.104 km3/year. Using my personal range, we get a 0.0285-0.0733 km3. I believe that the loose caldera-block is a pretty weak inhibition for uplift and the uplift that we see on the peninsula is more accurate to the magma chamber. Even with this, the uplift is still working against gravity and against something that is not technically flexible so using such simple methods gives us a minimal figure for magma supply. Using the uplift of the peninsula as a proxy for the magma chamber we get far more realistic numbers(that still can reach as high 0.1 km3) for Ioto’s growth. There is another way to calculate the supply, the last uplift cycle resulted in the cone-sheet intrusion getting pressurized by 10 MPA, interesting to note that there was no subsidence of at the volcano meaning that the chamber lost no pressure as it supplied a large volume of magma to the system. I am not sure how accurate those numbers are and don’t know Calc 3 but if we got some mathematicians up here. Here’s a problem to solve.

Now that we’ve got a mechanism for the recent unrest, we must now explain why the volcano has started to erupt as of late. We will now address the horizontal deformation, the main driver of this feature isn’t the inflation as it continues in the absence of uplift and even in subsidence. The cause of this is the crustal thinning as the caldera-block is gradually ripped away from the volcano. At one point, it needed magma supply to sustain this process but now that the intrusion has overpressurized and the crust could’ve thinned over 400 meters by now. We’ve reached a runaway point where uplift is no longer needed for this process. This means that the cone-sheet can no longer just harmlessly expand is starting to shift away from horizontal expansion and is now starting to lean towards the vertical direction. The crustal thinning will decompress the cone-sheet intrusion, leading to faster inflation which will in turn increase the crustal thinning, a nasty process. With this piece the eruptions will start small but will continue to increase in size as the years progress but that’s not all! The Northern portion of the caldera has uplifted more than the southern portion in the last 20 years and it’s possible that the caldera is tilted depending on what portion has risen more altogether

The whole island is breaking apart and it’s only going to get worse. The Motoyama block has a large crack going right through it, a testament to the stress the volcano is under. The northern portion is heading south while southern portion heads north. The west portion was moving east while the east portion is moving west. This due to the uneven uplift and non-uniformity of the magma intrusion.

This is probably responsible for the subsidence and dense material at the center of Motoyama. The deformation from the cone-sheet intrusion and crustal thinning is compressing segments of caldera-block! This will eventually give rise to larger M4 and maybe even M5 earthquakes! The compressing of the caldera-block may inhibit uplift but when these quakes start happening, the resulting decompression spikes will trigger pulses of high inflation which only just make the horizontal deformation worse, increasing compression on the segments! This also a testament to the size and pressure of the intrusion that it can compress billions of tons of rock This is what will trigger a caldera-forming eruption. If a relatively weak seismic swarm with no earthquakes above M3 can cause 4-5 cm/day uplift and a small VEI 2 eruption then imagine what a swarm dozen or hundreds of times bigger could do. I doubt the volcano could handle it.

Unfortunately, that quake is probably on it’s way as we speak. The N-S deformation within the caldera has stopped completely and E-W deformation has slowed and almost stopped as well. However, the deformation at J605 is unchanged and may have actually accelerated. This means that the block has reached it’s limit and is accumulating stress. These segments move faster than any other fault line and will build energy quicker and a rupture is on its way.

Depending how long it will take for failure, a caldera-forming eruption could be imminent. Even if the quake doesn’t trigger the CFE, the runaway crustal thinning and overpressurized intrusion would just start rapidly recompressing it immediately.
There is another earthquake threat, the process that I described above isn’t what happened in August. As you can see the previous swarm had caused ruptures that aligned with pre-existing faults…or did it? It is odd that all of these faults would rupture at the same with such weak quakes. What is more likely to have happened is that the crustal thinning had triggered had put strain on the faults but in a different way. Instead of rupturing from compression, they were stretched and extended, causing the quakes and cracks. As long as this continues, this will happen again. The deformation will likely continue to accelerate and things will inevitably break. This is the tipping point,

I’ve given my complete model and now we must answer the question, how big and intense will Ioto’s climactic eruption be? This will be far more contentious of a discussion but I already know most will still lean towards an intense low-end VEI 7 but since the magma chamber is likely above 12-16 km wide, this volcano may have the capacity for a larger eruption of around 114-201 km3 DRE. My model implies that the pressure is so large that caldera-block is being dislodged like cap about to be burst off a bottle. One thing that we have to understand is that his block hasn’t just now started to be compressed now, it’s been this way for decades, maybe even centuries.

The fast uplift we’ve seen at the volcano is not indicative of it’s full potential as it had to deal with 300,000,000-800,000,000 tons being pushed down on it. I don’t know by how much or for how long but the magnitude of this is insane for sure. The crust along the caldera is being ripped apart but at the same time, the caldera block is being crushed. There is so much shallow magma and such massive amounts of pressure that’s ripping the whole top of the volcano. All of these forces that we’re seeing now are beyond insane.

The compressional force will add to the eruptions intensity when it finally happens. There could be over 100 km3 of magma that is just 1.2 km from the surface just that is almost guaranteed to interact with seawater. On top of the volcano being plugged rather well and the potential for gas-cap developing akin to what happened at Hunga Tunga in 2022. Iwo-jima has an extremely diverse range of magmas, to Basalt to Basalt-andesite to andesite to Trachyte to Trachydacite to just dacite. The potential for magma-mixing is high and this on to of everything else we just established. This likely could be more intense than HTHH and Krakatoa. Ioto is an extreme amongst extremes and It has earned the title of King.

Conclusion

I’ve placed my bets and I call. I am eagerly awaiting to see how much, if any, I will win. As I wait, I shall loosen my chains and indulge my self on the other volcanoes that I like. (Yes, they do exist) Rest assured as soon as something anything big happens I will be on it like butter on toast. There is no way that I am going change my picks unless the runner-ups for my top dogs do something. Oh I never talked about my secondary picks have I? Might have to fix that…

Sources:

Pilicita Masabanda, Mothes, 2025: https://bibdigital.epn.edu.ec/bitstream/15000/26268/1/CD%2015044.pdf

IG-EPN bulletin 2025: https://www.igepn.edu.ec/servicios/noticias/2246-informe-volcanico-especial-complejo-volcanico-chiles-cerro-negro-no-2025-001

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2025GC012319

https://www.researchgate.net/publication/395458500_Stress_interactions_between_earthquakes_and_volcanoes_in_South_Iceland_Application_to_Eyjafjallajokull_and_Katla

https://www.gsi.go.jp/BOUSAI/ioto_kisen.html

Click to access 20250217-mxt_jishin01-000040346_4-2_2.pdf

Isana Kobune, Youichiro Takada (2024). Uplift of Iwo-jima island during 2007-2023 detected by InSAR and its
physical interpretation: Effect of thermal stress, Japan Geoscience Union Meeting 2024. https://confit.atlas.jp/guide/event-img/jpgu2024/SVC26-13/public/pdf?type=in

Nagai, M., & Kobayashi, T. (2015). Volcanic History of Ogasawara IOTO (Iwo-jima), Izu-Bonin ARC, Japan. Journal of Geography (Chigaku Zasshi), 124(1), 65–99. https://doi.org/10.5026/jgeography.124.65