Chile-Cerro Negro: Is this the one?

There are so many volcanoes right now that have the size and history to produce a massive eruption but only one volcano has me worried for the imminent future and you’ve heard it’s name before, Chiles-Cerro Negro. As of late Chile-Cerro Negro has been having a massive swarm with accelerating deformation which has caught some attention from our community and as the volcanoes representative it is my duty to give you an update on the volcano’s current situation. I have already wrote too many articles of subpar quality concerning this volcano and I don’t really want you to go back and read those. But I also don’t want to retrace old ground and this article will be all you need to understand this volcano’s current situation, and what is so concerning about this volcano.

Located on the border of Columbia and Ecuador, this system consists of the 2 stratovolcanoes and 1 caldera at the minimum and it has been dormant for over 12,000 years. Something changed in 2013 when an intrusion began, starting a massive swarm and for almost 10 years this volcano has been under constant changes which leads me to believe that this volcano has some scary potential. It may seem a bit disingenuous, after all this volcano at a glance seems to be your typical stratovolcano couplet but this couldn’t be further from the truth.

There are 2 calderas and several other volcanic features near the volcano that are all uplifting or under seismic stress. That is not indicative of modest potential. 20 km wide area was under uplift surrounded by a ring of subsidence, something that occurs at caldera volcanoes but not really at stratovolcanoes. On top of that, regional faults have been under stress for over 8 years. This never sounded like your typical volcanic unrest but now? Now it’s clear as day that something is very wrong with our black hill.

The red flags began in 2018 when the second swarm began. Despite being reasonably large, there was no official confirmed cause but it had been postulated that this was the result of magma chamber pressurizing. 200,000+ quakes don’t just happen for no reason and I was confused to see an underwhelming response by the geological agencies. More than 4 volcanoes under unrest at once? Large inflation? Stressing regional faults? Dormant for years? This all sounds pretty interesting!

But after 2020, the activity at Chiles-Cerro Negro fell of a cliff, deformation stabilized, quakes became scarce. It got to a point that I started to wonder if the volcano was about to back to dormancy but I noticed while Chiles-Cerro Negro activity was going down, Cumbal’s was going up. Now I don’t believe Cumbal is part of the same magmatic system but these two volcanoes share the same tectonic system and the hydrothermal activity at Cumbal is influenced by the tectonic stress at Chiles-Cerro Negro. A seismic uptick at Cumbal gave me suspicion that everything hadn’t returned to normal and I was right.

Starting in April, LP earthquakes started to take place at our Black hill with a SHARP rise in deformation. Let me just say that if the instruments are working properly then this is the most incredible deformation I have ever seen on an Inclinometer. Since the swarm began there has been a shift of over a million microradians at two instruments and uplift has rose to over 10 cm/year at one station with faster uplift likely further south.

This isn’t it though, despite the scary numbers the real fear-stoker is where the LP earthquakes are taking place; in April these were taking place 30 km below the surface but now they’re taking place 1-2 km below the surface with more LP earthquakes than any other of the past swarms. The current unrest is most likely being driven by a large volume of buoyant magma, and to make matters worse, the hydrothermal system is being disrupted by this magma and there is still no surface degassing of this shallow magma which means the system is plugged.

First swarm- Magma intrusion

Second swarm- chamber pressurization

Third swarm-ascending magma

I still don’t think we’ve reached the point of no return but only a fool wouldn’t watch this volcano like a hawk. I can’t speak to how exactly big this volcano is, or if it’s going to erupt but if it does erupt, it’s going to be big. I have never seen such a coalition of so many insane numbers in one volcano and nothing points to this volcano being small or modest in size

Is this the VEI 6+ caldera-forming volcano we’ve been anticipating? We’ll see.



80 thoughts on “Chile-Cerro Negro: Is this the one?

  1. At last! Chile-Cerro Negro. Great article and thanks, Tallis!
    I’d like to say let’s hope you are wrong. But with volcanoes you can never be too cautious, as Hunga Tonga showed us all. You’ve done your research very well. I hope they will listen to you.

    • Unfortunately, The IGEPN is dragging their feet when it comes to reporting data, it’s been two weeks since they published a weekly report and 3 months since they’ve published a monthly report. They’ve only released gps data for one station when there are 5 stations. Hopefully they’re being straightforward with they’re reporting.

      • poor country maybe not enough resources? I wonder if they can ask for help monitoring things or perhaps the powers that be do not want folks to become scared or they are trying to encourage trade and investment so limiting info. The rest of the scientific world should offer assistance.

        • Well, we probably should be getting involved already to be honest. This volcano *is* marked on the USGS Volcanic Disaster Assistance Program, or VDAP. We’re already prepared to help here, at least in theory.

          • The VDAP Cerro Negro is a different volcano, in Nicaragua. VDAP is a brilliant program. The list you found is for volcanoes where they have provided assistance in the past.

  2. Scary times… Potential VEI7maybe. Potential biggest nuclear accident ever…

    Better stock up on toilet paper…

  3. Thanks Tallis! Been looking forward to this one.

    I genuinely search for news out of South America on this volcano just about daily right now. Of course none of us can divine the future here, but there’s just something about this system that “feels” major. It reminds me, a bit, of everything I’ve read about the run up of Pinatubo in 1991; identifying the monster and realizing this could be a problem. We’re not there yet in full, nothing is “imminent.” But I fully agree with you that this needs to be watched like a hawk.

    Maybe it does nothing. Maybe it burps. Maybe it has an effusive event a la the first Quizapu eruption. Or maybe it intrudes a massive plume of ash and gas into the stratosphere, and we’re looking, mouth agape, at an eruption of incredible power.

    I do wish that it decides to make its intentions clear enough that the locals can GTFO in due time.

    Thanks Tallis, this was a great summary and I appreciate getting a chance to see that data.

    • Speaking of the locals. What’s the population like in the danger zone? How many are at risk if it decides to go big?

      It’s a scary beast for sure and the signals make me uneasy. Can’t shake the bad feeling I get about this one. I would much rather go back and watch beautiful red stuff fountain from the ground than see this bad boy blow up.

      • The city of Tulcan lies about 20km east of the edifice of Volcan Chiles with about 50,000 people, and another 8km or so further east lies Ipiales with an even larger population. Cerro Negro de Mayasquer lies a few km northwest of Volcan Chiles.

        It’s going to depend on where the potential center of activity is and of course exactly how large the event becomes. Of course if we’re talking a very large VEI6 with powerful pyroclastics, it looks like a lot of people will need to evacuate the area.

        Probably why they’re hosting evacuation and eruption drills, from what I saw in local news, to better prepare for an event.

    • The volcano has some potential but don’t bet on the agencies taking this seriously. It was fun to speculate on this volcano before but now that magma is rising and is just 1-2 km below the surface, there is no excuse for the lackadaisical response. The volcano has just become one of the fastest uplifting volcanoes and the expanse of the activity is impressive. Back in 2020, the LP earthquakes were clustered in the NE portion Cerro negro and were happening at 50 km below the ground so we’re dealing with system that is over 30 km wide and 50 km deep. Someone needs to take this seriously and give some good data on this interesting system.

  4. Chile-Cerro Negro: Is this the one?

    It’s the one alright; well in terms of interest to me at least. Sounds like the perfect disaster waiting to happen…

    – Long dormancy.
    – Stale magma.
    – Large earthquake swarms that occur more frequently.
    – Large area of uplift.
    – Evidence of previous calderas from large eruptions.
    – Sizable magma chamber.
    – Near the equator, so ash has easy access to both hemispheres.

    I did see someone mention that there seems to be 2 different depths of earthquakes where the inflation is occuring and they thought that there may have been 2 magma chambers inflating. Any guesses as to how big the capacity of these chamber(s) might be?

    • I don’t know, it really depends on the systems structure and how the possible multiple chambers are connected but my guess is around 10,000 km3 of Magma. (20×30 are the systems dimensions at the minimum)

      • Note however that the volume of intruded magma can only be as large as the volume of the domed up area above it. This is because intrusion of magma requires a displacement of rock away from it to accommodate the intrusion, in dikes this displacement is horizontal, in magma chambers, sills and cone sheets the displacement is vertical, upwards.

        Here the inflating area is about 300 square kilometres. If 10,000 km3 of magma had been intruded here then it would mean a 33 km uplift of the ground, which is clearly not the case. It is hard to tell the amount of uplift without fieldwork, hard to know how much magma could have been intruded under the area. Certainly not more than 300 km3 though, or the uplift would be very obvious.

        • That doesn’t tell you how much magma there is, though, just how it has changed. The change will be a combination of new magma and reheating (and expansion) of what was already there.

          • Yes, the recent documented topography changes indicate new magma mainly.

            What I was referring to, however, is that there should be a remnant topographical uplift from all magma that has ever been intruded in that area, even the magma that is now completely solidified must have contributed to uplift. Of course characterizing such an uplift would be very difficult given the irregularities in the terrain, erosion, and deposition of volcanic materials, so it is hardly useful unless a very detailed analysis was made, documenting faulting and folding of strata, right there on the field.

            See this for a visual example:

          • Whose to say there isn’t a dome here? The dome or uplift Uturnucu was missed for years despite being over 1km high and 70 km wide due to being surrounded by regional “junk”, Calderas. lava domes, and an overall complex topographical setup made it hard to spot. With a smaller and lower dome could be missed for similar reasons here

      • I don’t know man, the primary reservoirs don’t show *that* much depth. Based on the seismic spatial distribution, i only come up with a total volume in the 1,000 km3 range. at the absolute most. at least in the main brittle crust region. there’s probably more in the deep reservoir, but.

        • My 10,000+ figure is for deep crustal chamber, if this volcano were to produce a caldera forming eruption the magma would come from the deep chamber. In 2020 there was a smaller swarm of LP earthquakes taking place 35-50 km below the ground with some distance from the main activity, and it should be noted that the area of the seismicity is almost always smaller than the systems total area. I do think there is some evidence that points to extensive deep chamber, the aforementioned deep LP swarms and the extensive multi-volcano deformation all support this. None can really speak on the shallow chamber since we don’t know where exactly it is to begin with, how deep or wide it is, ehich portion of the surface activity is it influencing. I didn’t include my thoughts on the systems size in this article because any number we come up with would be nothing but speculation without any significant evidence.

  5. Great article Tallis, Thanks. I remember Pinatubo, I was working for a park here in the USA the year after that eruption. Well, it rained excessively that summer, it just poured and was cool constantly. It was finally Labor day weekend, the last official holiday of summer and of course it poured rain. As I turned the park watch over to the night guard I had to drive past several cabins only to see the renters out in the pouring rain trying to play volley ball. My thought was “yeah, this was the worst summer ever folks”. So imagining another 6+ means a big weather change as it is close to the equator it could impact both hemispheres? Definitely it will be on my radar to watch out for.

      • There is reason to speculate that the Super El Nino of ’97-’98 was (in part) a whiplash event following the cooldown caused by Pinatubo.
        Once the atmosphere gets sufficiently destabilized, it can take many years for a new state of equilibrium to get established.

        • I’m fascinated to see exactly how the climate forcings from HTHH will play out over the next few years.

          While it appears the injection of water vapor into the stratosphere was enormous (~10% of the normal total up there), yet the SO2 flux was rather low (roughly 1/40th of Pinatubo, depending upon the exact figures you take for either), I still believe some disruption to the normal ebb and flow of the various oscillations will play out, and exactly what that will be is very fascinating to me.

          We’re entering a third year La Nina which, though not unprecedented, is rather unusual.

          • At present, it appears that the spike in stratospheric WV is having a greenhouse effect…hence instead of volcanic cooling, we’re seeing volcanic warming…especially in the SH. Much to learn here, fer sure.
            Note that the warming is happening at a time of pre-existing accelerated Antarctica ice loss, and IMHO the cold melt water is being transported to the equator via the Peru Current which in turn is constructively interfering with the prolonged La Nina.

      • It snowed in San Francisco and there was ice on the sidewalks in the daytime. That is very unusual. Cold winter 1991-1992.

  6. It does look like this place will have a very different look in 10 years than it does now. Chances are that it will resume stratovolcano building, which might mean the first eruption is less of an ignimbrite and more of a stable plinian eruption with relatively low range laterally. Or it might begin effusive as seems to often be the case. But if uplift is over such a big area at some point it will break its mold and go caldera properly, which might be in the low 7 range if it really self destructs. Hunga Tonga showed that ignimbrites are incredibly fast, and seem to be that way regardless of magma composition, as it was hot crystal poor andesite, a lot like the fissure 17 lava from Kilauea in 2018.
    Im starting to think VEI is not applicable above a high 6, VEI 7s and 8 probably involve multiple collapse events of the caldera, not one that is bigger. Kilauea collapsed sequentially and every time the eruption got stronger temporarily, the same thing happened at Bardarbunga, it seems to be how calderas form all over. Taupo in 217 AD was a 6 in volume but with the power of an 8. So you get a caldera collapse that starts, and the first blast is a 6, and in bigger eruptions there are more collapses, until it cant keep going. So we could be looking at a supervolcano scale blast radius if this thing does go for a VEI 6-7 ignimbrite. It doesnt look crazy populated but no doubt it will be a disaster, Columbia already has a claim to the worst recent volcanic disaster, even though that one was human error not the volcano itself or the volcanologists, it is not a good track record…

    Excellent article Tallis 🙂

    • Insightful as always, Chad.

      Albert made it click for me the other day when he mentioned how an observer in the future would look back at Fagradalsfjall 1 & 2 as the same eruptive sequence. A year of separation is nothing.

      How many large eruptions in the past are multi-stage events that happen over a timeframe that would be quite long to a human observer? I know some we can tell with a bit of precision, while others we’re not entirely sure.

      It made me think of Saskunarvatn and how the tephra was originally thought to possibly be Iceland’s only singular VEI-7 but was then revealed to be a sequence of moderate to very large events over a few hundred years. A few hundred years is multiple human lifetimes.

      Just very interesting perspective in there if you think about it.

      • RE: “but was then revealed to be a sequence of moderate to very large events over a few hundred years. A few hundred years is multiple human lifetimes.”

        Those looking back will have the advantage of voluminous and accurate data which will eliminate a great deal of the speculation current research is often obliged to employ in their analyses.

  7. Well Tallis, you’ve piqued my curiosity. I’ve gone back in time a bit and now wonder if you have any thoughts or projections, using your Volcanic Societal Impact scale, as what the outcome might be for not only the region, but the planet as a whole, if the system uncorks?

    • Thank you! If we’re talking about the worst possible scenario for the volcano then I would say VSI 12.

    • I don’t know how it is with Icelandic moss, but ground fires can sometimes be burning below the surface through glowing combustion. I think it’s more likely that the heat is caused by the fire than the fire being caused by the heat. Remember that rock is not a good heat conductor. If the ground was so hot from fresh magma that it could set moss on fire it would probably already be erupting.

  8. GeologyHub had an interesting video about the Chiles-Cerro Negro complex some 9 days ago. He speculates that there are 2 magma chambers present.

  9. Thank you Tallis for the article.
    Could you share some links to online gps graphs and so?

    Dragons, the link under the first map doesn’t work.

    Link fixed


    Some really nice images. RUV has reported that the lava fountains are now a lot taller, the high bursts as seen in the above images are now more than 100 meters. I think we wil lget quite a show as thsi thing evolves, especially if the lake around the vent starts to shrink as the outflow becomes more focussed. It is hard to see the eruption right now but it also looks like the central fissure is a lot more singular now, it is almost a single vent. Nothing on whether pressure has been equalised in the system, but as there have been no reports the effusion rate has increased I am assuming this has not changed and more vents could still open. Or the existing one might get more powerful.


    • The weather is terrible but the occasional glances show that the fissure with its three parts remains active. Impossible to tell whether it is fountaining more. The cone is not building fast, suggesting most of the output is streaming, not blowing

      • The fountains are not necessarily higher but the taller jets are happening more often than early on. It also is definitely more focussed on the middle fissure too, the two edge vents are not so active as before. But they are all still going, and with that big quake showing there is still pressure underground… I dont recall last year that any of the other vents had a precursor other than the first vent slowing a bit in the preceeding hours.

    • Trigger quakes from the dyke expansion. Question is if it’s a delayed response or if the dyke is still expanding.

      • My guess is that the dyke is still expanding. Swarm sequences tended to start near Krysuvik and meander westward. But I could be wrong.

  11. The RUV camera is looking the other way. Is there something we don’t know? Or has the operator dozed off and knocked the control lever?
    BTW I stand by my theory another rift may open to the SE of Keilir. You first read it here!

    • Rumour says it ran out of power during the rain and now it got stuck while moving on it’s regular pan after power up.. Don’t know if this is correct.

    • I think the operator subscribes to your theory and is aiming for any further fissure there. A bit early, perhaps

  12. What is the area like around Chiles-Cerro Negro? Volcanic field, rhyolite domes?
    Definitely appears to be surrounding older calderas, and magma is clearly closer to the surface than before.

    • I would say looking at the earthquake history there are potentially 3 magma chambers, one between Chiles and Cerro Negro, closer to Chiles. Another to the South-east, likely deeper. And another further to the south-east where an old likely Pleistocene caldera appears – though this could just be stresses causing the quakes.
      Some Dacitic domes and the magma composition hovers between basaltic, andesite and dacite.
      I’d say this isn’t quite fully developed into a VEI7 volcano yet but may have some large eruptions in between.

      • This is not particularly on topic but it seems like a good lead in for a question I had:

        What made Tambora a VEI 7 capable volcano, and isn’t the caldera undersized for the enormous amount of tephra produced in 1815? Does that imply a very deep magma chamber? Speaking of, I believe it erupted trachyandesite which isn’t at the extreme end of silicic magma, so wouldn’t that mean the chamber probably wasn’t even sitting for very long? I read Tambora was dormant for “a few centuries” prior to 1815, but that doesn’t scream “VEI 7 100km^3 + of tephra” to me. Do we know what Tambora’s older eruptions were like? Is this the first time it went big?

        And yes, thinking of it in relation to Chiles – Cerro Negro somewhat. Even Tambora’s extant edifice is enormous, so it clearly has a large magma source. Just curious how it all added up, and if we can infer anything about Chiles (not suggesting they’re necessarily the same scale).

        • All of the stratovolcanoes in that part of Indonesia are huge, I dont think it is higher magma so much as that they are very stable, calderascare refilled by more stratovolcanoes and repeat. Rinjani is also still mostly intact, it could be that magma chambers are deep here or are more veryically oriented, or perhaps that conduits get so wide they act as a chamber themselves?

          It might also be that they simply go caldera under their own weight, not anything to do with magma evolution, while no Mauna Loa these volcanoes are some of the biggest freestanding mountains on this planet.

  13. An eruption of this in the future is something I’ll wait for. Hopefully they evacuate everyone safely and there is minimal damages though.

  14. Oh dear, just seen that the time stamp isn’t moving so anything could be happening there in reality!

      • Yeah, Fiji is a relatively active volcano. That is why it is such a beautiful cone, little time for erosion. It had an all-ash VEI 5 eruption in 1707-8, which was a flank eruption, preserving the cone. It is a repeat offender with VEI 5s around 1350 BC and 900 BC. There was also a *huge* lava eruption in 864 AD, which covered about 30km^2!!! Lots of other smaller or poorly recorded eruptions. It also had a flank collapse around 300 BC that caused Lahers. In summary, it is no friendly giant, and is likely to do something decidedly nasty in the next couple hundred years.

        • RE:”and is likely to do something decidedly nasty in the next couple hundred years.”
          Much like St.Helens and others of its ilk, such an event would be a tragedy of many proportions.

          • I was surprised to learn Mt St Helens had a VEI 6 eruption a few thousand years ago. I believe it’s called ‘Tephra Layer Yn’.

            Couldn’t find an estimate of actual volume, but from the images of the deposit it was a mighty big eruption.

          • A quick estimation of the total volume of the pumice layers gives me 10-15 km3.

  15. Reactivating after 12,000 years does seem a bit ominous. Might be a bit more evolved than andesite.

    • There was a discussion on this a while ago, the magma is andesite overall but it is actually more rhyolite with mafic crystals, the actual liquid melt is rhyolite. In volcanoes that erupt only rhyolite usually they sit on top of a huge heat source, often a massive basaltic intrusion complex (hence why they are bimodal) so despite being high in silica it heats it up a lot so crystals can settle out. But in the Andes it seems the magma is not hot enough to do this, at least not typically. This isnt always the case, the southern Andes has abundant mafic volcanism and very hot rhyolite, and Reventador which is not that far from Chiles Cerro Negro erupts hot andesite, but it seems actual crystal free andesite magma is not too common in the Andes despite being the namesake… It might be why andesite is imagined as a viscous magma, if it is rhyolite with mafic crysyals in disguise, because andesite melt seems to flow easily if it erupts crystal poor.

    • Taal is always one to watch. Phivolcs should raise the alert to 2 since it looks like there is some more shallow magma and good deal of it seems.

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