Laguna del Maule. An explosive rhyolite ring volcano.

In the previous article I was talking about the volcanoes in Argentina, in the Andes, near the latitude of Buenos Aires, only a little more to the south: Payún Matrú, Tromen, and Domuyo. Now we cross the border into Chile, into the Maule Province of Chile. Here, almost exactly along the topographical divide between the east and west flanks of the Andes Mountains, three monster silicic volcanoes lie next to each other in a row. The most important, ongoing, silicic flare-up of the Southern Andes Volcanic Zone, if not of the Andes as a whole, is to be found here.

In the last article we saw Domuyo, the roof of the Patagonia, a prominent mountain which hides a burning secret. This remote snow-clad massif with more than 100,000-year-old rhyolite lavas gives every sign of being extinct. However, 60 cm of inflation between 2015 and 2020, as well as prolific springs of boiling water along the foot of the mountain, prove otherwise. In reality, the entire mountain seems to have risen by 2 kilometres, probably due to magma building up below. About 60 km to the north of Domuyo, lies Laguna del Maule volcano. Then, another 60-70 km to the north, lies Calabozos volcano, and about halfway between Laguna del Maule and Calabozos lies Puelche volcanic field.

In this article I will be looking only at Laguna del Maule, since this volcano is so interesting that it needs a whole article, and I will address the other two in the future.

I marked important volcanoes of the area in a topographic map from


Setting of Laguna del Maule

Laguna del Maule is part of a broad complex of volcanoes. The area around Laguna del Maule has seen many monogenetic eruptions, consisting of scoria cones of probably basaltic andesite or andesite composition, over an area 45 km long and elongated E-W. These can be distinguished as irregular mounds or patches of dark and red material, which are heavily eroded. About 20 km to the NE from the center of the lake towers a lonely pinnacle of lava and pyroclastic material, which is the remains of a dismantled stratovolcano known as Cerro Campanario. The stratovolcano is made of crystal rich basaltic-andesites, which contain 20-30% plagioclase crystals and 3-6% olivine crystals. It has a volume of 10-15 km3. The cone formed at some point in 200-150 ka (thousands of years before present). Another complex of inactive, eroded stratovolcanoes lies 20 km south of the lake, of unknown age and part of the chain of volcanoes that runs N-S from Tromen to Laguna del Maule. And a complex of stratovolcanoes, San Pedro-Pellado, is located 30 km to the east of the rhyolite volcanic field.

The San Pedro-Pellado complex consists of an older stratovolcano, Pellado, which grew during 188-83 ka, so that it was active for approximately 100,000 years. Pellado erupted mostly basaltic-andesite and andesites, to a volume of more than the 12 km3 that has survived erosion. San Pedro-Tatara stratovolcano grew immediately to the west of Pellado, starting around 90 ka, and took over activity. It has kept erupting into the Holocene. San Pedro-Tatara has 22 km3. It consists largely of basaltic-andesites, with rare andesites and dacites. Young lava flows formed during slow, long lasting effusive periods drape the flanks. Where the flows reach the foot of the edifice, they make tongues 20-30 meters in thickness. Part of the cone collapsed, probably during the Holocene, and made a debris avalanche that travelled 18 km following the course of a river. Lava flows then filled the collapse scar. Strombolian activity and more intense explosive erutions have issued from the summit of San Pedro, making a small conical structure at the top.

The two snowed peaks in the foreground are Pellado (left) and San Pedro (right). Laguna del Maule is the blue lake behind to the left. The skyline is formed by Payún Matrú shield volcano on the left, and its satellite Payún Liso stratovolcano on the right. Image from Gerard Prins in Wikimedia, link.

The area from the San Pedro-Pellado complex to immediately NW of Laguna del Maule consists of a thick lava flow plateau, with numerous monogenetic volcanoes, as well as dense dike swarms exposed in the walls of valleys, that carry the exact same ENE-WSW direction as dikes of Puelche volcano to the NE. This plateau produced eruptions ranging in composition from basalt to rhyolite. According to ages taken from the east and west ends of this plateau, from Laguna del Maule and San Pedro, the activity may have started around 881 ka, when a rhyodacite was erupted north of the lake’s dam and was shortly followed by a large 2 km3 rhyolite flow north of present-day San Pedro. Rhyodacites are magmas which straddle the compositional boundary between dacites and rhyolites. Activity probably continued in the plateau until very recently. A 63 ka basalt eruption near the dam of Laguna del Maule probably belongs to this system, and may have been some of its latest activity.

An interesting pluton is located underneath San Pedro-Pellado. This intrusive complex, known as Risco Bayo-Huemul, is very well studied. The pluton crops out in the lower walls of glacial valleys both north and south of the two stratovolcanoes. It is made up of 2 different parts. The older Risco Bayo Pluton formed between 7.193 Ma and 6.956 Ma (millions of year before present). Risco Bayo contains diorites and granodiorites, with 55 and 62-66% SiO2 respectively, which would correspond to basaltic andesite, andesite, and dacite magmas. There are also very minor gabbros, the intrusive equivalent of basalt. The younger Huemul pluton formed between 6.384 and 6.199 Ma. Huemul is made of more silicic magmas, consisting of monzonites, granites, and high-silica granites, with 62–63, 68–70, and 75–77 wt% SiO2, respectively, which are dacite and rhyolite magmas. Some minor diorites formed between these two main phases of intrusion.

The Risco Bayo-Huemul pluton is elongated north-south, and extends across 17 km. Risco Bayo is smaller, possibly more circular, at the northern end. While Huemul is bigger, very long, and extends south from Risco Bayo. They reach up to at least 1.5 km thick. The magmas become more silicic southwards and upwards. They likely correspond to magma chambers that would have been located somewhere 3-7 km deep, as estimated in some articles. I speculate Risco Bayo may have underlain a stratovolcano complex, while Huemul would have formed a long dacite-rhyolite chamber, maybe caldera-forming, probably similar to present-day Calabozos and Laguna del Maule. I also speculate that, during the 500,000 years of quiescence between the Risco Bayo and Huemul intrusions, plutons were formed, which collapsed during major explosive eruptions and were destroyed. Huemul would be the last intrusion that did not collapse.

It is very interesting that 7.2-6.2 Ma Risco Bayo-Huemul was contemporaneous with other known events in the area. Another pluton is very roughly dated at ~7 Ma, located a little to the north, under Descabezado Grande and Cerro Azul volcanoes, which we will see later. During this time, basaltic outpourings happened in the Payenia back-arc province in the Sierra de Palaoco. Also in the Payenia, the Chachauén volcano was active, it became active around 7.2 Ma and decayed around 6.2 Ma, with only very minor mafic later eruptions. As far as I can tell, the lifespans of Risco Bayo-Huemul and Chachauén are identical. It is possible that there was a regional pulse of activity in the Andes.

In the past article, I explained that subduction in this area of the Andes had probably shallowed since 14 Ma, which had caused volcanoes to move away from the ocean, into the continent. I had also briefly considered another option that didn’t make it into the article, that subduction had actually steepened and shallowed cyclically. Looking at the data again, I think this second option is actually the more reasonable one. In the area of Laguna del Maule, stratovolcanoes seem to have been active only in the past 200,000 years: Campanario, Pellado, and San Pedro. But where was the arc located before this time? I can’t find any signs of other volcanoes situated closer to the ocean, or at the same distance as San Pedro. Instead, I find that many eroded volcanoes are located farther from the ocean, up to 90 km farther east, into the back-arc. Tromen, that we saw in the last article, is one of the stratovolcanoes further inland. At this distance a belt of folds and thrusts is located which marks the eastern end of the stratovolcano and caldera domain, and the start of the basaltic shield volcano domain. In fact, the area immediately east of Tromen makes a huge, very obvious, anticline fold. A little more to the east, Sierra de Huantraico shield volcano has been folded into a syncline.

I speculate a flat-slab may have formerly existed which extended east to the present-day location of Tromen. A flat-slab happens when the oceanic plate that is being subducted under the continental plate doesn’t sink into the mantle, but instead stays right under the continental plate at 100 km depth, creating strong compression, folding, thrusting, mountain building, and often killing volcanism. Around 2 Ma rollback started, which initiated the stratovolcanism of Tromen, the flat-slab rapidly sank backwards towards the Pacific Ocean reigniting volcanism as it retreated, leaving a trail of stratovolcanoes, and from this trail major silicic systems sprung up, Tromen, Palao, Domuyo, Laguna del Maule, Puelche, and Calabozos. The period around 7-6 Ma ago, or so, may have been a time of rollback too, when caldera volcanoes like Risco Bayo-Huemul formed. This means the flat slab may have been present in the 6-2 Ma period. I suspect an even earlier flat slab may have existed somewhere around the 15-7 Ma period, when activity in the Payenia was very quiet. This idea would be a modification to existing theories about a Payenia flat-slab, but with the flat-slab being smaller, reaching only eastwards to Tromen and not the Payenia, and also being much more short-lived, only ~4 million years in duration. This would explain a bit more about how the volcanoes in the area came to be.


Laguna del Maule

Many caldera volcanoes have large scenic lakes in them. Usually because the caldera, formed during the collapse of a magma chamber, fills with water. Laguna del Maule is a little different. Its lake formed due to a rhyolite lava flow damming the valley. People then contributed to the obstruction by building their own dam and raising the water levels further. There is more than one water body here. Several rhyolite lava flows have erupted during postglacial times, obstructing multple valleys, and leading to the formation of four different lakes, Laguna del Maule being the largest one. Its name is not too imaginative. This is the Chilean region of Maule, and laguna means lake, so it just means the lake of the Maule. Maybe the volcano should be called Volcán del Maule.

The surrounding landscape, around the deep-blue lake, is a volcanic desolation, or it would be if there was anything to desolate, the place being already quite deserted on its own. Thick gray-colored pumice and ash thickly blanket the entire area. This is best seen in the older postglacial lava flows, which have such a deep amount of pyroclastics on them that you can barely reconize them in the terrain. Massive flows of molten rhyolite crept across the hillsides during past eruptions, now frozen in rock as chaotic surfaces of brownish broken-up lava nested above 100-meter-high walls of crumbling lava blocks.

Laguna del Maule and the Las Nieblas rhyolite lava flow visible behind. Image from Felipe Reis, link.

As mentioned before, the area of Laguna del Maule has seen earlier volcanism. A large volcanic field extends between the northern side of the lake’s basin and San Pedro stratovolcano. I would attribute the very infrequent flows of rhyolite during the middle-late Pleistocene over the northern half of the basin to this field. Two ignimbrites exist in the northern part too. However, I will argue in the future why I think these ignimbrites actually came from systems to the more to the north. In reality, Laguna del Maule lacks a well-defined ignimbrite apron, with no ignimbrites described to the east, south, or west of the lake. Ignimbrites to the east, in Argentina, should be well preserved, where extensive erosion has not happened, but I can’t find anything on Google Earth. Additionally, unlike the north, the southern half of the basin doesn’t have much earlier volcanism, most lava in that area has been erupted only in postglacial times. Because of this, I think that Laguna del Maule has not sourced any ignimbrite eruptions in the past, and that, as a rhyolite system, it may have emerged very recently. It may have first erupted only 14,000 years ago.

The first known eruption was a plinian eruption which produced an estimated 17 km3 DRE (dense rock equivalent) of pyroclastic material. The pumices of this VEI-6 have 75.5-76 wt% SiO2, a high-silica rhyolite, which is basically as high as silica gets. It is thought to correlate chemically with the Los Espejos rhyolite, which dammed the basin and formed the lake, which is the lava with the highest silica, 75.7 wt% SiO2. However, the plinian eruption is also thought to have issued from the present-day center of the lake, which is in conflict with the earlier idea. But is it? In reality, it is likely that some of the eruptions of Laguna del Maule have involved multiple vents, so it is not impossible that the large plinian eruption is the same that formed the lake. Radiocarbon dates taken from the plinian eruption layer suggest an age of 14,000 years BP. Ar/Ar ages give the Los Espejos rhyolite a much older age, however they also place this flow within the Last Glacial Maximum, at 26-19 ka, when we actually know the flow to be postglacial, so these ages are probably excessively old.

Since this initial activity, Laguna del Maule has done several eruptions of varied chemistry: andesite, dacite, rhyodacite and rhyolite. But I haven’t been able to find a proper eruption history. Ar/Ar ages are not very precise, and radiocarbon ages exist but are nowhere to be found in literature, save one article. It is likely that some eruptions involved multiple vents erupting too, which complicates things.

Geologic map of Laguna del Maule. From Wikimedia, work by Frugone-Álvarez, Matías; Latorre, Claudio; Barreiro-Lostres, Fernando; Giralt, Santiago; Moreno, Ana; Polanco-Martínez, Josué; Maldonado, Antonio; Carrevedo, María Laura; Bernárdez, Patricia; Prego, Ricardo; Delgado Huertas, Antonio; Fuentealba, Magdalena; Valero-Garcés, Blas. Link.

Each rhyolite eruption started in a plinian manner, building a pumice cone with a crater usually around 1 km wide, but in one case 2 km wide, the size of the crater shows the great intensity of these eruptions, since a crater represents the diameter in which material is ejected too violently to be deposited. As the eruptions continued, lava was effused, while explosions continued at lessened intensity. Rhyolite Las Nieblas (rln) on the south side of the lake is a spectacular example. Las Nieblas has an imposing lava front 100 meters tall, a thickness of probably more than 150 meters in its center, and a total volume of maybe 1.4 km3. Lava thickness is variable. It is one of the thickest and most complex flows, with lava flowing along two/three different tongues, and with two overlapping sheets of lava at places along the front, its eruption was probably a little slower than the others. The surface of the flows has two colours, one is a darker brown, which I think represents the glassy lava surface, the other is a beige colour, which I think is pumice ingested by the flow. Explosions at the vent would have produced pumice which landed on the lava, this pumice flowed downstream following the faster flow areas, it rolled into the flow due to differential movement of the crust respect to the melt, and mixed with the lava, making an intermediate beige colour between the white pumice and the brown lava. The flow has no ash on it, except, of course, for the syn-emplacement pumice that is mixed with the lava.

Las Nieblas rhyolite flow.

Most other Laguna del Maule flows are thinner and more simple. A flow of the Cari Launa (rcl) vent, to the northeast of the lake, that flowed to the SW of the crater, is down to 20 meter thickness along the edges, which do not exceed 35 meter thickness anywhere and its consists of a single, very spread out, tongue of lava. It has the same alternating beige and brown crust as Las Nieblas and some other flows. The lava flows from the polygenetic vents along the east side of the lake resemble that of Cari Launa, and probably effused more rapidly than Las Nieblas.

Most of the vents seem monogenetic, and make a ring around the lake. However, three rhyolite vents on the east side of the lake’s basin are polygenetic. Cari Launa (rcl) erupted twice. A vent to its south, Divisoria (rcd), erupted twice, too. They both have an older lava flow, which was buried by a later plinian eruption that also formed an overlying pumice cone and younger lava flow. I think that Cari Launa and Divisoria erupted simultaneously during, at least, their younger eruption. Why? These two vents are only 4 km apart. They both formed massive pumice cones in powerful plinian eruptions. But there is a problem. Both Cari Launa and Divisoria have practically little visible pumice on the surface of their youngest flows. Only the earlier has some ash in places, while the latter doesn’t have any visible pyroclastic cover at all in most parts of the flow. In fact, Divisoria’s crater is the largest in the field, 2 km wide, and its encircling pumice cone is possibly the most voluminous in the field. Pyroclastic flows from Divisoria’s lava front clearly dusted the edges of the Cari Launa flow. So, if anything, Divisoria erupted after Cari Launa and is stratigraphically higher. Thing is that Divisoria is possibly the eruption that was responsible for a reported pyroclastic fall deposit that is 4 meters thick 22 kilometres away in Argentina. A VEI-6 eruption, maybe? This plinian eruption is less than 7000 years old based on radiocarbon data. Given that Divisoria has the most impressive crater/pumice cone, this makes it the best candidate. So Divisoria’s massive plinian eruption, that is, if anything, younger than Cari Launa, should have completely plundered the Cari Launa flow, located only 4 km away, in a mantle of pumice. But the later’s lava flow is pumice free in many places. Conclusion? I think both vents reactivated together, producing simultaneous plinian eruptions, followed by simultaneous lava flows. It is not unlikely either that they may have erupted together with some other vent, maybe Las Nieblas, which, similarly to Divisoria, is ash-free. I think the Divisoria multiple vent eruption corresponds to an ash and lapilli layer of rhyolite composition in the lake’s sediments, which is dated at 4050 BP, and is the most substantial rhyolite event within the past 7000 years found in sediment drill cores. It is also the youngest rhyolite layer found in these drillcores.

Divisoria pumice cone and younger lava flow in the foreground. The short scarp near the lower left corner of the image is the edge of the older Divisoria flow, which is almost entirely concealed under what must be up to a few tens of meters of rhyolite pumice. CarI Launa lava flow stands behind.

Further south, we find the Barrancas Complex. This is the most complicated volcanic edifice of Laguna del Maule. Barrancas (rcb) has probably erupted 4 times. Eruptions have involved E-W fissures opening up along the same line, and issuing multiple flows. The last eruption thickly buried all the earlier flows in a pumice cone, and erupted two new lava flows from two different vents along the fissure system. These two flows are mantled in a well-distributed layer of pumice, maybe from the eruption of Las Nieblas, which is upwind, or maybe from the Divisoria multiple vent eruption. At least one of the earlier eruptions was fissural, too. The earliest eruption of Barrancas may have formed a huge dome complex at least 300 meters thick. It collapsed repeatedly and produced pyroclastic flows which formed an ignimbrite apron that extends 12 kilometres downslope.

Barrancas Complex.

The rhyodacite flow eruptions on the west side of the lake are different. They seem less explosive than the rhyolite eruptions overall, and formed craters 300-500 meters wide. The explosive phase of the eruptions consisted of andesite or basaltic-andesite compositions, which showered black scoria, while the effusive phase produced rhyodacite lava flows. One eruption (rdcd flow) first produced andesite/basaltic-andesite explosively along a fissure, and then issued short flows of rhyodacite. Another eruption (rdcn flow), however, produced a flow of rhyodacite with a volume of 0.3-0.4 km3, but then entered an explosive phase of andesite/basaltic andesite composition that built a scoria cone on top of the flow, and then erupted rhyodacite again making a small bright-colored dome inside the dark andesitic scoria cone.

Scientists have taken drillcores from sediments on the lake’s floor. There are two young layers of lapilli in these sediments. Lapilli is likely to have come from nearby vents given that it’s heavy and won’t travel far. These layers are radiocarbon dated at 2285 and 3659 years BP, and have basaltic andesite composition. It is almost certain that these two explosive events came from the rdcd and rdcn eruptions that I just described, which erupted dark scoria in strong explosive events that is mapped as andesitic in geologic maps. Rhyolite layers in the lake predate those of basaltic andesite, so it is possible that these two bimodal eruptions or rhyodacite and basaltic-andesite were the last in the volcanic field.

Three flows happened to the west of Laguna del Maule, outside the ring of vents that encircle the lake, in valleys outside the basin. They have a young appearance, probably Holocene in age. Geologic maps usually leave out the three flows due to their distal location. One flow, Cordon Rodrigez, produced dacite. Two other flows erupted andesite or basaltic andesite that is very viscous looking, they seem as thick as some of the rhyolites, and with a sluggish channel flow. Both constructed the classic black and red scoria cone with 300-meter wide craters. As far as I can tell, all three erupted relatively fast as single sheets of lava.

Rhyolite eruptions have shifted in composition, from early eruptions with 75-76 wt% SiO2 which formed domes now deeply buried in pumice, to younger rhyolites with 73-74 wt% SiO2 that have erupted from Las Nieblas, Barrancas, Divisoria, and Cari Launa. The rhyolites have 1-13 vol% phenocrystals and no mafic inclusions (blobs of entrained mafic magma). Rhyodacites have 68-70 wt% SiO2 and 9-16 vol% phenocrystals. They also carry abundant mafic inclusions. I expect it must be inclusions from the basaltic andesite that erupted explosively during the same eruptive events. The Cordon Rodrigez dacite flow has 65 wt% SiO2, 18-22 vol% phenocrystals, and carries inclusions of basaltic andesite with 53 wt% SiO2. Lastly, one of the andesite flows, Rio Saso, has 59-62 wt% SiO2, and some mafic inclusions.

Thermobarometry, a discipline which studies the pressure and temperature conditions in which the minerals in the magma formed, adds more information into the plumbing of Laguna del Maule. The rhyolite lavas seem to have formed their crystals at shallow depths only, as indicated by the pressure conditions in which the minerals formed of about 6-7 km deep. So a shallow rhyolitic chamber exists around 6-7 km below the surface. Dacites and andesites instead crystallized their minerals at depths of around 15 km, which shows a separate, deeper, storage region. In contrast, rhyodacites cover the entire pressure range between these two storages, and often show intermediate values, crystals grew in both the 15 km deep storage and the 6-7 km deep storage, presumably their final destination, and also along the way between the two. The rhyodacites may include magma that has convected between the two storages and finally ended up at 6-7 km depth before erupting from the ring structure vents that include the rhyolites too.

Taking chemical and thermobarometry data, together with the distribution of vents, I think we can learn some things about the plumbing of Laguna del Maule. Another important piece of information comes from gravity surveys which have studied the area and mapped a low gravity anomaly, presumably a body of low-density rhyolite-rhyodacite magma. The low gravity area is about 13 km long and 7 km wide. And also, there is a carbon dioxide degassing anomaly to the SW of the lake reported by SERNAGEOMIN. This anomaly is located in an area of strong seismic swarms. The map below combines all the information.

There are some interesting things that we can observe. Vents follow a ring distribution around the lake. The east, north and south sides of the Laguna del Maule ring structure erupt rhyolite. The west side of the ring erupts rhyodacite. Vents happen outside the ring to the west, and erupt dacites, andesites, and maybe basaltic andesites. The CO2 anomaly is located in the west side too. The presumed magma body is elongated with the long axis roughly aligned with the CO2 anomaly. The ring of vents is larger than the magma body, especially on the east side. In particular, the Barrancas rhyolite vent complex is as much as 10 km away, horizontally, from the edges of the magma body.

My interpretation is that the ring of craters is fed by cone sheet intrusions. The cone sheets radiate outwards like petals from the 6-7 km deep rhyolite/rhyodacite chamber, which is something typical of other well-studied caldera systems, including exposed plumbings of extinct silicic calderas, like for example Gran Canaria, Boa Vista, or Mull, to name a few. The cone sheets radiate by up to 10 km horizontally while also reaching up towards the surface. The west side of the chamber has rhyodacite magmas mixed with basaltic andesites, either because this side is deeper or because it is closer to the feeder. Dikes rise from the 15 km deep chamber and erupt andesites and dacites to the west of Laguna del Maule. The location of the CO2 anomaly could well be the vertical feeder that carries magma from 15 km deep to 6-7 km deep. Magma might degas after decompressing and send CO2 towards the surface, perhaps triggering those occasional intense swarms of earthquakes.


The present and future of Laguna del Maule

The rhyolite composition and existence of a large-area magma body make this volcano a candidate for major caldera volcanism. It is thought to be a good example of a rhyolite system building up towards a cataclysmic eruption. Additionally, Laguna del Maule has been experiencing very rapid inflation since 2007. During the past year, for example, Laguna del Maule inflated 16 cm, and in past years inflation rates have been at times even higher. Measuring gravity and deformation, scientists have found that the composition of the intruding magmas is probably basaltic. Although I think basaltic andesite is more likely, which is the most mafic magma erupted in the field. Influx rate is estimated at 0.044 km3>/year. Assuming the rate has remained constant since 2007, which I think is good enough, then about 0.7 km3 of basalt or basaltic andesite may have risen into the shallow chamber of Laguna del Maule since that year.

Laguna del Maule is also experiencing a massive earthquake swarm as we speak. SERNAGEOMIN reports that starting on March 30, and until April 26, Laguna del Maule has produced 30,000 earthquakes of up to M 3. It seemed that the swarm was dying out after the initial seismic crisis, but then earthquakes escalated again on April 22, with 4100 earthquakes that day, and activity continues as we speak at a rate of about 1000 earthquakes per day. These are earthquake counts, not located events. Most of the earthquakes that SERNAGEOMIN has located are centered in the SW corner of the volcanic field, around the CO2 degassing anomaly. What is making these many earthquakes? I doubt it is an intrusion of magma towards the surface. We would know already if it was, I think. It is very unlikely to be due to pressure too, since Laguna del Maule had been seismically quiet for almost a whole year before this swarm started, and pressure can’t have changed that much, all of a sudden, without showing in the GPS. I think some surge in carbon dioxide degassing is more likely responsible for the swarm, perhaps triggered by a deep basaltic recharge, but this is speculative. Inflation doesn’t seem to have accelerated, at least so far. Pressurized gas can probably trigger earthquakes as it moves through the rock.

Does all of this unrest mean Laguna del Maule will erupt in the future? I don’t know. A volume of 0.7 km3 is very substantial. Some past eruptions of the volcano have been smaller, particularly the andesite-rhyodacite eruptions have probably been smaller than this, so it is a very significant recharge. Based on this, an eruption in the near future doesn’t seem unlikely. However, Laguna del Maule sometimes builds to much larger eruptions. Eruptions are infrequent. The last event around the lake was probably 2300 years ago, so based on eruption frequency alone, chances of seeing a Laguna del Maule eruption are rather low. It also happens in some calderas that cycles of inflation and deflation happen, with deflation sometimes nullifying completely the inflation, perhaps due to changes in magma pressure at depth. So I can certainly see the possibility that all the inflation since 2007 could go away due to an equally significant deflation. But I can also see this inflation leading to an eruption.

Can Laguna del Maule produce a major caldera forming eruption? A caldera forming eruption would probably need to be a large VEI 6 or a VEI 7 in a system of this size, since Laguna del Maule appears to have done VEI-6 events without collapsing, at least once or twice. But does the system contain this much magma? I’m not sure of this. There aren’t signs of a major scale resurgence in the area. The magma body covers an area of about 80 km2, so to inflate by 8 km3 the roof would have to rise 100 meters, to inflate by 80 km3 will require ten times as much uplift. This inflation is likely to extend over a broader area and also partly be absorbed by compression of rock around it, but it will probably reach a point when the ground will break into grabens, and where uplift will be very obvious in the landscape. Domuyo and Calabozos, for example, have clear large-scale inflation visible in the topography. However, there aren’t any grabens or any visible resurgence in Laguna del Maule. So I personally think the amount of magma contained in Laguna del Maule is rather small, and that its magma chamber might be a thin, sill-like body that swells up and contracts with each eruption cycle. So my opinion is that Laguna del Maule will probably not form a caldera in the near geological future, next few tens of thousand of years. Although this volcano is still capable of VEI-6 eruptions.


Andersen, N. L., Singer, B. S., Jicha, B. R., Beard, B. L., Johnson, C. M., & Licciardi, J. M. (2017). Pleistocene to Holocene Growth of a Large Upper Crustal Rhyolitic Magma Reservoir beneath the Active Laguna del Maule Volcanic Field, Central Chile. Journal of Petrology58(1), 85–114.

Contreras, C., Cashman, K. V., Rust, A., & Cortés, M. (2022). The Influence of Magma Storage and Ascent Conditions on Laguna del Maule Rhyolite Eruptions. Journal of Petrology63(12).

CA Miller, G Williams-Jones, H Le Mével, B Tikoff. Widespread Gravity Changes and CO2 Degassing at Laguna Del Maule, Chile, Accompanying Rapid Uplift. AGU Fall Meeting Abstracts 1, 4811

Cáceres, F., Castruccio, A., & Parada, M. Á. (2018). Morphology, Effusion Rates, and Petrology of Postglacial Lavas of Laguna del Maule Volcanic Field, Chilean Andes, and Implications for Their Plumbing System. Geochemistry Geophysics Geosystems.

Frugone, M., Latorre, C., Barreiro-Lostres, F., Giralt, S., Moreno, A., Polanco-Martínez, J. M., Maldonado, A., Carrevedo, M. L., Bernárdez, P., Prego, R., Delgado, A., Fuentealba, M., & Valero-Garcés, B. L. (2020). Volcanism and climate change as drivers in Holocene depositional dynamic of Laguna del Maule (Andes of central Chile – 36° S). Climate of the Past16(4), 1097–1125.

Hildreth, W. (2021). Comparative Rhyolite Systems: Inferences From Vent Patterns and Eruptive Episodicities: Eastern California and Laguna del Maule. Journal of Geophysical Research: Solid Earth126(7).

Nelson, S. T., Davidson, J. P., Heizler, M. T., & Kowallis, B. J. (1999). Tertiary tectonic history of the southern Andes: The subvolcanic sequence to the Tatara–San Pedro volcanic complex, lat 36°S. Geological Society of America Bulletin111(9), 1387–1404.

Schaen, A. J., Schoene, B., Dufek, J., Singer, B. S., Eddy, M. P., Jicha, B. R., & Cottle, J. M. (2021). Transient rhyolite melt extraction to produce a shallow granitic pluton. Science Advances7(21).

Singer, B. S., Thompson, R. A., Dungan, M. A., Feeley, T. C., Nelson, S. T., Pickens, J., Brown, L. R., Wulff, A., Davidson, J., & Metzger, J. (1997). Volcanism and erosion during the past 930 k.y. at the Tatara–San Pedro complex, Chilean Andes. Geological Society of America Bulletin109(2), 127–142.

Tephra in Argentina establishes postglacial eruptive history of Laguna del Maule volcanic field in Chile. IAVCEI2013 Scientific Assembly-July 20-24, Kagoshima, Japan.

92 thoughts on “Laguna del Maule. An explosive rhyolite ring volcano.

  1. Excellent Hector! Im too working on my Io articles

    • That’s great! Ionian volcanoes are fascinating.

    • Will be fun two articles comming first one about Ionian eruption styles and one article about my favorite Ionian eruption

  2. So, no immediate danger of a civilization-threatening kaboom here. It’s still doing cone sheets, not ring dikes. This is a caldera system in waiting, an infant not even knee-high to Toba, say, still many millennia from its first time doing the collapse thing.

    What about its neighbors to the north, though, which have a past history of caldera-forming events? And are we seeing an age progression here, with Domuyo to the south being still embryonic and the northern neighbors (with 1 resp. 2 caldera events) being successively older and more mature?

    • The northern systems, Puelche and Calabozos, have been more proficient at making calderas, each sourcing 2 or 3 VEI-7 events in the past. But Calabozos is younger than Puelche. And Tromen is probably the oldest with rhyolitic activity going back to 2.3 Ma ago. Domuyo is very poorly dated, but it might be similarly old, some silicic intrusions have been dated at 1.8 and 2.5 Ma. So there might be more of a northwards younging trend. Although Laguna del Maule is the youngest felsic system here, I think.

      I think Calabozos is next to go caldera. Domuyo may be capable, but this volcano is an oddball and I don’t know what to expect. Domuyo is a non-erupting volcano, basically.

      • How can Domuyo not be the youngest, when it’s the only one where the surface rocks are still mainly nonvolcanic?

  3. Great piece, Héctor.
    I just think your imagination doesn’t take you back far enough. I’ll put a link to an article plus interview with Ronald Blakey under this. Blakey is more or less specialized on the North American West Coast.
    Not only with Blakey, but also with other authors I became aware of the fact that all paleo-tectonic maps end somewhere around the equator, and the South of South America and also of Africa are like two tails that always look the same through times.
    This is probably completely wrong and must be the product of lacking science. As all continents changed all the time the south of the two continents must have changed as well, esp. the Latin American west coast being an active margin, Africa less.

    When I look at the first picture in the Atlantic article, an island landscape of the North American landscape I feel (and speculate) that the west coast of South America must have looked about the same at some point. So, this Andean mass of volcanoes must have been island arcs like Indonesia, and Indonesia – I also speculate – will look like this area, but not in 1-10 million years, rather in 50-100 million years from now.

    So I believe that your area has a deeper past underneath and was once island arcs, of course, just like there where island arcs in the Eastern Tethys before the Tethys plate was completely subducted when India closed in. The only difference is that west of South America there is no subcontinent so far, but huge oceanic plates endlessly subducting.

    So I believe that your area has a very deep and complicated and underresearched history which, with your pieces, you shed some light on. Thanks.
    In order to go deeper into the past there we have to assume that there are parallels and therefore compare with areas with a history of longer research.

    • This being said I have to modify it for Africa. Africa is relatively easy as it has practically no subduction zones. It has a passive continental margin, and it was visible as early as at the beginning of the 20th century to Alfred Wegener that it must have split from South America.
      So, when the spreading ridges were discovered later things were more or less clear, concerning Madagascar and India, the African west coast and the South American east coast, the rests of the LIP being discovered adding to it.

      The North American west coast is complicated, but well understood I think, due to accessibility and lots of money and research. Middle America and the Caribbean Plateau are surrounded by question marks and also complicated. The discovery of the meteorite crater neas Chicxulub must have been good for the area coming into focus. Adding to research there are the dangers of volcanoes and earthquakes for densely populated countries. The Southwest of the Americas though must have a similar history, but there seems to be little knowledge about its deep past, 1) because of inaccessibility, 2) most research there still being in Spanish, 3) a sparse population in the Andes themselves.

      Something similar on a smaller scale concerning Europe might go for France. The South of France seems to have a fascinating volcanic history, and Tethys seems to have reached up north nearly as far as Val d’Isère. France has phantastic Earth Scientists, but much of the research is in French.

      That’s why we know more about the Philippines than about Chile or France. That will change, but the inaccessibility, well proven by the disappearance and death of Astrophysicist Thomas Marsh, will stay.

      So, Héctor tackling this region has to be praised. It is a fascinating area, very complicated because of subduction for probaby hundreds of millions of years, neighbouring an eternal ocean that always gave birth to new plates. I think it is interesting that many species of the dinosaurs lived around that ocean, one of them being Patagotitan Mayorum whose eggs were also found in what might have been volcanic fields with hot springs.
      This wikipedia page is brillant:

    • Thanks Denaliwatch. I don’t know much about the earlier history of this area of the Andes, before the Miocene. But I do know it was submerged underwater in the Jurassic-Cretaceous. I think the Patagonia has remained relatively unchanged since the Permian or so. The Choiyoi Silicic Province, which is Permian, is found in this area, it forms the basement in parts of the Payenia and Domuyo area, which was likely a back-arc caldera province. So there hasn’t been much accretion of terranes from the Pacific side.

  4. Take this video by Christopher Scotese on yt about America and Africa drifting apart. Note that the west coast is always the same. The man is a geologist.

    This is the only mountain chain in the world which was always the same (irony), from 160 Ma till today.
    Same smooth coastline southwest without any structure in the researchgate image, second link.

  5. An earthquake swarm seems to have started around Salton Buttes including 3 M4.0+ earthquakes, previous swarms seemed to occur closer together for years but there was a bigger time gap this time, not sure if this will turn into a significant swarm or just a small event.

      • While the area around the Salton Sea is very seismic due to the abundance of faulting/folding etc,
        that there are now 3 swarms that are still ongoing within a radius of about 40-45 miles is pretty unusual even for that area…especially since three different fault lines may be involved?

  6. Is there any indication if off-shore islands / sea-mounts were subducted around the time the Southern Andes’ plate motion / subduction style changed ??

    • Not as far as I know. The Queule and Nahuelbuta mountains, in the latitude of Tromen and Domuyo, are ancient basaltic seamounts which crashed into South America during the Paleozoic. They make the present-day coast of Chile around Concepción city. But this is much older, of course. As far as I know, these are the youngest accreted seamounts.

    • The gaps in volcanism do line up with where spreading ridges are being subducted. I guess with the ridge there the crust must be too hot to sink. It is also not impossible that this has some indirect links to the Payenia volcanism.

      At least as far as I can tell, this is the only place where a MIR is actively being subducted at a right angle to the spreading. There was a similar situation in the late Cretaceous to middle Cenozoic, that happened under North America, where the Kula and Farallon plates were subducting, but that is no more, only the Juan de Fuca plate is left now, a remnant of the Farallon plate, and the ridge there is going to subduct parallel to the spreading not at a sharp angle.

      I guess it is not impossible that the former spreading zone of the Kula and Farallon is indirectly related to the Columbia River Basalts and Yellowstone trail, although if it is then it is only a distant relation now.

  7. I noticed something about the 1868 vents on Mauna Loa, it actually did begin growing a cone before it stopped. There are several areas where the lava surface is buried in tephra and has deep crevasses where this buried lava has slid down. It is liek a crater, although the eruption stopped before it could form.

    Only one side of the fissure has these, I guess the lava was all liquid on the other side. But if this does represent the edge of fountain fallout then the fountains in this segment of the fissure were going on 250-300 meters high…

    It is something to wonder if this eruption happened in 1968 instead, how much bigger would have been, seems liek it was a failed attempt to fully collapse Mokuaweoweo. It is very interesting really how the very intense activity of the 1850-1950 era didnt actually result in a full scale collapse despite the level of activity.

    • Really interesting! I had no idea. Fountains must have reached 300 meters on average along portions of the fissure. Probably as tall as the fountains of Hapaimamu, but more short-lived.

      • It is quite spectacular, reminds me a lot of those photos from 2018 that showed the entire flow channel from the vent to the ocean. It really was a crazy eruption, it was like the earthquake just opened a hole in the mountain and let its entire contents drain out.

        Still falls far short of 1950 though…

        • Some of the stories of the area ranchers were harrowing. That was the first eruption since the European settlement where the lava came to their houses rather than a two-day hike to go see it.

  8. Laguna del Maule was the subject of a recent paper I read that detailed how rapid magma rejuvenation was possible there. The theory involves a heat pulse from below that reacts with the high crystal content in the vast upper magma chamber (estimated around 460km/3) which could cause the mush to rapidly turn liquid and in turn expand and become eruptible.
    So, the increase in quakes and deformation may not be so much as from an increased volume of new magma being injected, but rather upper-chamber magma that’s already emplaced is being altered/reactivated by an influx of just heat from below??
    The idea isn’t new…in fact it has been speculated that Yellowstone could go off in as little as 50-75yrs should a similarly new deep-mantel heat plume develop that could rapidly liquify the massive expanse of semi-solid magma that’s been accumulating there for the last 660,000 yrs.

    • The idea that new magma, of basaltic or basaltic-andesite composition, has been intruded comes from the following work, which documents a gravity increase over the NW end of Laguna del Maule magma body in 2014-2013. In the presentation, the authors seem to model successfully both the inflation and gravity increase as an intrusion of basaltic magma. There could be some additional re-melting too, but the main mechanism seems to be an inflow of new melt, at least during 2013-2014.

    • I wouldn’t be surprised, though, if all the Laguna del Maule uplift eventually goes away. For example, Yellowstone had a gigantic episode of inflation in 2005-2009, where the entire resurgent dome, an area more than 70 km across, came up. Using gravity and deformation, a magma inflow of 0.1 km3/year, almost as high as the supply to Kilauea, was measured. Probably the fastest inflation of a silicic caldera in the past 20 years or more. Since the inflation lasted 3.5 years, about 0.35 km3 must have been intruded in total, half the volume intruded at Laguna del Maule. However, starting in 2010, Yellowstone started to deflate. This deflationary trend has continued with only one brief episode of inflation. As we speak, Yellowstone has basically deflated to the state it had before 2005. So all the magma has presumably drained back into the mantle.

      • I find it more likely that it is not just the volume of magma that is causing these inflationary tendencies but rather the volume of gas as well.
        Yellowstone has the largest geothermal field in the world, at least that I know of, so I believe that deflation was caused by the dispersion of the gas through secondary volcanism.

  9. Regarding magma mixing and rejuvenation of crystallized mush, has there been a lot of research or study into the dynamics of reactivation after an eruption has already started?

    Over the years, I have continuously read that magma below a certain crystallization threshold is uneruptible. I certainly don’t dispute that, but I can’t help but feel that this always ignores that the level of crystallization is subject to change. Most of these articles acknowledge the fact that change can occur with the injection of fresh basalt either slowly or during an overturn type of event.

    But what about after an eruption occurs?

    We know that crystallization is dependent on both heat and pressure along with a few other factors such as chemical composition. So why do we ignore the fact that the onset of an eruption breaking the overlying seal on a magmatic system can by itself cause rapid and significant depressurization?

    This would become especially more intense during any type of eruption that could open up a significantly large conduit, or trigger any type of structural collapse of the overlying roof (caldera collapse, flank collapse, etc).

    Am I missing something here, or is this something that simply is not being modeled or accounted for?

    • A simple illustration of this type of scenario would as such:

      A large magma chamber lets say 500 cubic KM in size has around 20% eruptible magma. Over time, the 20% of eruptible magma builds enough overpressure that it starts to break the overlying rock, forming a conduit. Eventually, the magma finds a path to the surface, which leads to a significant explosive eruption as the magma moves towards the surface and gases expand out of the molten magma. I believe the typical model of this is that roughly 30% of the molten chamber would erupt here, giving us a decent sized VEI-6 30km sized eruption.

      But that’s where I bring into question other dynamics that are triggered by the initial explosive eruption. Lets say that this initial 30km eruption produces a significantly large conduit along with a small collapse crater.

      Since the overlying seal has essentially been blasted to pieces and multiple new cracks opened, suddenly the pressure on the previously uneruptible 400 cubic KM of crystal mush drops precipitously. So much so that, in many areas, the temperature / pressure curve drops below the melt point, causing a very rapid and sudden return to eruptibility of the 400 cubic KM of magma. The magma below this curve then starts to rise and erupt itself, triggering further depressurization of magma below. This leads itself into a larger eruption, forming a caldera after the runaway depressurization finally reaches equilibrium.

      Given, there would still be a lot of unerupted magma left over, but this dynamic at least shows the chain-reaction that to me, always seems to fit with the behavior of caldera forming eruptions.

      • Many caldera-forming eruptions tend to be followed by smaller dome or vent building exercises, occasionally of a similar or same type of magma. It’s clear that your model above is closer to the norm than one that entirely decimates the magma chamber. Regularity of eruptions is probably key however, along with fresh influxes from below, in order to keep the pot churning. Yellowstone for instance may genuinely not be able to erupt again without a new batch of basalt.

        • I think the sentiment towards Yellowstone has been pushed too far away by all the clickbait doom and gloom. It is certainly not a dead volcano, it might not do another VEI 8 but that is a very high bar to set if it has to do that to be not extinct…

          I havebt done the investigation myself but I think on one of Hectors older articles it said Yelliwstone has erupted more lava since its last VEI 8 than the DRE of that eruption. 1000 km3 is a lot for any volcano, in any timescale, and that is just since the Lava Creek eruption. Evidently the Huckleberry Ridge caldera would have done similar activity, and the Henry Fork caldera is filled in to overflowing with basalt.
          Not to mention the Snake River volcanism, which is different but related. Craters of the Moon is an Icelandic style flood lava fissure volcano, which has in the Holocene done eruptions almost as big as Laki. Its a pitty the area is only known for doomsday predictions and the equal rebuttal that it us all dying, both are equally far from the truth in my opinion.


          • Volcanocafe just really doesn’t seem to like Yellowstone. There are no articles devoted to it specifically. Imagine any other repeat producer of VEI 8s, the most recent 0.6 Ma, that has produced many, many lava eruptions larger than Laki since then. Even if it has been generally deflating since the Ice Age and has barely more than 1,000km^3 of melt in its upper chamber.. They would probably get more than one!

            I would think the hype would if anything be a reason to produce an article seriously looking at the actual risk (not our lifetimes, high on geological time scale).

          • Yellowstone is a dangerous one to cover. Almost anything could (and would) be used by the ‘we are doomed’ brigade and that is not what we are after. We covered it a bit in the Snake river post and in the posts on supereruptions (also Hector’s super series). The bottom line is that Yellowstone ranks very low on any list of likely disasters. It is like a big asteroid impact: it would be devastating but is unlikely in the extreme in the near future (‘near’ being 10,000 years). Yellowstone has potential but lacks power. It has done nothing for almost 100,000 years. The bouts of inflation are probably hydrothermal. The geysers actually indicate the quiescence: they occur where conditions are stable. Furthermore, small (or even middling size) eruptions here do not impact many people: a national park would be ideal for this. So we have stayed away from Yellowstone and when it was covered, it was with extreme caution. I am far more concerned about Naples where even a minor caldera eruption would be a disaster.


          • Not to pin the blame here but there is an old article by Carl long ago that is comparing Grimsvotn abd Yellowstone abd this at least as I can tell is where it comes from that Yellowstone is dead. It is also where the idea that Grimsvotn us some sort of monster volcano comes from, that it has got 400 km3 of magma ready to go and erupt at any time, and that Grimsvotn gets 0.5-1 km3 of magma yearly. Maybe that much magma is generated in the mantle under it but very little of it makes it into the actual magma chamber that feeds Grimsvotn, the eruption rate is only about 1 km3 a century, which us significabtly below Bardarbunga and is nit even in the same order of magnitude as Kilauea or Mauna Loa.

            Likewise, if this plutonic magma reservoir does count as part of Grimsvotn, it is not the largest in the world either. The deep rifts of both Hawaiian volcanoes are a lot bigger although it is unclear how much those are open to the mantle. And speaking of Yellowstone has got a deep mafic cumulate zone that is in excess of 10,000 km3, possibly far more if the Snake River volcanism is related, it is likely the largest active mafic magma body on the planet.

            I dont want to bring this up as a hate on anything or anyone, because this is only really clear now with a decade of hindsight and gained knowledge, back in 2014 Holuhraun just happened and hype was there, and no one had any idea Kilauea could do anything other than ooze lava. It was also peak of the Yellowstone conspiracies… But I think it is time to move on.

          • I did that series a while ago, 10 volcanoes with supereruption potential, I talked a little about Yellowstone, putting it in the fifth position of likeliest VEI8 source but I didn’t do much justice to it, I think. If was to do a list of volcanoes with VEI8 potential right now Yellowstone would be in the 1 or 2 position alongside Toba. They simply have the largest inflation structures (domes) in the planet. Instead I put two VEI-7 contenders and a half-cooked volcanic field in the podium.

          • Yellowstone is a very longterm dormant volcano. It is very, very unlikely to do something magmatic in our times. But I like the hydrothermal activity. Steam explosions can be exciting and dangerous. The hydrothermal system can change anytime, and this makes it interesting.

            Is Yellowstone really a hot spot (as the official version tells) or can it also be seen as back-arc volcanism like what Hector talked about in the last article on Argentina’s volcanoes? This may also explain the volcanism of Auvergne and Eifel as back-arc volcanism behind the Alpine orogency.

          • Yes Volcanophil, that could be. I got the impression recently that subducted spreading ridges and slab gaps started to become a topic when tomographic signs for mantle plumes are dubious.

            Many years ago it was decided that the Snake River Plain must be a plume trail and that therefore the American Plate must rotate clockwise. The funny thing is though that the American Plate is moving north-west and might rotate counter-clockwise to become locked under Siberia. These two things don’t really match unless the American Plate has stopped moving under Siberia.

            So, the Snake River Plane might have had a plume or not, also a plume that is now dead. If the American Plate moves in the direction of Siberia the trail theory doesn’t fit. The science into slabs and their specifics seems intelligent to me. Mantle Plume was a cheap explanation when there was no other one.

            Mantle Plumes: Probably Hawaiì, Kerguelen/Broken Ridge and Réunion/Mascarenes/India, Louisville, possibly Iceland (for Carl and his darling paper from Kresten), plus some others with trails. Aside from that, when there is subduction or extension and spreading and no real sign of mantle plumes science is asked for alternative explanations.

            We had this discussion the other day when I came along with the dubious plume trail in East Australia. I believe that it is difficult to prove a mantle upwelling or plume under continental crust. And subduction can do real fireworks too, see HTHH, Krakatau, Tambora, Pinatubo.

            Albert says further up that he is more worried about the Gulf of Naples. Me too. Enormous volcanic field between Marsili in the west (submarine), Stromboli, Etna et al. in the South, the maars north of Rome in the north and Vesuvius and the Campi Phlegrei in the East. Microplates, subduction, earthquakes, instable terrain, hard to understand. Very populated. A little bit like Nicaragua. Disorganized. Sub-governments by families.

            The US would realize in time if smells foul around Yellowstone. They had two deaths at Mount St. Helens, people who didn’t listen. Very different situation in Italy.

          • There is no clear curvature in the Snake trail: that came from matching up the wrong lava flows. The river itself is curved but this is because it connects up several pre-existing water courses. The Columbia flood basalt is displaced north but the presumed origin at Steen Mountain (where the dikes come from) lies on the straight and narrow. The motion of the American plate has been consistent. There is a problem that the first eruption came out of nowhere: there is no pre-Columbia trail. But plume heads are complicated things. You can also get backflow from the plume head, causing renewed volcanism well after the spot itself had passed.

          • USGS:
            “As for the worst-case scenario, even previous Yellowstone supereruptions did not cause extinctions, and ash fallout on the other side of the continent was minimal.”

            This is an important point. No extinctions. So no meteorite-like scenario. I rather think that there was lots of water involved. There was a huge seaway there until 70 Ma, and there is lots of hydrothermal activity. While talking about magmas and subduction vs. plume the devastating influence of water can be ignored.

          • @hector, I was just rereading those articles from a few years ago (10 volcanoes with supereruption potential). It was a great read, even if you would have some changes nowadays to it.

    • Any thoughts on the original question here? Things got a bit sidetracked into a Yellowstone discussion (nothing wrong with that to be fair).

      Is it possible that we are underrating how fast magma can transition from uneruptible crystal mush to an eruptible state upon the depressurization that arises from an eruption?

      • Probably shows just how much a Yellowstone article is due 🙂

        It is something to consider is magma really even gets stored as a crystal mush that way. It seems with few exceptions that the magma erupted at calderas is crystal poor regardless of composition, crystal mush might be formed by the crystals settling out but not so much the magma actually cooling into a solid.

        At least, looking at Kilaueas lava lake now might give a great insight, the lava obviously cools but it doesnt do so like a coolign water block that will cool down all together and freeze together. The lava that erupted in Jaunuary was extremely liquid but would have been lava that was sat in the lake since about 2 years earlier potentially, it seems like magma chambers cool fro mthe side and only by direct contact, heat conduction is very low. And this is on a magma body that is in contact with the atmosphere, one that is may km underground and in a warmer environment will cool much slower still, and Rhyolite has both a higher heat capacity and I think lower conductivity than basalt and presumably is more viscous too, no wonder these places stay hot for so long.

        I guess there would be some remelting, but probably only by a hot magma, a basalt presmably, otherwise you might just get crystal rich magma erupting. it is notable that Yellowstone only erupts very high silica rhyolite and primitive basalt, nothing inbetween, so this remelting doesnt mix them it only makes more of the rhyolite

        But then, if that is the case then what Hector described above would be just such a recharge, and a very significant one at that, if a volcano in Iceland got half a km3 of magma supplied in a couple years it would be all over. For once I am actually happy that didnt happen, the doomsdayers would actually have been a tiny bit validated. But that much hot basalt would have moved things around.

        It is very hard to answer this question, there is so much uncertainty about how Yellowstone behaves…

  10. Fun piece on Etna last night in Clive Myrie’s Italian Road Trip with an interview with Boris Behncke.

  11. Nice article about a fascinating area. Thanks a lot Héctor!

    Small thing: There’s some missing html markup in the final paragraph. A closing sup-tag is missing the last angle bracket, causing the final part of the text to be all superscript.

  12. Regarding fixation on Yellowstone, I think most people who have been active readers and commenters on VC for a long time recognize that the biggest risks to society from a disaster perspective are not from VEI-8’s. It’s not that those are not a risk, but the probability is extremely low of anything occurring in any near geological timeframe. Roughly speaking, this is what the VC decade volcano list was formulated on. I wrote my own list on a now-defunct website not long before the VC list came out, and it was fairly similar (although it was not a top 10, but rather a tier list of estimated risk).

    10,000 years of human history (roughly the holocene) reveals that the big risk from what is likely as well as what has been shown to affect societies is the VEI-7, of which there is ample evidence that they’re more common than we for a while had thought. That’s not to say all VEI-7’s are equal, but especially if you get significant climatic effects, there would almost be guaranteed disruption to the world aside from the immediate disaster zone. And of course, there is a big difference between a small VEI-7 (such as Tambora) and something that’s much larger such as Kikai or Kurile lake.

    For global risk assessments, potential VEI-7 eruptors, or VEI-5-6 in highly populated areas are the biggest risk.

  13. Answer to Albert:
    ” The motion of the American plate has been consistent.”
    Okay. I used the Dymaxion map instead with the North Pole as a centre. Then it makes sense.

    It is hard to get the two-dimensial school teaching out of the brain. Flat earthers, sort of.

    • Yes, on a sphere every straight line becomes curved! And every plate rotates around a fixed pole, which may be far outside the plate. It is very hard to visualize

    • Something else seems to make sense to me: That a supercontinent is forming around the North Pole, the opposite of Pannotia which might not have been completely closed – opinions differ. That continent would have to be called Panarctia.
      South America would be the first part to break off, together with the Somali plate, and then form the core of a new Gondwana. These are long term processes though.
      The process of wandering north and gathering around the North Pole is clearly visible.

      • All of the reconstructions I have seen have the next supercontinent in the northern hemisphere, the only wild card is whether Antarctica joins in. The model where it doesnt is called Amasia and the model where it does is called Novopangea. I think it will but it is less certain that Antarctica will be in one piece as it does so, it is enormoys and as we can see in Africa the breakup of Gondwana is not a finished process. If a subduction zone forms to pull Antarctica north it might break up in the process.

        There is also Pangea Ultima which is where the Atlantic closes. It is widely depicted but it seems a stretch to think the Pacific will grow when it doesnt have a MIR in most of it. It also seems to be more common that rifts within a supercontinent will become the global ocean of its successor, sort of inverting it.

        • If you look at the past you can see Rodinia in the middle (more or less) about 1 billion years ago (average), then Pannotia in The South, then Pangaea middle, so it makes sense to suspect the next in the north, and btw, basically it is already there, and then another Gondwana with Antarctica, South America and East-Africa and Laurentia with possibly parts of West-Africa and Australia, and then a recollection in the middle again. Just in case there is a certain rule for the process.

          So it would make sense to name the next one the opposite of Pannotia (Pan-South). Just saying. But someone with the loudest voice will name it.

          The discussion about Antarctica is sort of silly. Obviously, Antarctica is staying where it is for the time being as it is surrounded by a spreading ridge with the exception of a slim piace of submarine connection to Chile. As long as the spreading ridge is in place, Antarctica won’t move significantly.

          South America has a spreading ridge on both sides. North America only in the East. So, I suspect – always if nothing changes- that South America might separate from North America.

          • It isnt silly to talk about any possibility regarding plate tectonics when the timescale is 200+ million years ago. Antarctica is already probably rifting slowly as it is.

            South America isnt surrounded by spreading ridges, it is bordered on the west by a trench, which is probably the most powerful on the planet if the scale of earthquakes that happen there means anything. So there is no push from the EPR, if anything the descent will actually pull the overriding plate towards it, which is basically what back arc rifting is. Eventually as the plates fully merge at the Drake Passage the subduction zone will probably extend south and go around Antarctica at least along the peninsula, where there is an inactive zone already. As Australia collides with the islands to its north a convergent zone will probably also form on its southern margin, perhaps where the Diamantina fracture zone is, which will ultimately draw Antarctica north although probably slowly.

            It is also not impossible the Tasman sea would begin to expand again when Australia becomes fixed, allowing Zealandia to cross the Pacific and end up far north, possibly overriding the Hawaii plume in the process, emerging as a continent once again and then promptly becoming the Deccan Traps 2.0…

            Really, after a couple tens of millions of years the best we can do is guess at the locations of the continents, actual plate boundaries are so dynamic. Even only 70 million years ago when the continents were in recognisable positions the plates were wildly different especially under the ocean which is where the engine that drives it all is most easily seen.

            Then there are also all of the continental rifts, which may or may not lead to new oceans. East Africa is quite obvious, at least I think it will become something eventually but not all sources agree. The red sea already is an ocean basin but it is also opening into an area of compression and convergence so might not get far. Baikal is another, but it is in the middle of Eurasia which really is probably big enough to count as a supercontinent already, it is as big as Gondwana was. And currently all of the other continents are converging on it so I think Baikal will become a fossil rift like the Superior rift, but just my opinion. Perhaps not before it does some major volcanism though, but that too is in the future if it happens. West Antarctica also apaprently is a rift, which is why I mentioned it, but there isnt really much data on it.

          • Well, Iceland has a spreading zone, the MAR, right? That’s why Iceland West and Iceland East are moving apart on the American resp. Eurasian Plate. This applied to Antarctica would mean that around Antarctica move north. And that is precisely the case. The rift (extension zone) inside Antarctica is about 100 million years old which speaks volumes. The African Rift’s age is only a quarter of this.

            Another objection is to New Zealand:
            New Zealand obviously is stuck at the Chatham Rise and the other volcanic plateaus there. So I dare doubt that it ever crosses the Pacific Ocean. When Siberia travelled north those volcanic plateaus were not there yet. It makes me wonder why the main part of Zealandia is under water. Everything in that area seems to be destined to an Atlantis fate. The area seems special. The Pacific Plates partly overrides the Australian Plate. Very special situation.

            So what we see is a north movement with the exception of Antarctica for obvious reasons.

            Next objection is to subduction on Australia’s south coast. From what? What should subduct there? Okay, one day, the Indian Ocean will start to subduct somewhere, sure.

            Basically I would place a bet on an Antarctica staying in place. As long as that spreading ridge exists. If it is staying there in one or two pieces is another question.

          • It’s not just Eurasia. Check out a map for the last glacial maximum, when the Bering land bridge was exposed.

            There’s a supercontinent right now, shaped like a key-ring with two keys, a circle around the north pole with a narrow gap between Greenland and Europe, a long key with two prongs hanging down (the Americas), and a shorter key with one prong (Africa). Only Antarctica and Australia are really separate, from it and from each other. But Antarctica might not be for long, as the Drake Passage looks an awful lot like the near-equatorial passage that used to exist where the Central American Land Bridge is now. Give it a few million years and there will likely be another land bridge at the southern tip of South America, and only Australia will be separate, plus smallish things like Madagaskar. Though a larger chunk might break off Africa not long after.

            Give it longer still, though, and those chunks may be ramming, with the Arabian peninsula, into south Pakistan, extending the Himalayas west, and Australia might hit Indonesia (= a mostly submerged large chunk of Asia). Africa will have crushed the Mediterranean, and the northward pushes on Eurasia might have crushed the Arctic Ocean too. At that point we’d have a Pangaea-like supercontinent with all or almost all continental crust in it and extending from pole to pole, likely a narrow but long one spanning well over 180 degrees of the planet’s circumference and maybe even 270 from the southern tip of Africa north to the north pole, then south along the opposite meridian all the way to the south pole, with some lumpiness to the sides here and there and two narrow isthmuses near the south pole and near the equator.

            But that’s assuming more rifts don’t start up, or major new subduction to pull things in jarring new directions. Especially if new subduction zones open, all bets are off.

          • Not sure how you can object to a hypothesis, or with certainty onto a long term extrapolation. This is all speculation not an absolute.

            Ocean plates are chaotic and seem to break somewhat easily. Really big ones like the Pacific maybe not so much, it has survived Hawaii after all, but smaller ocean plates probably rift and stop a lot. There is a northward movement of New Zealand creating the Alpine Fault, continental crust is not necessarily a barrier to this. There is also very active spreading in the back arc of Tonga at the Lau basin, it is one of the hottest and most active spreading ridges on the planet. Not inconcievable that it could extend south into the Tasman in the event Australia cant move north any longer. Plates vehave more like scum on a liquid than like plates of ice on a river. The lava lake crust analogy works well.

            Australia getting a new zone on its south coast is a result of its collision, the only option eventually is to form a convergent boundary there. And given the Diamantina zone already is highly fractured and goes down over 6 km depth in places it isnt really a stretch to imagine it… much more likely than a new zone forming along the Atlantic coast of the US anyway, which has no push to form at all any time soon nor a fractured seafloor, it is deep but not trench-like.

            In a way Australia is like a giant terrane, same as for India. Both are still colliding but when that is not possible anymore the plate will subduct itself at the continental margin.

          • The thing is though that keys from key rings are lost easily.
            As South America is neatly closed in by the MAR and the EPR plus the subduction of the Nazca Plate it looks more or less stable to me.
            One single big caldera event in Middle America, say in the area of Lake Atitlán or in Nicaragua could open up a new horizontally running ocean, déjà vu with Tethys.
            Whatever time you look at, South America seems to have been always around that area. The same goes for Antarctica. And partly for Africa.
            I don’t think that this is a miracle as South America is mainly built of huge cratons with accreted terranes around them. Also the west of Africa has these cratons that were once combined with those on the other side of the Atlantic Ocean.
            Also Antarctica is mainly consisting of a craton.
            This is a big difference to say Europe or the East of the United States. These cratons are the beginning of continents. I doubt that they will ever cross the equator, at least not in one single piece. When the Wyoming craton crossed the equator there was less continental mass around the craton and in general. The same goes for Siberia. South America and Antarctica, both relatively small, compared to Eurasia, are mainly consisting of cratonic mass, both over 50%, Antarctica certainly over 70%. They might not travel significantly.
            Then there is a bolt between North- and South America. That is the Caribbean Plateau. The same bolt as east of New Zealand. Let Middle America have a VEI 8 caldera event in the next 10 millenia – who knows – an ocean will separate North- and South America.
            Middle America is unstable. South America and Antarctica seem to be more stable.
            So my prognosis would be more for another form of Laurentia with parts of Africa and Australia attached and a new albeit smaller Gondwana.
            Concerning the suspected mantle plume under Big Island, Japan is the first candidate as Japan split off Eurasia and is moving out.
            So, let me place a second bet on South America staying South and a third on a revival of Tethys. Beers are served in heaven. The loser doesn’t have to pay as things must be free there.

          • Concerning the key ring it has an opening, the Mid-Atlantic Ridge. This opening should – if the MAR stays in place – become larger whereas the Bering Sea might disappear. This would mean that there is only one opening which would have huge consequences on currents and climate – side thought. With the North Pole in the middle on the Dymacion map you would see a more longitutinal continental mass with the Pacific Ocean on top of the map and the Atlantic Ocean on the bottom.
            The Pacific Ocean shrinks – link:

            and the Atlantic Ocean is the saviour.
            The Pacific Ocean might not disappear though if new plates appear. It has this long history of plates being subducted and new plates being born. We don’t see this now, but it may happen in the future.

            My betting business is an appeal for eternal life. It would be really shitty if we cannot see what becomes of our ideas (not hypothesis, as we cannot look for proof, just ideas).

  14. Interesting video by GeologyHub about a new development at Sheveluch; new and vigorous fumaroles on the west flank near an ancient flank lava dome accompanied by an earthquake swarm up to M4.8. One to watch…

      • The drumplot shows tectonic quakes and nothing magma-ish. But these are big shakes which can create pathways for eruptions. See what happens over the next few weeks. I can imagine Eldgja starting like this..

        • Katla twitched just before the August swarms at Bardarbunga preceding Holuhraun in 2014. The twitch was not as impressive as the three >4 earthquakes, though.

          • Getting tired of my volcanoes being stuck in tease mode, hopefully this is precursor to an awesome eruption in Iceland, (Grimsvotn and Katla are the best options)

          • I am popping up out of hibernation (?dormancy) because of today’s EQs at Katla, so I’m as intrigued and ready to be excited as the next VC habitué, but – and Sorry – when people want an “awesome eruption” out of Katla I wonder who the imagined audience is.

          • An awesome eruption from Iceland might not do much for European comms, aviation and food production. Ditto North America and Asia, if the eruption was ashy and gassy enough. My preference is for the tourist eruptions.

          • Nice one, Merlot. I wonder what my preference is. A big one would shut some mouths in Germany talking mainly rubbish, belonging to our green child-party and their foot(wo)men – they insist on the -wo- in the media for a while. They are going to forbid oil-and gas-fired heating systems, and more and more ppl are running out of money. They do their politics without ppl. They are all highly paid while ppl are asking themselves how their children will manage esp. if they become academics. The most intelligent ppl in the world are paid the shabbiest salaries – ask Albert. same in England. End of pol.- not appreciated here being boring and annoying stuff contrary to volcanoes.

            Anyway – one day Iceland will produce a big one, we just don’t know when.
            I myself hope for an eruption of CCN to make Tallis happy.

          • Denali just buy a few of these and a solar panel, connect it to a heat pump 🙂


            Wont make you energy endependant on a property level but you wont be stuck buying gas for heating anymore. and if that doesnt work at least you can watch power your computer and internet without the grid so if CCN erupts you can talk to Tallis about it 🙂

          • Thanks Chad. I sold my house due to higher mortgage rates and figuring out that in a year I would have to extend my mortgage with these rates plus the oil fired heating system becomimg unpayable – and I moved for rent into a house with a heat pump and solar panels. All fine. Only one problem: I don’t like it here, miss my home and feel uprooted.

            I am better off than some others who feel that they might become uprooted, who will have these problems in the future. Most of us are older, contrary to some countries in the poorer world, and what gov. plus industries are doing to us, making us utterly unhappy is a crime against humanity. In Germany against people who worked like farm horses and saved some money and bought a small house to be kept well at an older age. Who behaved well, were obediant (mistake) and are now plundered and uprooted, while some others in Brussels are thinking about accelarating that process comfortably living on our tax money which, together with social security and money for unemployment eats up the German salary until the middle of July.

            Adding to this we have to feed mainly Afghan migrants, thanks to the US and Russia before who managed to destroy that country. That is a fully developped catastrophe, and I see no end to it. These kids sitting glued to the streets have no idea how they will live in the future il this process isn’t decelerated and made more human with reason, intelligence and without ideology as a motor.

    • Interesting. Went from being pretty quiet over the last year or so (relative to seismicity for the previous 10 years) to having some pretty large quakes. Katla often gets swarms in the spring I believe relating to melt.

      That being said, every year gets further and further into the far side of the historic range of eruption frequency for Katla.

      • I’ve been watching it on this graph for a little while that the Met Office provide. It spans back to the start of 2011.

        It’s had a few areas of higher activity in the past, this one seems to have started last June up until now but doesn’t seem as intense as the others…

        • The upkicks in 2011 and 2017 are associated with possible subglacial eruptions.

          • Interesting. What’s the (IMO’s) level of confidence about that?

    • What kind of hydrothermal activity is going on below Katla glacier? Would subglacial “Geysers” like Yellowstone’s Steambote Geyser cause earthquakes like this?

  15. A peculiarity is that the Katla quakes tend to be very shallow and that is also the case at this time!

    • Too small 😉
      Otherwise Carl will pop up. Doesn’t anybody miss Carl?
      I think that Albert is a diplomat, poetic and scientific, Héctor is very scientific, and Carl is a smoking gun. The contrast is attractive. I miss Carl, a typical feature of doctors, I guess.

      • We all miss Carl, but I suspect he’s very busy poking holes in the ground, trying to save the world.

        • He will appear when Grimsvotn is about to erupt, so until that happens we know it isnt ready to erupt yet 🙂

        • So we told Carl that we miss him. Can`t hurt. Carl is very emotional although he tries to hide it under his John Wayne costume, alone in Central Africa, Tibesti and so on. Living on a caldera, having earthquakes and so on. Digging around the most dangerous volcanoes and so on.

          So Carl, TGIF. A few beers on all of us missing you. Have a nice week-end. Hope your wife is safe under Fuego.

    • “As of 10.00 hrs, pyroclastic flows have also reached the Seca and Santa Teresa canyons, situated on the western volcanic flank. The eruptive column is now over 6,000 m asl (2,237 m above the crater summit)and has spread over 70 km, expected to reach over 100 km within the next six hours, over 7.5 million people live within this radius.”

      Not that small.

  16. This is probably a coincidence but has anyone seen the uptick in earthquakes around Prestahnúkur in Iceland that seemed to start around the same day as Katla’s swarm?

    They seem to appear mostly around 5km deep and they appear to be forming a SW to NE trending line (likely a fault).

    I think it’s tectonic, but any thoughts?

    • Plates / faults accommodating magma ascent? The big questions are where is magma ascending and where will it emerge?

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