Sleeping in our back garden: the past, present and future of the Eifel volcanic fields (part I)

The deposits of Laacher See at the Wingertsbergwand, with a child (and footprints) for scale. Image credit: Marcel van Mosseveld

Think of one thing that has interested you for as long as you can remember, or at least for so long the level of factual knowledge you have of it is almost ridiculously vast. That one thing that always brightens up your day when you hear or read something about it, no matter how busy you are or down you feel. A passion that goes beyond the level of having an ordinary hobby, because you don’t grow tired of spending time on it and learning more about it. It could be anything. Maybe a football club, or collecting fossils. Perhaps a specific model of a car brand. Or when you pick up your camera for yet another round of bird photography. It doesn’t truly matter what it is, because it hits home with anyone who has that bizarre enthusiasm for something seemingly trivial in the eyes of most people. To me, that one thing that stands out above all my other interests, is the Eifel volcanism.

Volcanic areas of the European Cenozoic Volcanic Province. Image credit: Hans-Ulrich Schmincke

The volcanic fields of the Eifel

Take some of the bigger names in the world of volcanoes. Etna, Mount St. Helens, Pinatubo, Vesuvius, Krakatau and of course any one pit, mountain or crack spewing lava or ash that happens to make the news. Not many people actually know the relevance of those names from a historical, let alone geological perspective. Yet they do ring a bell. What volcanic area most certainly isn’t on that list? Yes, the one I’m going to describe to you. The Eifel is located in the west of Germany, and is comprised of three different volcanic areas, located on the Rhenish Massif. One of those, the Hocheifel Volcanic Field, is of Tertiary age and lies between the much younger West and East Eifel Volcanic Fields. Scattered across Germany are many volcanoes of Tertiary age, but for the sake of not turning in this article into a book, I’ll stick to a series of facts regarding the youngest products of volcanism that can be found in this part of the world. That means the aforementioned volcanic fields west and east of the Hocheifel, where volcanism took place between approximately 700,000 years ago and 11,000 years ago.

The West Eifel Volcanic Field and East Eifel Volcanic Field. Image credit: Hans-Ulrich Schmincke

So what are we talking about then, as these volcanoes seem to mean so little in the world of what can arguably be seen as the most visually impressive of natural hazards? All of the volcanic vents in the area are part of so-called ‘monogenetic volcanic fields’, meaning they tend to erupt only once before going extinct. That is, the individual vents, not the volcanism in the field in its entirety. In most cases, a very small amount of magma makes it to the surface, producing an eruption that is often over as quickly as it started. The magmas that erupt onto the surface do so mostly in the form of small ash plumes, scoria and lava flows, only affecting an area directly surrounding the vent. The resulting volcanic edifice: a ‘scoria cone’. When this magma comes into contact with ground water, a hydrothermal explosion occurs, known as a ‘phreatomagmatic eruption’, which is explosive, short-lived and leaves behind an often circular crater known as a ‘Maar’, but again, the effects of such eruptions are mostly of a local nature. Both of these types of volcanoes can be found in great abundance in the Eifel volcanic fields, and maars even got their name from the regional, Eifel name for ‘lake’. All in all, the fields consist mostly of these fairly tiny edifices. Some 200 scoria cones and about 70 maars in the West Eifel Volcanic Field (WEVF) and mostly scoria cones of the ~100 volcanoes in the East Eifel Volcanic Field (EEVF).

What does this mean for the landscape? What does it look like? The volcanoes aren’t hard to spot in quite a few cases, but don’t expect any enormous mountains of the likes seen in the Cascade Mountains, the Andes or Japan. In fact, the scoria cones of the Eifel quite often do count as ‘mountains’, depending on what definition one might apply, but their prominence is rarely more than just a few hundred meters over the surrounding, elevated terrain of the Rhenish Massif. Scoria cones formed by a single eruption just don’t grow that tall. Maars are often hard to spot, but in all cases they are depressions in the landscape, in some cases surrounded by a ring of tuff produced by the Maar-forming eruption. Most however, are very hard to spot, and the same can be said for the majority of the scoria cones; they’re just too tiny to stand out, whether that is the result of having been produced by a comparatively small eruption, the effects of the exogenic forces of weathering and erosion or both. In other words, the volcanoes are there for those who know what to look for, but that’s pretty much it. The Eifel isn’t densely populated, especially not the Westeifel, but its far-from-dramatic undulating terrain and mix of forests and agricultural land give it a very friendly looking, photogenic charm that many tourists appreciate quite a lot.

The ‘Dauner Maare’ in the WEVF. Image credit: Gijs de Reijke

The threat of eruptions: an unwelcome surprise?

So it’s a fact that the Eifel has been relatively recently been volcanically active, but what does that mean? No activity even came close to there being any sort of historical records of it, at least not of actual eruptions. In geological terms, for an area not to be volcanically active for just over ten thousand years, means nothing. The actual cause of the formation and rise of magma under an area is very likely still present after such a relatively very short time, and in the case of the Eifel it truly is, although I’m not going to delve into that in this article.

So are we to expect an eruption anytime soon? My answer is ‘Yes!’, but that doesn’t mean we’re currently aware of any magma making its way to the surface at such a velocity that we can detect it and that we should panic about it right now. Monogenetic volcanoes are being fed by tiny amounts of magma, often rising directly from the Earth’s mantle in a matter of hours to days. Types of magma that are very ‘primitive’, which means they didn’t really have their chemical compositions changed by what we call ‘magmatic differentiation’. Processes like cooling down somewhat and absorbing a lot of materials from the Earth’s crust. The presence of very primitive lavas on the surface indicate a few important things: matters can change quickly and without a lot of warning, although the effusive and intrinsic mildly explosive nature of the molten rock means any threat is likely to remain local.

However, geoscientists, authorities and the local population are fairly ill-prepared for an eruption if it were to happen anytime soon. Those with any degree of responsibility often tend hide behind statistics and often meaningless facts like the number of years that have passed since the most recent eruption. Being aware and ready for an event that is likely going to happen at any time in the near geological future is being smart about it.

Taking both statistics and the speed at which things can go from ‘Nothing going on at all’ to ‘Oh Scheiße…’, the WEVF seems to be the most likely candidate for the next eruption. There’s reason enough take action on this specific threat, but it doesn’t really exist in the minds of most locals. It doesn’t mean that there’s no attention for any potential future volcanism in the Eifel. Without going to great lengths, one can easily find information on something stirring in the EEVF, where a completely different kind of beast snores in its slumber.

The East Eifel Volcanic Field: a story of evolving magma

About a hundred volcanoes, most of them monogenetic scoria cones. Pretty much the same as the WEVF, just containing just over a third of the amount of vents that once produced lava and ash. The East Eifel Volcanic Field sounds like smaller sibling of its counterpart about 30 kilometers to the southwest, but you’d be wrong to assume the differences stop there. In fact, the EEVF is much larger when we look at the volumes of the erupted volcanic materials we find there. That’s because, among the scoria cones, a few monsters are present.

Located in what is the middle of the volcanic field, are several volcanoes that have been fed by variants of a magma called phonolite. Mafic magmas like basanite and tephrite, which are generally fairly hot, effusive and typical for producing the small eruptions that are common in volcanic field like those of the Eifel, have formed numerous scoria cones that are still clearly visible in the landscape today. In some places, though, these magmas rose to form large magma chambers that have taken tens of thousands of years to grow before erupting. At the same time, the magma partially cooled down and only the minerals that didn’t solidify remained eruptible, becoming phonolite. Phonolite is a so-called intermediate rock, which means it has its place between mafic and felsic. Its viscosity is substantial, which allows for pressure to build up inside it quite efficiently, turning it explosive in most cases. That also happened on a small number of occasions in the EEVF over the last few hundred thousand years. Two of the phonolitic magma chambers have produced eruptions that were even large enough to create calderas.

Going big: the first caldera

After an initial phase of erupting ultramafic magmas occurring in the EEVF between 650.000 and 450.000 years B.P., the Phonolitic eruptions started in what is now called the Rieden Volcanic Complex between 450,000 and 350,000 years ago, which was long considered to have its own caldera, but the depression there is likely to be of an erosional nature than of anything that has to do with the collapse of a magma chamber. Numerous lava flow-producing vents and even lava domes formed in this phase of volcanic activity in the Eifel, before eruptions stopped for about 135,000 years, producing a total volume of ~10 km3 of volcanic deposits. Then, around 215,000 B.P., the ‘Hüttenberg Tephra’ was erupted. It is currently assumed this eruption may have been a high-end VEI5, having erupted a bulk volume of phonolitic ash and pumice that quite possibly lies somewhere between five to ten cubic kilometers. Another substantial, explosive eruption occurred from this volcano about 150,000 years ago, covering the landscape with the ‘Glees Tephra’, which has been produced by an eruption maybe reaching low-end VEI5 with an estimated 1 km3 of ejecta. Very few volcanoes have magma chambers that will not collapse after such events, and this volcano is no exception. Now known as ‘Wehrer Kessel’, which basically means ‘Wehr’s Cauldron’, the volcano is named after the village that can be found in the western half of the almost two-kilometer wide caldera. Currently, the volcano only produces amounts of CO2 that can be expected from extinct volcanoes, but since 2015 unexpected subsidence has been observed within the crater. More on that later.

Earning true infamy: how one volcano took it to the next level

Dispersal of the Laacher See tephra over Europe. Image credit: Hans-Ulrich Schmincke.

As nasty as Wehrer Kessel’s behavior has been, its next door neighbor is the true beast of the lot. It is currently assumed phonolitic magma started accumulating between five and eight kilometers deep from approximately 30,000 years ago. After a series of large intrusions it accumulated to possibly 18 cubic kilometers (v. d. Bogaard & Schmincke, 1984) before an eruption finally took place an estimated 13,078 years ago (remember that date). And what an eruption it turned out to be. It started with large, phreatomagmatic explosions taking place at the southern end of what is now known as the crater of this volcano. Ash of these events was mainly blown towards the southwest. The main phase of the eruption commenced not long after, opening up a new vent just to the north of the one that had previously formed. The most powerful of the explosions produced ash columns that rose to an altitude of possibly 40 kilometers, before being dispersed toward what is now Scandinavia and Italy. It took an estimated eight to ten days before the eruption was over, and what was left was a vast area that was buried beneath tens of meters of pyroclastic flow and tephra fall deposits. Approximately 6.3 km3 worth of phonolitic magma expanded into some 20 km3 of mostly ash and pumice. The nearby Rhine valley was blocked by two natural dams formed by pyroclastic flows, blocking the river Rhine and causing the flooding of the Neuwieder Becken, a wider valley east and southeast of the volcano. The resulting lake was about 20 meters deep before it catastrophically drained due to the breaking of the dams. At the site of the eruption itself, a caldera formed that measures 2.5 by 3.5 kilometers from rim to rim, still visibly featuring the two different, but now merged explosion craters from which the eruption took place.

Ring faults and CO2 emissions (‘Mofetten’) of the Laacher See caldera. Image credit: Goepel et al, 2014.

Comparing the eruption to well-known events

What happened in the EEVF just over 13,000 years ago is an event of a magnitude that occurs globally no more than a few times every century. Between the years 1900 and 2000, only three events of a similar magnitude occurred, using the logarithmic Volcanic Explosivity Index as a standard to work with. The first eruption at Wehrer Kessel was in all likelihood, as stated above, a large VEI5. But its big brother to the southeast went VEI6, having produced a bulk volume of ~20 km3 and placing it firmly between the 10 and 100 km3 which define an eruption of such magnitude. In 1902, Santa María volcano in Guatemala erupted 10 km3. In 1912, in Alaska, the Novarupta vent formed as part of the Katmai volcano, blasting out between 25 and 30 km3 of ash and pumice and in 1991 Pinatubo in the Philippines produced the world’s most recent VEI6 by erupting 11 km3 of volcanic materials. These events live in infamy because of their destructive legacies, on a list that features Krakatau, Huaynaputina and Ilopango as well, to name just a few exceptionally nasty monsters that have violently erupted over the last few thousand years. Although there was a number of much larger eruptions during the Holocene, ranking as VEI7, a VEI6 is by no means a small event, definitely earning its status of being ‘colossal’. Any event of this size would dominate the news on a global scale for at least days, if not weeks.

A deceptive serenity

A thunderstorm over Laacher See, photographed from the ‘Lydiaturm’ on the northern crater rim in the summer of 2017. Image credit: Gijs de Reijke.

After the EEVF eruption of 13,078 years BP ended, the caldera got partially filled up by water, forming a lake that is now 2 by 2.3 kilometers in diameter. This lake, known as Laacher See, gives the volcano its name. The crater walls are covered by a beech forest, an abbey dating back to the 11th century can be found in the southwest of the caldera and the lake is being used for all kinds of recreational purposes. Many paths stretch far and wide in and around the volcano, allowing hikers to enjoy a fine bit of nature. A campsite is located on the northwestern shore, as well as a hotel on the northern crater rim as one next to the abbey, enabling a stay of more than one day for anyone who’d be interested in doing so. Directly surrounding the caldera are numerous villages, various museums and castles and a very fine brewery. The area is bustling with anything and everything that has to do with having a good time. The volcanism of the area is mostly something nice for tourists to be entertained by. Shapes of volcanoes can be seen in the landscape, as well as rock quarries featuring layers of ash and lava. CO2 is being emitted visibly in a few places, like the ‘Andernach Geyser’, which is the result of a borehole blasting out CO2-pressurized ground water to a height of 30 to 60 meters every 90-110 minutes, making it the world’s tallest cold-water geyser. Spectacular and fun, as is underscored by the many signs in the field explaining the geological importance of the volcanic features of the area. The ‘Lava-dome’ volcano museum in Mendig helps to make things more understandable for those of a younger age. It would be easy to think of the Eifel volcanism to be done and dusted, as many have done who live and have lived in the area and those who visit it for work, recreation or social reasons.

One would expect I’m going to state that nothing could be further from the truth than the perceived serenity that is present in both Eifel volcanic fields. Although going to spice things of a bit, it has to be said that nothing even close to the activity of well-known volcanoes like Etna has ever been detected in the Eifel. I mentioned before that things can change quickly in the WEVF, but does the same thing apply to the other field? For both areas we can state that the most recent eruptions have occurred long before there ever could’ve been historical records of it, not to mention not having modern geosciences to our aid to help understand things. There are plenty of other volcanoes around the world which feature much more acute signs of unrest that require monitoring and everything that comes with it, and not every country can easily come up with enough cash for such a project. So does it make sense to invest some time, effort, know-how and money on a topic like the volcanism of the East Eifel Volcanic Field? In my opinion, that is most certainly the case.

Another building with a religious purpose was present within the Laacher See caldera, located on its eastern shore. This ‘villa’ was built in 1870 for a group of Jesuits, but in 1871 things started going wrong. On no fewer than eight occasions, a young Jesuit was found dead in his bed at the start of a new day. At the time, these deaths remained a mystery. Nowadays, it is being assumed they were poisoned and suffocated in their sleep by volcanic CO2 rising up from the partially collapsed magma chamber, through the ring faults and into the bedrooms on the ground floor of the villa. CO2 has a higher density than oxygen, and can kill quickly and without any sort of stress when it fills of room to a level that is higher than that of someone sleeping in a bed. No visible traces of the villa can be found in the landscape today, but the Jesuits are still interred in the grounds of the nearby abbey of Maria Laach.

‘Mofetten’ at the eastern shore of Laacher See. Image credit: Riet de Reijke-Gubbens.

One might say the Laacher See volcano has already killed several people in fairly recent times, earning a bad reputation. CO2 can still be seen near the eastern shore in the form of so-called ‘Mofetten’, where bubbles are visible and audible in the lake. A smell of rotten eggs, pointing out the presence of Hydrogen sulfide (H₂S), is a common occurrence on a day with little to no wind. But does CO2 output mean this volcano can erupt in the near future? No, not really. Magma chambers, especially larger ones, tend to take some time to cool down, all the while the system inevitably degasses. We’d have to look for other signs to figure out if there’s a more substantial volcanic threat coming from this rather big hole in the ground. Think of earthquakes and tremors formed by the motion of magma, or changes in the amounts and compositions of volcanic gasses emitted. Ground deformation, and especially localized rising of the Earth’s surface, is something to be concerned about. Is any of that going under or close to Laacher See? There’s a score of at least two out of three for the EEVF.

Coming to grips with reality

Deep low-frequency earthquakes and tectonic earthquakes beneath the EEVF. Image credit: Hensch et al, 2018.

For plenty of geoscientists, getting to do research on a quiet, yet young volcanic field like the ones of the Eifel, especially when they contain nasty beasts like Laacher See and Wehrer Kessel, would be a very interesting project, to say the least. It might surprise you that until recently, nothing substantial had ever been undertaken to get a better perspective of the potential threats of future volcanism in the area. As part of a study (Hensch et al, 2018), using an array of both permanent and temporarily installed sensors, so-called ‘Deep low-frequency earthquakes’ have been detected below the EEVF for the first time between 2013 and 2018. These tiny earthquakes are typical for the motion of magma within the Earth’s crust. Quite a few of these events have been observed at four distinct zones ranging between 44 and 8 kilometers below the surface, most of them being too deep to be of a tectonic origin, although tectonic quakes occur frequently in the area as well. The shallowest of the microquakes were located almost right under… Laacher See. The findings of the very important study concerning this topic caused a bit of a stir, but no major amount of attention by the public formed as a result of this research.

Ground motion close to Laacher See. Blue and cyan is up (Glees), orange and yellow is down (Wehrer Kessel), green is stable. Image credit: BodenBewegungsdienst Deutschland.

Upward motion of the ground in the north of the village of Glees. Image credit: BodenBewegungsdienst Deutschland. Image credit: BodenBewegungsdienst Deutschland.

How about very localized ground deformation? I’m not referring to the steady rising of the entire Eifel and surrounding areas by about 1 millimeter per year (Kreemer et al, 2020), which also happens to be quite relevant for the volcanic activity of the region, but the upward motion of the ground in and near the village of Glees. This place, counting about 600 inhabitants, lies a few kilometers northwest of Laacher See and northeast of Wehrer Kessel. The ground on the northern side of the village has been rising quite a bit since 2015, which is when measurements started. The most recent available data, dating from the end of 2020, shows an increase of about 3.5 centimeters, in some places more than 4 centimeters, since early 2015. Again, this is close to nothing compared to what’s currently going on at volcanoes like Campi Flegrei or Edgecumbe, but an area that has always been thought to be extinct or at least very quietly dormant by many, it’s a fact that has caused the raising of some eyebrows over the last few years. Several clusters of tectonic earthquakes near Glees have been observed (Hensch et al, 2018), which may be attributed to the formation of sill-like intrusions of magma and/or increased, CO2-produced pressure. And might there be a connection to the very local subsidence in Weher Kessel? As it stands, magmatic inflation under the Glees area cannot be ruled out, but more research is needed to get a much-needed understanding of what actually is going on, which leads me to a concerning, yet exciting conclusion: we don’t know enough. To my current knowledge, no extensive monitoring is being done in the area, apart from keeping tabs on the deep low-frequency earthquakes and ground deformation. How about gas measurements? Is there still no eye being constantly kept on what’s coming out of the ground? As you will likely understand, I’m quite keen to be kept informed on whatever is going on beneath the feet of those who live in the Eifel and visit that fascinating place for whatever reasons one may have.

Not just interesting for future eruptions
So far for the most exciting volcanic region of Europe north of Naples, which should be mandatory for any European geology class. It is one for the future. But is also helps to understand the past, as will be shown in part II. Stay posted.

 

 

Gijs de Reijke, April 2022

 

 

Hensch, M., Dahm, T., Ritter, J., Heimann, S., Schmidt, B., Stange, S., Lehmann, K. (2019). Deep low-frequency earthquakes reveal ongoing magmatic recharge beneath Laacher See Volcano (Eifel, Germany), Geophysical Journal International, 2019; DOI: 10.1093/gji/ggy532

Schmincke, Hans-Ulrich (2007) The Quaternary volcanic fields of the East and West Eifel (Germany). In: Mantle plumes – a multidisciplinary approach. , ed. by Ritter, R. and Christensen, U.. Springer, Heidelberg, pp. 241-322.

Schmincke, H.-U., 2006. Environmental impacts of the Lateglacial eruption of the Laacher See Volcano, 12.900 cal BP. In: von Koenigswald, W., Litt, T. (Eds.), 150 years of Neanderthal Discoveries. Terra Nostra, Bonn, pp. 149- 153.

Goepel, A., Lonschinki, M., Viereck, L., Büchel, G., Kukowski, N., Volcano‑tectonic structures and CO2‑degassing patterns in the Laacher See basin, Germany, International Journal of Earth Sciences 104(5), December 2014, DOI: 10.1007/s00531-014-1133-3

Sundermeyer, C., Gätjen, J., Weimann, L., Wörner, G., Timescales from magma mixing to eruption in alkaline volcanism in the Eifel volcanic fields, western Germany, Contributions to Mineralogy and Petrology volume 175, Article number: 77 (2020)

Ginibre, C., Wörner, G., Kronz, A., Structure and Dynamics of the Laacher See Magma Chamber (Eifel, Germany) from Major and Trace Element Zoning in Sanidine: a Cathodoluminescence and Electron Microprobe Study, Journal of Petrology, Volume 45, Issue 11, November 2004, Pages 2197–2223, https://doi.org/10.1093/petrology/egh053

Schreiber, U., Berberich, G., Why does the Size of the Laacher See Magma Chamber and its Caldera Size not go together? – New Findings with regard to Active Tectonics in the East Eifel Volcanic Field, EGU General Assembly 2013, held 7-12 April, 2013 in Vienna, Austria, id. EGU2013-5908

Kreemer, C., Blewitt, G., Davis, P.M., Geodetic evidence for a buoyant mantle plume beneath the Eifel volcanic area, NW Europe, Geophysical Journal International, Volume 222, Issue 2, Aug. 1, 2020, pp. 1316–1332, https://doi.org/10.1093/gji/ggaa227

Ritter, J.R.R., Jordan, M., Christensen, U.R., Achauer, U., 2001. Mantle plume below the Eifel volcanic fields, Germany. Earth Planet. Sci. Lett. 186, 7–14.

Meyer, R., Foulger, G.R., The European Cenozoic Volcanic Province is not caused by mantle plumes, www.manteplumes.org (2007)

Schmincke, Hans-Ulrich (2009). Vulkane der Eifel – Aufbau, Entstehung und heutige Bedeutung, Spektrum-Akademischer Verlag 2009, ISBN 978-3-8274-2366-5.

Meyer, W. Geologie der Eifel, Schweitzerbart, Stuttgart, 4th edition (2013).

106 thoughts on “Sleeping in our back garden: the past, present and future of the Eifel volcanic fields (part I)

  1. Wow, did not know there were actual central volcanoes in Eifel, Laacher See was an evolved magma but always assumed that was kind of a freak event, but maybe not so. Itbis far from a ‘supervolcano’ but for sure nothing to scoff at, a bigger eruption than Novarupta or Krakatau and from a setting that would only be expected for tiny mafic eruptions, as you say. I wonder why there are calderas here but not at some other volcanic fields in intraplate settings, like those in Australia, or the western edge of North America.

    • Conditions are assumed to be better for the EEVF than for the WEVF, because of wider faults allowing for more magma to be stored at different depths in the crust. This means it can cool down and undergo other processes within a time span of at least tens of thousands of years. The concept of magmatic differentiation isn’t exactly a great mystery, but getting a proper perspective of how it works in a specific location often is.

      • It is really pretty incredible that magma can sit for so long in the crust and still erupt. It must cool down over time but intermediate magmas need to be pretty hot to remain mobile so there is something going on down there. The high CO2 flux might mean there is more active magma down there than the activity level suggests.

        Laacher See might be similar to the caldera volcanoes in central Italy, around Rome. Those go many millennia between eruption cycles of significant scale. These sorts of rogue calderas might be the most dangerous volcanoes, if they erupt they go all or nothing, VEI 6-7.

    • When you look for them, these rogue calderas are not so uncommon. Australia has had a few in the past, Tweed volcano about 23 million years ago and probably others that I’m not aware of, none of them are active but it shows the potential for calderas is there. Western North America has some huge active calderas like Long Valley, or Valles, which are in areas of weak, potassic, volcanic fields.

      • Although now that I’m thinking about Laacher See it doesn’t strike me as a caldera. Meaning it doesn’t have the characteristics of other calderas like Krakatau, or the phonolitic Las Cañadas caldera in Tenerife. The first clue is that Laacher See did not produce an ignimbrite, instead it mainly resulted on some mid distance ash surges and airborne tephra carried in multiple directions by the changing wind conditions. I do not know much about the area but I can only find mention of one eruption of Laacher See, in other words a monogenetic vent. It is a common misconception that monogenetic volcanoes erupt small, for example México has seen some monogenetic effusive eruptions of about 10 km3, like the andesitic El Metate, or the twin rhyolitic lava domes of Las Derrumbadas. The same volcanic field of Las Derrumbadas, Serdán Oriental, has also done some significant explosive eruptions, like the VEI 6 Quetzalapa pumice, or the massive rhyolite maar of Cerro Pinto which I’ve never seen an estimate of its size but the amount of volume it erupted seems close to Las Derrumbadas ~10 km3.

        As such I personally think Laacher See would be best seen as a huge silicic maar crater, not properly the collapse of a magma chamber. It would be one of the largest maar craters of the world in that case, but not unique. For example Lake Chala, a monogenetic flank vent of Kilimanjaro has a maar crater with roughly the same dimensions as Laacher See, and there is another nearby maar next to Meru of the same size.

        The LP earthquakes rise up to 10 km under Laacher See. We could assume the magma storage is at this depth. A reasonable assumption I’d say, given that two other basanitic-tephritic volcanic fields, La Palma and El Hierro, which could be seen as oceanic equivalents of the two Eifel volcanic fields, have shown in recent eruptions to have the main magma storage 10 km underground. Thus there would exist a sizable magma storage under the center of East Eifel, centered under Laacher See, which has evolved phonolitic magmas. This long lived magma storage would have been supplying occasional phonolitic explosive eruptions, maars and lava domes for hundreds of thousands of years. Not having ever collapsed, the storage being possibly too deep or too diffuse to do so. This is speculative, but is my take on the plumbing of the East Eifel volcanic field. It could be compared to volcanic fields such as the Chaine des Puys, Harrat Khaybar, or Pinacate, which are dominantly mafic but sometimes can come up with silicic eruptions.

        This is the center of Harrat Khaybar volcanic field, dominated by white colored silicic materials, from lava dome and tuff ring eruptions. Including vast amounts of pumice:

        • One type of volcanism doesn’t exclude the other from being possible. The Laacher See eruption started with a Maar-forming phase, but became much more powerful and voluminous when the intrinsic explosivity of the phonolitic magma was driving the eruption. 6,3 km³ of magma forced itself a way out from a magma chamber that is located between five and eight kilometers below the surface. Details concerning the size and shape of the magma chamber are still a bit unclear, but what is certain is that the Laacher See as a hole has primarily formed as a result of classic caldera subsidence.

          I wouldn’t go as far as stating the absence of an ignimbrite could be a clue to a volcano not being a caldera, the same as the presence of an ignimbrite is not necessarily indicative of a large collapse structure being a caldera instead of a maar. Lago Albano in Italy, part of the Colli Albani volcano, is considered a maar and has produced ignimbrites.

          Laacher See has produced voluminous pyroclastic flow deposits which may not be as strongly consolidated as the hardest ignimbrites we know, but the materials that can be found in places like the Brohl Valley (‘Brohltal’) are definitely viewed as being ignimbritic.

          https://oceanrep.geomar.de/id/eprint/46664/1/Schumacher_Schmincke.pdf

          • Yes, not all calderas have produced an ignimbrite. However the classical Krakatau-like caldera has a very particular eruptive style, following an initial plinian eruption phase with interspersed pyroclastic density currents, a second phase occurs, often the most violent and voluminous, where a massive pyroclastic density current spreads out radially in every direction of the volcano leaving very thick ignimbrite deposits and reaching up to multiple tens of kilometres in distance from the vent.

            Not all calderas are like this, some shield volcanoes can collapse in a largely effusive manner. Some collapse craters, like that of Pinatubo, traditionally considered calderas, have formed in plinian eruptions that lack the pyroclastic density current dominated second stage of Krakatoa-like calderas. There is a wide spectrum. Also, sometimes distinguishing calderas and maars can be problematic, given that maars can achieve diameters of a little over 3 kilometres, and that they can also be the source of powerful plinian eruptions, as well as erupt silicic magmas.

          • If you think about it, topographically, Laacher See is a lake surrounded by a tuff ring, it seems difficult to fit 6 km3 in it. The lake barely reaches 50 meters deep in its center and it is somewhat less than 200 meters below most parts of the crater rim. Being generous, Laacher See could be about 1.5 km3 of collapse, in reality it must be much less given that most of the walls of the crater appears to be tuff deposited during the eruption. There is a difference to be considered between deepening the center and rising up the sides.

            I’m aware that all scientific articles talk of Laacher See as a collapse caldera, and that as such saying otherwise is going against the current scientific agreement over the origin of Laacher See. However I ought to be skeptic when considering the volcano, its shape, history, and eruption deposits.

          • The current depth of the lake will be much less than the original one. sedimentation is high in this region

          • Maybe a good example of an eruption where the magma storage was too deep to collapse into a caldera.

            Sounds a lot like what happens at Hekla, which has no shallow storage at all and has survived borderline VEI 6 eruptions in the past largely intact. I wonder if maybe Hekla looked a bit like Laacher See in the past, a tuff cone with a tall rim, maybe slightly elongated. Maybe the bulge on its north side is a remnant of this old volcano which has survived burial. It was already a mountain in 1104 but has also been said to have changed considerably since then and that is little elaborated upon.

        • We know too little of how volcanic plumbings are structured. Normally magma should be stored within complexes of stacked sills. When there is an eruption magma will be drawn away from those sills, they will shrink, the ground above will gently sag over a wide area, but not collapse. Even a 10 km3 explosive eruption may not make any collapse, like Quizapú in 1932.

          A magma chamber instead is a singular body of magma at shallow depths, when it collapses, and it can easily do so, a ring dike can develop, the chamber will rapidly blow out through the ring dike, leading to a very particular extremely violent eruption style, Tambora, Krakatau, Hunga Tonga are probably good examples.

          How a magma chamber forms remains somewhat enigmatic. In some cases it can probably grow by pushing up the floor of the caldera, this could work for Bardarbunga or Sierra Negra, who lift their calderas like pistons. It cannot possibly be the case for Piton de la Fournaise or Kilauea where magma chamber develop without doing occurring.

          At Kilauea I think there might be a link between the deflation-inflation events and the growth of a chamber. I had a model of how DI events happened, but I have replaced with a better one, one that I think could definitely work. There is a complex of stacked sills under the summit of Kilauea, a very large number of sills. For example there were recently sill intrusions in 2021, 2015, 2012, and 2006. The layer of rock separating two sills is probably unstable. What I think happens in a DI event is that a small dike intrudes the solid layer that is located between two sills, in an area that is already unstable and nearing collapse. The dike intrusion takes up pressure from the chamber triggering the deflation. Once the dike is completed the block of rock breaks up from the rest and returns to a relaxed shape. The dike had compressed the rock, making the deflation, now the rock snaps back to being relaxed, displacing away the magma, and causing the inflation. The block of rock then sinks to the floor of the underlying sill. There are probably advancing fronts of collapse, disintegrating the barriers between sill intrusions, similar to how overturning happens in the crust of a lava lake. The lake swallows up pieces of crust along an expanding, advancing arc. This way, after a long time, tens or hundreds of sills can collapse and focus magma at the top of the complex, into a vast chamber.

          • Sounds plausible. With the huge number of DI events this past decade the chamber must be growing rather rapidly.

          • In fact, if this theory happens to be correct or to be close enough to reality, then the magma chamber that collapsed at Kilauea in 2018 would have assembled mostly in just about 10 years. This is because DI events only started to take place frequently in 2008. There had been DI events since 1986, but very rare. So as soon as it started forming it collapsed with the first lower than Pu’u’o’o fissure eruption that showed up (2018).

          • It was the chamber that formed in 2008 that formed the 2018 s collapse feature as it drained

          • Same time as the lava lake appeared. Now there is a new open vent, and DI events were happening even before 2018 ended.

            I guess per this theory DI events could happen from other magma chambers too, if those grow large enough on the ERZ. Could give indication of where activity will focus in the future.

    • Looks like basalt to me. Anak Krakatau is not really very big, and the lava flowed into the sea nearly immediately so will build up behind the flow front, like happened at Kilauea in 2018. Tall fountains also tend to make more viscous flows because the lava cools in the air, even in Hawaii in the 1980s Pu’u O’o had viscous fountain fed flows and fluid lava rivers at the same time. Is also why a lot of flows on Etna are viscous looking, fountain fallout, when it is effusive Etna is a lot more fluid.

      Made quite the substantial cone in only a few days, must be over 100 meters.

    • Anak Krakatau lavas are classified as basaltic-andesites with 55 % wt SiO2 when looking at whole rock composition. However it must be considered that Anak Krakatau erupts magmas that are 40-50 % phenocrystals in volume, or in other words solid. The remanining melt between the crystals I haven’t found any anylisis of its chemistry, but if had to guess I think it could be andesite or dacite. The melt is logically going to be more evolved than the crystals. So that explains the high viscosity seen in videos.

  2. Also just today noticed this. From HVO report.

    East Rift Zone Observations: No unusual activity has been noted along the East Rift Zone or Southwest Rift Zone; steady rates of ground deformation and seismicity continue along both. One short tremor episode was observed over the past day. Measurements from continuous gas monitoring stations downwind of Puʻuʻōʻō in the middle East Rift Zone remain below detection limits for SO2, indicating that SO2 emissions from Puʻuʻōʻō are negligible.

    Maybe it is because I presently reside right along the ERZ of Kilauea, but this really got my attention. Obviously nothing major but still shows magma may be finally high enough in the caldera to push eastwards underground, a lot earlier than I was expecting it to. It is not clear which rift was the source of tremor, however, and the SWRZ did activate last year. The wide swath of the south flank that is moving is not a good sign though, even east of Kalapana, further than in 2018.

  3. An outstanding start to the series.
    I’m sure part 2 will be equally informative and interesting.
    Having my attention focused mostly on other volcanic regions, I know almost nothing of this history.
    One question: might elastic rebound explain some of the ~ 1mm regional rise?

    • Thank you!

      It has been considered a possibility, but the uplift under the Eifel is something very specific to that region, and stands out quite a lot from anything and everything else that’s going on on the European mainland north and west of the Alps.

      The publication by Kreemer et al., ‘Geodetic evidence for a buoyant mantle plume beneath the Eifel volcanic area, NW Europe’, to which I linked under the article, is an interesting read regarding this topic.

  4. Good read Gijs!
    Thanks much. I am looking forward to part II.

    Do you know any overview; book, article, website published about volcanic activity in Germany in general?
    There are many interesting places, thinking also of Thüringer Wald, Erzgebirge, Zwickau and surroundings of the Mulde valley in Sachsen.

    • Thank you!

      To my knowledge, no such book exists. I have plenty of books on German geology, but nothing is as specific as and deep-delving as ‘Vulkane der Eifel – Aufbau, Entstehung und heutige Bedeutung’ by Hans-Ulrich Schmincke., although his book ‘Volcanism’ goes even further when it comes to Laacher See. Germany has many volcanic areas of Quaternary and Tertiary age, and lots of stuff that’s even older than that. I guess it would be hard to write something very comprehensive about it, but leave it to Germans to come up with quality when it matters.

  5. It’s interesting that these central volcanoes have formed in the alpine orogeny-induced rift system.
    Something about the crust in these areas able to host magma chambers, where weaker parts erupt quickly and monogenetically? Either way there will be more to come from this area.

    Nice article.

    • Thank you!

      What we can be certain of, is the presence of an ‘anomaly’ below the Eifel that at least somewhat resembles a mantle plume, but there are distinct differences as well. How it formed and how it might be related to the Alpine orogeny is a topic of much debate, which I’m not going to touch with a ten-foot pole as long as nothing more definitive has been published.

      • Could well be a plate-derived hotspot. I don’t think there is a deep plume at work in the area as there isn’t the classic bulge etc. but clearly there are long-lasting volcanics over a significant area of land. I always saw it as propagating cracks from the collision of Africa.

  6. Thanks for this interesting article of a region largely unknown to me.

    I find the low frequency earthquakes interesting. Often seismicity seems to trace volcanic conduits down to a depth of 30-45 km. For example the Kliuchevskoy group has a prolilific source of low frequency earthquakes about 30-35 km deep between Kliuchevskoy and Ushovsky volcanoes. In Hawaii the deepest low frequency earthquakes are those that happen 45 km directly under the summit of Mauna Loa, this is also the depth of the deep volcano-tectonic earthquakes that make swarms in the southern side of the island, and there is also the 41 km deep occasional spasmodic tremors under Pahala. During the Cumbre Vieja eruption the conduit flared with seismicity down to 35-40 km, and some of the earthquakes looked like tremors or low frequency events in the drum plots. Also, during the Pinatubo eruption, the deep low frequency earthquakes were about 30-35 km deep. And the Mayotte dike intrusion and eruption that started in 2018 generated seismicity down to 30-40 km.

    • Thank you!

      The DLFE activity detected under the EEVF should be enough to get more permanent equipment installed. Quite obviously, the area is dormant, not extinct, which means proper monitoring should be in place, like in many places in the world. Germany is ridiculously rich, like most European countries, and taking care of a thing like this shouldn’t even be up for debate; it just has to be done.

  7. Interesting subject. Enjoyed the article. Thank you Gijs.

    Also enjoyed your word choice: “our” back garden. Made me feel like a citizen of the world.

    • Thank you!

      The Eifel is on the doorstep of a few large cities in one of the richest countries in the world, surrounded by other countries that are similarly wealthy. Very few people, especially outside of Germany, even know the Eifel has volcanoes. Even fewer are unaware of the volcanism being dormant, not extinct. It takes me a 2.5-hour drive to get to Laacher See, but I pass cities and villages with hundreds of thousands of people live completely oblivious to what is going on in their back gardens.

      I’m not an alarmist, though. Facts like ‘The Eifel is still very much alive’ excite me, and I can’t shut up about what nature can do close to home and how interesting it might be for people to just take a closer look. It’s not just volcanism; earthquakes, tornadoes and Aurora Borealis, to name just a few things, are on that list as well. It’s why I teach geography and why I’m a landscape photographer.

  8. I love this post. Few volcanoes erupt often enough to be seen by all generations. So knowledge is lost, or may never have existed. Any volcano which has not erupted in living memory is considered harmless. (Vesuvius will soon reach this point.). But it may just be taking its time. A monogenetic field also has the problem that the next eruption will not come from an existing vent, but somewhere in the open. It makes monitoring so important – and so hard to fund.

    One comment: the rotten egg smell is H2S, not SO2. The outgassing is indeed SO2, but it changes into H2S from chemical reactions in the water. That is actually a good sign (if a bad smell), as it means that the outgassing is slow enough that the lake can catch and convert it. It shows that the volcano is quiet. If the lake begins to expel SO2, it means that the outgassing has increased so that the lake can’t cope, and it is time to call the tourism office.

    • Thanks!

      And you’re absolutely right about the Hydrogen sulfide, so I corrected it in the article.

    • I have wondered for a while how H2S forms geologically in that way. Unless the sulfur in magma is actually largely elemental and it is later oxidised or reduced on the way up?

      Might be 3SO2 + 2H2O = 2(SO4)2- + H2S + 2H+ ? That doesnt balance though, so there must be another component, probably something in the rocks, like iron or calcium. Fe2+ might be a suitable reducing agent, it is why sometimes hydrogen flames are seen on Kilauea, reduction of water by Fe2+ in the magma. Is also why a lot of basalt turns brown over time on the surface.

      I would have assumed the H2S is more biological in origin, being in a deep presumably anoxic lake

    • Vesuvius is one of the volcanoes though that will never be forgotten due to the excavation. The Romans and also the Greeks are s.th. special.
      I even saw an excavated villa in Positano, but that wasn’t Vesuvius directly, but mud lahars instead. The effect of Vesuvius was larger than first thought.
      Btw, I read the other day that the Romans wanted to build an aqueduct in Jerusalem, but the population of Judaea didn’t want it. Astonishing.
      I admire the Romans most for their engineering.

  9. Hello Gijs,
    I didn’t know you, and you might be new. Nice photographs, also here:
    https://www.natuurfotografie.nl/gijs-de-reijke-in-beeld/

    You seem to specialize in weather, also storms, which are not unusual in the Netherlands.
    The article is very good and clear, separating the different volcanic fields in Eifel. Contrary to you I always tended to skip the region and go right to the Netherlands (or England) which is somehow – I think – typically European.

    I was wondering about the source of the tectonic quakes. That might be the Rhine Graben.
    I think it is odd that, aside from the Philippines maars are very typical for Europe, up there and again in Italy from Alban Hills to Campi Flegrei.
    If anybody knows a reason for that feature being predominant in Europe come forward, plaese.

    Congrats for your clear and precise piece and also for the beautiful pictures.

    • Thank you!

      The source most of the tectonic quakes is the ‘Ochtendung fault zone’, one of many faults in the area.

      Maars can be found in many places in the world. It’s just a matter of having enough water in the ground where magma intrudes. It’s not just Europe that has a lot of them.

      Thanks again!

      • Having a rainy but cool climate with low evaporation probably does help in creating maars

      • Lots of maars in Australia too, west of Melbourne at the southwest half of the Newer Volcanics. Some are massive, Tower Hill next to Warrnambool is 3 km wide, even a bit bigger than Laacher See, it isnt a caldera but still the eruption must have been very significant.
        It formed at about 37600 years ago at the same time as the effusive Bunj Bim volcano, which is about 60 km west. There was also a stone axe found in the ash from Tower Hill, so the event was witnessed.

        • If you once happen to have some spare time, Chad, you should write a piece about that little known area in Australia, I think.

          • Will try, actually I have been trying for ages to write something about the volcanism in Queensland but apart from the visual tourism at Undara there is not much. Particularly very little on accurate dates.

            But given both areas have had Holocene eruptions some of which were rather large in scale, I expect underground there is abundant magma at both. Newer Volcanics was even tholeiitic basalt flood lavas at its peak, which suggests major melting. Atherton in Queensland was too, both are now monogenetic a lot like Eifel with lots of maars. But McBride/Undara is massive and voluminous already, and has not yet gone through a tholeiite stage, if only we had a way to look at the plumbing because I think this could be a monster in the making.

  10. Thanks for a very interesting post.
    I had, obviously, heard of the Eiffel, but your article has placed it at the forefront of my interest in European volcanoes
    Thank you.!

  11. Looking at the map, do you think the more evolved magmas have anything to do with the location above the Rheinish Shield? The rift seems to be propagating through it but not yet completely, so the underlying magma has to break through tough crust and gets stuck?

    Area is very interesting, much more active than I thought before reading this 🙂

  12. Gijs mentioned that there is sparse population in the area. But Koblenz, where the river Mosel flows into the river Rhine, is only 30 km from Maria Lach, and is well populated. Immediately south and south-west of Koblenz the vineyards start, and the vines produced there are among the best. So, a larger eruption would certainly be a catastrophe. It is a classical “Volcano-giveth” (Carl) region.

    The other well populated area (besides Naples) is Rome with the Alban Hills and Monti Sabatini in the North:

    https://www.nature.com/articles/s41598-020-65394-2

    Wikimedia commons

    https://i0.wp.com/www.volcanocafe.org/wp-content/uploads/2019/02/alban.jpeg?ssl=1

    VC, from
    https://www.volcanocafe.org/volcanic-winter-hypothesis-and-candidates/
    by Tallis, seconded by Albert

    Looking for this I saw that you have written a guest post on Eifel in 2019 which I hadn’t seen so far, sorry.

    • Albert, I wonder whether you could make the picture of Alban Hills from VC show up here, as it beautifully shows (imho) a maar with its low rim and round shape.

    • I’ve stayed in Duren and Koln years and years ago, they are only an hour away. Had no idea at the time!
      Beautiful places by the way, and it was in the build up to the 2006 world cup so everything was decorated.
      A lot lot cleaner than British cities. And lots of green.

      • You think Koeln is clean? I think London is clean. You know why? Because I am a tourist and stay mostly in Kensington/Chelsey.
        Edinburgh is fabulous. I could show you some really rotten places in Berlin. Believe me, there’s no significant difference.

        • You couldn’t pay me enough to live in London. Grotty, overpopulated.
          Up in the north we have vibrant cities, architecture, lovely sandy beaches and then a half hour trip inland mountains and countryside. Edinburgh is a lovely city, as is York.

  13. Interesting subject, thanks for the story Gijs!

    “the most exciting volcanic region of Europe north of Naples”.
    -Iceland says hello! 😂

    (Iceland is Europe for me even though it’s half American.)

    • Iceland admittedly was not considered ‘European’ volcanism by me. Too independent minded. But if it is, it indeed wins first prize.

  14. Laacher See was a big eruption, and I think what might have played a big part in it’s eruption was deglaciation and isostasy / rebounding of the surface. There are signals that after deglaciation the number of eruptions rose. Sea levels also change at a time like that, and this will change pressure levels. Like Antarctica will go like full eruption mode / flood basalt if it would lose it’s ice or if the glaciers would melt. Luckily – despite climate change – this is unlikely to occur soon, or we really have to mess up for millennia.

    Laacher See is however a bit overhyped, i think. The fact that it was even considered as a possible cause for the Young Dryas event, is weird given eruptions like that normally occur once a century (and at the time probably more often even). It might be that increased volcanism played a role, but Laacher See definitely wasn’t a sole culprit. It looks to be unlikely as Laacher See’s timing is a few centuries off with the onset of the Younger Dryas.

    There’s an asteroid impact hypothesis but deglaciation and massive freshwater release into the ocean probably did impact ocean circulation a lot, so I think that might be one of many possible causes as well. And they’re continuing to do research regarding the impact hypothesis. Science hasn’t a good answer on that yet. They’re debating the hypothesis, but the crater found in Greenland is not an impact crater related to this time but many millions years older (actually a PETM crater). There was one other closely around but at first glance it looked to be an older crater. Of course we might discover a lot of other stuff beneath the ice.

    • Younger Dryas may have been caused by massive reapeating Ice collapses in the north that sent cold water Into atlantic and cooling the climate in Europe called ”Henrich Events” but Im not soure and not the expert

      For Antartica to go Armageddon You needs a powerful mantle plume, and probaly is not a souch there at current and the Erebus Plume is rather weak. Perhaps needs more mantle tomography on Antartica

      • Right, Jesper. You would need what you like most: An AAMP (Ant-Arctic Magmatic Province). Antarctic Traps. Not for us to see that.
        Even Icelandic Volcanoes, not too bad, have managed to melt down the ice there.

    • Laacher See is not overhyped as the author wrote. Science has taken up some speed recently there which isn’t bad at all as things learnt there might also be applicable in West Italy or also Auvergne. A huge eruption in the Eifel area would involve places like Koblenz, Köln, Maastricht and is not to be taken lightly why monitoring is as important as in Campi F. Auvergne by contrast is more isolated. The most famous product from Auvergne is Cantal Cheese.

      Antarctica as Jesper indicates has only volcanism in the West, basically in the part which can be considered a continuation of the Andes.
      Antarctica is huge and wouldn’t melt from an eruption of say Erebus.

      • Antartica haves the west antartic rift system and the Erebus plume .. and perhaps other plumes

        But There is not a superplume under there or something like Hawaii

        • Perhaps one could form though, given the stationary nature of the Antarctic plate for millions of years and the ice ‘lid’. Magma not being circulated.

      • Let us not forget the Balleny hotspot, which I doubt is truly a hotspot but still a bit of a random gilb of volcanism. And Kerguelen is still potentially active.

        • Given how places that we know for sure are hotspots have huge scale volcanism, most places that are considered hotspots are probably something else. The term was made to explain Hawaii and its location, ans later to explain why Iceland isnt part of the seafloor. But Hawaii and Iceland, and Yellowstone, and Galapagos, every hotspot shares one thing, the magma composition. Magma is tholeiitic basalt with a very high degree of melting, and in most cases also an extremely high rate if melt production and a very high temperature. The only place where a plume is probably responsible and which differs in composition is under Africa, but those plumes are emergent, not yet at their full potential, in the next million years Virunga will probably turn tholeiitic.

          Volcanism elsewhere even if weirdly isolated seems to be different, maybe more driven by deep hydration melting, upper mantle processes rather than core-mantle boundary like major plumes seem to be.

        • There should be no random volcanism. Random volcanoes are just those we don’t yet understand

    • As you say, the impact hypothesis is dead in the water, as we tried to show in the Hiawatha post.

  15. Another example of western European volcanism is the Auvergne, also with maars:

    This is Lac Pavin from wikimedia commons. It is an unusual lake as being meromictic like Lake Kivu and circulating only the upper two thirds of the water whereas Methane, Carbondioxide and a Sulfur combination is retained on the bottom third.

    The same that goes for the West of the Rhine Graben also goes for the West of the Rhône Graben:
    “In contrast, Puy de Dôme was created by a Peléan eruption; this type of eruption is characterized by long dormant periods periodically interrupted by sudden, extremely violent eruptions.[3]
    Future eruptions at the Chaîne des Puys are possible and would result in the formation of new mountains.”
    https://en.wikipedia.org/wiki/Cha%C3%AEne_des_Puys

    • Lac Pavin is also very young, the youngest eruption of the Auvergne, only 6900 years old, erupted together with two other scoria cones in the area. The next oldest eruption is that of La Vache and Lassolas volcanoes 8600 years old. Before La Vache and Lasolass the Chaine des Puys would erupt once or twice every millennium. But it shut down with Lac Pavin for whatever mysterious reason that we do not yet understand.

      • “we do not yet understand” is precious and should lead to awareness.
        I was there once. Beautiful region.

        • I’ve been twice to those volcanoes, very beautiful. I was to the Chaine des Puys, and then the second time to Monts Dore. From that second trip I remember Lac Pavin quite well, I entered the visitors center and the air felt weird, it was impossible to breathe, I got out and it was good, but then after a while I started feeling sick. Never again have I felt something like that. I was thinking about what you were saying, that Lac Pavin is meromictic, but there may not really be any connection.

  16. Is there any well preserved cinder cones in Eifel
    I cannot find any in Google Earth: I guess everything is so overgrown simply by agiculture
    A new cinder cone eruption there coud be very similar to Paricutin, but more fluid since souch comes directly from mantle in monogenetic mafic eruptions

    GVP ”240 scoria cones, maars, and small stratovolcanoes covering an area of about 600 sq km About 230 eruptions have occurred during the past 730,000 years”

    Most of the times Eifel woud have been a freezing dry arctic tundra during the glacials and during the Interglacials it woud been pleasant forests there, the arera was roamed by Megafauna for most of its existence

    • If you want nice cinder cones hop over to Auvergne. The cinder cones in the Eifel area must be the victim of enormous erosional processes. The older volcanic cones were under water when our dear dinosaurs died.
      Erosion: Enemy of Geology.

    • Cinder cones in Europe are often victims of mining. Here in Spain the volcanic field of Campo de Calatrava has seen a great number of its scoria cones mined away, for construction purposes. Not that they were very well preserved either being very old and subjected to degradation for hundreds of thousands or even millions of years.

      The situation in Eifel is probably similar with the cones being mined away as well as being very old. The Chaine of Puys is younger and better preserved.

      If you want to see well preserved cones and tuff rings I suggest you go to Arabia, the harrats of Arabia are huge volcanic fields incredibly well preserved.

      • Arabian cones can be in nice shape for many 10 000 s of thousands of years because of the dry climate

        Arabia was even drier during the Ice Age so flows surivive long there in fine shape

        Althrough sand erosion coud be problematic over time

      • Contrary to Eifel, Calatrava might have peeked out of the water. On every watery map of the past you see the inner part of the Iberian Peninsula and Avalonia peeking out.
        But mining would have added to the process, of course.

        • Well, the rock is limestone in that area. I have a friend who collects a lot of tiny ammonite fossils not too far from where the volcanoes are. However as far as I know the volcanic field is much younger than the limestones.

  17. When I pursue one of my hobbies drawing lines on maps and draw a straight line from Naples to Iceland I will fly right over Snowdon and have Auvergne close to the left (estern) side and Eifel plus Edinburgh close to the right side.
    Probably no meaning to this, but who knows. In case it has a meaning it must have s.th. to do with the African Plate.
    If I go further south I will end up around the Afar Triangle and have Santorini (Thera) close on the Eastern side.
    Just an interesting hobby.

    Everybody is having lunch I guess or taking a tour, not me though (late breakfast). I am sitting in the rain (not singing), temperatures around 10°C, plants four to six weeks late. Everybody sure with Hunga-Tonga? What do you think, Albert or Héctor (Carl seems to be in hibernation)?
    Unusual spring, late, but extremely nice blossoms, more birds than last year. Just noticing.

    • It’s most likely a regional effect.
      The mid-latitudes across the entire NH have been in a rather persistent (meaning repeating) pattern of “zonal flows” for most of this Winter, as dominant High pressure cells generally circle the globe between ~45N down to ~10N (i.e. ITCZ), with periodically higher amplitude blocking over Greenland into the Urals and another block over the NE Pacific.
      The pattern was very stable, as the Polar Vortex (PV) was unusually strong this Winter, and remained constricted around the pole…hence a lower than average precipitation pattern over much of the mid-latitudes resulted.
      There was/is one exception to the rather languid pattern, which is dozens of storm centers, (some very intense), developed east of Asia as cold Asian/Siberian air hit the warm west Pacific waters. Several of these lows migrated far enough northward to set off a “ripple” effect in the jet stream that at times propagated eastward, with several troughs getting amplified just west of North America before pushing eastward over the U.S. then into the north Atlantic where they re-amplified before racing towards Europe.
      But in general, if you happen to live on the ENE side of either of the recurring blocks, then cold, dry air gets advected SSE, and vice versa if you live on the western flank of the block with warmer, juicier air flowing SW-NE.
      A good example is here in northern California, where we are now 3yrs+ into the worst drought on record, and the synoptic pattern has not deviated…which is High Pressure sets up over the western US and shunts/dries out the west-Pacific storms before they can reach the coast.
      I make mention because there really isn’t any appreciable signal that this dominant NH pattern has changed from what it had been, other the typical change(s) associated with the onset of Summer.
      On the other hand, in the southern hemisphere it may be a different story.
      Australia (record flooding in the south, and record drought in the north) were/are experiencing extreme/long lasting weather patterns that “seem” to have origins near the same time as Hunga Tonga….however they were already in a La Nina-driven pattern, and it will take some time (years?) to sort out if this anomalous weather/pattern was a result of purely atmospheric variabilities or if/how much of an impact from Hunga-Tonga there was.

      • Thanks. I’m not complaining, don’t get it wrong, please. We had a basically beautiful winter and a long coldish spring. Exactly like about 30 years ago. If it staid like this, I’d be more than content. Your explanation btw. doesn’t fit to my area close to the Austrian Alps. Our winters are getting colder since 2019. Just one fact to be noticed. And it is a good process for the ones who are older, reminding them of the times when they were young. So, that’s how it is here. About elsewhere I don’t really know enough.
        Your explanation doesn’t cover the Alps. And contrary to California which is more or less in a vertical position the Alps are a horizontal barrier in the middle of Europe with the weather on the northern and the southern side mostly being strikingly different which is useful for us as we sometimes can flee the rain.

        • Thanks for your observations…I find them most informative!
          Most interesting is your comment of a colder regime setting in around 2019…which also (perhaps coincidentally, perhaps not) with the onset of the deep drought we’re seeing here in northern California and the western U.S. in general.
          The Alps are a world all in itself weather wise…but note in the same time frame (2019-present), the area has also seen recent extreme events such as the massive flooding in western Germany/Belgium in 2021.
          To say that drought in California could cause flooding in Germany is not the issue (it can’t)…rather what is the common denominator that’s driving such weirdness on both sides of the NH at the same time?
          In the case of the question of volcanic influences, IMHO there isn’t any (at this time)…with AGW/climate change the most likely (root) culprit for the increasing number (and intensities) of the anomalous patterns that are emerging at various places around the planet.

  18. Looks like we haves a New convecting lava lake at Halema’uma’u: perhaps filling the 2018 s drainout bowl as well at the same time.

    The New lake is still kind of rootless I think
    Its filling the pit 2018 s drainout pit rather than circulating. The magma supply is so very high / large that everything just gets pushed out

    A flank vent probaly needs To be present for these days at Kilaūea to have a circulating lava lake that can tap the magma column, thats why Puu Oos effusion keept the 2007 – 2018 overlook lava lake at Halema’uma’u from overflowing. Now everything gets pushed out without a flank vent

    But the lake that we have now is not overflowing into the caldera floor either as it should perhaps do if everything was pushed out at Halema’uma’u now, so perhaps is circulating and filling the pit at the same time 🙂

    • There is breakouts on the pit floor around the lava lake so its still filling the pit as pressure accumulate under the crust

    • It is an open conduit into the lava below the crust of the lake 🙂

      Whether it is also an open hole from the lake into the deeper magma chamber is unknown and probably will be until it drains back down (or doesnt), but would seem likely given the situation. I think the reason it doesnt overflow is because now it has built up the rim fairly high, so pressure that would cause an overflow would instead cause the lava to erupt at the edge of the lake.

      • So still rootless then .. : ) and No pipeline connected on the submerged floor

        • Well that is what we dont know. In this case though, rootless would mean basically the eruption is driven by pressure holding the vent open, like was the case a year ago. I doubt that is the case, because the eruption has actually stopped a number of times to resume again. It depends on how big you want the vent to be before it counts, but it doesnt have to be a hundreds of meters wide cylinder, a 10 meter wide hole deep below the surface pool underneath the lava lake would still count.

          More than likely there is an open connection between the lake and the magma chamber, possibly there are several drains while the lava is all erupted from the vent that was on the edge of the lake when it all began, and which is now deeply submerged below it underneath the active complex of cones and the visible lava pond.

          Most probably whenever the next major intrusion takes place and the lava can sing back, it will reveal an open hole, inside which will be a violently boiling lake not unlike those which existed on Ambrym. Probably as soon as the flank event is over that open vent will rapidly overflow and flood the collapse again as happened in the 19th century. I would also not rule out high fountaining from a vent exposed like that.
          One thing that could happen is if the lake gets high enough that it can directly intrude into the cracks in the SWRZ from sheer pressure at the bottom (which is already equivalent to being 1 km deep underwater today), it might drain itself without actually affecting the feeder vent. With the pressure removed the vent might erupt like a geyser.

      • It is rootless since its still filling the pit rather than circulating

        • Not sure that is a correlation. Nyiragongo had an open conduit before 2021 that also saw the crater filling in at the same time, it is just like a shield forming except trapped inside a caldera. Here on Kilauea the same thing is happening in a slightly different way.

          The lava lake as a whole is rootless because it doesnt sit within a vent, but there are probably multiple open conduits that feed into it, the eruption began from within the lake before vents opened on the side. If the old Overlook lake ever overflowed and filled in the rest of Halemaumau with lava, that is basically what has happened here except way bigger. It isnt the same as in Kilauea Iki where the lava lake was physically disconnected from the vent.

  19. This article reminds me of the Boring Lava Fields in the Portland Oregon region. We had an advanced sensor and detected deep volcanic stirrings, so I rented a state of the art portable gas chromograph – mass spectrometer and my friend started the field survey work in his truck as the helium levels were 5x normal. We were able to successfully map about 20 or 30 of the 90+ vents and discovered that the largest gas concentration was near TV Hill (see ) We sent the field survey map and recorded readings back to certain people in WA DC and later, we were congratulated for our work, but told that we were about 1 month too late on our initial discovery of the volcanic stirrings. This occurred around 2012 or 2013.
    As to the helium, I could not differentiate between He3 and He4, except that our levels were well above normal ambient, and did correctly correlate with known vent areas.

    So yes, it is important to keep a watch on volcanic areas like the Eifel Fields and the Boring Lava Fields.

  20. Earthquake swarm in Krysuvik, not huge but I dont recall a stand-alone swarm happening here before. Really seems like the next eruption could be just about anywhere.

    • It’s been lively near Krýsuvík before, including during the run up to Geldingadalir.

      • Yes, I remember. But I dont remember seeing it go when it is quiet everywhere else, like now.

        Is it actually completely confirmed that the eruptions in the last Reykjanes cycle were progressive to the west? GVP lists that Krysuvik had eruptions as late as the 1300s based on tephrochronology, more eruptions than the two that are written about. Same for Reykjanes and Svartsengi, and the eruptions further out in the ocean happen more or less a couple times a century with no real cycle. Seems that the western half of the peninsula more or less is active at the same time.

        As I understand it, there is actually very little completely direct literature on these old eruptions, mostly that they were known to have happened at all but location is uncertain.

        • Could be tectonic. There are a couple of earthquakes between Myrdalsjökull and Vatnajökull.

          • They are all tectonic to begin with though, the rift has to open first in places like this and then magma flows in rapidly to fill the gap if it is wide enough. If the rift involves a magma chamber that is where you get the big curtains of fire, otherwise there is a slow eruption.

            Probably nothing imminent but swarms happening now probably means the area is primed to fail, so expect eruptions here too in the coming decade. Probably this area will be the most active part of Iceland for some time.

  21. Great read Gijs thanks! It’s sounds like the German volcanic story isn’t quite over yet! As in similar way to Australia’s last recent volcanic activity in Victoria, South Australia and Queensland.

  22. I have to second Lakigigar, I too feel Laacher See is overhyped.

    Ok – new science has proven that it isn´t fully asleep and rather restless instead. But that is probably true for many old systems if you apply the same new sciences to them. When you compare the Laacher See system with what else is out there in the world, and how much attention (both studies and media attention) the calderas of Central America, Philippines, etc get, for me there is no question the Laacher See system is overhyped.

    I do find the system interesting since it is not just oozing out basalt but could actually do something exciting at some point (not our lifetimes obviously), and there are interesting minerals to be found (my real passion), but that´s it. Yes – Laacher See has potential to threaten lifes – but when put into perspective (Taal, Naples area, Lake Atitlan, etc etc) really it is getting lots of attention. It would be very interesting to know how many comparable systems are lurking below the densely populated areas of say Central America and never got any proper studies!

    • I did enjoy the article though, thanks a lot!! I grew up not too far from Laacher See, roughly 5 hours towards the Alps and swam in the Maar once, a pretty area!

  23. Spain likewise has volcanic fields in the north close to Barcelona, as does Romania further east. Seem unlikely areas until you look at the local tectonics. Spain also has a lot of maars as well as pyroclastic cones – the fields are Garrotxa and Calatrava. Intraplate volcanism is definitely the most intriguing

    • Yes, basically in the Pyrénées, but probably also further south, magmatic phases, esp. in the Perm.

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