Frisian Sûdwalvulkaan coming to life again?


Fig1. Last active between 160 – 145 million years ago, the Zuidwalvulkaan is showing signs of unrest. Its location just off the Dutch coast is a cause for grave concern (

The Sûdwalvulkaan (Zuidwalvulkaan) has been sitting dormant at 2 km under the Waddenzee (Frisian Sea) in the north of the Netherlands for some 150 million years. In 1970, Elf-Petroland discovered the volcano when looking for natural gas in the Waddenzee. While drilling, for which they only received a permit in 1988, they found an anomalous temperature at lower depth and anomalous variations in magnetism. And then they also hit on volcanic rock. The dormant giant’s presence is one of the reasons the north of the Netherlands has natural gas, and just as important, huge salt caverns.

Nowadays, the gas platform ‘Zuidwal’ sits on top of the volcano and extracts gas, which is directly transported via a pipeline to Harlingen for further elaboration. It is one of many locations where gas is found in the Netherlands, as the northern part of the Netherlands has many gas and oil fields. The best known gas field is that of Slochteren in the province of Groningen, which is the largest in Europe. I will come back to that later, because the impact of the gas explorations in that area have had a much deeper impact on the substratum of the area than previously assumed and calculated.

The volcanic edifice is hidden under the sand of the Waddenzee and is found in the Vlieland Basin. In its days, it was a pretty big stratovolcano, measuring about 1000 meters in height. It was formed 160 million years ago, during the Cimmerian Orogony, when the Turkish and Iranian plates slammed into the Eurasian plate while the Cimmerian plate was already subducting under Laurasia, leading to a series of volcanoes to pop up at the other side of the continent, most of which are now hidden mostly under the North Sea floor. The volcano was active during a period of around 12 million years. When the Sûdwal was active, it produced short but fierce and explosive events of trachite-phonolite eruptions [Van Bergen & Sissingh, 2007]. During the Oxfordian, volcanic activity in the Vlieland Basin was coupled to transpressional wrench tectonics which divided the basin in a marine and continental part (Herngreen et al., 1991).

Its activity led to the ascent of gas originating from the Carboniferous layer. That process went on long after the volcano had gone silent. The gas could not further ascend after layers of salt and sandstone  had formed on top of the now dormant volcano. The gas field sits right on top of the ancient giant.

The Sûdwal’s sandstone covering  stems from the early Cretaceous. It was deposited after the Vlieland Basin was ripped apart in the Cimmerian Orogenesis. This sandstone layer serves as the reservoir rock where the gas is harboured. It is being kept in place by a layer of shale that formed on top of it. Other studies of the substratum of the area have concluded that rifting also played a part in the formation of the Sûdwal volcano [Cottençon et al., 1975; Herngreen et al. 1991] An new study by the The Geological Survey of the Netherlands in 2011 revealed many features of the Dutch subsurface hitherto unknown.


Fig 2. Another view of the location of the Zuidwalvulkaan, this time from Google Earth

Recently though, the suspicion that the old Sûdwal giant may be waking up, is growing. There are signs of unrest such as slight earthquakes, reported by ‘wadlopers’ (persons who walk the low-tide mud flats) and altered waterways, as was reported by people on the nearby islands who use the smaller waterways for fishing activities.  Al large part of the Wadden Sea is tide-land and is without water at low tide, but larger and smaller navigable channels remain open for ships. Recently, gas bubbles have been reported by local fishermen who were right on the spot where the Sûdwalvulkaan is located. They also reported a slight sulfurous smell in the area, causing slight nausea and irritation to the eyes.


Fig. 3. Mud-flat hiking on the Wadden Sea. [Source: Wikimedia, under Creative Commons; author Michielvd.]

This, together with the other indications, has led the University of Delft to set up an investigation headed by Professor E. Eisinga. Preliminary temperature measurements in existing boreholes have shown that the soil in the area is slightly warmer since the measurements from 1987 – when the existence of the until then only hypothetical volcano was first established. It then was thought to be extinct, so no further investigations or surveillance had been undertaken since. Unfortunately, existing seismic stations are too far away to adequately register any movements in the area and there are no stations in the area that can give more conclusive measurements. Prof. Eisinga told Omrôp Skylge that a set of seismic stations will be placed on the islands of Flylân (Vlieland), Texel and Skylge (Schiermonnikoog) and his team is also considering stations near Harns (Harlingen) and Wieringermeer.


Fig. 4. The Wadden Sea is ridden with small channels on low tide, which make it a difficult to navigate are. [Image source:]

More in depth studies are planned for the coming months. A bathymetric scan of the underground will have to wait until FUGRO’s ship, the M.V. Fugro Equator, returns from its current mission near Australia, where it is deployed to search for the missing Malaysia Airlines flight MH370. The ships of the M.V. Fugro Supporter class are equipped with a Kongsberg HUGIN 4500 autonomous underwater vehicle, the capabilities of which can be read on the FUGRO’s website. One of the aims of the investigation will be survey of known fault lines and possible changes in them, but also the possibility that new ones are forming due to mining activities, will be explored in depth.


Fig 5. Geomagnetic survey of the Zuidwalvulkaan (From Perrot & van der Poel, 1987)

The recent developments at the Sûdwal follows upon the recent unrest under the population and substratum of the adjacent province of Groningen. The extraction of gas from the Slochteren Field near Groningen, one of the world’s largest natural gas fields, has caused several damaging earthquakes over the last few years. Since 1986, there have been around thousand of them and they were of increasingly stronger magnitudes. At first, the connection between quakes and gas extraction were denied. Studies had never shown them to be a risk. Only much later they had to admit there was a relation. Yet, the magnitudes at which they took place, are still astonishing experts. Some make a cautious prediction that the maximum magnitude might reach a 5.7. Here you can see a visualization as an animation of the induced earthquakes that have taken place over the last odd thirty years. Because they take place pretty much near the surface, they are felt, even at minor magnitude.

Over the years, the amount of extracted gas grew larger and larger, and so did the amount and magnitude or induced quakes. The largest induced quake under the Slochteren field until now, was a 3.7 [according to EMSC] on the 16th of August 2012, which had an Intensity of IV. Over the course of events, many buildings have been damaged and a few even have collapsed. The subsoil under Groningen and adjacent areas, such as Friesland, is very complex and not so much is know about it. Apart from earthquake damage, the soil sunk considerably, around 30 cm until today, which is a lot considering this part of the Netherlands already is beneath sea level. Also, the subsidence is larger than previously assumed and calculated.

Under pressure of the population in the area, and after a reprimand by the Netherlands Institute for Human Rights, the Dutch Government at last gave in and reduced the output. The Dutch state is a 50% partner in the exploits while the NAM, a joint venture of Shell and Exxon-Mobile, owns the rest.

The extraction of gas has now been reduced, but the damage is done. Even so, the chance of a 4+ quake in the nearby region, remains large and the activity set in motion in the area, will not seize, even if the whole gas exploitation would come to a complete standstill today. That the activity in the earth may now be spreading over a larger area, was also unforeseen. The geological institution of the University of Delft fears that an old, relatively unknown fault line may have been reactivated that affects the deeper edifice of the Sûdwalvulkaan.


Fig. 6. Depth map of the base of the Zechstein Group with fault lines – Late Permian. Image Source: Dinoloket

In response to the series of increasingly larger earthquakes under the provinces of Groningen and Friesland, the NAM has lowered the gas output already significantly during the last few months.


Fig 7. Production platform Zuidwal, prospecting for natural gas just next to the volcano, is one of the suspects to have caused instability in the underlying bedrock (image:

Another potential cause for unrest, both underground and above ground, is the mining for salt. In the province of Friesland you can find a salt industry that extracts salt from deep caverns under the Wadden Sea as well as in Delfzijl and Veendam in Groningen. They use vacuum salt technology: you pump water into the domes that lay deep in the underground and pump brine out. Near Harlingen, at around 10 km from the Sûdwalvulkaan, salt is extracted a a depth of around 2800 meters. The company and other parties involved try to sell it off as sustainable, because in the future gas, CO2 or oil can be stored inside the caverns caused by the salt extraction. The company recently received a permit from the Dutch authorities to extend their operation under the Wadden Sea to a larger area. The subsidence that will result, is a ‘calculated risk’, while critics who did their own calculations warn of a much larger subsidence than foreseen in the official reports.

Taken together, the effects of gas and salt extraction may well give similar effects as that of isostatic rebound, which is known to lead to an increase in volcanic activity. Whether or not the recent signs of unrest are true signs of the Zuidwalvulkaan reawakening or merely the effects of man’s exploitation of natural resources will have to await further study, Professor Eisinga concludes.


Fig. 8. Zuidwal Volcano, cross section and depth (Image credits: NITG – TNO; Source: NPO Wetenschap)

Further reading on the Huizinge/Loppersum earthquake:

Further reading on the Zuidwal Volcano:

/Fopke Brandarius

92 thoughts on “Frisian Sûdwalvulkaan coming to life again?

  1. GeoLurking,
    How very appropriate you should review this volcanic edifice at this time. We in northern Europe are rarely made aware by our politicians of the risks we run from natural hazards. Thank you for the reminder. IIRC many years ago this volcanic field was reviewed by a Turkish/French geologist. I am not confident I have his name right, because Google scholar doesnt throw anything up, but it was something like Retep d’Lobboc. His analysis of the likelihood of eruprtion was similar to yours. But it lacked the timeliness of your article.

    • One thing about water. You never know what’s under there. I’ll have to tell my sister there’s a volcano down the coast from her. 🙂 She lives Biloxi, MS area, but has friends in Louisiana.

  2. Fopke, of course, is a female name. Explains the excellent quality of the piece. Hadn’t heard from Eise Eisenga for some time! For some considerable time. He was at the University of Franeker, before ot was closed.

    • Fopke is a intriguing lady, a member of the Fryske Akademy and a nationalist. She actually is the great-grandchild of Eise Eisinga, although related through an illicit child of his. I met her at the Oerol Festival last year where she took part as a performing member of a group of DaDa-inspired artists. She is deeply worried about all the developments around and under the region, especially the subsidence which will result in salt water seeps from under the sea dike around Friesland that keeps the sea out of the low lying land.

      Salt water seeps would render the land inhabitable. It would also mean the end of “kaatsen’, a ball game which is the Frisian national sport, carbide shooting, fiereljeppen (far leaping) and of course, there will never be a skating race around eleven Friesian cities, an Elfstedentocht again. With brackish, water there’s no way that the channels and lakes will ever freeze again. She is furious about “those regents [in The Hague]” who “want to inundate us and make us live on our ‘terpen’ again, surrounded by the sea” because “they have always conquered their enemies by inundating them and it would be the perfect final solution for them to do away those rebellious Frisians and their infamous Frisian Freedom!”

      Her next art project for the Oerol Festival will be the erection of a (working) volcano in the Wadden Sea. Like her great-grandfather she fights false beliefs. Eise Eisinga had to deal with religious zealots who believed the world would be destroyed when all planets would line up, so he built his world famous planetarium to show them how wrong they were. Fopke fights against the Idols of the Marketplace that will destroy the Frisian world, Groningen and the Wadden, so she will build her volcano.

      Eise Eisinga’s Planetarium:

      • Hey, I see Diana’s video is here and where did the one I put there wander off to?

        Oh well, on reload all is fine again. Graboids. That’s all.

        • Dunno, I stuck one on the follow up and then later yanked it since I felt mine was a bit too much. Silliness is only appreciated in moderation.

          … unrelated, but why do I get the impression that Eise Eisinga had roughly the equivalent name as Ice Iceman.

      • beauty against fright stories. It long outlived the scare which it was designed to resolve. As well as its university. You can’t always guess what will last.

  3. An early rumination here & coffee #1 . We here in the UK have had indications of this for a few years. A series of strongish (for the UK) earthquakes have been felt in Britain. Normally very earthquake resistant! , Is it possible they could be due to Dike intrusions similar to those which developed at the beginning of the Bardarbunga eruption?.
    Looking at that diagram of faults It does look like very large dikes occur both northward and southward of the ancient volcanic plug
    I am not an expert but I am wondering if that volcanic plug is actually causing a block on the dike system. Like Bardarbunga, this cooled plug or “lid” is holding it all together and once it is pushed a fraction more upwards then more magma has access to the Nederlands dike system and even beyond into the straits of Dover.
    Maybe Albert or Lurking could comment on my hypothesis. I confess the geology of the area is highly complex and some of the papers I have read are a little too “In depth” for my maths phobic brain.
    For once the Daily Mail has actually picked up on a genuine piece of scientific fact .and has written quite a good article about UK Earthquakes. of course it is alarmist as usual and use that wonderful Non Volcanic word …..”OVERDUE”, but they do have correct information (at time of printing). maybe they have a new Science Editor on board.
    I don’t think though they have correlated the figures for the Dover Straits area and extrapolated them to the wider European Faulting System. Us Brits have always been rather parochial and have historically resisted any input from Europe!!!! 😀
    Here endeth rumination and time for coffee #2 . I leave you with the Daily Mail. I’d be interested to hear other’s comments.

    • Sorry, I’m too put off with the media right now to have given it much thought. An Indian online news site has proven that they have just as much attention to detail as The Grauniad.

      See anything wrong with the picture and the story? That’s a US Arleigh Burke class destroyer. Though superficially, it may resemble a Shivalik-class frigate, I’m pretty sure that India doesn’t want their ship to be mistaken for a US vessel. Our history with Yemen port of calls didn’t turn out so well in the past. There is also a difference in about 2000 tonnes in displacement.

      I addressed the Cole issue during my retirement speech and pretty much killed the festive nature of the event. (well, it was my retirement ceremony, and my choice, I felt that the crew could use the good wishes from fellow sailors while they were in extremis trying to save their ship.)

      BTW, many thanks to the crew of the HMS Marlborough who came to render aid. I never heard about that from the media, so consider this as a thank you from a US sailor of that era. (I was not in theater at the time, but I’ve been through there several times)

      • My cousin (another Sailor in the family ) was on the Cole when it got hit. She was at her duty station when the Bad Men attacked.she decided not to go to chow, but was working on some intel at her station. That saved her life. She’s about to get out as a Senior Chief.

        • Smart move. I probably could have made that had I stuck around for another hitch, but I was so fed up with idiots that I needed to either get out or I was going to wind up clocking one of them. I did manage to expose my principle antagonist for the fool that he was to the command, achieving some retribution. (a word of warning to all the second tour lieutenants out there, be sane. There will probably be a CPO out there that will call you on your idiocy, and has the temerity to do so.)

    • ‘Daily mail .. genuine — good article..correct’ I must be dreaming. Oh – April 1st. I believe that the UK independence party has a policy to block all migration of magma to the UK. Magma that has already migrated will be returned. The treasury has wanrned about the dangers of inflation caused by the migration.

  4. Haha,funny. The volcano is there, but there is no Eisinga at TU Delft, and the name “Fopke” is real, but contains the word “fop” which comes from the verb ‘foppen’, which means to trick or to hoax. April foolsday joke – well done though!

  5. Nice article. It must have been quite difficult to avoid the term “overdue”.

    Still it would be interesting to see what would happen if it did start to reawaken.

  6. I think that the Slochteren natural gas field is becoming a caldera which will be filled with seawater. If the Zuidwalvolcano would erupt, the magma would have to break through the thick layers of wet sediment above the volcano. This sediment will impede the magma rising to the surface. Magma will find an other way and will form sills and laccoliths in the subsoil there.

    A volcanic eruption in the Eifel region is much more probable due to the mantle plume of hot magma below the Eifel rather than any eruption of the Zuidwal volcano.

    Here is a documentary about how it would be when a volcano in the Eifel region erupts. “Was wäre wenn – Vulkanausbruch in Deutschland” at

  7. Thank you for your detailed analysis, GL. Is there any danger of this hidden volcano disturbing the recently discovered Swedish super-caldera that’s ready to blow? After all, there could be an awful lot of jokulls between the two places…..

  8. I think there might be some good in this – if the volcano is re-awakening then there will probably be years, even hundreds of years, before it erupts. Meanwhile there will be substantial uplift as magma moves in which will raise the level of the Netherlands – a notoriously low-lying country. Soon tourists will be visiting the Mountains of Holland. If the uplift is as much as I think it will be, then the North Sea will disappear and Britain will once again join the European mainland. This will enable many Brits to travel to Europe without getting seasick or having to go through a tunnel.

  9. Is there a mud volcano in the offing? 😉 Heated water in the sedimentary layer causing mud to bubble up.

  10. I felt I ought to end the day on a happy musical note. “Tulips from Amsterdam” is dedicated to all our wonderful friends in the Nederlands. Remembering always our close political relationship with the invasion of William of Orange and Mary his wife. They were popular monarchs and brought peace to our Islands. Let us hope that the Dutch Volcano will stay quiet and peaceful also.
    So here is a special rendition of this lovely, flowery song in true Volcanocafe style.

    • Retracted my vid link. Diana’s vid link is sufficiently “out there” 😀

      All I can really observe is that Tulip mania of the 1600’s is probably our first example of how an economic bubble progresses.

      “At the peak of tulip mania, in March 1637, some single tulip bulbs sold for more than 10 times the annual income of a skilled craftsman.”

      My personal opinion is that the cash outlays from the dot com bubble migrated over into the mortage back security market and drove that to it’s peak and bursting.

      • Good evening Lurking 😀 I can see you now in your yard dancing merrily to that tune. Sweeping Mrs Lurking off her feet again . Just do mind her bad foot though 😀

      • That ain’t happening. Grand kid just left after picking up the “tooth monster” for his vet visit. He checked out fine other than having an allergy or something. I was actually more concerned for the grand kid since he was hobbling around. Seems he had stepped on a nail… again. I swear that kid needs to get better shoes or pay closer attention to where he steps. I’ve done the nail thing and it ain’t no fun. His tetnus shot is up to date since his last nail stomping was less than a year ago.

        • Yup! Rusty nails are dangerous. been there done that too 😀 Now back to the flower power thing…..and bulbs but this time English and Welsh Daffodils that hit the cut flower stands in our supermarkets back in February this year.
          We have problems with assorted immigrants both legal and illegal who are not conversant with our British passion for gardening. This is NOT an April 1st was a genuine news item.

        • That may be related to what “tooth monster’s” problems are. Dogs have a tendency to self medicate on grass shoots when they have an upset stomach. Fortunately, he is in good health according to the vet.

          Many Many years ago, I was puzzled by the little lumps of spinach that were appearing all around the yard. Turned out it was the Dobermans that we had at the time.

    • Family joke bout that part of Missouri-called “Lapland-where Missouri Laps over into Arkansas..”
      Don’t like quakes and sedimentary deposits..

    • Yeah, that “bootheel” was directly caused by the 1811 series of quakes. A guy bought up all the distressed land on the cheap and when Missouri applied for statehood, he petitioned to be part of it.

  11. It’s 7:10 UTC time. Looks like quite a bit of steam coming up on Mila 1. Down below on the left of Valdala. Could be lava still moving through lava tubes? ❓

  12. On the Mila 2 cam it looks as though someone is actually walking out over the lava field. I tried to take a screen shot but it’s not pasting here (work computer!)

  13. There’s a lunar eclipse April 4. In the U.S. the western half will see a total eclipse and the eastern half will see a partial eclipse. In North America it begins in the morning of April 4. Here’s the Info from below:

    Be sure you know the right date and time of the eclipse. For example, the eclipse of April 4, 2015 – which will be visible over North America, the Pacific, east Asia, Australia and New Zealand – begins at 10:16 UTC. For us in North America, that is 5:16 a.m. CDT on April 4, 2014. So if you’re in North America, and you hear “April 4″ and plan to watch that evening … you’ll miss the eclipse.

    Meanwhile, this same eclipse is visible in the evening for Eastern Asia, Indonesia, New Zealand and Australia.

    So be careful. Watch the times. Note that the times are often given in what is called Universal Time, or UTC. Here’s how to translate Universal Time to your local time zone.

  14. Looks to be some action around the Holurhaun crater around 16:50z, I think a little more than just steam.
    With above freezing temps forecast for the next few days things may become “interesting”

    • At 7:10 this morning I mentioned I saw a lot of steam below Valdala too on Mila 1. I just checked and it’s still doing it. I’m very curious as to what’s happening on Mila 2 & 1.

      • It will take a long time to cool down. Years, possibly. As long as water gets in, steam will come out. It lasted for decades in the Valley of Ten Thousand Smokes but that was a bigger eruption.

  15. Friday 03.04.2015 05:29:21 64.596 -17.173 21.5 km 2.7 99.0 17.6 km ESE of Bárðarbunga

    New movement?

  16. With earthquakes having decreased dramatically IMO are probably keeping there eyes out should more happen. Personally though I think Iceland has gone quiet. The earthquake cycles go up and down though. Thirty eq’s a day is rather low.

      • That’s a fact. Here he does his Neil Peart emulation on Tom Sawyer.

        And on the guitar side of things, a 14 year old girl does her Eddie van Halen imitation on Eruption… and a 7 year old girl does the guitar part for Sweet Child of Mine by G&R. When her fingers get longer, she is gonna be quite adept.

        True to form, here she is at 10 playing a Steve Vai lick.

        And, Ozzy actually appeared on stage with Japanese prodigy Yuto Miyazawa on guitar for Crazy Train.

  17. Hi all! Thank you Fopke for this nice and revealing article! I nearly was fopped, but then, living in Germany and knowing all about our branch of Frisians (I’ve heard the East Frisians were the prototype of homo stultus, but that may just be a rumour) I was somewhat reluctant to believe and see a volcano erupting in the North Sea… 😀

    I actually wanted to let webcam watching people know that I have put up an Alaska page to my webcam collection. This should be almost the completion of it, I don’t want to let it get much bigger in regard of pages. It will now only be add and/or remove, so it doesn’t take all day to go through them.
    (If your browser doesn’t show the new page, press Ctrl+F5 to refresh avoiding loading of the cached “overdue.html”)

  18. Major bummer!

    “Rusty” a point of contact that used to handle IT in the adjacent county and whom I’ve had contact with several times over the year, passed away yesterday. It’s a really bad day for it, I spent the day watching grandkids rummage around for eggs and what nots and chatted with many members of my extended family. I really feel for Rusty’s wife and kids… and since I spent the day driving, I was a bit alarmed that he was two years younger than I and seemingly, was in better health. Quite active, and not lugging around the extra weight that I do. The fact that I have had two strokes in the last year or so kind of makes you think about your mortality. Add to that the additional fact that one of my co-workers expired just a few months ago (also the same age category) and just as suddenly, and the hair on the back of your neck starts tickling.

    RIP Rusty.

    • Sorry to hear that. I always get a jolt when someone younger dies – and I aim to take up yoga, or diet or do more exercise. It never quite works out and I carry on until the next reminder of my mortality.

    • Aw I’m sorry to hear that. My heart goes out to his wife and kids. I wish you good health as well. It’s times like this that you appreciate those you care about.

  19. Sorry to learn of your news, GL. Just keep on trucking. None of us know when it’s our turn so just get on living and enjoying. R.I.P Rusty.

      • Listening to Beethoven while watching the sun set over the sea has to be a wonderful way to go – if any of us gets a choice. They don’t make films like Soylent Green any more, do they?

      • Nah, we are too busy trying to live out most of the dystopian scenarios presented in movies all at the same time.

        On a somewhat humorous note, what does it say about Maynard James Keenan when the natural choice to render your lyrics is the vocal register of a young girl.

  20. For all.

    I have received two guest posts and am in the process of prepping them for publication. Which one I publish first I am leaving up to you. One is on Bardabunga, the other is on Kerguelen. Let me know in the responses to this post which you would like first.

    Bardabunga, we all are somewhat familiar with, Kerguelen is the above water manifestation of the Kerguelen Plateau and one of the more often overlooked systems when people go spelunking on the web for Volcano information.

  21. Pingback: Friese Sûdwalvulkaan – Nederlandse vulkaan wordt wakker? | Barnhard Blog

  22. Pingback: Dutch Volcano coming to life again? | Geographical news

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