The forgotten volcanoes of Libya

The Oasis Caldera of Waw an Namus, not a tourist friendly volcano.

The Oasis Caldera of Waw an Namus, not a tourist friendly volcano.

In my last article I wrote about the Turkana, volcanism that is part of the Great African Rift. But unbeknownst to most this is just one of several rift systems in Africa that are tearing the continent apart.

The regional setting with the Ti Besti line transecting Northern Africa.

The regional setting with the Ti Besti line transecting Northern Africa.

In this article we will be making an initial contact with an even larger, younger and far less understood rift system that over time will spell the end of what we know and understand today to be the African continent.

This rift system is so large that we will have to walk through it country by country, but in the end we will see how it is connecting well known large volcanic features at the very outer ends of this huge continent creating the largest continuous volcanic system on earth if you do not count the Mid Atlantic Rift.

Now, how big is big? Well, without going into detail the volcanic rift system starts at Etna and Pantelleria in the north and goes all the way down to the Cameroon Volcanic Line and from the Red Sea in the East all across Northern Africa well past Chad to the West edges of the continent.

As at pretty much every other large rift system it is where two different rifts intersect you get the largest scale volcanism, or were the rift volcanism is affected by a mantleplume. In Libya there is one major triple-junction were the main north to south rift transects a local East to West rift.

The "local" volcanic rift that continues out into the Red Sea. 1. Al Haruj, 2. Jifarah, 3. Jabal al Sawda, 4. Jabal Nuqay. Waw an Namus is directly south of Al Haruj.

The “local” volcanic rift that continues out into the Red Sea. 1. Al Haruj, 2. Jifarah, 3. Jabal al Sawda, 4. Jabal Nuqay. Waw an Namus is directly south of Al Haruj.

But before we start I feel an urge to talk about Wikipedia and not always trusting what it says. Many years ago I walked through Sahara from West to East, and part of my trek went through Libya, and one of my pit stops was at the Waw an Namus oasis that is inside the caldera of the same name. It is by all means one of the most remote places on earth. Back then Qaddafi kept some sort of order in the area, but today it is one of the most dangerous parts of the world. It is suicide to go there. Still Wikipedia states that it is an increasingly popular tourist attraction; I would take that statement with a pinch of salt the size of a mountain.

Local rift volcanism

From the border towards Tunisia there is a Northwest to Southeast trending rift that runs all the way through Egypt into the Red Sea. It follows the same trajectory as the far larger Ti Besti rift that cuts all of North Africa in half.

This local Jifarah-Jabal Nuqay volcanic rift system consists of 4 volcanic centers, from NW to SE these are Jifarah, Jabal as Sawda, Jabal al Haruj and Jabal Nuqay. This local rift transects the major North to South rift at Jabal al Haruj creating a triple junction volcano of prodigious size.

Al Haruj Al Abiyad

Detail from a volcanic fissure line of the Laki type at Al Haruj.

Detail from a volcanic fissure line of the Laki type at Al Haruj.

Libya has two Holocene volcanoes, one of which is on the local rift. It is the 45 000 square kilometer Al Haruj Al Abiyad flood basalt center. During the last 6 million years it has erupted in an extended series of rifting fissure eruptions with an average length of 60 kilometers per rift event.

The average size of eruptions is roughly twice that of the far more famous Lakí eruption giving an average of 30 cubic kilometers per eruption. Since Al Haruj has been active in the Holocene this makes it likely that the last eruption rivaled the Thjorhsahraun commonly thought of as the largest Holocene flood basalt, but both size and exact age is badly constrained for this eruption and we are not likely to receive good data for the foreseeable future due to regional instability.

Large vent from Al Haruj with a sand lake.

Large vent from Al Haruj with a sand lake.

The volcanic complex is littered with more than 150 visible cones, dozens of shield volcanoes, rootless lava flows and pit craters and the eruptive styles are similar to the Icelandic large rift eruptions, but with the exception that there is no magma/water or lava/water interaction here leaving the lava highly pristine.

The lavas are mainly alkaline basalts or alkali hawaiinites with a high degree of fluidity. Recent petrochemical analysis gives at hand that there are marked similarities with lavas from Pantelleria and Etna.

Unlike the other 3 volcanic centers on this line Al Haruj is still active and is likely to erupt again over time, but there is insufficient data about average time between eruptions and there is no equipment in the region that monitors the volcano (with the possible exception of oil companies), so we are unlikely to know when an eruption would occur until lava breaches to the surface.

Waw an Namus

Detail of the Waw an Namus oasis inside the caldera. Image by Rolfcosar.

Detail of the Waw an Namus oasis inside the caldera. Image by Rolfcosar.

To the south of Al Haruj we find the subsidence caldera of Waw an Namus, it is 4 kilometer wide gently sloping caldera that features a central tephra cone of Holocene age and no less than 3 alkali/saline lakes with a high sulphuric content.

The oasis has been used by the caravans going into Central Africa for a very long time and it is a very interesting place to visit, especially if you have been walking through the vastness of the Libyan desert for a couple of weeks.

The oasis is aptly named since Waw an Namus means the Oasis of Mosquito’s, so any visitor needs to go heavy on the chloro-quinine as a countermeasure against getting malaria. Climbing the tephra cone is hard going, but generally well worth the effort. The view is quite stunning and I slept one night on the crater rim watching the stars.

The caldera formed as a large shallow magma reservoir was emptied out about 200 000 years ago in an eruption that created large scale lava flows around the volcano. The young tephra cone was created as alkaline basalts interacted with water inside the caldera and the local region is covered in tephra that is quite visible from space.

The tephra is young, but there is no exact dating. If it had been old it would have been covered by the frequent sand storms in the region.

As volcanoes go, this is about as far away you can come from the beaten track. There are no roads leading here except for the caravan tracks, or if you are walking the traverse desert route that I did. The only good way to go visit would be via helicopter, but the political instability in the region makes this about as hazardous as walking. This is definitely not a tourist attraction volcano.

Conclusion

This article was just a start to what is to come. Next time I will meander off into the far more fertile volcanism of Chad and the Ti Besti rift. What I find so interesting with the volcanism here is that it is so badly studied and poorly understood, even though it may in all fairness be the world’s largest volcanic system.

This series of articles is in part a call for more studies and it is also very hard to write since there is so little material to be had.

CARL REHNBERG

Map images above from: “Plio/Pleistocene Flood Basalt Related Scoria and Spatter Cones, Rootless Lava Flows, and Pit Craters, Al Haruj Al Abiyad, Libya” by Németh et al.

Additional sources: “Miocene to recent alkaline volcanism between Al Haruj and Waw an Namous (southern Libya)” by Bardintzeff et al.; “Multiphase Alkaline Basalts of Central Al-Haruj Al-Abyad of Libya: Petrological and Geochemical Aspects” by Abdel-Karim et al.

102 thoughts on “The forgotten volcanoes of Libya

  1. I like this series of places not well known, it reminds me of black swans being something we don’t expect, or looking for.

    • Well, that is an important aspect of swans. You don’t typically see em coming.

      • In Australia it would be the white swans you don’t expect and the black ones are everywhere. Why can’t swans do colour?

        • In a couple of hundred years all swans will be black. Here about 10 percent are black now.

  2. Nice article Carl, wikipedia has some good stuff (including the ability to fix it when you spot something wrong – which I’ve done), I wonder if the references from this section of a wikipedia article https://en.wikipedia.org/wiki/Tibesti_Mountains#Geology are any interest. There is at least one Oppenheimer there. But I don’t know if the Tibesti Mountains fall along the rift line you mention.

    • I think it has to do with the entire Libya being under an embargo. For the first time in my life I found a thesis that was restricted due to UN Embargo.

    • Actually, it has nothing to do with anything remotely political. None of the volcanoes in Libya are currently considered to be Holocene, largely because the only dates available are significantly older. Earlier this year GVP started publishing Pleistocene volcano profile pages, but that expansion has not yet been integrated into the search system, for various reasons. It’s easy to complain and speculate here, but a friendly email to GVP will often get you an explanation.

      • I would like to point out that there are references to holocene eruptions at both Al Haruj and Waw an Namus, but as I noted above the datings are not as exact as I would like.

        And thank you for clearing up the part about GVP.

        • Waw an Namus “last 2000 years”. And Al Haruj “Holocene”.
          As I wrote the eruptions are badly constrained.

          Only thing I can say is that Waw an Namus is recent. The tephra layer is still very marked and fresh and has hardly been altered at all by the ever blowing sand. When I visited I reacted to it even though I was not as huge a volcanoholic as I am today.

      • Does it have to be friendly? Vitriolic correspondence can be entertaining. (and embarrassing)

        • In my part of the world we tend to 99.9 percent of the time do the friendly and polite thing.
          The rest of the time we get bad mead from monks, grab our axes, get into the boat, whack said monks and force them to write a letter about what happens when we are unsatisfied mead customers.

          “In this year fierce, foreboding omens came over the land of the Northumbrians, and the wretched people shook; there were excessive whirlwinds, lightning, and fiery dragons were seen flying in the sky. These signs were followed by great famine, and a little after those, that same year on 6th ides of January, the ravaging of wretched heathen people destroyed God’s church at Lindisfarne.
          Never before has such terror appeared in Britain as we have now suffered from a pagan race … The heathens poured out the blood of saints around the altar, and trampled on the bodies of saints in the temple of God, like dung in the streets. God beware us of the wrath of the Northmen.”

          The mead must have been horrendous indeed since we did not stop until we had secured the whisky in Scotland in 1066.

          • Is this from the year 565AD? The aerial bombardment that brought about the literally dark ages has only been half investigated via tree rings in preserved bog oaks in Ireland and Wales

          • No, this is from the first recorded Viking attack as we raided to cloister at Lyndisfarne in 793AD.
            “God beware us of the wrath of the Northmen”, may be the best PR slogan ever… 🙂

  3. Regarding the Al Haruj Al Abiyad eruptions: For rift eruptions it can be difficult to know what constituted a single eruption. Even Laki consisted of a series of separate events within the same eruption. Come back in a million year and you not easily see how often it erupted and measure the size of individual events. The number of 30km3 for one eruption may be correct, but it could also combine separate eruptions. Another way to look at the size is by giving the average rate in km3/yr. On that scale, how would it compare to Lurking’s dead zone?

    • It is a bit hard to say exactly what the eruptive rates have been, if we calculate it over six million years it was 0,0025km3 per year. But, the bulk of it was erupted 1.2 to 0.2 million years ago giving a peak rate of 0.01km3.

      A fissure eruption per definition is an eruption of a fissure, so assigning separate parts of a co-erupting fissure-line as separate eruptions does not really ad anything to the picture. Instead it would make the picture far muddier.

        • Muddy rift? Lakagígar. “Rootless cones” all around the magma field.

          → Ground water boiling up through the overlying magma in a festival of phreatic activity as the marshes and rivers were covered.

  4. From HVO
    Tiltmeters at Kīlauea’s summit are recording deflationary tilt. The lava lake is estimated, from webcam images, to be 5-8 m (16-26 ft) below the rim of the Overlook Vent this morning. Yesterday lava lake levels rose high enough to create small flow lobes, both east and west, onto Halemaʻumaʻu’s floor.

    mac

  5. A small earthquake in Antarctica. That is a rarity. It looks fairly close to Deception island

    • I think it is Lurking and his technological skew. There are probably quite a lot of those that are not noticed due to the lack of equipment.
      (I know you know this, but I wanted to mention it for the casual passer by)

  6. Could one of these volcanoes be responsible for the fabeled “missing” eruption? They lie at or near the equator, all are sufficiently isolated, & the Sahara is infamous in its ability to bury things very quickly.

    • Which missing eruption are you talking about? The early 1800’s one? There are quite a few that are worth knowing about or learning about.

      If we’re talking about that eruption, I would think we would see more deposits and it would be easier to spot. I think you’re a bit mistaken, deserts are actually very good at preserving volcanic products and past eruptions. In a desert environment, there isn’t much biological activity causing erosion (roots, lichens, biomass covering deposits), the lack of water means there isn’t much erosion, and the only real thing that would cover a past eruption would be sand-drifts.

    • Not any of the volcanoes in Libya no. At least not any of the recent unknowns. Could be that an unknown one around 10 000 years or older could be Al Haruj, but that is about it.

      I wanted to slightly correct CBUS a bit. The deep Sahara rarely destroys things as you say, but it frequently hides things and is ever changing. You can have something fairly new that has disappeared under a hecatomb of sand and something very old close by that looks all pristine after having been buried for tens of milleniums.
      But, a good bet is that if you have fine tephra looking pristine it is fairly new since otherways it would have been intermixed with sand or blown away in the persistent winds going east to west.
      Sahara is not nearly as sandy as people believe since most of it is rock dessert, but there is enough sand there to make it’s mark (normally in the underwear).

      • Thanks Carl/CBUS for the feedback.

        It WAS the early-1800’s ‘missing’ eruption that I was referring to and I was specifically thinking about the Sphinx when I talked about the burying Sahara – as I recall, very little of it was “above ground” as late as the late-1800’s/early-1900’s. It had to be dug out from beneath almost 30 meters of sand, I believe.

        The dune basin/sea east of Qatrun and south of Murzuq [Libya] could easily hide a moderately-sized mafic eruption: the region covers over 70.5k km2. If there was a very gassy eruption in there, the prevailing Westerlies would quickly relocate those gasses into and over the Caribbean/South/Central America as well as northeasterly into and over Greenland/Iceland/Great Britain [think: Any Atlantic hurricane track originating from the Cape Verde’s and/or any of the winter ‘Nor’Easters’ that wreak havoc across America’s New England and the Canadian Atlantic Provinces every year take this very same path] and then the Sahara could have buried the local evidence immediately post-eruption. And, the area does lie along the Ti Besti Line.

        Granted, this is admittedly rather unlikely, but like we stated earlier, the region was sparsely populated at the time, was and remains very isolated, and has not been studied or explored well in modern times. There just are not many places on Earth that 1) this can be said about during the early 1800’s, 2) it is still not well studied/explored, AND 3) could still produce the observations then and signatures that are present now.

        The only other place like this that I can think of is the Windward Arc of the Southern Caribbean [a ‘Kick-em Jenny’ like volcano] due to the very same prevailing westerlies/Nor’Easters with the Atlantic quickly reclaiming any remains of the volcano above sea level: but the region was not nearly as isolated and was much more populated then and is well studied now – ongoing, even.

        It is just a theory. And an easy one to test and/or disprove…. I just don’t know how. 🙂

    • Africa is as interesting as the Philippines/Indonesia and the Andes to central America region. It is just that we are missing out on all the fun since so many of the volcanoes are in regions that are hard to get to, or just bloody deadly to visit.

  7. One thing I’ve noticed about Mauna Loa–the upper NW flank earthquakes have really ramped up in the past two weeks. This is one area that woke up about two years before the 1975 and 1984 eruptions. I had the next eruption pegged for 2019, I may have to revise slightly…winter 2018-19 🙂

      • I was looking at
        http://hvo.wr.usgs.gov/maunaloa/current/monitoringdata.php
        and comparing to the epicenters on the short-term plot.
        Then in the context of:
        …In August 1974 a swarm of earthquakes occurred northwest of Mokuʻāweoweo, centered at intermediate depths of 5 to 8 km. In December 1974, a shallower earthquake swarm (depths less than 5 km) occurred beneath Mauna Loa’s summit. In February 1975, after a brief lull in seismicity, the intermediate source region that had been the center of activity in August became active again, and the numbers of earthquakes steadily rose until an eruption began on July 5, 1975.

        Mauna Loa was quiet for 3 years following the July 1975 eruption. Then in 1978, regional seismic activity resumed, with rates of seismicity at both shallow and intermediate depths gradually increasing in areas that were seismically active before the 1975 eruption. Seismicity rates ratcheted up in 1981 and then increased again in 1983. Shallow earthquake activity dramatically increased beneath the summit caldera in March 1984, three weeks before the eruption started on March 25…

        I’m not struck by the intensity, more by the amount and location.

    • There has also been steam from the flank all night and morning (still ongoing).

  8. Does anyone know a link to conductivity measurements from Katla? The only ones I can find show flow and depth, but not conductivity.

    • Not to hand, but you can find them on IMO’s website. Go to the Home page and choose Hydrology from the blue bar. If you know which river you want, you can find it in the drop down menu, otherwise select any river and then check the left hand bar for Myrdalsjokull; you’ll find the relevant rivers there. Only some rivers have conductivity measurements.

    • You may have to log in to get to the data. There is a hack for it that I have forgotten, but someone else will remember it.

  9. And the 2017 Nobel Price in Physics leaked today. It is the first time it has leaked who will be laureates this far in advance.
    The Nobel Price in Physics 2017 will go jointly to the physicist Doctor Brian May and the astrophysicist Doctor James Hetfield for the joint discovery of the Supertwang that merges stringtheory with the 11-dimensional Boose-Marshall super-symmetrical Stack.
    The new Hetfield-May effect is believed to have an audible impact on the visible spectrum laser industry. The original paper was published in The Vibe Scientific Journal.

    • The 2017 Nobel prize for Physics will be for the discovery of gravitational waves. But I didn’t know May’s music was loud enough to make the Universe shake!

      • It is the force of the supertwang 🙂

        One of these days I will get around to reading Hetfield and Mays dissertations, as you know they are actually holders of the titles I listed above.

    • Can’t rule it out. Many of us have been misquoted or taken out of context somewhere on the Web since the cafe started. I tend to only discuss the more alarming potential events in an alternate channel since I don’t want to be cited as proof of an impending disaster for a doom monger. Can stuff get ultra nasty? Usually yes, but not because I said it’s possible.

    • Yes, there is one guy who reads the café and then take everything out of proportion and make a hash out of it.
      It is the umpteenth time he does it. But this time it really shines through since this is a first that a Volcano-site has done an attempt to explain Africa and it’s volcanism for the general population.

      • Btw, thanks for pointing out a rift line that I was unaware of. It’s gonna make go back and look at triple junction orientations just to get my head around it. It also helps explain some of the seismic. Noisiness just south of of Spain… and three “large caldera” systems near there.

        • I am not sure that hubbub in the waters south of Spain was related to this particular rift, but there is a rift there that is an extension of sorts from the Atlas range.
          I will though soon come with a list of large ass calderas for you.

        • The one I refer to came from a paper loming at why one of them was well mineralized and te other two were not. The final verdict was water percolating through the caldera concentrating ore at economically viable levels.

          • I was pondering to put in mineralizations in the next article. I think I will have to since you brought it up.

  10. Be it noted:

    Tomorrow is October the 20th.

    With the exception of some minor activity – and a couple of decent bangs – in June/July – Sakurajima stopped erupting on May 20th.

    This is the longest silence I can ever recall. I’d be interested to know thoughts on this – or any grapevine vibes as to what JMA et. al. think is happening.

    • JMA is always good at saying very little.
      I think we should try to get our own grasp on it Mike.
      Do you have links for seismos and gpses for Sakurajima and the caldera at large?
      If so I think we could do our own ponderifications upon it.

      Generally speaking I do not like when the security valve that was previously open (on a caldera that still kept on inflating) suddenly shuts. It could over time create pressure increases that could be detrimental.
      And for the easily excitable, I do not say the caldera would go boom. I am just pointing out that the next eruption of Sakurajima could be a bit larger if this continues for a prolonged time.

      • Thanks for another interesting Africa post. So finally, Africa our original home breaks in pieces!! How come it held together for so long?
        And now again, Katla is heard slowly boiling with GPS tracks indicating inflation for the last week or so.

        • Why it held together for so long? Well, that is a very good question indeed. One that I do not think there is a very good answer for.

          In regards of Katla, it is more that ENTA and AUST deflated a bit before returning to regular values for the season. Remember that those two station can move a lot over the year.
          The reason for the rapid deflation was settlement after the jökulhlaups and now it is adjusting itself back.

          • OK. I understand, not alarming with Katla. Still a little more activity compared to the last few years:

            http://hraun.vedur.is/ja/Katla/katla_qu.html

            Also, Africa has been considered as a relatively safe haven in which our species had time to evolve with enough but not too much of natural disasters. Early ancestors migrated out from there at several occasions but were wiped out. Now with your posts we learn that there are and were much more of dramatic geological activity also in Africa. Looking forward to more!

          • Not only was Africa unbreakable, it also did not move. For the past 30 million year it has been the one (almost) stationary continent on Earth. The main damage it suffered was losing bits on the east: Madagascar and India

          • Africa actually moves a tad, I will get back to that in the next part. And the effects it has had on my latest little area of foray.

    • Did the eruptions taper off before the cessation? Or did it suddenly stop?

      • Probably more of a sudden stop with a few puffs mixed in.

        If you remember around a year ago (I can’t remember specifically), there was a strong seismic swarm that prompted JMA to raise the alert level. This had convinced them that there was a strong possibility of a large 1913 style eruption oncoming at Sakura Jima, but the seismicity died down.

        But ever since then, the eruptive pattern has changed significantly. At first, there were very few eruptions that were far-spaced out. More recently, it seems the eruptive activity has entirely ground to a halt.

        Considering we went from a phase of very high activity into a phase of little to no activity following the seismic event, it is pretty clear that the seismic event changed something in the system. I think determining what and how the system changed can be potentially important in the future here, but I will personally say that blocking the Showa crater that had been previously erupting is probably not a good thing. If it’s true that the crater is blocked, then this will allow more pressure to build, and will also force magma to find new pathways to erupt from.

        The Showa crater has been a pretty good place for eruptions to occur with all things considered. It’s far away from Kagoshima bay at a higher altitude, erupts in a direction that generally does not face highly populated areas, and is in a pretty stable part of the edifice. I would worry if a new eruptive vent were to form, it could open up the system not only to an explosive eruption, but an increased likelihood of phreatic sequences due to the nature of Kagoshima Bay. Phreatic eruptions and effects really are the last thing you want to see here.

      • A bit of both: here’s the VAAC data in easily-readable form:

        https://www.volcanodiscovery.com/sakurajima/explosions/table.html

        I see a decline in activity through March – and a sharper decline through May. Then only a brief period of activity in June. So not a completely sudden stop.

        And it’s all quite different from a couple of years ago say – when we would see multiple eruptions daily (although of course the weaker eruptions probably didn’t register on VAAC).

  11. this http://www.nature.com/articles/ncomms13192 looked a bit interesting – A pulse of mid-Pleistocene rift volcanism in Ethiopia at the dawn of modern humans.

    the bit that caught my eye was
    At both Aluto and Corbetti the youngest post-caldera eruptions have taken place within the last 100–1,000 a (years), underscoring that these remain active volcanic complexes

    especially given that gvp has large population within close range to corbetti http://volcano.si.edu/volcano.cfm?vn=221290 (I can’t find the alutu volcano on gvp)

  12. Yesterday there was a M1 quake at 16km deep in Katla. This means magma is at move also deep under the volcano. It has been increasing over time, but not yet at alarming rates.

    I would expect perhaps deep earthquakes swarms in Katla a week or two before it erupts. So far it never happened.

    Also of remark is the almost daily earthquakes at Hekla, over the past few months. Sometimes shallow, sometimes at different depths up to 10km deep. Still relatively shallow… as quakes in the eastern part of SISZ often reach this depth.

    • huh…

      I was fully ready to jump in feet first and say clouds… now I am not so sure!!

      I have sent the video to our friends at ACANVOL (Asociación Canaria de Volcanología) and let’s see what they say!

      • If it is fumaroles just wonder if this is all to do with the recent swarm of earthquakes in Teide and in the Atlantic Ocean near to Tenerife..

      • Might it be condensing cloud from the warm crater? I gather it is still pretty warm inside the cone, so a cold wind over the top might get light condensing cloud? A thought. Would be exciting if there is an increase in heat though… time for another holiday to Tenerife!

  13. a reply from Acanvol!

    “Son fumarolas, suelen haber en un volcán activo como es el Teide, lo que no es normal que se vean tan claras, podría ser debido a las inclemencias del tiempo.”

    “they are Fumaroles, there are often in an active volcano as it is the teide, what’s not normal to be so clear, it could be due to inclement weather.”

    • Grrr, damn wordpress comment threading!

      this was supposed to be a reply to Janet!

    • how cool is that – I thought I’d done well when I mentioned that article (further up the page) and now I see the author commented in the previous thread but got eaten by askimet 🙂

      • We need to have a word with aksimet.. it seems to take its guidance from the UK home office. Well spotted!

  14. Pingback: The forgotten volcanoes of Chad Part II | VolcanoCafe

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