The Mountains of the Moon

Credit Tanya Gentle

Have you seen the Mountains of the Moon? There are several ways to answer this question. The most common answer will be, yes, and I loved the movie. Less common would be, yes, I just got my new telescope and it was the first thing I looked at. And the least common response would be, yes, it was brilliant but I got malaria.

The story

The Nile had always fascinated people. It is not a large river (in spite of being the longest river in the world), but it flows in an utterly barren landscape. It is a reliable source of water where everything else is bone dry. The floods are so regular that you can set the calendar by it. The Nile made Egypt habitable. It provided essential water in a complete desert (albeit a few thousand years ago the Sahara was not quite as dry as it is now) and the annual floods fertilized the fields. The word ‘Nile’ is semitic: ‘nahal’ means valley. The Egyptians called the river ‘Ar’, meaning black: this is the colour of its flood sediments. But in such a parched land, where could the water come from? Pliny the Elder thought that the river originated underground. Herodotus thought the river came from the western side of Africa, perhaps assuming a connection to the Niger. Later writers assumed that the Nile started in Ethiopia, and was fed either by the heavy summer rains there or by snow melt. (The sediment indeed mainly comes from the Ethiopian plateau.) They speculated about an unknown, high mountain, in an unexplored area, which was the true source of the Nile. But it was impossible to find this mountain. The Nile valley becomes impassable in south Sudan, where it widens into a wide swamp. Anything south of that remained a true terra incognito. There were stories, but they relied on hear-say.

Ptolemy’s Geographia, written around 150 AD, tells the story. It wasn’t his story: he copied the details from an earlier manuscript, an atlas by the geographer Marinus of Tyre which no longer exists. (Ptolemy did the same with his star atlas, the Almagest, where the data came from Hipparchos and was centuries out of date by Ptolemy’s time — which he did not notice.) Ptolemy was not an explorer, and was interested in math more than in geography. Much of his Geographia is about devising a system of coordinates for mapping the round world – we might call him a geo-mathician. For the data and descriptions he turned to others. Ptolemy wrote: Marinus the Tyrian is known to have found out many things that were not known before. He has searched diligently the works of almost all the historians who preceded him. That was exactly what Ptolemy needed.

According to Ptolemy, Marinus tells a story he had heard from a traveling merchant named Diogenes. (This makes his story third-hand! It was just like an ancient Facebook.) That merchant-traveler was sailing along the East African coast around 110 AD, when he was blown off course and landed in a town called Rhapta. The name has not survived and the location of this town is unknown. Traveling 28 days in-land from there, by accident he discovered the source of the Nile: a pair of lakes fed by snow melt pouring off of what he said the locals called the ‘Lunae Montes’: the Mountains of the Moon. The name was too good not to be true, and Ptolemy’s report, like an ancient twitter, went viral.

The story is confused, and Ptolemy in one place says that Marinus put the lakes near the coast, and elsewhere in his manuscript places them far in-land, based on information from other travelers. The coordinates he gives are pretty much in the centre of Africa. Ptolemy’s map of Africa (which was drawn many centuries later, based on his list of coordinates) shows the Nile flowing from two parallel lakes fed by waters from mountains. On later maps these lakes acquired the names of Zaire lacus (Lake Zaire) and Zaflan lacus (Lake Zaflan). Sometimes they were shown side by side; sometimes they were shown in sequence. But which lakes they were was lost in time. So was the identity of the mountains. Ptolemy at one place describes it as a ‘great snow mountain’, and this is generally thought to be Kilimanjaro. If Diogenes story is true, he may well have meant Kilimanjaro as it is not impossibly far from the coast. More likely seems that Ptolemy or Marinus amalgamated several stories about the Nile, the lakes and the mountain. No one managed to repeat the exploits, and find the lakes and mountains.

From Sebastian Münster’s Cosmographia universalis (Basel, 1554). [Princeton Historic Maps Collection]

The story grew into that of a mysterious mountain range that existed somewhere in Africa. Even in the 18th century, maps of Africa still showed the mythical mountains and their lakes, in various different locations – the African version of ‘Here be dragons’. An example is the Münster map of 1554. Münster, a professor of Hebrew at Basel, was the first mapmaker to print separate maps of the four then known continents. His map contains some dubious features: a one-eyed giant over Nigeria and Cameroon which represents the mythical tribe of the “Monoculi”; a dense forest located in the Sahara Desert, an elephant filling much of southern Africa. The Niger River begins and ends in lakes. Clearly, the map maker used some non-fact-checked resources. Even Madagascar is missing. And he depicts the source of the Nile as two lakes, fed by waters from a small mountain range: the fabled Mountains of the Moon.

The mythical Mountains of the Moon were sometimes shown dissecting the entire continent, sometimes more localized. They were used as an impassable barrier, used to cordon off the parts of the continent that were unknown. Though no one had seen them, they remained an eye-catching legend.

Until the 1850s, when Richard Burton and John Speke traced the origins of the White Nile to Lake Victoria. Kilimanjaro is 300 km from this lake, and no river flows in between. But 200 km to the northwest lies a small but spectacular mountain range, snow-capped and located between two lakes. These are the Rwenzori mountains. Burton and Speke fell out badly about whether Lake Victoria or the Rwenzori Mountains should be considered as the true source of the Nile. We now recognize that the Nile has many sources. But only one mountain range is seen as the real Mountains of the Moon: the Rwenzori’s, the snowy mountains of the tropics.

Although revealed, they still remain unknown. People have heard the old name, but it still sounds mythical and evocative. This is for a reason, as traveling in these mountains can be very difficult. Some of the landscapes are out of this world. But they might as well be on the moon.


The Rwenzori mountains run along the eastern edge of the Albertine rift, in between Lake Albert to the north and Lake Edward to the south. The mountain range is small, only 120 km long and 65 km wide, but it packs a punch. The tallest peak is called Mount Stanley, in an echo of colonial times. At 5109 meters high it is the 3rd highest mountain in Africa, and the highest peak in both Uganda and the Democratic Republic of the Congo (the border runs over the summit). There are 6 separate ranges, with deep gorges in between.

The explorer Stanley gave them the name Ruwenzori; it is based on what he said was the local name. It seems to originate from Swahili, ‘rwe nzururu’ meaning ‘place of snow’. The spelling has recently changed from ‘Ruwenzori’ to ‘Rwenzori’.

There is something funny here. You would expect a mountain range to form where two tectonic plates collide. If no such plates are available, volcanic activity may still throw up decent mountains in unexpected places. But here, neither is the case. There is no plate collision, and although there are fascinating volcanoes here (more about that later), they are not in the mountains. And the impressive height sows that these mountains are young. They are not a remnant of some continental merger a long time ago. The Rwenzori mountains are the highest non-volcanic, non-orogenic mountains in the world! They are mountains without a cause. Perhaps they did come from the moon.

(a) The Portal Peaks, 3911 m high and surrounded by deeply incised valleys. (b) The rugged topography of the Mt. Speke massif. (c) The Bigo valley; the floor of the deeply incised valley is about 3,800 m high and infilled with raised bog, to the left (N) is Mt. Speke (4,890 m) and to the right (S) is Mt. Edward (4,843 m). Source: Uwe Ring,

What are these mountains like? The west side of the range is especially steep, rising from Rift valley. The east side is a bit more sedate. The rivers runs in deeply incised, densely vegetated valleys. The views are spectacular, but are rare. The highest peaks are normally hidden in the clouds, and rain is daily. There are tours you can take. The western side is difficult to access: it is located in the DRC with expensive visas, little tourism and dubious security. The eastern, Ugandan side is better equipped. The local population provide guiding services. You would be ill-advised to go on your own — The guide is not a luxury! The tours are mainly for climbers. You need to be fit, able to walk for a week while climbing many kilometers, equipped to deal with rain, mud, hail, and snow. To climb the peaks, crampons are essential. Everything you bring should be water proof. You will come back exhausted, thrilled, wondering what happened to the vistas, and longing for dry warm weather. You will have seen few people other than those in your group. And you will be very grateful to your guide.

In May 2020, many of the trails were damaged in land slides and flooding. The local population has been rebuilding them, waiting for the tourism to restart.

Afterwards, you may want to visit the other attractions in the regions. Chimps in Kibala forest, volcanic lakes near Forth Portal, gorillas on the far side of Lake Edward. There will be many more tourists there – but they won’t have seen what you have seen. They won’t have been to the moon.

The African Rift


Africa has a problem. It has long been losing parts to the Indian Ocean. This problem dates back all the way to Gondwana. When Africa split from Gondwana, it formed the Indian Ocean. This split happened some way east of the current edge of the continent. India remained part of Africa, but some time later it rifted off, and sailed to Asia. The sharp edge where it split off is still visible on the African coast line. Next came a rift further south, allowing Madagascar to move off.

The third rift formed north, and it split off Arabia. Arabia does not have much room to move and has remained close, but deeply non-attached. The split started as a triple junction from a hot spot in Afar, Ethiopia. Since that time, the southerly rift from the triple point has slowly grown its way further south. It has formed the famous African Rift valley. Standing on its edge and peering into the verdant green valley below is quite an experience. It is threatening yet another separation, this time sending Somalia into the Indian Ocean as yet another floating micro continent.

The rift has run into its own problems. Tanzania refused access, and the African rift valley instead developed two branches, going around it on either side. The two are in competition. The eastern branch runs through Kenya, close to Nairobi before petering out. It has some nice volcanism, and it is famous for its soda lakes (think flamingos). The western branch begins in Tanzania, runs along the Uganda-Congo border, through Malawi and ends in Mozambique. It is famous for the Rift lakes. The northern part of the western branch is called the Albertine rift, and this is where the Rwenzori mountains are found.

The rift reality is more complex than a simple story, of course. The African rift is far from complete. Neither the eastern nor the western branch line up well with the Ethiopian rift. The eastern branch goes nowhere. The western branch has gaps and offsets, and is interrupted by the Virunga bulge which contains Africa’s best (but not tallest) volcanoes. There may even be a third branch, off-shore between Africa and Madagascar but this is not as well defined.

What has caused the African Rift valley? Afar was a significant mantle plume. It shows the typical triple-point pattern, and the Ethiopian rift is clearly associated with it. But there is limited evidence that the Afar hot spot is responsible for the entire Rift valley. It is just too far. A separate plume has been postulated to be underneath Kenya and Tanzania, responsible for the southern extension. The uplift of the region into a large bulge shows that there is heat underneath. But there is no obvious triple point. The earlier rifts in East Africa long predate Afar. And there are scars of other, failed rifts across the continent. They seem too numerous to all blame on mantle plumes. And there is a lack of hot spot tracks which would be a clear sign of mantle plumes.

The Virunga volcanism has been argued to be another hot spot. But this story too might be too simple. Once a rift forms, it can allow for upwelling which brings further heat: this could cause the volcanism there. Virunga is just one aspect of mantle warmth across a large area. The volcanics in Kenya sit on a bigger bulge than Virunga and would be a better candidate for the location of a plume. Perhaps this is all a long-lasting thermal anomaly, a lingering remnant of the previous continental splits.

Taking the long view, the African rift is indeed just the final part of the breaking-up of Gondwana. The present is just the current state of the past. That would also be a much more African way of thinking about life. And indeed, some parts of the African rift may be a re-activation of the ancient faults that tore Africa apart in the past. For instance, the third branch between Africa and Madagascar is at the same location where the old rift that rifted Madagascar should be hiding.

The Making of the Mountains of the Moon

The Albertine rift is some 13 million years old. The Rwenzori mountains are much younger. They were uplifted within the past 5 million years. The height is due to their youth, and the ruggedness is caused by the extensive glaciation.

But how did such a small range become uplifted in an area of rifting and subsidence? No continental collisions here! The Rwenzori mountains are almost on the shoulder of the Rift valley, and their origin clearly lies, somehow, in the rift.

The Albertine rift contains a patch work of tectonic faults. The west side of the mountains is bordered by the Bwamba border fault, with a step-over connected by the Lamya fault. The east side is bordered by the Rumi-Wasa fault and the Nyamwamba fault. Other faults run through the mountain range. It is not surprising that this is the most earthquake-prone region in Uganda.

The Rwenzori faults, taken (approximately !) from Uwe Ring, Not indicated is the Bunia fault on the west side of the Rift. The Ibimbo fault is inferred, not detected. The Ketimbi-Semliki fault had an M6.6 earthquake in 1966.

The Rwenzori mountains fill in a substantial area of the Rift between Lake Albert and Lake Edward. Before the mountains formed, the two lakes were joined together. The Rift valley now bends around the mountains, to such a degree that the Bwamba border fault runs on the west side of the Rift valley close to Lake Albert, but becomes the east side along the Rwenzori mountains. Bwamba is the fault that accommodated the uplift – more than 4 km between the bottom of the valley and the highest peaks in the central area of the Rwenzori mountains.

The highest peaks of the Rwenzori mountains are confined to a small region, bordered by the Lamya step-over fault. They seem a bit off-centre. If you draw a line along the ridge of the mountains, the central area is offset to the west. The model is that the entire range was uplifted slowly over the past 5 million years (and possibly starting earlier), but this central area had a rapid separate uplift, relatively recently, and a bit of clockwise rotation.

The whole structure is a horst, where the sinking blocks on either side push up the block in between. This is a common process, but here in a small area, the uplift became extreme. There are various explanations in the literature and a consensus has not yet been reached. Yet another fault has been postulated running through the central range of the Rwenzori mountains, with the accelerated uplift only occuring on the west side of this fault. In this model, the development of this new fault caused the extreme uplift, but only in a small area. Where did the fault come from? Accusing glances are directed at the unassuming Lake George, south of the mountains and outside of the Rift valley. This lake is considered a failed rift, a branch that didn’t make it. The Rwenzori mountains were caught between the two. The interaction caused the mountains to rotate clockwise, strongly enhancing the stress, and up the mountains went.

This is a mountain on the move, reaching for the stars – or at least for the moon.

Edited from Jess et al, Earth and Planetary Science Letters, 2020.

Volcanoes in the mist

Although the mountains of the moon are not volcanic, there are several volcanic fields around it. Three adjacent fields are located near Fort Portal: The Fort Portal field just north of the town, the small Kasekere field northeast of it, and the larger Ndale-Kasenda Volcanic Field about 20 km to the south of the town.

Fort Portal, looking towards the northeast with one of the small cones in the background

The Fort Portal field contains around 50 monogenetic tuff cones, nine of which have crater lakes. The largest lake is Kyaninga, some 3 km northeast of the town. Most of the eruptions produced tuff and ash, but the Kalyango cone, west of the town, is the source of a 5-meter thick, 0.3 km2 lava flow. The tuff and lava are carbonitite, consisting for 30% of CaO, 5% MgO, 15% CO2, and mostly less than 20% SiO2. The phosphor content is notable, with 2-3% P2O5. The cones look young and this has been confirmed by C14 dating: the eruptions took place 4000 to 6000 years ago. Fossil wood embedded in one tuff layer has been dated to 4070 ± 120 BP. The cones and craters formed first. One or more explosions produced a 2-meter thick carbonatite tuff layer covering 140 km2; it has a volume of 0.25 km3. The lava flow was the final event in the eruption sequence.

The Ndali-Kasenda Volcanic Field (also called Kyatwe) is about 20 km south of Fort Portal. It contains some 60 steep-walled crater lakes. A typical case is lake Kifuruka, around 5 meters deep, 200 meters across, and surrounded by weathered lava soils. Other lakes are Lake Lyantonde, lake Nyabikere and Lake Nyinambuga. Not all lakes survive as lakes: for instance Kabala swamp is a filled-in lake, 100 meter above the surrounding area. C14 dating of a core taken inside the swamp indicate that it formed 20,000 years ago and is considerable older than the Fort Portal volcanoes.

Immediately south of the Rwenzora mountains lies the largest volcanic area of the region, the Katwe-Kikorongo Volcanic Field. This is a rare example of a volcano on the equator! The northern edge of the field just touches the equator. It lies between Lake Edward and Lake George, covers 200 km2 and includes a large number of craters (78 maars, according to those-who-know, i.e. Volcano World). But the ground is so densely covered with the explosion craters that many have been obliterated by later events. In the densest area, I counted 20 visible craters within 10 km2. Perhaps this is the densest volcanic field in the world! Those-who-know describe the area as resembling ‘the surface of the moon’ – quaintly appropriate, next to the mythical Mountains of the Moon.

The largest crater is 3 km across. There is not much lava, just four small flows with a combined volume of 0.03 km3, within the Kitigata and Kyemengo crater areas. The age is not well determined. Local folklore suggests historical eruptions, but this should be treated with considerable caution. As elsewhere in the region, the main fault on which the craters lie runs SW to NE. The pyroclastics contain carbonate, and the rocks in this region are potassic to ultra-potassic in composition.


Sentinel image, sensitive to moisture. This brings out the in-filled craters.

Finally, 20 km southeast of Katwe-Kikorongo is the Bunyaruguru volcanic field, immediately to the south of Lake George. It contains more than 130 craters, many only faintly visible but 27 of which still contain lakes.

There are two unusual aspects about the volcanism: the monogenetic, clustered explosions, and the carbonitite. The monogenetic events themselves seem typical for water interacting with a high heat flow, and do not involve any large magma chambers. The heat may percolate up through faults: the faults here trend SW-NE and that is also the line of activity at Fort Portal. The events are mostly phreatic. Actual lava is rare. So that is explainable. But why the carbonitite?

G. Nelson Eby, Felicity E. Lloyd, Alan R. Woolley, Geochemistry and petrogenesis of the Fort Portal, Uganda, extrusive carbonatite,. Lithos, Volume 113, 2009, Pages 785-800

Carbonitite comes from melted carbonate. It is known at over 500 locations on Earth, of which only Ol Doinyo in East Africa is active. It melts at very low temperature, of 500 C. Carbonate contains CO2, so it is very gaseous and as a lava becomes very fluid. It can flow like water. The presence of carbonate can therefore trigger volcanism where other rocks would not. If it weren’t for the carbonate, perhaps neither Ol Doinyo nor the region around Rwenzori would be volcanically active. These are regions of higher heat flow, but not enough for a decent melt.

Carbonitite contains a mixture of Na2O and CaO (together with the CO2). The lava from Ol Doinyo are particularly sodium rich. Sodium rapidly leaches out of the lava and within days to months, and the solid lava becomes dominated by CaO instead. This may have happened at Rwenzori as well.

But where does the carbonitite come from? The obvious explanation is that it is melted limestone. But that does not seem to be the case. Instead, the magma appears to come from the mantle. A plausible model is that it involves subducted oceanic plates, at the transition zone of the upper end deep mantle at a depth of some 400 km. The low melt fraction leaves the silicate rock untouched but melts the carbonates. The melts percolates up to the bottom of the continental crust (or lithosphere). The African rift has broken the thick continent, and this has allowed the material to come up from the bottom of the crust. The low melt fraction implies that there is no strong plume involved, and in fact Uganda lacks the vigorous volcanism found further south and north along the Rift valley. This is true for both branches of the Rift.

An interesting aside is that carbonitite contains half the rare earth deposits in the world! The association between carbonitite and rare earth elements is seen in many places: a good example is Mountain Pass mine in California, at one time the main source of rare-earth elements across the world. The rare earth elements are likely from the same source as the carbonate: marine sediments that are subducted deep below the continent. The rare earth elements readily dissolve into CO2-rich fluids, and come up with these fluids to become part of the continental crust.

Feeding the Nile

Rwenzori’s other local name is Gambaragara, which means (approximately) ‘place of boiling clouds’ . It is often translated as ‘rain maker’. Both names, ‘place of snow’ and ‘place of clouds’ refer to precipitation! The prevailing wind comes from the east, the Indian Ocean. The 5 km high mountain chain forces the air upward. As the air cools, the moisture condenses and the rains begin. Annual rainfall is 2-3 meters. The climate officially has two dry seasons, one around January and the other around July, but even in those months it may still rain on most days. April and November are particularly wet, as the low pressure of the Inter-Tropical Convergence Zone passes the area.

Around the summit the rain falls as snow. The Rwenzori mountains carry the largest glaciers of Africa – in spite of being almost on the equator! Good views of the glaciers are uncommon because of the frequent cloud cover.

The glaciers are now in rapid retreat. In the 19th century they covered 10 km2, but by 1990 only 1.7 km2 was left and by 2003 it was reduced to 1 km2. At that time it was expected that the glaciers would be gone by 2025. Of the 6 glaciated mountains, at the moment only Mount Speke (4890 m) and Stanley (5109 m) still carry glaciers. The glaciers on Mount Speke are small, but the ones on Mount Stanley are still substantial, with the longest (on the Stanley Plateau) over 1 km long. The decline is due to three factors: the recovery from the Little Ice Age since 1850, the change in rainfall, and in recent decades the global warming.

The snow cover makes the Rwenzori mountains identified as the fabled Mountains of the Moon. But are they really the source of the Nile?

Rivers in the Rwenzori mountains are fast and furious, at least high up. The hard rock is impermeable and the never-ending rains runs off immediately. The rivers that run west end up in Lake Edward or in the Semiliki river, both heading for Lake Albert. The rivers on the east side mostly end up in Lake George: this lake gets half of its water from the Rwenzori mountains. Lake George empties into Lake Edward and on into Lake Albert. Lake Albert in total receives some 2.5 billion cubic meters of water per year through these three routes.

Lake Albert flows into the White Nile. But so does Lake Victoria. The total flow rate of the White Nile south of Lake Albert is 33 billion cubic meters per year (half of which is lost to evaporation in the swamps land of South Sudan). The Rwenzori mountains contribute less than 10% of that. And other rivers contribute to Nile, especially the Sobat river and the Blue Nile. Inn total, the Rwenzori mountains contribute about 3-4 per cent of the water in the Nile. The Mountains of the Moon they may be, but they are only a minor source of the Nile.

Between glaciers and savanna

In spite of its mythical status and extraordinary height, this is a small range, no more than 50 km wide. That gives an immense variety in climate over small distances, from the tropical Rift valley to the icy glaciers. The plant diversity has to be seen to be believed.

It begins with African savannah, down in the valley. Above 1000 meters this gives way to rain forest (and boy does it rain!) If you like wild bananas (pretty inedible), this is for you. Above 1500 meters, the grass returns but in an unexpected form. Here grows bamboo (a type of grass, after all) and forms a 30 meter tall forest (Sinarundinaria alpina). Above 3km, where nights may bring frost, there is heather, but not like you know it. The tree heather (Erica kingaensis) grows into ten meter tall, moss-covered trees, as a fairy-tale (but open) forest. And finally, at 3.5 km the alpines rule again, as giants. Giant, 10-meter tall lobelia (Lobelia stuhlmannii) are found here, and even sun flowers (Helichrysum stuhlmannii) and groundsel (succulent daisies: Dendrosenecio adnivalis and Dendrosenecio friesiorum) have evolved into trees in an other-worldly landscape. They grow in the (reportedly) muddiest place on earth where slipping on tussock grass (Carex runssoroensis) can leave you chest-deep in mud. It slowly gives way to a barren landscape with lichen covered rocks, before finally the snow and glaciers rule – 100 km from the equator.

And it is not only the plants. Some animals here are found nowhere else on earth, including the Rwenzori Leopard (Panthera pardus ruwenzorii, black-spotted and now very rare) and the Rwenzori Turaco (Ruwenzoronnis Johnstoni). 19 bird species are endemic.

Source: wikipedia

But in spite of this variety, the number of species is actually significantly smaller than in other national parks, and the alpine region has half the species found on Mount Kenya. The flora has even been described as ‘impoverished’. On the other hand, a record number of those are endemics. This is probably due to the geographical isolation. This mountain range is young, came from nowhere and is not in contact with any similar mountains. Alpine plants cannot migrate easily in Africa. It has been suggested that there were no high altitude plants in Africa until about 20 million years ago when a land bridge formed with Europe. Tropical plants don’t easily evolve to handle frost.

To go where none have gone before

Rwenzori is beautiful, but not easy. The mountains are steep, high and very very wet. Walking here will make you understand the meaning of ‘bogged down’. The rain seems perpetual and vistas either far between or fully absent. Kilimanjaro, a single volcano, is visited by 50 times as many people as this mountain range. It doesn’t help, of course, that the western side is in the DRC, a country not known for tourism facilities. And if the highest non-volcanic , non-collision mountain range in the world where heather grows into trees is not enough, the densest volcano crater collection in the world is just next door. The Mountains of the Moon are more than the source of the Nile. They are out of this world.

Albert, February 2021

See also

And for those with access to BBC content, Part 2 of David Attenborough’s Africa ‘Savanna'(2013) covers the Rwenzori mountains with lots of pictures of clouds. As of writing, this is available on BBC’s iplayer.

200 thoughts on “The Mountains of the Moon

  1. Thanks Albert! Its a masterpiece
    Uganda haves Some of the strangest magmatism in the solar system…
    Some are carbonatites, some are sillicate But with hardly any sillicate at all. Not far below are the ultrabasic – ultramafic Nyiragongo. I woud absoutley love to go to Uganda and collect lava rocks.. these magmas hardly exist anywhere else

  2. During the Middle Ages and Renaissance Africa was seen as ”burning hot” The Equator a place where pale skinned
    ”cannot cross” I think If I remebers correct that some old medieval scholars thought that the Equator was hell itself

    Snow on Kilimanjaro and Mountains of the Moon must have been an amazing sight for these earliest of explorers.. they sourely wondered How souch thing was possible.. in the lands of unbearable heat

    • Uganda is not as hot as you might think. Kampala is typically around 30C maximum. The country is at quite high altitude, after all. Tropical diseases probably were more important in keeping us temperates out.

    • Thats true like Goma arera thats a mild highland haves around 23 C all year around ..

      But for me and others that comes from Arctic Europe anything with high humidity and above 20 C will feel very hot indeed..

      Nyiragongos lava lake keeps rising anyway.. getting taller and taller.. putting pressure on the sides around it, the lava lake is overflowing again

  3. Wow – fascinating place. Thank you Albert! This makes me wonder what the volcanic future will be for the area.

  4. Fantastic article.
    If I may theorise on two bits, the Rwenzori mountains could be caused by the counter-clockwise rotation of the proposed Victoria plate/craton. It is worth noting that Lake Victoria itself has volcanism particularly on the east side/Homa Bay area (give it a look on Google Earth).
    I also believe that the rift was quite simply caused by a difference in movement across the north and east sections of the african plate, basically it has drifted northward but found it’s movement more restricted to the east because the bulk of the Eurasian (and Arabian) plates are there, whereas northward it has the lubricating Mediterranean. This caused long distance strain and inevitably a tear developed.
    It could also be in a previous area of weakness, further weakened by the Afar plume and/or linked to the Central African Shear Zone – it is parallel to this in the east. Or a combination of all of these.
    The Baikal Rift can likely be explained in a similar fashion.

    • The rotation of the Victoria plate has been suggested as involved. But it didn’t seem likely to me. The rotation mainly comes from the fact that the eastward movement at the southern end of the western rift is much larger than that at the Albertine rift. It doesn’t seem to give much movement at the Rwenzori mountains, nor does it single out this area as especially affected. The alternative explanation of rotation of the block between the Rift valley and the Lake George rift seemed more likely to me. But this is an open, on-going discusson.

      • Good point, the evidence is mainly based on GPS movements.
        I also just read about apparent kimberlite volcanic products – apparently the youngest kimberlites in the world – right in the centre of the Tanzanian craton well below Lake Victoria in a place called Igwisi Hills. Does this prove a higher than expected heat ascent – perhaps another triple junction like Afar where the Victoria and Lwandle plates connect with the rift?
        I don’t really think there has been anywhere near enough output to suggest another plume.

  5. Love the article Albert! Thanks much!

    Few remarks. Tree heather vegetations on the mountains slopes are characterized by Erica species like E. trimera and E. kingaensis. Those are the heathertrees, not heather in the trees. Carex is Tussock (growing there too). Seems as a spectacular blanket mire to me!

    The bbc llink doesn’t seem to work.

    Some more great pictures (including one showing glacier retreat) are found here:

    • Thanks Rob. I fixed the BBC link. The Carex was a silly mistake of mine, as I knew it was an erica species – I know erica’s well from the fynbos! These plant names have been fixed. The pictures are great, well recommended viewing. And they show what weather to expect from an alpine mountain range in a rain forest!

  6. I wasn’t aware of any other relatively young carbonatite activity outside of Ol Doinyo Lengai and Mount Homa. Very interesting read.

  7. You are really great at telling stories Albert.
    A bit similar landscape and transitions in vegetation can be found from Merida (900m) in Venezuela, fortunately they have a cable car which brings you to above 4500 meters which make it a bit easier, and you can walk down, It’s small fish compared to these Mountains of the Moon though.
    And if you ever visit Venezuela, go to Canaima National Park, it looks like a truly lost world with the highest waterfall in the world and when it has enough water – which is not the case in dry season – it’s absolutely stunning, pictures don’t do it right. Don’t get bitten by the conga or 24 hour ant. I’s nicknamed liked that because once bitten you can get in a comastate for a day, according to folklore.

    You sure brought back memories with this article and pictures, thank you.

  8. That is a very big carbonatite flow, 0.3 km3. It must have been like a massive flood of black lava erupting all of it in a few days to stop it reacting with the water in the air. Not hot enough to burn trees but it would have been a scary sight if anyone was around, if its 5 meters thick that is 60 km2 of area, not far off of Holuhraun, flooded by 500 C black liquid that flows at fast walking speed and you wouldnt be able to see it in the jungle :O

    Maybe it was not that fast but it must have been a lot faster than a pahoehoe flow, otherwise it would react with the water in the air.

    • Elephant stuck in the lava
      Only the trunk sticks out : O

  9. Mauna Loa’s swarm is continuing with small frequent quakes, about 3 km directly below the summit

    • I just looked at the quakes on Mauna Loa on the USGS site, and they are forming a line through the summit.

      • Every summit eruption from 1926 to 1984, except for 1942, erupted through basically the same fissure at the summit. 1942 was on the north ring fault. It is likely that most eruptions will do this until either a lava lake is created with an open conduit (at this point unlikely) or a collapse happens.

        The quakes are not exactly on that line but close to it. The next eruption will probably be a fissure in Mokuaweoweo that either stays in the summit (1975) or starts continuously extending down either of the rifts (1950, 1984). Most likely to me is the latter, 1975 was preceded by 1 year of inflation, while 1984 was preceded by 10, and today we are going on 20 and still counting, an eruption like 1975 would have been more likely in 2002 or 2003, we are far past that point now.
        Mauna Loa I think is going to show us how dangerous effusive volcanoes really are quite soon…

        • What happened after the last 45-50 year gap in activity on Mauna Loa?

          • 50 years has possibly never happened in the last 1000 years, 1984-now is the longest without an eruption that I know of. Before 1843 the previous eruption was I think in 1809 but that was down on the southwest rift at the Manuka flow, was quite small and there could be summit activity at that time.

            My guess is the last time a gap like today happened was in the 18th century, because Kilauea was very active and Mauna Loa had a caldera collapse at the beginning of that century.

          • Hawaiian natives said that the last prehistoric eruption of Mauna Loa had been in 1780 and that the volcano erupted again in 1832, which would have been a 52 year dormancy. Of course there is a chance there was some small eruption in between that wasn’t noticed. The 1832 eruption was very small, at the summit. In Hawaii the size of eruptions doesn’t correlate, at all, to the preceding dormancy.

          • Most stuff I have read says the 1832 eruption probably didnt happen, because its only observation was in Maui and only once but from such a distance it would need to be a pretty big eruption with part of it on the flank, which isnt known of that age nor observed by anyone closer to the volcano.
            On the new map of the Ocean View area it has the Manuka flow being from about 1809, that eruption was probably not long, and if it happened mostly in one day and during the day could be missed easily. It does though also look like it could have been part of a bigger eruption at higher altitude, so will have to wait and see the new maps.

            On Wikipedia it has a reference to eruptions in 1730, 1750, 1780 and 1803 with no more information.

    • A paroxysm (which is what we’ve been having) doesn’t cause much deformation on the flank, so there shouldn’t be any increased risk of the flank collapsing.

    • Really scary. Just had a look at the map where a zunami would go..

  10. This is very interesting. I had no idea there were snow-covered mountains in Uganda.

  11. How did the Mountains of the Moon look like during Last Glaciation Maximum ?

    • You can still see the moraines from the ice ages. Around half the national park was covered in ice

      • A quick read gave that the most recent ice age had ice down to 3 km, mainly on the east side (prevailing wind). An earlier glaciation (either 270 thousand or 400 thousand years ago) had ice down to 2 km and covering 500 km2.

        • Wow !! Down to 2 kilometers
          How cold was the Equator during the coldest episodes of the glaciation?

          • Checkout the #SnowBallEarth theories but better ask the question since how long is the Equator at his actual position…

  12. There is Carbonatite lava and Natrocarbonatite .. Whats the diffrence?
    Does carbonatite.. not react with water?
    The other certainly does

    • That is mentioned in the post. The sodium leaches out of the carbonitite lava very quickly, possibly within days. After that the natrocarbonitite solidifies as normal (calcium) cabonitite. That may well have happened at Fort Portal

    • Fort Portal Have many white Carbonatite pahoehoe desposits perhaps better to resist water than Lengais compositions, at Lengai it breaks down very quickly

      A magmatic limestone is the weirdest thing on Earth .. erupting like black sludge

    • I was able to watch it live, it was quite exceptional, lava fountaining up to 1000m and also exceptionally long for a typical etnean paroxysm. It shows in the tremor graph, there was a much slower build up than usual.

    • Here is another video from last night. It almost looks like a fissure.

      • Would be very much like this, magma is very similar at Katla and Etna.

        Eldgja was probably the biggest strombolian style eruption in the Holocene anywhere on earth, you can see just north of Myrdalsjokull the main vent area for the biggest flow, its not a fissure like Laki but several gigantic cinder cones.
        Eldgja was pretty ashy, some of it was probably from eruptions under ice near to Katla but the entire fissure was erupting a lot of tephra anyway, there must have been colossal fountains.

  13. 1000 meter tall fountains for Etnas last eruption, not many reach that milestone. Jesper now has his pillar of hell eruption 🙂

    One has to wonder the structural integrity of the cone after this. Would not be surprised if a few more of these eruptions and the cone rifts and erupts as a fissure, it did that in 2014. I guess we will see in a few hours.

  14. Mystery photo of Lengais 2007 – 2008 eruptions and its early in the evening…when carbonatite should not glow, carbonatites can only glow red in the pitch night. Coud this be a Nephelinite lava flow? the 2007 – 2008 activity erupted Nephelinitic materials

    • Flank vent too .. coud be : )
      But perhaps a Nephelinite
      ( Nefelinit in Swedish ) woud glow more in the evening?

      • I do have a lava rock from Nyiragongo, its my most loved rock in my collection.. knowing how rare Nephelinite is, Almost no extrusive sillicate igenous rocks on Earths surface is Nephelinite. I got it from friends that visited Nyiragongo a few years ago Im so happy.
        The rock is dark and quite heavy. It looks kind of like normal basalt, but with some colour gloss diffrence. There is no visible crystals at all. Its crazy odd Nyiragongos rocks..almost no sillica at all, down to 35 to 36% in some samples. Nyiragongo really is the rarest stratovolcano in the solar system, there is no other volcano like this. The entire Nyiragongo is ultrabasic so something else is resposible for its steep shape, perhaps tall fountains when it formed. Now Nyiragongos conduits are too wide and open for fountains. Nyiragongo lava lake is today a hole into the magma chamber. For now the lava lake keeps rising, been overflowing alot this month according to social media posts

        Holding it the rock in my hand..

        ..My …. preeeciiouussssssssss……

    • There are multiple vents active, the largest fountain seems to issue from the easternmost side of the southeast crater, then there are two other vents active to the west, much like the last paroxysm.

    • The Mascalucia cam gives a good overall view with the surroundings. That’s about 12km away.
      Etna looks amazing!

      • And there it goes settling down now, in Javi’s link. I was interested to see a new vent open on the slope just before the paroxysm settled. Etna is…interesting…right now.

        • I noticed that too.
          I also noticed what looked like a glowing crack across the entire cone.

          At what point does the paroxysm melt the cone that it is spouting from? It looked like that was happening a little bit.

    • That was beyond amazing, Etna did it again! The whole row of vents along the southeast crater bursting into a colossal fire curtain. These paroxysms just keep getting bigger, I’m looking forward to a sixth now.

      • Next time I Hope she provides a Ticuantepe 2.0 : D

        That woud require huge overpressurize from the large deep crustal resovair. Etna haves a huge supply these years

      • I’ve had the webcam open a few times on an evening, seems to only want to erupt on a night time. Nocturnal Etna.
        (Depends what time zone you’re in I guess)

  15. A new effusive vent have opened on the Etna NEW SEC vent .. Ooozing lava.. perhaps an open feeder channel formed now. If we are luckly the supply is large enough to feed it for a very long time

    • It was the 4th big eruption of Mt. Etna. Who can give a guess, how moch volume we have seen so far? Yes, only short lived, but up to a kilometer high…..

      • On November 23 2013 there was an eruption similar to the recent fountains, I think the last time a 1 km fountain happened from SEC complex. That was 1.5 million m3 in 45 minutes. The recent eruptions were much longer, the 4th paroxysm was 4x as long and judging from the size of the lava field and presence of more than one vent probably a higher eruption rate total too, so possibly 5-6 million m3 for both #4 and todays fountain. I guess its all guessing but the last week I think has seen somewhere around 20 million m3 of lava erupted, Kilaueas lava lake is about 35 million m3 for comparison.

        • Thanks a lot. That is some good Volume for this short Eruptions.

  16. Well looks like my optimistic prediction was an underestimate, Boris Behncke shared a photo of todays eruption on his instagram with a caption saying the fountain peaked at over 1500 meters tall which is by far a record for the SEC, and would make it one of the tallest fountains ever observed on camera.
    And it was all recorded live in its entirety 🙂

    I am going to reach for the stars, the next fountain will get to 2 km and either break the total record or break the volcano.

    • I requested a Ticuantepe 2.0 : D
      from Etna. The biggest hell – pillar of fountain tephra that you can ever imagine, an angry orange ligthing filled mess.

      The next eruption: ” I will break her … ”

    • When Nyiragongo lava lake reformed in 2003 the Goma arera was showered in tephra.. An intense glow was reported at night.. and in day an enormous steam cloud as well as dark tephra was seen over Nyiragongo.. the observations are a bit blurry and the weather was bad. A massive collossal So2 spike was measured during these bad weather days at winter of 2003

      Is this supertall lava fountains too?

      • Those were probably some vent formation explosions, same as the explosions in 2008 when the Overlook Crater lava lake showed up at Kilauea.

      • Volcanologist
        Dario Tedesco watched glowing ejecta rise over Nyiragongo during that event: Perhaps a 600 m tall fountain. The fountain calmed alot in 2004

        • I read the report for the 2003 expeditions, the glow visible from Goma was an illuminated steam plume, not a fountain. Activity in 2003 was though intense with a 300 meter fountain at one point, but that was also when the crater was 700 meters deep so would still have been pretty small in comparison.

          Nyiragongo is like Ambrym, they are both volcanoes that should be lava shields but are mostly made of tephra, and yet most of their eruptions are still effusive. They are also both rifting volcanoes that are near water.

          • There are deposits of both lava fountaining (scoria) and phreatomagmatic/vulcanian eruptions (fine ash) in the upper walls of the crater of Nyiragongo. The shape of Nyiragongo reminds me more of a cone formed from lava fountains, it has some resemblance to Vesuvius, for example, a volcano with very fluid, more so than Etna, CO2 rich magma that produces high fountains. The magma might have been very CO2 rich, coming from great depths, when the construction of Nyiragongo started. But I guess it is impossible to know for sure.

          • Vesuvious can erupt very very fluid alkaline basalt
            In some videos its almost as fluid as Hawaii. Vesuvious was in early 1900 s up to 44 in open conduit condtions and pahoehoe fillings in grand crater. It woud not a all suprise if it goes into Villaricca style in the future with a small lava lake in the summit. But it depends on the supply rates and state of the volcanos system.

            Here is it 1929 with a very fluid lava lake with even lava waves in it.

            1930 with pahoehoe and hornitoes

    • Supertall fountains like Etna and larger is the only way for Nyiragongo to have grown so steep.. and the crater walls does have alot of Brown Puu Oo like materials. The entire Nyiragongo is ultrabasic, so something else rather than magma composition is resposible for its steep shape.
      The cone have later been draped in thin chocolate like overflows of Nephelinite from high standing lava lakes

      • Could also be phreatomagmatic, Etnas fountains are probably so tall because of the relatively high viscosity of the lava, my guess is a pressure driven fountain in a fluid lava probably wont get a lot above 500 meters. Kilauea has done many fountains in all parts of its active system and they all top out at 500-600 meters, Nyiragongo is probably going to be the same if all things are equal. You get way bigger fountains with extra force though, a caldera collapse forcing out magma through a ring fault, or the powerful expansion of external steam.
        Ticuantepe was both of those happening together, as well as maybe low pressure from a draining system letting the magma degas at great depth. I dont think it was 10 km3 though, that is all of the Masaya Tuff eruption, Ticuantepe might be only 1 km3. That is still like Etna erupting like it did earlier today continuously for a few days non stop though.

        • Ticuantepe was much more intense, produced a plume 25 km high and rained fragments of rock 30 cm across 15 km away. Unlike the paroxysms of Etna it would be able to cause serious damage and fatalities, rock fragments big enough to kill people on impact would be raining over the populated lower slopes of the volcano, it would be disastrous if such a thing happened on Etna.

          • What is the age of the big lava flows in the caldera at Masaya? If the obvious caldera was formed 1500 years ago then it must have been very active at some point after that, but since the 1600s it has only had an actual lava flow once, there are lava lakes but the eruptions are very small and localised. Most of the caldera is barren, so the lava flows must be young.

            The gas output is very high too, at times as high as at Kilauea even though the lava output is very small, so there must be a lot of melting in the mantle but most of it doesnt actually rise into the volcano for whatever reason. The same thing happens at Ambrym, which is also a shield volcano in a subduction zone that often has lava lakes, maybe thats not a coincidence.

      • Nyiragongo indeed does have much much lower viscosity than Etna. A Nyiragongo fountain woud look like Hawaiis tall fountains.

        I guess Nyiragongo is quite hot too for being a Nephelinitic melt

  17. Speaking of rift valley volcanoes some serious contenders for ultra-plinian eruptions in the years to come. Think Paka caldera had 21cm of uplift in a year not so long ago. Looks like there’s a diapir in the crust in the Kenyan section, crust is only 15km thick in places.

    • Yes its a shame most of those volcanoes are not monitored, probably it will stay that way until one of them erupts too which is quite likely this century. Its a strange part of the world, its the place we began in and we have been there ever since, yet we know so little of the volcanism beyond a few hundred years ago. Africa in general is getting much more modernised now though so possibly many of these questions will begin to get answered soon. I expect there will be some surprising discoveries in the coming years.

  18. Quite some shaking in Iceland at the moment. Three locations with a star, multiple stars (>10) in the southwest and one EQ of 5.7. Something brewing or rifting only?

    • Probably will lead to nothing like the other swarms this past year but because there is magma involved in all of this an eruption is very probable in the long term. If it is like most rifting episodes though the first eruption probably will be very small, bigger eruptions might still be years later and we might still be a while off of an eruption at all just yet. If lava does erupt though it will definitely be noticed, nice and accessible and safe eruption, drive right up to it 🙂

      • Let’s be clear. This appears to be a tectonic event along what is mainly a transform fault. It is a bit early to call in the volcano gods.

          • I’d say it’s too far away to be affected. That said, it has been quite active lately, so there is definitely a chance that it will do something. If it does it is however entirely coincidental.

            I’ll keep my eyes a bit closer to the action. The weeks prior to this event there were some heightened activities in an area stretching from Hengill to Langjökull. There was also an M2 and a small swarm at the eastern end of the SISZ (around longitude -20º). I’d say those places are better bets.

  19. Very heavy shaking in Reykjanes, following an M5.7 on the peninsula. Stars all over the place including in some unlikely locations in Iceland, probably misplaced by the automated systems. There was an expectation of an (up to) M6-ish quake along the Reykjanes peninsula, as it seemed due one -perhaps this was it. In that case there is a risk of another quake this size as they sometimes come in pairs. The rest is aftershocks and they will continue for some time.

    • This is the second >M5 in the episode that’s been running since early last year, isn’t it?

      There was an M5+ back in October last year, when the Prime Minister – who was being interviewed live on TV (in English) – showed typical Icelandic sangfroid, only interrupting herself to say, “Well, this is Iceland … Yes, I am perfectly fine.” There was another video showing the Parliament in session: the Speaker sat calmly while the Pirate Party member ran for cover.

  20. By chance I was looking at the GRV recorder yesterday and noticed the usual tremors before this lot took off. The only thing that caught my eye was the ‘popping’, the sort of seismic noise that might come from steam fracturing rock. I see it is still there today.
    Might there be some steam moving about in the system?

  21. Fun stuff in Iceland this morning. The M5.7 just after 10 am was strong and lasted a good 15-20 seconds, followed by a long series of aftershocks that steadily rattled Reykjavík University over the next 15 minutes or so. We had some additional strong jolts a bit after noon.

    • Be interesting to see if the activity remains focused on the Reykjanes Peninsula and / or whether it moves along the MAR to the other volcanic regions. Stay safe.

      • Good point: I think you are right. And if my memory serves, when this episode kicked off last year, it was Reykjanes that was put at yellow.

        I’ll be interested to see how much the Seltun geothermal area has changed with this recent activity next time I’m able to get there.

        Which reminds me of an off-topic question that occurred to me last time I was in Austur Reykjadilir. Hvinandi used to have the reputation of being the loudest steam vent in Iceland, but when I was there in 2019 it seemed pretty quiet – Storihver was much louder. Do any Icelanders / Icelandophiles on here know anything about this?

        • Perhaps the action is between the two and they picked the closest for the time being?

    • Yes, and Grimsvotn, too.

      I’d noticed that, but it’s been a while since I’ve looked: does anyone know when G was elevated? Presumably last year sometime, since IMO / Almannavarnir have been saying an eruption is likely for about the last six months.

  22. From the IMO news site “Frettir”, translated using Giggle.
    Note: translated as eruption in the news should be “swarm” I think.
    There is no eruption ongoing this moment.

    The earthquake on the Reykjanes peninsula
    The largest earthquake measured M5.7 at 10.05. Part of the eruption that began around Krýsuvík a few days ago. Increased probability of larger earthquakes when such a crash occurs.

    Post at 10.15

    Today at At 10:05 there was an earthquake of magnitude M5.7 3.3 km SSW of Keilir on the Reykjanes peninsula. It was found in many parts of the southwest corner of the country, e.g. in the Westman Islands. A number of aftershocks have followed and further aftershocks can be expected.

    (Several updates not translated)

    Updated at 13.58

    Kristín Jónsdóttir, director of nature conservation at the Icelandic Meteorological Office, says in an interview with the RÚV news agency that instability covers a large area. This morning’s earthquakes have been between Kleifarvatn and Grindavíkurvegur. However, no earthquakes have been found between Kleifarvatn and Bláfjall this year. There have been magnitude 6.5 earthquakes in history. This could be an indication that the area is locked and does not release tension there except in larger earthquakes. “We are in the middle of an event now. We believe that while this instability is raging, there is an increased chance that there will be even more earthquakes and even larger earthquakes. more than 20 km long area o between Kleifarvatýell .. ”

    Kristín says the eruption is unusual, it is powerful and it is accompanied by many powerful earthquakes in a short time. There are no indications of eruptions, however, but the Meteorological Office’s experts have, among other things, been conducting gas measurements in the area to assess whether there are any noticeable changes in gas emissions. Traces of magma gases, if any, could be seen in gas measurements.

    It is important to be aware of the dangers posed by crises such as these:

    Landslides and rock falls can occur after large earthquakes, most likely in areas with unstable slopes, steep rock walls and loose material, e.g. in the vicinity of Kleifarvatn.

    Earthquakes of magnitude M5.5-6.5 can occur on the Reykjanes peninsula. Such earthquakes can cause damage in many places, e.g. in the capital area.

    Gas can accumulate in depressions when there is a calm or slow wind.

    • We could do with a decent webcam. There used to be a few but they’ve gone. 🙁
      Thanks for this link, Jesper!

          • Paroxym is starting up… and very visocus basalt today again

          • Very very viscous basalt…. very visocus today
            Perhaps similar to the Heimeay 73 basalt in visocisty and temperature

          • Very very vioscus.. perhaps the most viscous basalt on Earth for the moment.. Etna is really odd stuff.. but erupting at low temperature

          • All subduction zone basalts are very viscous, like Etna or sometimes even more. Many intraplate basalts are also similar to Etna’s viscosity, like the Canary Islands…

          • Masaya is a subduction basalt… and its very fluid…
            Much more than Etna.. look at these videos of Masaya

            Masaya is probaly the most fluid subduction basalt… at 1160 C
            Its not far from Hawaii … even if Hawaii is lower viscoisty still.
            Masaya likley rises very quickly from the source without diffrentiation

          • SEC cone is growing enormous if this frequent eruptions continues day after day. When SEC was in 1999 s and 2000 s it did many paroxysms too. But now we gets Paroxyms almost daily, certainly a huge supply behind this, perhaps soon it will dreg up hotter and more fluid materials from Etnas depths.. or is it already deep stuff knowing that the edifice chambers are very small

          • Soon the fountains are breaking a 1000 meters we will see if we can get a subplinian basaltic hell column with nucleation deep down in the conduit

          • Theres s big fountain from the saddle crater now, different from the one erupting earlier. Maybe it will stop soon but if it doesnt there could be a big flow outside the Valle del Bove to the southwest.

          • I get the impression of lateral explosions and pyroclastic flows coming from vents on the southeast side of the cone, plus a vent opened on the west side of the cone too, and 3 or 4 high fountains along the top of the cone, crazy.

          • The paroxysms in 2000 was more fluid than these.
            But the first of these 7 … 2021 paroxysms was very fluid

          • Remember too that the flows are being fed from the fountain fallout, if the lava erupted in a crater and was able to pond around the vent then it would not be so viscous. On Pu’u O’o the fountains in episode 4-20 lava flowed from a pond in the cone so was very liquid and reached long distances very fast, 14 km in episode 18. After this the crater collapsed and filled in, so the next eruption the fountain was unobstructed, it reached a maximum height of 550 meters not long afterwards, but the flows were all very viscous a’a flows that rarely made it a long way from the vent. Theres pictures of some of the 1980s Pu’u O’o flows and they look identical to the recent Etna flows.

          • It is getting very interesting as these eruptions repeat. The first was a rather standard lava fountain, but each episode has been more intense than the last to the point that now we have multiple massive fountains from different vents and even pyroclastic flows in the most recent paroxysm. It is looking pretty clear the cone isnt going to hold up much longer, the pyroclastic flows especially are a sign of oversteepening. There have been only a few eruptions as powerful as this series in Etnas recent history, and as far as I can find a recurrence of three fountains over 1 km tall in the span of 4 days is a new record.

            I have said it before and ill probably say it again 🙂 Etna is going to do a big eruption outside its summit in the coming weeks, whether it is a big effusive lava flow or a curtain of hell eccentric fissure eruption, or both, it will happen soon…

        • Looks like she is stopping… but she will be back again sooon..

        • Last nights Etna lava was very viscous even at startup with low fountains..

          The first Paroxysm last week seemed much much more fluid… with almost clean hawaiian fountaining

          Btw If SEC grows taller on that steep slope.. its going to collapse and slide down

        • Chad: since Etna is almost ultrabasic: imagine If she started to erupt Nephelinite at Nyiragongos temperature, souch lava woud flow down very quickly indeed. A saddle vent eruption woud flow down to ski lifts quickly with that composition. But the results woud be the same viscous Aa lava, only diffrence woud be near the vent.

          But Etnas melting rates in mantle is probaly too large to produce anything ultra alkaline.

          I think Etna coud turn more subalkaline If melting rates increases in the future. If I remeber correct, the first Etna lavas 500 000 years ago was thoelitic pillow basalts

          • Yes the first lavas that erupted in the area were tholeiite basalts, but Etna didnt exist yet as a proper volcano. Stratovolcanoes began to form after more alkaline magma erupted, the last one being from 45-15000 years ago. Since then Etna has erupted basalts on top of that volcano, its probably also much more active now too, more like a shield volcano than a stratovolcano. Maybe melting rates are increasing again, it could erupt tholeiite basalt in the future.

            Lava temperature is not low in the paroxysms though, 1140-1170 C, the first lava in the fountain is degassed and from the previous eruption so has cooled, if the hot new stuff under it was erupted effusively it would be fluid. If the next paroxysm is from a vent that is in the saddle crater instead of the NSEC then the lava might pond over the vent and drown the fountain, which could lead to fluid lava flows, at least more so than from fountain fallout.

    • Etna is areally cold and visocus basalt… almost as viscous as many other baslatic andesites.
      Yet Etna is an almost ultrabasic alkaline basat.. erupting at low temperature, sillica content is 46%
      But its taffy and viscous perhaps 1110 C. Holuhraun was 1180 C for comparison

  23. Today’s shakes.

    A shock, a bigger shock, and aftershocks. The big shock was quite shallow.

    • Curious lack of P waves for many of the quakes?…perhaps some antecedent rock fracturing going on?

  24. “The earthquake was very powerful,” states Óskar Sævarsson, park ranger and resident of Grindavík, speaking of the strongest earthquake of many that hit Southwest Iceland this morning. It measured 5.7. Óskar was at Vör restaurant in Grindavík when it hit.

    “First, there was a very strong one, and then everything trembled for about a quarter of an hour afterwards, ” he tells . I’ve never felt an earthquake this strong …The chandelier swung back and forth like a pendulum,” he states.

  25. I haven´t commented here in a long while.
    Interesting large earthquake swarm in Reykjanes.

    I lived 5 years in south Iceland and feeling small earthquakes was relatively common, but larger earthquakes of around magnitude 6.0 are uncommon (a few every few decades), mostly in South Iceland Seismic Zone but also in Reykjanes. I did feel a magnitude 4.7 once and it felt as if my house was being crashed by a truck 3 or 4 times.

    The Reykjanes peninsula is a kind of hybrid between a transform region and rifting region. The plates move 45 degree in angle to each other. So stronger earthquakes (like in transform regions) happen here. But also large rifting events (though not as large as in the region of Laki and Holuhraun or Askja).

    The region seems to alternate every few centuries between behaving as a transform region, without any volcanism, and only occasionally large earthquakes, and then a period of several centuries with large rifting events across the four volcanic systems that occupy the peninsula.

    There seems to be evidence that the peninsula is now returning back to a more volcanic period. And this swarm is probably related to that.

    I cannot remember clearly now the way that the peninsula behaves during such periods, but usually the activity starts in one side and then gradually moves eastwards or westwards (I cannot remember exactly what the peninsula did during the last active period between circa 1000 and 1350; I think volcanic activity, as far as I remember, started east and moved westwards).

    I expect larger earthquakes, up to mag 6.0 to occur closer to Reykjavik, at Brennistensfjoll, Blafjoll (or even Hengill), as earthquake activity seems to be more in a locked state there.

    • I should mention that also, occasionally, shield volcanoes form in the peninsula. Usually between somewhere east of Krisuvik and Hengill, and extending towards Langjokull.

      Last shield eruption in Iceland happened actually in Langjokull around 1000 years ago, so relatively recent geologically speaking.

      • Would be nice to have a shield, an Icelandic Pu’u O’o. Shields seem to respond to deglaciation so maybe we will get a short burst of shield eruptions when the glaciers melt, at both Langjokull and at Bardarbunga, but probably not Grimsvotn which is a trapdoor caldera. An eruption lasting for decades in Iceland would be a boom for tourism.

      • I always enjoy reading Irpsit’s informed and informative contributions – thank you.

    • Welcome back! We hope that you have recovered well. This swarm is very close to the Thorbjorn inflation. That inflation ceased many months ago but I think set up the stress that pushed the fault into transforming. Note that the fault failed in two places, about 10 km apart. It is tectonic. It started near the surface and the aftershocks were deeper. Anything volcanic would have gone the opposite way.

      I don’t remember where the M5 quake last year was located.

      A few of the local GPS’s show movement from the quakes. Grindavik moved a bit northeast and Thorbjorn a bit north (both are located south of the transform fault), and Svartsengi (north of the fault) moved quite a bit west-northwest. I suspect that both the transform and one of the Riedel faults moved. But there is no indication of any rifting, just transform motion.

      • My point is that tectonic activity might lead to volcanic activity.

        A year or two ago, earthquake swarms near the blue lagoon (at Thorbjorn) resulted eventually in a magmatic intrusion too.

        Earthquake activity moved then eastwards. There was a M5 earthquake at Fragadalsfjoll in Jul 2020. That is some 8km east, of Thorbjorn (where an intrusion occurred). In Oct 2020 a M5.6 happened at Núpshlíðarháls, further east towards Krisuvik. And this swarm is affecting mainly those areas as well as areas just west of Krisuvik.

        My prediction is that we will see a large earthquake at Brennisteinfjoll and Blafjoll a few months from now. And then maybe activity developing at Hengill.

        Historically earthquake activity seem to unfold eastwards.

        I don’t expect an eruption anytime soon. These things take time. Perhaps a few decades from now.

        Grinsvotn, Oraefajokull, Askja, Katla are more likely to be the next options for an eruption.

        • This IMO plot shows where the previous quakes occured along the peninsula. Yesterday’s event filled in the gap between the two 2020 quakes, and also extended it a bit further towards Krisuvik. I expect that the next one in the sequence will be east of Krisuvik

          The IMO plots also show that there was a swarm of small quakes a few hours before big bang which may have triggered the failure. The regions remains very noisy but the aftershocks are mostly directly north of the big shake.

          • Two maps made using .

            First mapped are the M3+ eq’s in the period 26 02 2020 to 23 02 2021.
            There is a clear west – east pattern.

            Secondly M3+ in the period 26 02 2020 to 25 02 2021.
            The 5.7 in about the centre of the map.
            It overrides the pattern more or less.

          • Ah, its fun to play with this map!

            Same period, M4.5+.
            Showing the last eq filling the gap between the former eq areas, as Albert pointed out. But also the eastern path of the quakes.

          • Looks like the complicated pattern comes from the fact that the region in between the two quakes had already broken last year. There was no transform movement there. The transform of the two quakes pushed the immovable central region out. And it does indeed look like one or two of the transverse faults also failed. They carry the stress caused by the partial movement.

          • Here you can see the swarm that happened a few hours before the main quake, in the same location. The vertical axis is longitude, horizontal is time

        • I just read in a French blog on volcanoes (I don’t speak French – it has plenty of info in English!) that steam jets were reported coming out of the ground in geothermal areas in Reykjanes.

          Sounds like a magmatic intrusion to me, if not tectonic faults getting loosened up a bit, allow steam to escape more easily.

          • Yes, that is correct. There are two pictures of the steam doing the rounds. But it is a hydrothermal area so it is not too strange that the shaking has opened up pathways for the steam. It should quickly die down again. IMO raised the warning level on Krisuvik yesterday but as a precaution, I think, not because they are expecting an eruption. In the longer term, though, it is likely something will happen on the peninsula, as irpsit pointed out.

          • Is the blog They do a post once a day in both French and English, they are especially a good source for when Reunion is erupting, and I suspect also if Pelee wakes up in the coming years.

  26. Well, on april 1st, 2020 the tourist office decided that the eruption of april 16st 2020 should be pursponed, due to corona, to 2021. This is the preparation for that.

    quote from that article:”It was therefore decide to stop the on-going inflation. Completely cancelling the eruption was not considered because of the touristic impact. The eruption is instead rescheduled for 2021″.

  27. I was about to call an end to the KIlauea eruption, but that appeared premature. The webcams still show heat and smoke. But the SO2 is almost at pre-eruption levels, the GPS’s have largely returned to their pre-December positions and are stable, and little or no shaking. There are two notable changes: the tile meter at Pu’u’o’o show collapse (-25 microrad in a week), and the GPS’s south of the caldera have moved eastward. I wonder whether the magma that fed the eruption had collected in the upper end of the southwest rift zone: that seems to to fit the pre- and post-eruption movement there.

    • Interesting to have an eruption there, been nearly 50 years. Is also very similar to the early 19th century, those eruptions were long duration pahoehoe flows while lava was also erupting in the summit, just like Pu’u O’o, very safe and accessible 🙂 . I guess maybe a more vigorous eruption could happen like the one in 1974 though, but right now we are used to watching 2 hour fountains from Etna so a 10 hour eruption would be a long time…

      I think the Pu’u O’o signal might be just from the ground sagging locally though, its not exactly stable, it rains a lot and the tiltmeters are very sensitive. I would expect the deep 2018 crater is filling in still which means it is also slowly getting wider, a few instruments have already met their end this way.

    • Actually the SO2 is similar to Pu’u O’o lava after the overlook crater formed, so it is degassed. The question is where the gas rich lava is going, because the cross caldera GPS plot is rising at the fastest long term rate I have ever seen. The current eruption is probably if anything just acting to prevent a new vent opening, once it shuts down we get a new much more powerful eruption much like the beginning of this one in December.

  28. Africa haves unusual magmas
    Is there any stranger sillicate magmas than Nephelinite and Kimberlites? Whats the strangest and most unusual of potential sillicate magmas that coud exist?

    • Today would be Komatiite, even though geologically that would not be rare making it today is hard. Its possible though, Kilauea Iki was actually very close…

    • Phonolites and Tephrites are strange too (superalkaline intermidante Sio2 andesites )

      But anything stranger?

    • The Nephelinite is a personal favorite the most sillica poor sillicate lava that exist!

      Certainly not common

    • Why do Diamonds not react in so deep, hot and pressurized (~750 km) birthplaces? Swimming in liquid Carbon or secured by a vacuum bubble?

      • It is stabilized by the high pressure. To change to another form of carbon, it would need to expand and it can’t do that. On the surface it can, but it requires a high temperature. On the way to the surface, it actually passes a region where pressure and temperature do allow for a change. Many diamonds don’t make it. These are kimberlites with carbon residuals where diamonds perished. The cooler eruptions are perfect for diamond survival.

        • Hmm I don’t know, I think there are too many possible reactionspartner like oxygen or sulfur for the two (or more) carbon-modifications around in this climate down there…

          Would you expect to find much higher Diamonds concentration (carats per m3) in much deeper mines than the one they use today? Do you know any statistics with carats per m down?


          • All I know is in here:

            Diamond are found in the pipes, down to 2-3 km. Below that the pipe turns into a dike, and you do not normally find diamonds there. They need to get up as fast as possible, before the heat turns them into graphite. getting stuck in the dike is bad news. The eruptions that bring up the diamonds reach close to Mach 1!

          • Thanks Albert, nice post too, but there are some questions about this statement:

            “The eclogitic diamonds tell us that subduction existed 3 billion years ago, and therefore plate tectonics is at least that old.”

            Would the CO2 respiration of earth also be a proof for subduction of tectonic plates?

          • The reason for this is that the earth formed from volatile-poor material. There was very little water and CO2 ice here (this is different from Mars). These things came later. CO2 rich material in the mantle is likely to have come from the surface – i.e subduction.

    • An entire heard of elephants was encased by nephelinite in the 1977 eruption. Sometimes just severely charred and covered by a glass caparace. This flank Nyiragongo eruption lasted less than 1 hour.. rapid draining

  29. Is fresh magma constantly rushing in from the mantle below into the Etna? How big is the chance that the Etna will do a VEI 6?

    • It basically cant, you actually do need silicic magma for a VEI 6. This isnt because if the viscosity but because silicic lava tends to have more trapped gas, because fractional crystalisation concentrates the volatiles in the remaining liquid. You can get VEI 6 hydrothermal eruptions like at Masaya, which can basically ignore that technicality but Etna is not at all suited to that. I doubt it even has that capability at all now actually, there is probably no water anywhere close to its summit vents because of the heat abd its likely been that way for decades now. Even if that isnt true the biggest scale we are looking at is maybe a high 4 or low 5, not anything like a 6.

        • Yes large volume basaltic eruptions are going to be effusive. The exceptions I am aware of all involve water. There are a lot of basaltic volcanoes with capability to do eruptions of VEI 4 scale without water though, which is still a big eruption and one that could do a lot of damage. Etna is probably the most dangerous of these because like Kilauea it has gained a reputation of being ‘safe’. Kilauea has shown its true colours this decade and its now well accepted it is not at all a safe volcano like we thought in the 20th century, but Etna has not had a dangerous eruption in living memory, so now a million people live next to it…

        • How does the current erupted material compare to the picrite described in the paper, on the primitive-evolved scale?

          • Picrite is basalt that contains a lot of olivine. As a whole it is ultramafic but the actual melt is normal basalt. On occasion though you do get lava with the same composition as picrite that actually is a total or near total liquid, but as far as I know this is only erupted in Hawaii, and infrequently, last time was in 1959, normally this magma cools down a bit in the magma chamber. This lava is basically the same as komatiite, except that the ancient lava that actually is called komatiite as a rock was erupted at 1600 C, nowhere can erupt that hot today.

            I would expect if there is an actual comment on the matter that the recent eruptions could be somewhat picritic, but its hard to do a detailed analysis in a week and it would be dangerous to go and collect lava samples.

    • She’s done a couple of VEI 5’s according to GVP. No 6s recorded. I guess the time to worry is when she produces another caldera or there is any edifice failure?

      • Yes one of those was in 122 BCE and was observed, that caldera is still visible as a flat area around the summit though it is well filled in now.

        Flank collapses probably dont have a big risk of eruption, the Valle del Bove doesnt actually reach to the summit vents so probably the original collapse stopped short. There were VEI 6s in the Pleistocene but Etna today is a very different volcano than it was then, there was a lot of evolved magma where now it is all primitive basalt, and the supply now is also a lot higher which stops magma from stagnating on the way up.

  30. Giggle translate
    “Horizontal records of GPS telegraph stations on the Reykjanes peninsula (blue arrows) between 23 and 24 February 2021 together with model calculations (black arrows). Red circles show the reviewed locations of earthquakes on 24 and 25 February from the Icelandic Meteorological Office. A white star shows the source of the main earthquake that occurred at 10:05 on February 24th. Green circles show the locations of GPS measuring points, measuring instruments are only permanently located where blue arrows are shown on the map.”

  31. Etna is taking a bit longer than before to erupt, its overdue to follow its recent cycle. Maybe that shouldn’t be surprising after the last episode but it does bring up the question of whether its next paroxysm will be bigger again than the recent series. The original gap was 30 hours and then after the first 1 km fountain it took 48 hours, but the next paroxysm was huge, and then they followed regularly again at 48 hour intervals. Now we are past that again, and the last paroxysm saw a lot of extra vents open, the next one could be very interesting.

  32. After today’s crashes, the fire outbreak forecast changes. Based on the quake from noon yesterday until 5 pm today, the forecast is according to the picture. As before, it is within the fiery red areas that eruptions are most likely to occur. Compared to our previous post, there has been a big change in the forecast map. The most likely areas are near Trölladyngja. Once again, the forecast map is based on underlying research in Reykjanes, with the addition of the events that took place today. The next step is to run lava simulator models and see where lava will flow best in the event of an eruption. Somehow when it’s done it comes in here.

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