Pelean eruptions – the catastrophe of 1902 in the Lesser Antilles.

The recent eruption of La Soufriere volcano in Saint Vincent island reminded me of the events of 1902, of the tragedy that was unleashed by the two Caribbean volcanoes, La Soufriere and Pelée. Our current method of ranking explosivity, the VEI, doesn’t capture at all the violence of these two eruptions nor any of their kind. To avoid another disaster like this from happening it should be understood how these eruptions happen, how big they are, and how they deal their damage, and because our models and classifications do not make any justice to their real intensity, I decided to do an article that fully focuses on this style. This article is about Pelean eruptions.

The eruption of La Soufriere in Saint Vincent, 1902.

La Soufriere was a beautiful, lush, tropical mountain, topped by a large bluish-green crater lake enclosed in steep, verdant walls. But it also had a bad reputation. La Soufriere had produced major explosive eruptions in 1718 and 1812. It was probably for this reason that the local Carib people were very wary of the mountain in which they were living. When frequent earthquakes started to be felt in the month of April the people living on the western slopes of the volcano  prepared for evacuation.

La Soufriere before the 1902 eruption.

May 5th , the day before the climax, a column of steam rose from the crater, and soon the western slopes were being vacated at full speed, with the few available boats being sent to the northern coasts to carry the news and rescue people. It happened though that the summit was constantly shrouded in clouds, due to the trade winds, when seen from the eastern and northern slopes of the mountain, so they didn’t see any of the steaming nor the incandescence that could be clearly seen from the settlements on the other side of the volcano, and because  no earthquakes or rumblings were felt either, most people in these areas had no knowledge of any unusual activity until only 3 hours before the climax, and then it was too late.

It was May 6th. At 11 AM the volcano entered a phreatomagmatic eruption with the typical ink-black jets of mud shooting water from the lake onto the ravines around the crater and pouring in powerful lahars down into the Rabacca and Wallibu rivers. Explosions were heard and light rains of pumice and ash came down to the east. Only now did much of the population on the cloudy, windward side realize an eruption was underway. Many people at this point went into hiding inside houses or cellars.

A little past 2 PM those around La Soufriere heard a loud roar and an increase in air pressure which made their ears hurt. A gigantic explosion had sent a wave rippling through the atmosphere. The huge volume of ash and gas came down in a huge pyroclastic flow that within a few minutes swept down from crater to coast, engulfing a radius of 4-7 kilometres all around the vent, and leaving death and devastation in in its way. The flow burned and uprooted trees. As it came down to the shore, where most of the people were, it had lost much of its destructive effects and it did little damage to trees or buildings, but it was hot enough to kill every person and animal who was out in the open. Most of those who were inside houses and huts died too while a few survived. Instead, those who had previously taken refuge inside cellars all survived. There was one case where a men and his wife, who were hiding in a cellar with 70 people packed together, had decided to take a breath of fresh air only to die just outside.

Wallibu river valley filled with pyroclastic flow deposits, craters are from secondary steam explosions.

The 2 PM explosion and pyroclastic flows came to be known as The Great Black Cloud. This is the account of some survivors who had evacuated the area, but then returned to retrieve some of their belongings, and on their way back from their village were caught in the edge of the cloud:

“The sea was perfectly calm and the day clear, though there had been a few drops of rain in the forenoon. The boat had just rounded the point south of Richmond River and was on the north side of Chateaubelair Bay. The cloud struck them like a strong breeze, though, being under the shelter of a high spur of land, they did not feel it much. Still it came over the water with a strong ripple and a hissing sound, due to the hot sand falling into the sea and making it steam. In a moment it was pitch dark and intensely hot and stifling. The cloud was highly sulphurous, and this irritated their throats and nostrils, making them cough. The heat was terrible and the suffocating feeling very painful. They threw themselves into the sea to escape burning by the hot sand. It does not appear that the surface of the water was boiling as it was in some other cases. They all dived, and when they returned to the surface the air was still unfit to breathe and the heat intense. So they continued to dive repeatedly, but when they came up again the air was almost as bad as before. How long this lasted they cannot tell, but they thought it might have been several minutes.”

La Soufriere then entered a sustained plinian eruption that lasted for 12-15 hours. Darkness fell over the whole of Saint Vincent, and ashfall extended to neighbouring islands. As much as this stage frightened the population it was relatively harmless, and except for some of the larger raining stones which, falling at an angle due to the trade winds, broke crystal windows and injured a few people, and some lightning which set the vegetation on fire, the plinian eruption otherwise did little damage. In many locations the ash and pumice was soon washed away by the first torrential rains and everything was back to normal. It was the part of island hit by the 2 PM explosion that was destroyed, and it was because of this brief event that 1600 lives were lost. The culprit was a singular but terrifyingly powerful explosion.

Rabacca river valley. The trees were broken by the pyroclastic flows of 2 PM.

The eruption of Mount Pelée.

It is quite surprising that barely 18 hours after the eruption of La Soufriere, and on a nearby island, Mount Pelée would bring an even bigger volcanic calamity, even though there is no apparent connection between the two events.

Before 1902 the summit of Pelée was a horseshoe shaped crater. The crater was known as Etang Sec, it was bounded by walls 300 meters high except towards the southwest where it was open, in the general direction of Saint Pierre, the city that would be destroyed. The pyroclastic flows in May 1902 advanced much further in the southwest direction, 9 kilometres, than to the other sides of the cone, 3-4 kilometres, which was perhaps due to the topography of the crater.

Map showing the devastation area from the May 8 blast that destroyed Saint Pierre, and the even bigger August 30 blast that destroyed Morne Rouge. By NordNordWest.

Unlike with La Soufriere the people around Mount Pelée did get plenty of precursory activity. The crater had been in eruption for several days, and had sent some lahars through the breach into the Riviere Blanche. However Pelée had already erupted in 1851, and this eruption was small. While many in the villages closer to the volcano did flee, mostly to the city of Saint Pierre, it was considered that Saint Pierre was at a safe distance, and this would be true if the 1851 scenario was to repeat. However volcanoes like to throw some variety, and had they known of Pelée’s previous eruptions, in the geologic past, they would have probably reconsidered their safety.

The eruption was not showing much sign of escalation either, eruptions were frequent but remained relatively small. All of a sudden, at 8 AM on the 7th of May, the top of Mount Pelée exploded with a roar that was heard all around the mountain, pyroclastic flows shot through the breach in the crater towards the city of Saint Pierre and the harbour. The blast broke away trees, blew down buildings, twisted iron beams, sent statues flying, while the temperatures of more 300-400ºC set everything combustible ablaze so that the whole city was soon enveloped in flames. The destruction was much worse on the northern side of the city, than on the southern side, where farther away from the crater the buildings were less damaged, although there was not a roof intact. Several ships that were on the harbour caught on fire and sank. After the pyroclastic flow powerful winds blew towards the destructed area and there is a description reminiscent of a fire tornado.

Saint Pierre before the eruption. From Lacroix, 1904,
La montagne Pelée et ses éruptions.

 

Saint Pierre after the eruption. From Lacroix, 1904.

An observer from Morne Rouge stated that the “burst of rocks” rose no more than 50-100 meters above the crest of the mountain, a maximum of 400 meters from the crater floor, quite low, and as I will further discuss later shows how the eruption clouds of pelean blasts move low over the ground. Several witnesses of the event indicate that the pyroclastic flow travelled in 1 minute from the crater to Saint Pierre, at an speed of 400 km/hour. The destruction was terrible and practically everyone within the city lost their lives, an estimated 28,000 casualties. Because of this there are very few accounts of how it happened. This is the description from Captain Freeman of the Roddan, the only ship on the harbour that escaped destruction:

” At about 8.15 he was in the chart room; a good many of the sailors were leaning over the side of the vessel watching the distant mountain, which was emitting dense clouds of smoke and occasional flashes of light. Mr. Campbell was talking to Mr. Plissonneau on the deck. On a sudden he (the Captain) heard a tremendous noise, as though the entire land had parted asunder. Simultaneous with the noise there was a great rush of wind, which immediately agitated the sea, and tossed the shipping to and fro ; he rushed out of the chart room, and looking over the town and across the hills he saw a sight he cannot describe. He remembers calling out to Mr. Campbell, and saying : ‘ Look ! ‘ —then an avalanche of lava was upon them. It immediately caught the town afire as it passed over it, likewise the shipping. It struck his ship with the force of a mighty hammer, and the lava rained upon the deck. Everyone, as far as he could see, sought shelter at once, but the heat was so great, and the air so suffocating, that Mr. Campbell and many of the crew, among whom was the chief mate, threw themselves in despair overboard.”

Pelée continued to erupt until 1905, producing occasional explosions with pyroclastic flows, and grew lava domes including a 300 meter high spine known as the Tower of Pelée, which later crumbled into rubble.

Pelean eruptions

The explosion that destroyed Saint Pierre and The Great Black Cloud of La Soufriere at 2 PM cannot really be classified as plinian eruptions. The two events did not involve tall eruption columns at first, instead the material travelled horizontally from the vent over the ground in the form of pyroclastic flows, or pyroclastic density current that is how they are now being called. The volume of material that is erupted within a brief span of time in the explosion is so large that can’t possibly mix with surrounding air fast enough and become buoyant, instead the heavy, dense volume sweeps over the ground at enormous speed in a devastating blast, and it is only now as it advances over the surface and mixes with atmospheric air, which becomes heated and expands, that the pyroclastic flow inflates up into a buoyant plume known as a coignimbrite cloud.

Scientists of the time understood that the two eruptions of La Soufriere and Pelée deserved to be made into a class of their own. This is when the term pelean was coined.  The eruption of Lamington in 1951 was also classified as pelean. After Lamington the term became somewhat forgotten and little used, and the type of eruptions that it had initially been created for remained little studied. Pelean was replaced with the term lateral blast, that stands for the same thing more or less, but seems to imply that the explosions come out laterally which is not true most of the times.

This is the exact way that pelean type eruptions were defined for the first time:

“Eruptions of the Pelean type are distinguished by the occurrence of one or more discharges of incandescent sand, which rush down the slopes of the mountain in the form of a hot-sand avalanche, accompanied by a great black cloud of gases charged with hot dust, which sweeps over the country with a very high velocity, mowing down everything in its path. All living beings within the zone nearest the crater are killed ; all plants reduced to charred and broken stumps. At greater distances men and animals are scorched by hot sand or mud ; plants are burnt, eroded, and stripped of leaves and branches ; but beyond the limits covered by the great black cloud no effects are produced, other than those consequent on the rain of ashes which precedes or follows the avalanche.”

This basically means eruptions with pyroclastic flows. While it is true that many types of eruptions can have them, which the authors were not aware of at the time, the 1902 eruptions of La Soufriere and Pelée do stand out for the massive scale of the flows, and the style in which they were erupted is distintive. A huge violent burst. It is similar to vulcanian explosions but much bigger. Vulcanian grades upward into pelean so it is just a spectrum between the two types.

What drives pelean eruptions? The sudden expansion of gases within the magma column or the flashing of groundwater into steam is what ejects a large amount of dense material. For this it is required that the pressure acting on the gas suddenly drops. Why this happens is not obvious in most cases. I am tempted to say that a clog seals the vent which causes magma pressure to rise in the conduit below, then when the clog is breached it explodes. In reality many volcanoes that have gone pelean were erupting just before the big blast came, so that it doesn’t look like the vent got plugged in any way, suggesting that it is more complex than this, and that such a simple reasoning would not be useful in any way.

Maar-type eruptions have a more obvious trigger. For example during the eruption of Tarawera a dyke of basalt lava intruded below Lake Rotomahana, which was a geyser field, and as the water came into contact with the magma it became superheated. When this natural, gigantic pressure cooker found a way out through the cracks, that the dyke itself was opening up, it simply blew up the whole lake in a very pelean way, and blasted away the famously beautiful Pink and White Terraces. It left behind a huge crater with a lake that was larger than before. This is called a maar crater.

Another obvious trigger is a dome collapse, or a landslide like how it happened to Saint Helens in 1980. There are suggestions that a landslide was also what started the eruption of Lamington in 1951. The lithostatic load is suddenly reduced which frees the gas to expand violently, and blows the conduit from within.

The eruption of Mount Saint Helens was closely monitored and is an insightful example. The pyroclastic flow it produced was so immense that it blasted down forests up to 20 kilometres from the volcano, which is an area far more extensive than in La Soufriere and Pelée eruptions. There are many photographs of the disaster that were taken from multiple angles around the mountain, even from a plane flying above its summit, and also the famous series of photographs taken by Gary Rosenquist from the northeast of Saint Helens.

Physical models created after the eruption together with the photographs captured during the event show how quickly the material is ejected. Saint Helens discharged 0.19 km3 of ash into the pyroclastic flow, or pyroclastic density current, that later swept northward, and this was within the span of 20 seconds This means Saint Helens reached VEI 4 in less than 20 seconds.

Mount Saint Helens erupts on May 18th. 1980. Photos from Gary Rosenquist.

VEI means Volcanic Explosivity Index, and while it is meant to measure explosivity it would still make no distinction between Saint Helens, and any other eruption that took hours or days to produce the equivalent volume, because VEI considers only the total amount of ejecta, whatever the eruption rate or style. Seems absurd doesn’t it? But it goes beyond the VEI, because the overreliance on this way of classification also reflects the aspects that we give most importance to, the total volume, and the column height, both very poor indicators of the destructive consequences that powerful brief explosions unleash. It does turn out that the vast majority of pelean eruptions are VEI 3.  The eruption of Lamington in 1951, which flattened the tropical forest over a radius of 12 kilometres around the volcano, had a volume of “only” 0.025 km3, and the same is true for the eruption of Taal in 1911 and many others. Often a pelean event reaches VEI 4 or more only when there are other stages in the eruption that produce a greater volume. The Volcanic Explosivity Index is so flawed that there are fire fountains which can be watched safely from up close, in the same VEI 3 slot as eruptions that could blast away whole cities.

Sparsely a single short explosion can have a volume of >0.1 km3, like with Mount Saint Helens, and even more rarely they may reach a much greater scale during caldera-forming eruptions. Krakatau volcano erupted in 1883 with an initial plinian stage during the afternoon of August 26.  The following morning came a series of 4 powerful explosions, I’d say pelean type, that produced massive pyroclastic flows, tsunamis, and killed 36,000 people. The largest of Krakatau’s explosions was heard 4800 kilometres away, and is estimated to have been 8 times more energetic than the blast of Saint Helens.

Pelean eruptions the most dangerous for many reasons, mainly: pyroclastic flows, lahars and tsunamis. A crater lake can be ejected into lahars during the initial explosion. The massive pyroclastic flows that ensue can generate lahars when they move over a glacier, like with Nevado del Ruiz, and can displace the water of a lake or the sea into a tsunami, like with Krakatau. Tsunamis and lahars extend the damage of the pyroclastic flows to greater distances.

The coignimbrite cloud

Initially the pyroclastic cloud is way too dense to rise so instead it flows laterally over the ground like a sheet. As it advances it mixes with external air increasing the temperature of the later, which becomes buoyant, so that the top of the flow inflates with hot air and rises in a powerful updraft, known as a coignimbrite cloud or plume. This creates an area of low pressure, drawing air inward, and often this inflow is strong enough to reach hurricane wind speeds that can deal damage on their own.

The eruption of Pinatubo in 1991 had a series of precursory eruptions before the climax, the first four of which were plinian, which were followed by thirteen pelean explosions with shockwaves and giant pyroclastic flows. The following image shows the coignimbrite cloud of one of the explosions, 8 hours before the climax. The line of mountains is 1 kilometre tall as a reference. The photo was taken only 6 minutes after the eruption started, which shows how fast the pyroclastic flows and coignimbrite cloud grow.

From USGS.

The shockwaves allowed the precursory explosions of Pinatubo to be identified. Pelean erutions make powerful shockwaves. This is why measuring the infrasound waves generated by volcanic eruptions might be the only way to accurately detect the individual pelean explosions, which otherwise are very sneaky, they happen quickly, often shrouded in the darkness of ashfall, and moving very close to the ground, as shown by people that were caught in the edges of Saint Helens’ pyroclastic flow, who often didn’t see it coming until it was upon them because it would be hidden behind trees or hills. The coignimbrite cloud then shoots upwards from the pyroclastic flow and would be detected by planes or satellites, but even then it can’t be distinguished from a typical plinian column unless you have a visual of the broad base, which probably isn’t the case.

Conclusions

There is too much attention being paid to the plinian style, a sustained jet of pyroclasts, gas, and hot entrained air that rises up into the air into a lofty umbrella. The VEI is appropriate to measure the impact of a plinian eruption in such aspects like aviation or climate. However pelean explosions, also known as lateral blasts, are far more dangerous to the immediate surroundings of the volcano, as well as very important to understand how volcanoes work, and to how ignimbrite deposits are formed, so should be given as much attention as plinian and the VEI doesn’t rank them properly.

Pelean explosions are brief but powerful and they may occur isolated, intercalated in plinian or phreatomagmatic eruptions, or at the onset or the end. They generate massive pyroclastic flows that will most living beings in their path, so the area should have been evacuated by the time they happen or else the loss of life can be terrible. And lets hope that no large city is ever found in the path of a large pelean blast, again.

Further links

History of La Soufriere and Pelée eruptions in 1902, definition of the pelean term, by Tempest Anderson and John S. Flett.

Gallery of photographs showing the ruins of Saint Pierre after the 1902 eruption of Mount Pelée.

Some photographs of Mount Saint Helens, including the devastating blast of May 18th, 1980. 

Another photo of the blast, Mount Saint Helens.

 

514 thoughts on “Pelean eruptions – the catastrophe of 1902 in the Lesser Antilles.

  1. Another wow for Hildur video!! Which brings to mind – I take it that over the years and or centuries the new lave will change its colour,at least from dark black to a brown.If that’s the case I take it does because rhe affects of our atmosphere gases on the lava.Am sure some smart cookie out there would know!

  2. All of the vents active in the last ~2000 years or so on Reykjanes, lava flows are still a work in progress 🙂

    https://imgur.com/a/7QuGxwY

    One thing I noticed pretty much immediately after finishing is that there are two areas on the peninsula that have not rifted in this time frame, one is where the current eruption is and the other is the valley that Kleifavatn sits in, which has had quakes as of recent… I dont know if there is any sort of alternation but it seems like the current cycle is opening these untouched areas instead of one of the rifts active in the last cycles.

    Not sure how this will play out, but Kleifavatn is a big lake and having a curtain of fire lava flood eruption go through it is going to be interesting, its a lot like Tarawera and so close to Reykjavik too…

    • Do you know the mantle temps under Azores?At least at Saõ Miguel It cannot be very hot or productive.. its both a transform fault and sometimes a bit spreading in some parts. The volcanoes are either very very stale alkaline sillicate calderas or monogenetic basanite cinder cone vents depending How evolved the melts are. The largest Island Saõ Miguel togther with Flores is the most ”stale”of the eight active Islands. Azores sits on somekind of leaky faults

      It does appear that most volcanic activity is on the Young Pico Island thats mostly alkaline basaltic and quite free of erosion, likley Here is the center of the Azores Hotspot. Most of Picos subarial basalt stratocone grew up during the holocene.. according to geological papers .. But I wonder If Thats true. But Pico lacks the stale volcanism of the other Islands

      • If the volcanism is mostly a leaky fault zone theres probably no extra hot mantle. I dont know if the Azores actually is a hotspot either, that idea was because the islabds form a line like Hawaii, but unlike Hawaii volcanism doesnt get older in one direction or the other, all the islands seem to be active just not very much at any location. Pico probably is not all Holocene, it would be impossible to tell if it was an entirely Holocene construction or an older cone covered in Holocene lava, but given it has not erupted that much at all historically it is probably the latter option. To create a massive cone like that in only a few thousand years would need a powerful magma source which would be visible today some way or another, but theres nothing like that.

      • There is extra magma production near Pico
        Most of that Island is a Late Pleistocene product. Pico is the youngest Azores Island. Its much younger than the other Islands according to deep drilling dating I think.
        IF there is any hotspot at all, then its located at Pico – Faial.

        But most of Azores are result of magma interacting with leaky faults. But leaky faults themselves Probaly woud not be enough to form the quite sizable volcanoes of the Azores. Its the existence of the Islands themselves that raise ideas of a Hotspot that sends magma into these faults.

        The Azores plateau are also extensive igenous basalt outpurings and is very much thicker than normal oceanic crust so close to a spreading center. Azores Plateau coud be an ”handprint from underground” by a dying mantle plume hotspot?

      • Here chad is the Azores Plateau.. the Igenous Province that Azores sits on.
        Its almost certainly the product of a Hotspot thats been active in a short pulse.
        On top of this oceanic plateau is 100 s of seamounts and the Azores Islands themselves.

        Its this plateau thats tought by Some conspiracy theorists to be the sunken continent of Atlantis. But its too old to be Atlantis and continents are NOT made from oceanic crust.

        Azores Plateau is miocene in age and probaly the inprint of the dying Azores hotspot on the seafloor. A much much stronger and vigorous version of this is Iceland.

        • Triple junction or hotspot…
          I don’t think the extra magma production is down to a mantle plume, more like edge driven convection and a thin lithosphere.

        • The litosphere is even thinner on some fast spreading oceanic ridges.. and they lack these igenous plateaus…. Oceanic Plateaus are pretty much always the result of a plume…but Azores is a weak example.. compared to Iceland. There are some geochemical signs that its a product of a plume. The Azores Plateau are also Thoelitic… with later Alkalines on top..suggestions that its a dying hotspot…

        • Its a triple junction… but somekind of hotspot.. maybe required to built souch relativly large volcanoes over leaky faults… as well as the Azores Plateau… go south on the MAR and there is no plateaus at all

        • This looks a lot like a failed third arm rift from a triple junction to me. If so, the Azores is not a hotspot, it’s akin instead to the Cameroon Volcanic Line.

        • Azores haves a strong helium signature… that only Galapgos, Iceland and Hawaii have otherwise… so perhaps.. this seemingly weak plume.. is acually a dying deep structure?

  3. It seems that the shallow eq appered again and guess what…besides the twins area….there is 3.3 km SW of Keilir a dot that crak compulsively at about 0,1km deep….do we have cam there around?

    • The only camera that would potentially cover that area, is the Keilir camera at Vogar, but it would need to zoom out. There have been shallow quakes around that area for a few weeks now, centred just to the west of Litli Hrutur and Kistufell.

      • hahaaaaa…nice aliniagment with the active fissure….and yeee the langholl cam could be turned around…anyway in the present position doesnt show much. If i were it tech I’ll turned it starting now….

        • It’s possible that they placed that camera there, in case of eruptions further north. The shallow quakes a couple of weeks ago were a little further west than they seem to be now. They are more centred around Litli Hrutur now, instead of to the west. In this area though, the laval would most likely flow west, before heading northwest or north towards the gap by Langholl. This would eventually give it access to the low ground towards the airport road.

  4. Excellent article, thanks!

    I think what you are seeing is actually two explosion phases. That seems the case with the current eruption, but this is not as obvious as the 1902 one.

    What happens is this: a local change causes a limited explosion in the throat of the pressurized volcano. In 1902 that was a phreatomagmatic phase in which rising magma interacted which a crater lake. There was no crater lake this time. Instead what you had was a dome forming. Eventually the dome became so big that gravity caused a partial collapse – which became a cataclysm because the dome was like a cork in a champagne bottle. Once the cork fractured the pressure underneath caused a Plinian outburst.

    The account of the sea captain in the bay of St. Pierre reminds me very much of the eyewitness accounts from ships near to Krakatau in 1883. Several accounts were published in the Royal Society report – which is a fascinating read. It was amazing that some sailing ships which weren’t many kilometres away from the island survived the four titanic phreatomagmatic blasts when sea water gained access to the throat of the volcano. I very much recommend that VC readers read the report, which freely available at the link below. The pumice rafts stranding ships years later is a fascinating aspect of the whole episode.

    The Eruption of Krakatoa and Subsequent Phenomena (1888)

    • There’s also a lot of steaming on other places. On Geldingadalir cam (12:59) for instance, just in front of vent 3, and especially on the last vent (most left). Also visible on the MBL cam.

  5. I tried to find s.th. about the Caribbean plate and the Lesser Antilles. There must be new stuff, but it is rather difficult. Either I have to be logged in or it’s French or Spanish. But I found an old paper (PDF) which is very detailed splitting the islands in The Windward Islands South, newer, and the Leeward Islands North, older, Martinique in the middle with an intermediate origin. So who’s interested in the geological development there, might like this: http://deepseadrilling.org/78a/volume/dsdp78a_07.pdf
    There’s considerable debate about the origin of the Caribbean plate, several theories. I’d be happy if the authors here tackled the subject at some point. I prefer the theory of the origin near Galapagos, but this is a non-scientific attitude. It’s just more exciting. On the other hand it bears some plausibility because of 1.) the thickness of the Caribbean plate being similar to Galapagos, 2.) the extinction of the South American dinosaurs and their deserted eggs that were found fossilized in Patagonia. This happened around 25-30 My before the Chixculub impact, around 90-100 Mya.

    • Dinosaurs didnt go extinct in South America 90 million years ago… There was a minor extinction event at that time but it was mostly in the ocean, that is when Ichthyosaurs went extinct most notably, and also Pliosaurs and Thalattosauchians. On land the only major group of dinosaurs that went extinct were the spinosaurs and carcharodontosaurs both being apex predators so not surprising, and maybe most or all toothed pterosaurs but those were already rare, as I said it was mostly in the ocean which is much more fitting to a submarine LIP anyway.

      • “Patagotitan lived during theLate Cretacious period, between 102 and 95 million years ago, in what was then a forested region.[” en.wikipedia. So far the biggest plant eater, found by a shepherd. It was a rather big fossil found. There were also lots of eggs. It might have been the subducting Nazca plate and the late Cretacious volcanism of Aconcagua and surrounding mountains. It’s assumed that there were hot springs like in Yellowstone while Patagotitan was alive, and that she placed her eggs in the mud near the hot springs. Big reptiles today, Komodo dragons or Galapagos iguanas seem to love volcanoes, but too big an eruption or too much like the Siberian and Deccan traps brought them to extinction. So life and death, volcanoes. If you can see Attenboroughs film about Patagotitan on BBC, I can recommend it. Well done. The work was done by José Carballido, Diego Pol, and collegues. The best specimen had a length of 37 m (121 ft) with an approximate weight of 69 tonnes (76 tons),

  6. is everyone just going to ignore those quakes at Grimsvotn? I’ll take a flood basalt with extra tephra, with no pyroclastic flows.

    • Grimsvotn.
      Iceland Volcanoes are a bit like waiting for a bus. None for a while, then two at once LOL
      It would not surprise me.

    • I just wanted to point that out, too. 🙂 No doubt that Grimsvötn is slowly getting more and more restless.

    • I miss them already.
      I so enjoyed watching the hypnotic, pulsating lava as it oozed out of Smeagol.

      But maybe soon we will have new vents and that’s exciting!

    • There are only 2 or 3 active vents left, I think. Most of the lava seems to come from one

  7. With the exception of Vent #2 which appears to have quit the field completely, the vents that are no longer producing lava are producing a lot of smoke instead, much more than when they were active. Why is that?

  8. It’s looking very like the subdued activity that has previously preceded new vents opening. Anyone want to take bets on one opening near Litli Hrutur within the next 24 hours?

    • It’s a little to the right of the original signals when the first vents first opened up, but not far off. I don’t think it is possible to say for sure if it is the existing vents or something new from that angle, but it woulwdn’t surprise me if there was something to the south of the first vents.

    • Judging by the normal Keilir webcam, it could be the way the wind is blowing the gases, but I’ll have a look at the current wind direction.

    • i’ve not watched the keilir’thermal cam before… are the ‘flashes’ normal????

    • There’s been a pretty constant glow/cloud since the eruption began. Not sure if this looks different, possibly crisper focus or nearer the camera??

    • I am so angry. They can take their petty attention-seeking narcissistic poseur antics and shove it where the sun don’t shine.
      Interfering with a live scientific/ family friendly webcam feed. They should be traced and prosecuted for gross indecency.

  9. At 22:28 there was a flareup in the Norðri vent. A few minutes later, a new fissure appeared to be opening immediately to its north, in the low spot between it and the vent some have dubbed “Ragnar” that is feeding the current flow into Meradalir; quite evident by 22:39, unzipping and emitting significant heat and vog. The activity seemed to come in pulses with a period of a few minutes. At 22:44, Norðri flared up again. At 22:51, lava became visible in the new fissure immediately to its north, before subsiding again for a time. And at 22:56, some moron turns the RUV1 cam left a bit, away from the new activity!

    • And he’s somehow managed to f**k it up completely. Damned vandal. I hope ICESAR are nearby and arrest the jerk.

      • And it’s working again. Maybe they were able to somehow remotely reboot it. Or it was just an extended period of being swamped by signals from the grockle’s cell phone.

        Norðri and the new vents to its left are glowing weakly now.

  10. And some dickweed has messed up the RUV cam again. It’s extremely glitchy and unstable now and won’t give an uninterrupted view of the volcano for more than a few seconds at a time.

    Who do we talk to to a) get it fixed immediately and b) get some access barrier more robust than an ankle-high(!) ring of yellow tape put around the damned thing?

    • It’s now fully non-working again. Nobody has responded to my previous comment. Nobody has lifted a finger to fix this.

      I have done nothing wrong, and therefore I have the right to a continued view of the eruption site, since I did nothing to deserve having that taken away from me. How do I claw this back, and how do I enforce that nobody can ever again take anything at all away from me without due process of law? I.e., they have to haul me into court first and prove, to some substantial standard of evidence, that I do not deserve to keep the thing they wish to take away from me?

      I weary of being treated like shit! Whoever did this has ruined everyone’s ability to observe what seemed to be new vents beginning to open near the preexisting ones, just to harass me. That is outrageous and should not be allowed to stand. But nobody steps up to defend any of the other affected people, possibly including scientists studying the formation of new vents at the site, for one simple reason: defending them would require also defending me, and nobody is willing to do that. And so the camera remains blank, and the new and interesting activity in and north of Norðri goes unobserved.

      A travesty.

      • I understand people being upset about the obstructions. Some of the interferents are playful, some aggressive, and one deliberately insulting. It is not a good advertisement for the country. It is too bad that in Iceland, it appears a camera needs a guard to avoid not theft but abuse. But we have no ‘right’ here. We can watch the eruption courtesy of Iceland. But we are not providing the guard, own the camera, or provide any payment.

        I do still hope for a camera pointing at Meradalir. But with the experience so far, I can understand if that is not worth the risk to those providing it.

    • Seems to be fixed now. But Norðri and the vents immediately to its north seem inactive again, cold and dark. I don’t get it. Previously when new vents opened, they soon ramped up to vigorous and sustained activity, and Norðri returned to same. This time, it’s extremely intermittent and remaining so. It’s not behaving like it did the earlier times. I think there’s more going on than is visible through RUV1.

      I wonder what is going on at the site of those quakes near Litli Hrutur right now?

    • There has been intermittent splattering/gas emission on and off at or near this site from the very beginning. It’s near the deepest part of the former valley, almost certainly within the deepest area of grassy bog that filled the bottom (my dissertation was on the palynology of an English Lowland Heath, so I do have some expertise in this area). This has almost certainly been baked into a loignite-like substance which can burn and give off gases, like those seen at the baby Gollum vent at the beginning of the eruption cycle.

      If it were a true new vent, then it wouldn’t peter out.

    • Indeed that looks nasty. I glad they are going in the right direction.

    • The only people in the world now who have breathing problems without thinking of Covid. Thanks for the film.

    • Looks like this vent coud perhaps become the dominant vent on this single eruption

      • Does look like there is a lot more lava flowing here now than there was the other day. I think the reason the other live views look so weakly active is because you cant see this fountain in any of them, only fissure 3 is easily visible on the original live view and it isnt erupting much now, just a lava pond that occasionally spatters a bit.

        There also seems to have been some degree of intrusive activity this week, no new vents yet but there were warm fissures reported south of the existing vents about a week ago, presumably meaning somewhere in or near Natthagi, it was never specified. It does though look like none of these will erupt, as the lava is all flowing out quite fast now from existing vents. The fact the lava flow turns into a’a on its own after flowing out of Geldingadalir despite the low slope angle suggests the flow rate is quite high, probably more than 5 m3/s that has been reported.

        This vent was designated as Ragnar by the stream too, lets see how big it can get 🙂

      • Erupting out beautyful picrite basalt .. and almost yellow despite being hit by direct sunlight.. this vent will be named ”Balrog Vent” after all Iceland is the most Tolkien looking place on the planet!
        I simply haves to move there!

        This coud be the final vent of this single eruption.. But more likley..yet more Fissures will open up as this dies down. ”The Hell Machine” is at work undeground by decompression melting

        • I doubt it is about to stop, the other vents are stopping because this one is an easier path but the effusion rate has not changed, its actually about 50% higher now than it was when the eruption began so if anything we are still only at the very beginning.

          I think the eruption will probbaly end up looking quite a lot like the bigger eruptions at Brennisteinsfjoll, like Hussfellsbruni, so basically a sort of a’a shield instead of a pahoehoe shield. If vents keep opening up along the rift though it will end up looking more like Lanzarote, it is probably not going to get as big as that but no one really knows for sure.

          What will be exiting for sure is if the eruption lasts for years and one of its neighbors joins in with a curtain of fire, lets just say there will be absolutely no doubt when Krysuvik or Svartsengi properly erupts…

          • I think that the eruptions of Brennisteinsfjöll also issued from a long rift in a way akin to Timanfaya, with long lived vents opening sequentially along the crest of Brennisteinsfjöll.

          • Some are along rifts but it looks like a few stayed in one spot the whole time so its a bit of both.

        • Ogmundahraun curtain of fire from Grindavik
          https://imgur.com/a/Vz2jrhF

          Eldvarpahraun curtain of fire from the same location looking the opposite direction…
          https://imgur.com/a/vRBlaZP

          Not sure exactly how good the translation is, but ‘Eldvorp’ supposedly means firework or firecracker, suggesting the fountains were very high and probably also pretty violent, possibly with a lot of water interaction where the fissure enters the ocean, it must have looked like the world was ending…

          • The compounds of Eldvörp are the noun Eldur (fire) and the verb Varpa (throw/cast (a little archaic), or lay [eggs])

            Fun fact, the Icelandic weird Eldvarpa means flame-thrower

          • Must have been particularly intense if it actually got the name of flame thrower, technically all eruptions do that but theres no other Eldvorp in this area, though there are a great deal of craters and cones called Eldborg and Raudhol.

            Theres also actually a very similar long fissure from about 2000 years ago, and it cuts right into the town center of Grindavik…

            It is such an onomatopoeic name too 🙂

          • A lot of those names were used by Tolkien too, for his dwarves. Dwalin, Balin, Kili, Fili, Dori, Nori, Ori, Oin, Gloin, Bifur, Bofur, Bombur, Thorin, Thror and Thrain. Those are characters in The Hobbit. I do like the idea.

            We should keep Smaug and Balrog for whenever an actual intense flood-like eruption happens.

          • Perhaps we should have a list of names similar to the ones that are often used for hurricanes or storms, and as new vents open up assign them those names.

            I did say that the location of eruption could keep shifting in a way similar to Timanfaya when there was still only one fissure, in the Reykjanes Fires article, so the prediction/hypothesis did come true.

          • Some of us in a fb geo group in Iceland have named them from south to north..

            Suðri, Norðri, Frár, Frægur, Glóinn and Draupnir.

            Last two had become inactive at the time so..Dáinn and Nár(both means dead in Icelandic:)

            Lava should be named Dvergahraun..Dwarflava.

        • The lava is superfluid now… really flowing smooth… but its well above 1200 C so thats not strange… starting to look like Hawaiian summit lava. Most other lavas on land are not this fluid

        • I can just imagine… how big the humid pyrocumulus convection must have been at the really big fissures and CAMP and Siberian Traps….. must have formed “Hypercell” convection over rootless dammed lava seas that coud have been 100 s of km wide

          • Hypercanes swirls over these flood basalts… feeding from the heat and volcanic water vapour : ) “Fire – Cane”

            But mostly severe LIP event was perhaps more like many Laki events going at once togther but each lasting many 100 s of years

  11. Hello Team
    What is going on 17- 20k,s below? Is there a magma chamber developing?
    As the lava rises reducing pressure a bit, more develops making a bigger chamber as it goes?
    And so on?
    Cheers Chris

  12. Not part of ‘the’ team but interested in the deeper quakes too… 😃

    Deeper quakes occur under some of the icelandic central volcanoes sometimes. Hamarinn (Loki-Fögrufjöll), Katla and Askja had some recently. The spot you prob are referring to is under the Vatnajökull glacier, a spot just east of Bardarbunga. What happens there isn’t quite clear and very intruiging. There might be a new central volcano in making. Or just some sort of magmachamber expanding. It is drawing attention the past years because of its steady deep quaking and is showing characteristic signals in the drumplots (best watch ).
    Volcanocafe has published some very nice articles about the phenomena called Greip in Volcanocafe.
    https://www.volcanocafe.org/greip-expectations/

      • I give up %$#÷=/:&& sigh
        The link does not show up for some reason. I am referring to djk highpass drumplot.

    • I dont think anyone really knows what Greip actually is, but I think it is basically the Icelandic version of that deep Pahala quake swarm in Hawaii, Greip is though shallower and probably not as intense.

      Its probably a bit of a stretch to say Greip is its own central volcano though, theres nothing actually right above it so if it is something it is new, and central volcano formation takes a long time. Probably it is a feed to Bardarbunga, which is very extensive much more so than is typically shown on maps, its overlap with Grimsvotn is also quite large and Greip is right in the middle of it all.

      • I do think that is an interesting possibility, Greip is very similar to Pahala except that it is much shallower. The magma of Greip must be going somewhere, if there are so many tremors that means a lot of magma is rising through, Bardarbunga is likely a option, particularly considering the relationship between Greip and Holuhraun.

        Bardarbunga is the most frequently rifting volcano in Iceland so it may well have has the highest supply. Other sources of spasmodic tremors similar to Greip may indicate the location of the feeders to other major Icelandic volcanoes, Katla also has a tremor source. The activity of these conduits could (perhaps) indicate the relative amounts of magma rising into the major volcanoes.

        • There were deep quakes at Greip before the Holuhraun eruption. I also think there was a paper suggesting it as a feeder for Bárðarbunga.

  13. The landholl webcam panned around to look north and there isnt any eruption there, looks like all the lava is erupting from Ragnar and that is taking from the other vents and they are closing up. I would be surprised if no more fissures open up at all but I dont think it will change much for a while now.

  14. Thanks Rob all very interesting stuff, but was thinking in terms
    of what is happening under Fagradalsfjalli. What might be happening down below the current eruption.
    I suppose it is really not known what is forming down there.
    Chris

  15. There is quite a high fountain now, its consistently going well above the height of the cone where it wasnt before. about 40-60 meters tall fountain I think, based on the time it takes for lava to fall from the apex (3 seconds, maybe a bit more)

    • Yes, it’s significant growth. Not as a Holuhraun yet, but there is an increment.

      • Perhaps gassy enough to form… reculite… and specialy if fountains get taller
        But only huge fluid extremely gas rich fountains does them in any large ammounts.
        Leilani 2018 was a fantastic reculite producer

  16. Missing eruptions spring to my mind when I read a sentence like this: “However, despite their significance, the Islands’ remote location means that no previous eruption has been monitored by a local, ground-based, geodetic, and seismic network. Consequently, there are no multidisciplinary studies of the volcanic processes underpinning Galápagos Island volcanism.” These islands are near the equator, and I guess before Darwin nobody would have noticed a volcanic eruption there. Just an idea. https://www.nature.com/articles/s41467-021-21596-4
    “Caldera resurgence during the 2018 eruption of Sierra Negra volcano, Galápagos Islands”.
    The location reminds me of Iceland, two plates, rift zone, hotspot, the volcanism is different though.

    • It is similar to Iceland, Grimsvotn is basically a Galapagos-type caldera. Galapagos volcanoes dont have long rift zones though, unlike Hawaii or Iceland. In the case of Sierra Negra though its ring fault is not well defined due to its caldera being wide and shallow so eruptions end up being long fissures on a line that loosely follows the north ring fault, an area called Volcan Chico. Thats where the eruptions in 1979 and 2005 were, and 2018 began there but later moved. 1980 was a massive eruption about 1 km3 of lava in 2 months, with an 8 km long curtain of fire, but is otherwise poorly recorded.

    • With so many orphan events, it wouldn’t surprise me if the Galapagos eruptions weren’t to blame for some.

      • Yes, and there was nobody, and before the Panama Canal the ships were further South. When scientists found out about the Orphan Tsunami in Japan around 1700 they asked the Oregon natives about the Ghost Forest in Oregon, finally, and some of the Natives (First People) knew about talk in their tribes that there had been something terrible around 1700 with whole villages vanishing. Since then Cascadia is more in the spot light. People’s memory is not unimportant. And from Peru/Ecuador to Mexico it could be interesting to look at location of the graves of the victims of sacrifice to the Gods (Inka). There are some on El Misti. They sacrificed children, when a chief died or when a natural desaster happend.

        • Concerning Cascadia a risk assessment was made, of course. It sounds awful for winter times and apocalyptic for a nice day in the summer. They might have done something about the flight paths by now. Nobody knows what a Tsunami would do to the bridges. I think it sounds pretty dangerous altogether. Without a big city like LA. Lots of schools and retirement homes close to the coast.

  17. The lava pond is expanding quite a bit now, both towards the north and south. It is a race for the exit

    • Given its been said that the lava is above the melting point of most rocks, its odd that the conduit isn’t melting itself a wide channel all the time.

      • I wonder if the demise of Smeagol/Gollum vent is something to do with a straightening out of the conduit. It must be pretty nearby, although not completely open; or the fountaining would be higher?

      • Its possible that it will happen at this vent… its around 1220 C I think so very hot..
        Most other basaltic lavas…. barely reach above 1100 C

        • I think that is the melt temperature (i.e. at 15-20 km depth), not the eruption temperature. I have not seen a number for the latter.

      • It cools as it ascends, and the viscosity keeps the hottest lava away from the sides of the conduit. There seems little evidence of any crustal melt getting into the magma

    • Aa lava too… and not strange with steep slope and faster eruptive rates… also feed by smooth liquid channels upslope

    • No need to apologise, I could watch that ad infinitum. Just think what the lavafall into Natthagi will look like if it happens…

        • Looks like we have a blockage happening on the south path soon. Several “floating” pieces may end up there at the same time (based on the sequence ’til 16.10 (Iceland time). It is a little bit as when the river ice starts to break up in spring in cold areas, blockage may happen…

          Look at the pictures from 14.10 ’til 16.10 here and you see what I mean:
          http://brunnur.vedur.is/myndir/listi/webcam_langihryggurN.html#

          • And it also looks like the southern flow is turning north into Meradalír now. The maps are indicating that this is the lowest path anyway. The older part of this section is what is blocking it right now, but that section is soon overtaken as well. Then the “road” (or rather the river) into Meradalír is open.

          • You’re right to point it out, the lava level in the corner is lowering and draining somewhere, from about 2pm onwards. In fact, so much so that part of the inner bank is left unsupported and breaks away.
            Edit: looking back on both the N and NW cameras, something happens at just before 12.20pm to kick up a cloud of dust. Behind it, on the N camera, there’s a small lava rapids as the lava drains southwards. I cannot see any evidence of a northwards flow, unless it’s happening inside a tube, buried within the eastern exit, and leaving absolutely no trace on the surface of it’s presence. The surface texture of the flow northwards into Meradalir is uncannily motionless.

          • This 3D map has to be my favourite, I think. Updated to 21st April, so still a few days adrift (but it’s an impossible task to have a contemporaneous model, and so much kudos is owed to the students compiling this model, because I know that I couldn’t possibly do it!).

          • If you look at this link

            http://brunnur.vedur.is/myndir/webcam/2021/04/26/webcam_langihryggurNV.html#

            the area that is expanding is the southern lobe filling the mildly moist area to the south and east, riding up the slope a tad. As of 17.10, there is no northern movement, it’s an artifact of perspective.

            The question now is, will the southern part of the lobe fill out enough to overcome the slight rise in slope to head south over the remaining cols towards Natthali? Which way round the little hillock will the flow go? Or will the northern part of that lobe get overriden by the rest and allow the flow to move back northwards, blocked as it will soon be by the northwestern slope of Langihyggur? We shall see in the next few hours/days.

            What I really need to learn is how to draw pretty arrows onto the geologic maps and models to explain better what I mean…

  18. A comment on the smoking vents, my best guess is that this is because sulfur vapor and sulfur dioxide is not being combusted, but is rising to the top of the fissure conduit due to its volatility and low melting point. It is able to cool enough to not ignite and continues from the vent as the thick smoke we see. If you study the 2nd cone from the left in https://www.ruv.is/sjonvarp/beint/ruv2 that the smoke is coming from the lava tubes.

    It would most interesting to get an analysis of this volcano smoke and see what its constituents are.

  19. The “Ragnar” vent (most visible on the mbl.is camera) is regularly chucking bombs 80m into the air. High enough to also see them on RUV1 occasionally, popping up from behind the backside of the spatter rampart.

  20. So two days ago when Iceland Uni last posted flow and size results for the eruption they also said the lava composition was changing. They posted two scenarios.

    The latter one was that this change could be a signal that the eruption was coming to an end.

      • The Earth is about to split in two and half of us will have to live on the moon.

      • Giggle translate because I’m really really bad at translating Geo language into english 😄

        New results on the chemical composition of magma:

        The chemical composition of the magma that erupts in Geldingadalur and flows down into Meradali has changed over time. The change is best seen in the weight ratios of external substances (those who choose magma over crystals) and can be interpreted in two ways. On the one hand, melts of different mantle material are mixing before the magma rises through the earth’s crust. On the other hand, the magma formed by less partial melting of the mantle material could be erupting at an increased extent. The second possibility of interpretation indicates less magma production from mantle materials, which over time will lead to the end of the eruption. Further measurements of isotope ratios help to choose between these interpretations.

    • Yes, that option should be considered. in that case the change is because the magma reservoir is being depleted faster than it is being replenished.

  21. The last two days have furnished plenty of additional evidence that RUV could still learn a thing or two from MBL about the care and feeding of wilderness webcams …

  22. The good old “Rückenfigur” composition of the early 19th century German romanticism:

  23. 20.41 on Geldingadalir webcam, very odd circulation pattern in the smoke from the vent at far left. Smokenado? Gas Devil?

  24. At 21:12 someone sabotaged RUV1 again. Started by turning it back and forth and eventually broke something outright as it then went black. This time I didn’t see who did it, even in silhouette; they stayed outside of its field of view. But someone turned it, and it blanked out while being turned, and presumably RUV would not blank it out, so presumably it wasn’t them turning it. It’s doubtful anyone else can turn it remotely, so whoever it was turned it physically. And then broke something, maybe by knocking a wire loose with rough handling.

    They really need to add some sort of security around that damn cam.

    I wonder why the RUV cams keep getting sabotaged like this but not the MBL cam? Does someone have a grudge against the RUV organization, perhaps?

    • This time it seems to have been fixed relatively quickly, within about 10 minutes.

      My opinion on the need for more security at the site is unchanged. This is happening too damn often, and now two nights in a row. Recall last night, it has been operating fine until someone walked up to it (and did get seen in its field of view) at around quarter to five in the morning(!) and fiddled with it, and after that it was unstable and increasingly glitchy and within 15 minutes had pretty much become nonfunctional. That time it didn’t get fixed for nearly four hours, probably because whatever damage the vandal did couldn’t be fixed remotely that time.

      If nothing is done, sooner or later one of these idiots is going to wreck the thing completely.

  25. Wow the fountain is huge now, twice as tall as the cone and sustained at that height too.

  26. “Ragnar” vent (fissure 5 or 6) now chucking rocks 120 meters straight up.

    • If someone coul sample those lovely tinkling glassy sounds, it would make a very cool musical instrument.

  27. I’m not seeing any flareups of light inside Norðri’s crater tonight, unlike last night. Why did it start to wake up again, only to stop again?

    • And in this one can also see that the lava will flow north into Meradalír from the current lava lake south-east of the cones. The lava is expanding north in the 10 minute picture sequences, but it is much slower than it was yesterday. But it is closing up to the slope down to Meradalír now.

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