1 million people visit Vesuvius each year. It is a big number which involves a lot of people struggling up the steep and dusty path to the rim. Rather more people visit the more accessible archaeological monument to Vesuvius that is Pompeii: counting those as well brings the total to 2.5 million. It makes it (reportedly) the most visited volcano in the world.
But that reported ‘fact’ isn’t true. Even including Pompei, Vesuvius appears to be only number 3. It falls well behind Yellowstone (4 million) and Mount Teide (3.5 million). Elsewhere in the world, Mount Fuji attracts 2.3 million, Mount Hood 2 million (albeit to the forest rather than the mountain), Auckland collects 1.7 million (many of whom may not realize what they are visiting), Etna sees 1.5 million, and Kilauea gets a measly 1.3 million. Who’d have guessed? Further down the list of volcanic glory, Taupo has close to a million visitors each year, Mount Halla (remember that one?) 900,000, and Mount Bromo 800,000.
It does depend on what counts as ‘the volcano’. Jeju Island, home to Mount Halla and entirely created by this single volcano, attracts a staggering 13 million visitors per year. And likewise, if Mount Teide may be substituted by Tenerife, its numbers increase to 6 million. These are a long way ahead of Vesuvius – and don’t you feel sorry for poor Kilauea? Of course, the large majority come for normal tourism and not for the volcano, so perhaps this is unfair competition.
Visitors to Tenerife are 8 times more likely to go up Teide, than tourists at Jeju Island are to go to Halla! The reason is obvious: there is not much else to do in the bleak (personal opinion) tourist resorts in the south of Tenerife – names of resorts such as ‘Oasis del Sur’ promise rather more than they deliver. I can recommend Puerto de la Cruz as much nicer, but it has less sun (a plus, in my opinion) and no beach (which is another plus).
At the other end of the ‘true volcano’ scale, Mount Erebus gets some 50,000 visitor each year, which is still rather more than I would have expected. Visits to Barren Island (the sole Indian active volcano) are very few (and uncounted) for reasons to do not only with the name but also with the fact that it takes a full day to travel there and back from the nearest habitation, and overnight stays are not allowed.
But there is one volcano missing in this list of volcanic popularity. Santorini, never listed, is visited by 2 million people per year. Many of the visitors may not realize that they just landed on a volcano, and would be worried to discover its devastating history – and its potentially equally destructive future. A bit of advice may be welcome: avoid travel insurance which excludes ‘acts of god’. Pele is hiding in many places, and she does not have a good reputation. As Belle says in Beauty and the Beast, there’s something in him that I simply didn’t see. (Admittedly she found the beauty in the beast, rather than the beast in the beauty.)
Santorini
‘Stunning’ is the appropriate word. The views of the white houses and blue domes below the blue sky, above the azure sea and the dark volcanic rim, attract tourists like moths to a flame. It is considered the most beautiful place in Greece. The most famous images are from the capital, Fira, but the whole island is exquisitely beautiful. Visit in summer and you may find the tourists shoulder to shoulder, crowding out the 16,000 inhabitants. Spring and autumn are better if you like some personal space. And if you don’t mind a bit of inclement weather, winter is the quietest time, albeit for a reason.
Santorini lies at the southern end of the Cyclades, a series of over 2000 islands which litter the Aegean Sea between the Greek main land, Crete and Turkey. Here, there is an island for everyone. Santorini, at the bottom of the Cyclades, is the crowning glory. But there is a something hidden in this castle. There is Beauty – and there is the Beast.
The geology here is equally fascinating. This is a complex region where several plates interact. We wrote a bit about it before. The Aegean Sea plate (a microplate) is being pushed southwards by the Anatolian plate (itself squeezed west by the Arabian plate). Southward, the African plate is kind-of subducting. Crete is the non-volcanic pushed-up part, while to the north of Creta a volcanic arc has developed. There are 12 documented volcanoes in this arc, stretching over 5 volcanic centres from Methana (near Athens) to Kos (near Turkey). Three of these volcanoes are submarine. Santorini is the best known and most active of those 12 volcanoes.
It is a volcano with history. Santorini is the site of the oldest known (and successful) complete evacuation of a town because of an impending eruption. It is also the site of the oldest known fatalities from an eruptive sulphur poisoning. (This ‘fact’ has not been fact-checked though.) Those tourists should perhaps feel a little apprehensive about the lack of indicated escape routes.
Santorini has had many names. The current name dates only to the 13th century. Before that time it was known as Kallisti, and before that as Thera, a name that is still often used but actually refers to an ancient city on the island. The oldest recorded name is Strongyli. This plurality of names already shows its age. There were thriving communities here as early as 6000 years ago (although we do not know what name they gave to their home). Santorini is located close to the major centres of early western civilization. Life here could be good.
Volcano!
The island has a funny shape: it consists mainly of a fairly thin arc which partly surrounds a large bay, with a steep edge dropping into the bay. The arc has a large opening on the east side and a smaller one on the northwest, so that it is not a single island. The central bay has all the hallmarks of a flooded caldera, and that is indeed what it is. At the centre are two smaller islands, Palaea Kameni and Nea Kameni: both are volcanic and were formed through ashy eruptions. These two islands are still volcanically active, are largely uninhabited, and are much younger than the rest of Santorini.
There are other volcanoes in the region. Christiana Island lies 20 km SW and the Kolumbo submarine volcano is 7 km NW, where the latter has erupted in historical times. There are also some 20 submarine cones. But Santorini is the volcanic boss here. It is a repeat offender: at least 12 explosive, Plinian eruptions have been identified. These happened in the past 350,000 years ago. The volcano itself is twice as old but the older volcanism was less explosive.
Santorini made headlines around 1600 BC when it single-handedly removed a dominant civilization from the eastern Mediterranean. (This well-known ‘fact’ has not entirely survived a fact-check.) The main city of the time was Akrotiri, and the people living there were the Minoans.
Akrotiri was already an ancient town. Although only rediscovered in 1967, it started more than 4000 years BC as a small fishing village. From 2000 BC it developed into a trading centre, with evidence for both pottery and copper. The copper was traded between Cyprus and Minoan Crete, whilst the pottery came from all over the Mediterranean. Akrotiri was more than a merchant import-and-export business: the copper was also moulded here. The town became prosperous. The houses were full of frescoes, a good indication of wealth.
The eruption around 1600 BC is one of the defining moments of the history of the eastern Mediterranean. Before the eruption, the shape of Santorini was different. The current caldera wasn’t there: instead there was a smaller caldera, also flooded, in the north of the island. This hole had formed 20,000 years earlier in an older eruption. There was an island inside this caldera, an older version of Nea Kameni. If you wonder how we know this, one of the frescoes found in the remains of Akrotiri depicted the landscape, complete with a fleet leaving and arriving. We know that the caldera was flooded because the explosion debris contains remains of stromatolites. Santorini itself was a round island – in fact Herodotus calls it Strongyli, ‘the round one’. Soon it wouldn’t be.
The Beast
Akrotiri came to a sudden end when a major eruption buried the town under meters of ash. It is now much like Pompeii: a buried town that was lost in history. Excavations of the town have shown us a window on the past, including those frescoes. But unlike Pompeii, not a single human body was found entombed in the ash. People apparently were able to leave in time.
The excavations of Akrotiri have shown that the eruption did not come out of the blue. It appears that the first trouble came from a significant earthquake, perhaps as strong as M7, which destroyed the town. In itself this is perhaps not unusual: this is an earthquake zone. The destruction from this event is seen in other island across the southern Aegean Sea: this was a larger tectonic event, a disagreement between the various plates. But Akrotiri was rebuild, more luxurious than it had been.
Perhaps 50 years later there was again serious damage in Akrotiri from an earthquake. There is a layer of debris on the streets and squares containing meter-sized blocks from walls coming from this event. People put up temporary housing while clearing debris and starting repairs. But those repairs were never finished. Some weeks or months later, Akrotiri was suddenly abandoned. The reason is not clear, but volcanic or earthquake activity is a possibility. The abandonment was well organized. The people took valuables with them (almost nothing valuable has been found in the excavations) and put food into secure storage.
A phreatic eruption now deposited a thin ash layer over parts of the island. There followed a hiatus during which things calmed down again. This may have been weeks or months.
The main event began with a plinian subaerial (on-land) eruption, from a location between modern Nea Kameni and Fira (neither of which existed, of course). It deposited as much as 7 meters of pumice and ash near Fira – although much less further away. Akrotiri received around 1 meter. This was a major eruption: the eruption column may have been 30 to 40 km high. As many as three pyroclastic flows are included in the layer.
The character of the eruption now changed to phreatomagmatic, as the vent moved south and dropped below sea level. The new layers of surge deposits are up to 12 meters thick.
The next phase was the most voluminous. It came probably from the same vent as the previous phase. There were further pyroclastic flows, but also mud flows which may indicate caldera collapse. The deposits are up to 55 meters thick (!) although that is reached only in valleys. The flows were unable to get over the caldera walls. Blocks up to 2 meters in size are included.
The fourth phase brought the ignimbrite as the eruption column collapsed. While the previous layers were mainly closes to the vents, this layer covers the outer areas of Santorini. Near the caldera rim they are 1-2 meters thick, but on the coastal plain they reach 40 meters. Together, these four phases may have lasted up to 4 days.
The volume of the eruption was around 33 km3 DRE, which would make it a VEI 6.5. There are claims for volumes which are 2-3 times larger but these seem based mainly on the size of the caldera. The caldera was in part already present before the eruption, and therefore this overestimated the eruption. This ‘fact’ seems too optimistic! The eruption was larger than that of Krakatoa, but although it is often compared to Tambora, Santorini’s Minoan eruption was not quite that size.
The eruption completely destroyed Akrotiri and buried it under 6 meters of ash. The 35-km plume pushed the sulphate into the stratosphere. However, the eruption was relatively sulphur-poor, and so climate impacts may have been limited. No clear sulphur spike has been identified in the Greenland ice cores, although there are a few candidates.
The date of the eruption is surprisingly poorly known. Tree rings, carbon dating and archaeology indicate that it happened sometime between 1650 BC and 1550 BC. But the local olive trees do not form good tree rings, and this also happens to be a period where carbon dating has large uncertainties. Recent papers have argued for slightly earlier than 1600 BC or as late as 1540 BC, not in particularly good agreement. Currently, a date closer to 1600 BC seems most likely, but this is a fact that might change.
(How can you read this? There’s no pictures! – Beauty and the Beast)
Tsunami
The eruption spread pumice rafts around the Aegean Sea, identified for instance extensively in Crete. It also caused a tsunami, which is often mentioned as widespread and catastrophic. The thick deposits off the coast of Santorini (up to 80 meters thick) make a tsunami more than likely, with the caldera collapse adding to it. Old Krakatoa’s eruption caused several tsunami waves for different phases of its eruption, and this has led to the assumption of a major tsunami event coming from Santorini. On the east coast of Santorini there are indeed thick tsunami deposits, especially in between the main pyroclastic flows. Modeling suggests the wave here may have been 35 meters high.
But there is only limited evidence for this tsunami elsewhere across the Mediterranean. Old tsunamis are difficult to identify: storms, flash flooding and tsunamis all produce similar deposits. (A possible sign is marine molluscs far above the high water line.) It is a bit easier when there is evidence for destruction of buildings, but even there, there is often more than one possible cause – including earthquakes. They can also be difficult to date.
Tsunami deposits associated with Santorini have been identified mainly in northeast Crete and in southwest Turkey. Claims for their existence further afield are more dubious. Some old studies find evidence for flooding mixed with pumice, but pumice will have taken weeks to months to get that far while a tsunami has to come very much earlier. Currently, it seems that a significant tsunami did affect the Aegean Sea and a devastating one hit Santorini itself (where no one was left to notice), but there is no evidence for impacts elsewhere in the Mediterranean.
An example is the ancient coastal city of Palaikastro on Crete. It was among the largest cities of Minoan Crete, and is a strong case for a Santorini-derived tsunamic destruction. There is volcanic ash from Santorini, plus a turbulent layer with marine shells which is carbon-dated to the era of Santorini. Further in-land, the ash-layer from Santorini is on average 5cm, in places up to 12 cm thick. The tsunami seems to have arrived shortly after significant airborne ash was deposited. Based on comparison with the 1956 tsunami, a 35-meter high tsunami at Santorini may have cause a 7-meter one at Palaikastro. The observed damage would in fact have required a 9-meter high wave, so this seems consistent. It was sufficient to inundate the town entirely.
Çeşme-Bağlararası, on a bay on the Turkey’s west coast, has been argued to have been hit by multiple tsunamis over a period of days. It shows layers of ash deposits and sand amongst collapsed buildings. These have been interpreted as caused by a series of three tsunami waves, perhaps hours apart, with ashfall in between. Afterwards, there was a quiet period during which people briefly attempted repairs, but a fourth wave destroyed these efforts. A skeleton which was found in the debris may be the only known victim of Santorini’s Minoan eruption! But it is not yet confirmed that this was indeed a tsunami. Elsewhere on Turkey’s southwest coast, the ash lies on top of the tsunami deposits, indicating the water wave arrive first (as would be expected given the travel speed), but this is not the case at Çeşme-Bağlararası. The evidence from there is not as secure as that of Palaikastro. Overall, the facts of the tsunami story of Santorini are somewhat less than fully established.
Minexit
The eruption certainly ended the Minoan occupancy of Santorini. Whether it also ended the Minoan civilization itself is often stated as a fact, but is unproven.
The main base of the Minoan civilization was Crete, an island that was affected by the ensuing tsunami. Their main towns were along the coast and may have been badly damaged. These towns were devastated by the eruption – but not destroyed. There was a lot of rebuilding afterwards with fine masonry, showing that the people and their skills pulled through.
Many ships (and their sailors) will have been lost, and the military supremacy over nearby Greece may have been severely weakened. Some decades to a century later, the Minoan civilization collapsed, and their writing adapted to the Greek language: they had been taken over by Mycenaean invaders from southern Greece. But was that a direct consequence of the tsunami? Or a drawn-out process with many causes? The Minoans were the traders of their days, and the loss of ships may have been a big problem. It has been suggested that a lot of their trade came via Akrotiri and that they lost an important trade route. But there were no palaces on Akrotiri, suggesting it was never as important as that to the Minoans.
Maybe it was just that they were unable to recover the dominant trading position after an absence of some years, and that the decline was direct consequence of less wealth. The terminal blow came from the Mycenaean invaders, but that came after a long decline. It may have started with the Santorini eruption, but that sounds a bit like blaming the political chaos in the US on the St Helens eruption.
Bittersweet and strange, finding you can change. Learning you were wrong. – Beauty and the Beast
The bigger beast
The Minoan Santorini eruption was not a unique event. Santorini’s explosive history goes back 350 thousand years. Over that time there have five eruptions large enough to form a caldera, of which the historical event was the most recent. (We’ll have six or seven! – Beauty and the Beast.)
As in many similar volcanoes, such eruptions are cyclic. After a caldera collapsed destroys the lid on the magma chamber, eruptions become frequent, smaller and less explosive. Later the eruptions the magma becomes more evolved and eruptions less frequent but larger. The cycle ends with a climactic eruption which leads to a new caldera collapse. In the case of Santorini, this cycle can take 50,000 years or more.
Before Santorini there was ancestral Santorini. This volcano existed from 650,000 to 350,000 years ago, when the eruptions were mainly effusive. The transformation from ancestral to modern Santorini happened when the eruptions became explosive. Before that time, this was a likeable neighbour volcano, a bit like the friendly fire eruptions of Iceland. Or so people thought.
Santorini sits at the edge of the Agean platform, the shallow area where all the islands are located. The platform contains some deeper basins. One of these is located west of Santorini, the Christiana basin (home of the separate volcano island of that name) and to the northeast is the Anafi basin; they are around 400 meters deep. The explosive eruptions of Santorini have left their tephra in those basins.
Recent drilling in these and other nearby basins uncovered a thick bed of pumice, tuff and ash, underneath around 50 meters of more recent deposits. The deposits are up to 150 meters thick. Further from Santorini the bed consists mainly of ash. The predominance of pumice suggests that the eruption that caused it was mainly – but not exclusively – shallow submarine. The distribution especially of the larger fragments indicate that they came from an eruption near Santorini itself. The composition of the tuff (ratio of various elements) is similar to that of Akrotiri deposits dated to ancestral Santorini, and quite different from what was erupted by Santorini or other nearby volcanos (Christiana, Kolumbo) during the time of modern Santorini. That is consistent with the age of around 510,000 years, during ancestral Santorini. The tephra has also been found on the islands but the layers there are much thinner. That suggests that the eruption was mostly (but not entirely) submarine. The eruption was rhyolitic, at a time ancestral Santorini was mainly erupting basalt.
The deposits are interpreted as turbidity currents generated by submarine pyroclastics. The volume of these deposits are estimated at around 90km3. This is a lower limit for the eruption, as it only counts what is detected, and does not count what was deposited elsewhere, such as pumice rafts. Correcting for the measured density of the layers gives a DRE volume of 30 km3, again a minimum value.
Thus, this eruption was at least as large as the Minoan larger, and probably was larger as the volume is based only on the submarine pyroclastics. There are similarities to Hunga Tonga, but the eruption may have been a bit deeper and it was considerably, perhaps ten times, larger.
The eruption must have left a caldera but this has not been found. It may have been located between Santorini and Christiana, in the region where the tephra is thickest: a distant vent of ancestral Santorini has been suggested. This was during an interstadial, when the climate was warm and sea levels high. The vent was submerged under shallow water.
The eruption was around the time that ancestral Santorini changed and became ‘younger Santorini’ with different magma. Did the explosion perhaps trigger this change?
In any case, Santorini is no Prince Charming!
The mini-beast
In the summer of that same year of the eighth “Indiction’, steam as from a fiery furnace bubbled up from the depths of the sea between the islands of Thira and Thirassia for several days, and in a short while, after it had increased and hardened by the furious heat of the blazing fire, the smoke began itself to seem like fire, and on account of the thickness of this solid matter, large pumice stones were spewed out all over Asia Minor and Lesvos and Abydos and towards those parts of Macedonia which overlook the sea. (Theophanis the Chronicler, chronicling the Nea Kameni eruption of 726. Source: https://www.santorini.com/santorinivolcano/kameni-islands.htm)
Currently, Santorini mainly erupts at Nea Kameni. These are effusive eruptions which have build up the island over the past 2000 years or so. The eruptions come from a short fissure at the centre of the caldera which runs through both the younger Nea Kameni and older Palaea Kameni islands. There have been nine documented eruptions at Nea Kameni, in 197 BC, 46 AD, 726, 1570, 1707, 1866, 1925 and 1950. The two Kameni islands together have a volume of 4 km3, likely coming from these and other undocumented eruptions.
Recently, drilling was done on the seabed within the caldera to investigate the eruption history of the Kameni islands. A high resolution seismic profile was also obtained of the caldera. This profile is shown below. It is taken along a rather complicated path which runs through both gaps in the caldera rim and around the Kameni islands. On the plot, the top is at sea level – everything that is shown is submerged.
The profiles and drilling cores showed five main layers, lying on top of the ‘acoustic basement’ which is expected to come from the caldera eruption of 1600 BC. They are called, somewhat factually, L1 to L5 where ‘L’ stands for ‘layer’. Layer ‘L5’, at the bottom of the pile, seems to come from the oldest lava flows of Kameni, which may have happened before the first reported eruption in 197 BC. Layer L4 seems to be non-volcanic, and consists of landslides or stream beds. L3 is again a layer of volcanic ash, deriving from several eruptions as it is itself layered.
Layer L1 is small, at 0.3 km3, and may come from the eruptions between 1570 and 1950 which build up most of Nea Kameni.
Layer L2 is the notable exception. It is a rather thick layer of pumice and ash, with a large bulk volume of 2 km3. The only historical event that fits this deposit is that of 726 AD. It was reported at the time that ‘the sea produced ‘steam as from a fiery furnace’ and that pumice covered the sea and reached Turkey. The pumice in L2 suggests this was indeed that eruption. There was not much tephra known from this eruption, so was mostly submarine and it was not thought to have been large. But the new data makes it a much more significant eruption. The event was probably centred between the two Kameni islands. An ash layer found in the sea over some 10 km distance can now also be identified with this eruption, adding another 0.4 km3 to the volume. That number does not yet include the pumice that escaped the caldera.
The surprise is how large this small eruption of 726 truly was. Here the ‘fact’ erred on being too cautious. There is an expectation is that eruptions early in the cycleare small, and in fact all other known eruptions at Santorini have been no more than VEI3 or 4. But the 726 eruption was a VEI 5. To put this in context, the volume was twice as large as that of St Helens in 1980. It appears that even in its current state, Santorini can do far more significant eruptions than we have seen and expected. The 726 eruption was not strongly explosive – it was no Hunga Tonga. But it could still be problematic, and the pumice could badly affect shipping in the region.
The sudden collapse of Anak Krakatau in 2018 showed us that rebuilding a volcano after a major demolition is far from safe. Anak Krakatau was sitting on a sloping basement, and the cone eventually slid down this basement. It may be a worry that Nea Kameni is also sitting on a slope, with the northern basin being much deeper than the southern one.
As an aside, in the year 727, the Byzantine emperor Leo, under pressure from the advancing muslim armies, tried to take control of the church and tried to put the pope under his authority. This attempt would eventually lead to the separation of east and west in Europe. The Eastern Roman Empire and the Franks under Charles Martel would now fight the invading armies separately, and the church began the process which would later lead to a break-up between the eastern and western church. It has been suggested that Leo had been frightened into action by the eruption and damage to sea travel done by the pumice. But there is no written document that makes any connection, and we can attribute this to coincidence. Sometimes there are no facts, just speculation.
I can feel it. We’re getting close – Beauty and the Beast
The other beast
7 km northeast of Santorini lies Kolumbo, a submarine volcano. Never noticed before, it sprang into action in 1650, when an eruption breached sea level. Before this, the existence of this volcano had not been known. The sediment near Kolumbo shows no evidence of any other eruptions after the Minoan event, only this one. 1650 was indeed an awakening after a long post-Minoan sleep. Kolumbo rudely intruded on the age of baroque. (If it’s not Baroque, don’t fix it. – Beauty and the Beast)
Kolumbo is the largest of a series of some 20 submarine volcanic cones which stretches out in this direction, called (rather blandly) the Kameni-Kolumbo line. (I guess ‘KK clan’ would have been a factual but not acceptable name.) These cones formed on a 40 km strike-slip fault, which apparently acted as a weaknes allowing some magma to pass through.
The activity had started in the previous year. Strong earthquakes were felt in 1649 and continued into the spring 1650. After a calmer period, the earthquakes returned on 14 September, now accompanied on Santorini by roaring sounds. The shaking continued for two weeks, strong enough to cause rockfalls on Santorini.
The eruption was first noted on 27 September, when clouds of dense smoke and flames were seen rising from the sea. Sulphur clouds reached Santorini and pumice was covering the sea. The series of eruption plumes continued during the 28th. On the 29th, the eruption became much stronger. The eruption column was now said to blot out the entire sky, and incandescent ejecta and lightning was seen. Large rocks were thrown out as far as 8 km. Ash fell in Turkey. (Earthquakes were also reported from Crete but this may not have been related.) One explosion was heard 400 km away.
On this day, the sulphur cloud over the northeast coast of Santorini became so dense that people suffered intoxication, with blindness, confusion and in some cases unconsciousness. Some 60 people died from this. The activity ceased late on the 29th of September, but only for it to resume strongly the next day. A few days later, on 2 Oct, the crew of a ship was found dead at sea, with burn wounds: they died from a pyroclastic cloud. This took fatalities to 70. After that the eruption became much less. There was again a stronger explosion in November, before it finally petered out in early December and Kolumbo went back to rest.
The deadly eruption formed a crater 2.5 km across and 500 meters deep. The total eruption volume was around 10 km3, half tephra and half pumice. It was a VEI 6, although not all of this volume was explosive. It was comparable to Hunga Tonga, with the explosive component amounting to perhaps half a HT.
Tsunami
But there was more, as Beauty and the Beast says, Something that wasn’t there before. A major tsunami hit the region in the evening of 29 September. The tsunami destroyed two towns on Santorini, and swept away churches, boats and trees. The water first retreated before reaching 14 meters above sea level. (Local reports that the flood reached 2 km in-land cannot be correct. No tsunami deposits have been found there and it would have required a far higher wave.) On nearby islands, it reached run-up heights of 20 meters, possibly 30 meters on Patmos.
Originally the tsunami was attributed to collapse of the central crater in the climactic eruption. But this was questioned: models could not represent the pattern of run-up heights on the various islands in the region well, and eruptions tend to cease completely after the collapse but in the case of Kolumbo continued for two more months, including some large explosions in November. The tsunami is now considered to have been cause by a flank landslide.
Seismic mapping has shown the presence of ridges on the northwest slope of Kolumbo. These indicate a landslide, and this is a potential cause of the tsunami. Models show that such a 1km3 slide, followed by an explosion 4 minutes later, can fit the tsunami pattern and heights. The explosion is suggested to be caused by depressurisation of the flank following the slide.
Activation
The big question is what caused Kolumbo to suddenly become active in 1649, after thousands of years. Why out of the blue (sea) this sudden major eruption? Why did this Beast, who concealed himself inside his castle (Beauty and the Beast), reveal himself? There are four other known layers of volcanic debris underneath the 1650 layer, showing the presence of five large eruptions. The dates are not clear, but it covers at least 70,000 years (and possibly much longer). This is not a frequent eruptor! It likes its sleep.
Kolumbo has its own magma chamber, about 4 km deep. The magma is silicic but there is also a small component of mafic magma which comes in at a very slow rate. It is probably this hotter magma which destabilized the existing magma. Models indicate an average inflow rate of around 6 kg/sec. (That is less than 0.01 km3/century.) The inflow rate is such that mafic magma adds about 10% to the chamber over 10,000 years. Five eruptions over a period of 70,000 years suggests that a level of 10% to 15% mafic magma may cause the silicic magma to become unstable. The critical level was reached in the 17the century, magma began to break out and events followed.
It will take a long time for that level to be reached again. The risk of another eruption at Kolumbo in the foreseeable future seems not high. But volcanoes are not always predictable.
The future beast
You have no reason to trust me, and an excellent reason not too – Beauty and the Beast
Tourists on Santorini all head for the caldera rim for the views of the sunset. It is a good place to reflect on the past. Santorini’s beauty has grown from devastation: it is beauty from the beast. And while admiring this window on the past, perhaps there should be a little trepidation about the future as well. The beast may be asleep, it has not gone. The most likely location for a new eruption would be at the Kameni islands, at the centre of the tourisic views. What a sight it would be. But perhaps too close for comfort.
Albert, September 2024
References
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K. Cantner et al., Integrated volcanologic and petrologic analysis of the 1650AD eruption of Kolumbo submarine volcano, Greece . Journal of Volcanology and Geothermal Research 269 (2014) 28–43
Konstantinou, K.I. Magma chamber evolution during the 1650 AD Kolumbo eruption provides clues about past and future volcanic activity. Sci Rep 10, 15423 (2020). https://doi.org/10.1038/s41598-020-71991-y
In a recent thread with Jesper regarding tropical thunderstorms, a question occurred to me what the role that lightning could have played In the earliest days of Earth’s cool down regarding how atmospheric O2/O* in abundance came to be. As the atmosphere was becoming fully established (i.e. density/pressure), is also when water was being brought to Earth in abundant quantities. With the Earth’s surface still screaming hot, and Space at the top of the atmosphere typically uber cold, atmospheric convection would have been incredible…and so would the lightning. The energy released by lightning is more than sufficient to “crack”/dissociate H2O into H2+O*. Based on what we see even today regarding how lightning can occur on a near-constant rate, imagine what the early/cooling Earth must have looked like from Space…it would’ve literally been glowing from the constant lightning across the entire planet. And at the same time, this constant lightning is also cracking the gaseous water into Hydrogen and Oxygen which then gradually accumulates in the atmosphere. Considering also that in the early days of the crustal cooling period, the crust would have remained malleable for millions of years, and due to gravity, the surface must have been at one time incredibly smooth since tectonics hadn’t really started yet to form mountains, continents, etc. As water continued to accumulate, the Earth’s surface could have had a uniform layer of water perhaps for millions of years or until continents and other landmasses started to emerge above the water. This water layer in turn would submerge any oxidizable rocks/minerals that would otherwise deplete/react out atmospheric O2, hence the concentration of atmospheric O2 would be regulated mostly through the oxygenation/saturation rate of the water layer and the frequency of the lightning (since oxygen-producing biology had yet to evolve). Eventually though, the Earth cooled enough for massive convection to wane, thus reducing the amount of O* that’s so toxic for biology. So in a nutshell, it may be that the evolution of life was directly impacted by lightning (or the relative decline)?
Anyway, pretty cool to think about what the possible impact that lightning could have played on how life evolved, as well as create a mental picture of Earth glowing from essentially a planet-wide thunderstorm!
Lightning, eh?
Chad posted an article a couple of months ago that talked about, among other things, that Kilauea Iki is a reflection of the deep magma conduit that bypasses Halemaʻumaʻu to the summit and that a surge in this conduit led to the 1959 eruption of Kilauea Iki and subsequently the 1960 Lower Puna eruption. Currently, the UWE Tiltmeter is currently moving not more than 20 nanorads a day. But the IKI tiltmeter looks like it moving several microrads over the course of a week in what looks like DI events. Given the high supply right now, it is possible that the deep magma conduit is shoving that supply down the throat of the ERZ to the MERZ?
I havent posted an article about Kilauea 🙂 so possibly it was a long comment.
I dont know if Kilauea Iki has a separate deep system to Halemaumau, probably both are fed from the same major source that is best expressed by the tilt at SDH, and which seems to mostly be between 3 and msybe as much as 10 km deep. Halemaumau is a shallower magma body that seems connected to it but is separated by solid rock. The rift connectors seem to branch off of it too. Kilauea Iki I think is a 3rd magma body, maybe it us structurally part of the ERZ but it isnt connected to the ERZ connector ir the rest of the volcanism there. 1960 was probably a huge intrusion that basically overpressurized the entire volcano, the same magma was erupted at Kapoho as in Kilauea Iki just 50 C cooler.
As for the supply going to the ERZ though that is exactly what I think is happening, and what the recent insar from HVO shows but things have accelerated in the last 2 days. There are now continuous quakes to Pu’u O’o, which in past has been a sign of something breaking within weeks or it stops for a while. Im holding for an eruption in the first half of November, say Nov 10. And same place as the last one or close by.
Jörmungandr is still stirring under Reykjanes.
Next eruption could be 30% larger (RÚV, 25 Oct)
He thinks the eruption when it comes may be further north, which will be a relief for Grindavik residents (if any are left).
It may be a relief for Grindavik, but it could pose problems for Reykjanesbraut, the main road to and from the airport.
In my opinion the landscape towards the north is very flat. There lava won’t flow fast and will prefer to build temporary lava ponds on the lava field. The road Reykjavik-Keflavik is safe as long as only Svartsengi erupts.
It is different if Fagradalsfjall resumes its eruptions with more force and volume than 2021-2023. Prehistorical lava flows there reach a ~10km long part of the coast, while prehistorical flows of Svartsengi failed.
If we only look at the average altitude of Svartsengi’s and Fagradalsfjall’s peaks, they differ by nearly 300m: Svartsengi’s summits are around 100m above sea level; Fagradalsfjall’s peaks are close to 400m high. If we remember the 2021 eruption, we had some fast running lavas over the steep slopes towards Natthagi valley. Grindavik’s eruptions also often had fast lava flows, but with higher rate (volume/second).
From Natthagi, it is a longer route to Reykjanesbraut and the flows go to the south preferentially.
The last eruption stopped about 2.7 km from the road, so if the next eruption was further north, then it would increase the risk. It is very flat, with some pulleys, but IMO were also starting to show concern before the last eruption ended. It isn’t a given, but with a high enough eruotive rate and long enough eruption, it does become a possibility.
The higher peaks might increase the flow speed, but those same peaks protect against northerly flows.
The average slopes in the Grindavik-Fagradalsfjall area are flat towards the north and steep towards the south. We witnessed this difference during different eruptions of the present Sundhnukur cycle. The eruptions which let lava flow to Grindavik, had higher speed than the recent eruption which let lava flow towards the north (August).
This average tendency of the landscape is interrupted by some old glacial Hyaloclastite volcanic hills & mountains that rise above the lava landscape. The Fagradalsfjall plateau and the peaks around Geldingadalir, Meradalir and Keilir itself are examples for this. Also Thorbjörn near Grindavik.
Found this signal on SDH Seismometer and also shows some similarity on RIM and WRM. See some noise on RSDD and HLPD but not to familiar with those instruments.
Not sure what this is. There is some weather around, but?
Overview over three tiltmeters:
1. SDH
?fileTS=1729953721
2. Kilauea Iki
?fileTS=1729953694
3. ESC (Chain of Craters)
?fileTS=1729953722
They all appear to confirm a deflation (loss of mass?). Controary to them Pu’u O’o today has begun a small upwards trend:
?fileTS=1729953730
Im not sure what it is but it does look like tremor. While it is inconsistent which stations actually show it all of the times it is obvious are from stations on Kilaueas ERZ. That along with the increased earthquake activity and now probably inflation at Pu’u O’o looks like it could be magmatic in origin on the ERZ.
November 10 2024, Napau to Pu’u O’o. If it is voluminous and on the eastern end of that range it could flow a long way down the south flank following the west side of the Pu’u O’o lava. Lets see 🙂
Grimsvötn’s GPS: [
http://brunnur.vedur.is/gps/grimsvotn.html
The GPS link should be this one: brunnur.vedur.is/gps/eldfjoll/grimsvotn/GFUM-plate-90d.png
Did anyone see the reports of an earthquake near Fantale yesterday afternoon? Volcano Discovery says there were people reporting it but it’s a bit unknown what the actual size and position it was at.
Im curious since that’s around the area where they keep getting earthquakes and a magma intrusion.
Just my opinion but it’s not even Fentale responsible. It’s the Awasa caldera system/the EAR.
Awasa / Corbetti is completely separate from the Fentale system. Obviously, both part of the EAR, but the magmatic systems are entirely separate here.
Ive been wondering too, i guess if it is a normal basaltic event it might have failed right now but will potentially be a repeat event like Svartsengi or Krafla, or Manda Hararo. So eruptions arent out of the question still.
Not buying it being an evolved magma where the dike is now.
Marapi did a nice Pyro-Cumulus-congestus cloud: https://www.volcanodiscovery.com/marapi/news.html
The meteorological cumulus congestus cloud is larger than “fair weather cumulus” and smaller than thunderstorm clouds: https://en.wikipedia.org/wiki/Cumulus_congestus_cloud
https://nat.au.dk/en/about-the-faculty/news/show/artikel/europe-was-not-covered-by-dense-forest-before-the-arrival-of-modern-humans
http://wheneuropewasanocean.blogspot.com/2015/10/lands-pristine-europe-during-eemian.html?m=1
What Eemian Europe was like: megafaunal temperate forest savannah, its competely otherwordly compared to todays European landscapes that are completely modifyed by human agicultural activities and forestry.. Europe lost its wild natural scenery long long ago ..
Europe’s woods were even completely different 2000-3000 years before today. We underestimate the impact of big cattles like Aurochs and European bisons on the natural structure of woods. They made woods look like big halls with tall trees. Each species shapes the natural landscape a bit. Europe’s woods also had bears and lions which influenced the behaviour of herbivores.
The experience of Yellowstone national park shows the influence of the wulf on the ecological system. Add one species, and you get a wholly new system. Eliminate one, and you get again a wholly new system.
A Russian academic published a paper a decade or so ago that I found interesting. The steppes, which included what is now forest over much of Northern Europe was kept as savanna (cold) by the woolly elephant/rhino etc and controlled by sabre-toothed cats. This (as sheep do in another very rare ecosystem: Western Europe fells) prevented trees from growing. The result was only a little snow would cover the bare ground increasing the albedo. This maintained a cold climate.
Then H.Sap came in and did what he does best and drove the megafauna to extinction. Pines grew, and these are evergreen and tall. The show fell on the ground far below and the dark leaves above decreased the albedo and the climate warmed, and it still is.
Seems only too plausible to me.
Saber tooth cats were extinct outside the Americas since the middle Pleistocene, Smilodon was only found south of the Laurentide and mostly in South America where it was gigantic. The biggest cats found with mammoths were Panthera like modern big cats. Also either massive wolves or hyenas, depending on location.
Apparently tigers hunt elephants sometimes, and cave lions in Europe were similar size to big tigers, but also social. Probably still a rare thing for a pride to take down a mammoth, but maybe more common than it is for lions to try today, given lions now are generally smaller and african elephants are a lot bigger than wooly mammoths.
Caveat is if ‘saber tooth cat’ is referring to Homotherium, which was definitely a mammoth hunter. It was not exactly saber toothed though, its teeth were short and blade like, not unlike a shark tooth. Probably looked like a lion with long legs, rather than like a bear with massive teeth as Smilodon did.
I did a Bezier curve fit to Bruce Garner’s data which seems to suggest the first or second week in December as when the next fissure eruption in the Svartsengi area is possible. .
We may well get a christmas eruption!
I havent seen the entire sequence plotted out like this before, it really shows how much magma is involved in newer eruptions. The first intrusion now almost a year ago was estimated at 0.13 km3 in volume, but from this it looks like the last eruption was actually an even bigger volume of magma that left the magma chamber.
In fact, it looks like every eruption has been about twice as big as its predecessor, although the volume actually erupted doesnt necessarily quite corellate. The speed with which the last eruption has been recovered so far and the overall trend of growing power indicates the next eruption will be a major one, over 0.1 km3 and very likely reaching the ocean somewhere.
The scary part about the November intrusion is the rate of magma flow, 9500 m3/s at peak. So far the eruptions havent got that strong but if the next eruption does prove to be a bigger event than the first intrusion its all over really.
Nice work! The base line of where the refills start is also informative – possibly predicting a downward trend in 2025?
I guess another way to look at it, the November 2023 intrusion was 0.13 km3 and on that plot has a 375 mm change. The total uplift from after that intrusion up to the August eruption is about 940mm, about 250% of 375, so there might have been 0.325 km3 of magma involved in this series so far. The given volume of lava so far adds up to 170 million m3, of which over 1/3 of that (61 million) was in the last eruption. So 52% of the magma has erupted.
Now, the volume of lava erupted at Eldvorp is probably at least 0.2 km3, maybe more. Arnarseturshraun could be even bigger still. So unfortunately I dont think it is over yet. That also ignores the whole fact that the volcanism of this cycle has been very intense compared to the Middle Ages, so its also possible there is a lot more magma available in general. And in general, however big eruptions are at Svartsengi the eruptions at Krysuvik are significantly bigger…
I have been keeping my eye on the Ruang Volcano in the Phillipines area. This is probably one of the most clear satellite photos recently taken There is going to be more activity from this volcano in the near future.
New post is up! Barren by name, barren by data
https://www.volcanocafe.org/barren-island-india/