Volcanic activity in Canary Islands 2021

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https://youtu.be/tNxs8S7PSfg

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Model by Ward and Day 2001
Ward and Day 2001 estimated that the unstable part of Cumbre Vieja would be at least 15 kilometres (9.3 mi) wide in north–south direction. In light of the behaviour of other documented sector collapses such as at Mount St. Helens, the headscarp of the unstable part of Cumbre Vieja is likely 2–3 kilometres (1.2–1.9 mi) east from the 1949 fault[1] and the toe of the sector lies at 1–3 kilometres (0.62–1.86 mi) depth below sea level. Bathymetric observations west of La Palma support this interpretation. They had not enough information with which to estimate the thickness of the block but assumed that it would have a volume of about 150–500 cubic kilometres (36–120 cu mi) and the shape of a wedge, comparable to the Cumbre Nueva giant landslide 566,000 years ago also on La Palma.[36]

The authors used linear wave theory to estimate the tsunami induced by the simulated Cumbre Vieja.[36] They used a scenario of a collapse of 500 cubic kilometres (120 cu mi) that moves at a rate of about 100 metres per second (330 ft/s) on top of a layer of mud or landslide breccia, which lubricate its movement, and eventually spreads 60 kilometres (37 mi) to cover a jug-shaped area of 3,500 square kilometres (1,400 sq mi). Ignoring that the landslide excavates part of the flank of Cumbre Vieja, thus assuming that it does not contribute to any tsunami generation, they estimated the following timing of the tsunami:[37]

2 Minutes: A 900 metres (3,000 ft) thick dome of water rises above the landslide.[37]
5 Minutes: The dome collapses to a height of 500 metres (1,600 ft) as it advances by 50 kilometres (31 mi); additionally, wave valleys form.[37]
10 Minutes: The landslide is now over. Waves reaching heights of 400–600 metres (1,300–2,000 ft) hit the three western Canary Islands.[38]
15 Minutes-60 Minutes: 50–100 metres (160–330 ft) high waves hit Africa. A 500 kilometres (310 mi) wide train of waves advances across the Atlantic.[38]
3–6 Hours: The waves hit South America and Newfoundland, reaching heights of 15–20 metres (49–66 ft) and 10 metres (33 ft), respectively. Spain and England are partially protected by La Palma, thus tsunami waves there only reach 5–7 metres (16–23 ft).[38]
9 Hours: Waves 20–25 metres (66–82 ft) approach Florida; they are not expected to grow farther as they hit the coast.[38]
France and the Iberian Peninsula would be affected as well.[39] Further, the authors concluded that the size of the tsunami roughly scales with the product of the landslide speed and its volume. They suggested that traces of past such tsunamis may be found in the southeastern United States, on the continental shelf, in northeast Brazil, in the Bahamas, western Africa.[38]

Later models
Mader 2001 employed a shallow water code that includes friction and the Coriolis force. Assuming shallow-water behaviour of the wave even with runup the eventual tsunami heights in the US and the Caribbean would not exceed 3 metres (9.8 ft) and in Africa and Europe it would not be higher than 10 metres (33 ft).[40] Mader 2001 also estimated that dispersion along the US coast could reduce tsunami amplitude to less than 1 metre (3 ft 3 in).[41]

Gisler, Weaver and Gittings 2006 used public domain bathymetric information[3] and the so-called "SAGE hydrocode" to simulate the tsunami[42] stemming from variously shaped landslides. The landslides generate a single wave that eventually detaches from the landslide as the latter slows down.[43] The waves have shorter wavelengths and periods than teletsunamis and thus do not spread as effectively as the latter away from the source[44] and decay away roughly with the inverse of the distance. Such tsunamis would be a greater danger to the Canary Islands, the eastern Lesser Antilles, Iberia, Morocco and northeastern South America[45] than to North America where they would be only a few centimetres high.[46]

Løvholt, Pedersen and Gisler in 2008 published another study that employed the worst-case landslide scenario of Ward and Day 2001, but used hydrodynamic modelling that accounts for dispersion, non-linear effects and the deformation of the landslide material itself to simulate waves generated by such a collapse.[7] In this model, the landslide had a volume of 375 cubic kilometres (90 cu mi) and a maximum speed of 190 metres per second (620 ft/s). It generates a high leading wave that eventually separates from the landslide, while turbulent flow behind the slide generates lower waves. Overall, a complex wave field develops[47] with a sickle-shaped front wave that is over 100 metres (330 ft) high when it reaches a radius of 100 kilometres (62 mi).[48] The waves do not decay at a constant rate with distance, with the crestal wave decaying slightly faster than 1/distance while the trailing wave decays slightly more slowly.[49] Thus at distance the trailing waves can become higher than the leading wave,[50] especially the waves propagating west display this behaviour.[51] Undulating bores also develop, a factor not commonly considered in tsunami models.[52]

In the Løvholt, Pedersen and Gisler 2008 model, the impact in the Canary Islands would be quite severe, with the tsunami reaching heights of over 10–188 metres (33–617 ft), threatening even inland valleys and towns and hitting the two largest cities of the islands (Santa Cruz and Las Palmas) badly.[53] The impact in Florida would not be as severe as in the Ward and Day 2001 model by a factor of 2–3[54] but wave heights of several metres would still occur around the North Atlantic.[55] Off the US coast, wave amplitude would reach 9.6 metres (31 ft).[56]

Abadie et al. 2009 simulated both the most realistic landslide geometry and the tsunamis that would result from it near its source.[57] They concluded that most realistic volumes would be 38–68 cubic kilometres (9.1–16.3 cu mi) for a small collapse and 108–130 cubic kilometres (26–31 cu mi) for a large collapse.[58] The initial height of the wave depends strongly on the viscosity of the landslide and can exceed 1.3 kilometres (0.81 mi).[59]

Løvholt, Pedersen and Glimsdal 2010 noted that landslide-generated tsunamis can have a leading wave smaller than following waves, requiring a dispersive wave model. They simulated inundation in Cadiz resulting from a 375 cubic kilometres (90 cu mi) collapse at La Palma.[60] The found runup of about 20 metres (66 ft) and the possible development of undular bores.[61]

Abadie, Harris and Grilli 2011 employed three-dimensional simulations with the hydrodynamic simulator "THETIS" to reproduce the tsunamis induced by failures of 20 cubic kilometres (4.8 cu mi), 40 cubic kilometres (9.6 cu mi), 80 cubic kilometres (19 cu mi) and 450 cubic kilometres (110 cu mi). These volumes were taken from studies on the stability of La Palma's western flank, while the 450 cubic kilometres (110 cu mi) reflects worst-case scenarios from earlier tsunami studies at Cumbre Vieja.[62] The landslide is directed southwestward and induces a wave train, with the 80 cubic kilometres (19 cu mi) collapse having a maximum wave height of 80 metres (260 ft).[63] At El Hierro the tsunami can shoal and rise to a height of 100 metres (330 ft), while the wave train surrounds La Palma and continues eastward with a height of 20–30 metres (66–98 ft).[64]

Zhou et al. 2011 used numerical simulations to model various tsunamis, including a scenario resulting from a mass failure at La Palma.[65] It assumes a smaller volume of 365 cubic kilometres (88 cu mi) as the collapse hits only the western flank[66] and does not assume a southwest-directed propagation direction, thus increasing the hazard to the US coast.[67] The resulting tsunami approaches the US coast between 6–8 hours after the collapse, in a north-to-south fashion.[68] Waves grow due to shoaling as they approach the continental shelf[69] but later decline due to increased bottom friction[70] and eventually reach heights of 3–10 metres (9.8–32.8 ft) when they come ashore. The impact of undular bore formation on runup is unclear.[70]

Abadie et al. 2012 simulated both the development of waves using dispersive models that include non-linear effects, and the behaviour of the landslide generating them through slope stability and material strength models.[71] They considered both volumes of 38–68 cubic kilometres (9.1–16.3 cu mi), obtained from research on the stability of the flank of Cumbre Vieja, as well as volumes of 500 cubic kilometres (120 cu mi) as hypothesized by the original Ward and Day 2001 study.[72] The slide has a complex acceleration behaviour and most of the waves are formed during a short period early in the slide where the Froude number briefly exceeds 1;[73] the initial wave can reach a height of 1.3 kilometres (0.81 mi)-0.8 kilometres (0.50 mi)[74] and eventually wave trains are formed, which are diffracted around the southern tip of La Palma and go on to hit the other Canary Islands. With increasing volume of the slides, the wavelength becomes shorter and the amplitude higher, yielding steeper waves.[75] Abadie et al. 2012 estimated a fast decay of the waves with distance but cautioned that since their model was not appropriate to use for simulating far-field wave propagation the decay may be exaggerated. In the Canary Islands, inundation would reach a height of 290 metres (950 ft) on La Palma;[76] even for a 80 cubic kilometres (19 cu mi) slide would reach heights of 100 metres (330 ft) in the city of Santa Cruz de La Palma (population 18,000) while the largest city of La Palma (Los Llanos de Aridane, population 20,000) may be spared.[77] The waves would take approximately one hour to propagate through the archipelago,[78] and important cities in the entire Canary Islands would be hit by substantial tsunamis irrespective of the landslide size.[79]

Tehranirad et al. 2015 modelled the impact both of a worst-case 450 cubic kilometres (110 cu mi) landslide and of a more realistic 80 cubic kilometres (19 cu mi) collapse on Ocean City, Maryland, the surrounding area, Europe, Africa and the Canary Islands, using the "THETIS"[80] and "FUNWAVE-TD" hydrodynamical models.[81] They found that for a larger volume, the leading wave is both larger and forms farther away from the island.[82] For a volume of 450 cubic kilometres (110 cu mi), the tsunami hits Africa after 1–2 hours, followed by Europe between 2–3 hours, the Central Atlantic between 4–5 hours and the US continental shelf between 7–9 hours.[83] At the continental shelf, the wave train slows down and the number of main waves changes. Bathymetry,[84] such as the presence of submarine topography, alters the behaviour of the wave.[84] In the 450 cubic kilometres (110 cu mi) scenario after slightly over 8 hours from collapse tsunami waves reach the areas offshore the US coast, where their height decays as they traverse the continental shelf.[85] The eventual wave heights at the 5 metres (16 ft) depth contour are about 0–2 metres (0.0–6.6 ft) for the 80 cubic kilometres (19 cu mi) collapse and 1–5 metres (3 ft 3 in–16 ft 5 in) for the 450 cubic kilometres (110 cu mi) collapse;[86] impact is worst in North Carolina but also New York and Florida are impacted[87] even if refraction around the Hudson River Canyon mitigates the impact in New York City.[88] In Europe, tsunami waves arrive after 1–2 hours; even with a smaller collapse of 80 cubic kilometres (19 cu mi) impact around Coimbra and Lisbon is severe[89] with waves of 5 metres (16 ft) height, as Europe is closer to La Palma.[90]

Abadie et al. 2020 repeated their 2012 simulations using a model which incorporates viscous behaviour to obtain wave heights in the Atlantic, the Caribbean Sea and Western Europe[91] for landslides with a volume of 20 cubic kilometres (4.8 cu mi), 40 cubic kilometres (9.6 cu mi) and 80 cubic kilometres (19 cu mi).[92] This simulation yields a lower initial wave height (80 metres (260 ft) for the 80 cubic kilometres (19 cu mi) landslide) and a flatter profile of the initial water level disturbance.[93] Wave heights reach 0.15 metres (5.9 in) in the Bay of Biscay, 0.75 metres (2 ft 6 in) south of Portugal,[94] 0.4–0.25 metres (1 ft 3.7 in–9.8 in) along French coasts, 0.75–0.5 metres (2 ft 6 in–1 ft 8 in) at Guadeloupe,[95] all for the 80 cubic kilometres (19 cu mi) case.[96] Tsunami heights at Agadir, Essaouira and Sufi exceed 5 metres (16 ft), at Lisbon, Coruna, Porto and Vigo about 2 metres (6 ft 7 in) and along parts of the French coasts 1 metre (3 ft 3 in);[97] in Guadeloupe even a small landslide (20 cubic kilometres (4.8 cu mi)) can lead to widespread inundation.[98]

Ward and Day 2006 indicated that the combined effects of several wave trains may amplify the tsunami impact over that of a single wave.[99] Research by Frohlich et al. 2009 on boulders emplaced on Tongatapu endorsed the hypothesis of large landslide-induced tsunamis[100] and Ramalho et al. 2015 identified evidence of a megatsunami, implying a single step collapse, caused by the collapse of Fogo volcano in the Cape Verde islands.[101]

Criticism
The findings of Ward and Day 2001 have gained considerable attention,[19] amplified by increased concerns after the 2004 Indian Ocean Earthquake about the hazards posed by tsunamis,[102][103][104] and in turn increased awareness of megatsunami risks and phenomena.[34] The coverage of the risk of a collapse gained criticism for exaggeration,[105] in particular the coverage in North American and English media.[106] They have triggered debate about their validity and the landslide and wave scenarios employed. Various models with different physical specifications have been used to simulate the waves induced by such a landslide.[23] Later estimates have questioned the assumptions made by Ward and Day 2001, mainly with regards to the following:[107]

The authors employed a linear tsunami model that may not properly reflect non-linear processes such as wave breaking that could reduce the height of the resulting tsunami by a factor of about 10.[108][7] Wave dispersion might also act to reduce tsunami height since the wave induced by the Ward and Day 2001 landslide behaves as an intermediate-water depth wave.[109]
The estimated speed and acceleration of the landslide may be unrealistically high for the slopes it would move on, and this inadequate to establish effective coupling between the tsunami and the landslide.[110] Later research has found evidence that sufficient speeds have been reached during collapses at other volcanoes.[111]
The landslide modelled by Ward and Day 2001 may be implausibly thick given the known volumes of Canary Islands mega-landslides, and collapses may have occurred in multiple steps rather than a single failure[112][7] or may have a smaller volume.[113] The thickness of the landslide is a particular issue, as different estimates have been obtained at various volcanoes.[114] Another issue is whether giant landslides occur as a single step failure (as argued for Hawaiian giant landslides) or multistage failures (as appears to be more common in the Canary Islands)[115] and stacking in turbidite deposits generated by landslides are a reliable indicator that these landslides occurred in piecemeal fashion.[116]
In general, many of these studies have found lower wave heights at distance than the original Ward and Day 2001 paper.[117] There are also questions about the southern limit of the width of the unstable zone,[118] about whether creep might stabilize it[119] and about whether it actually exists at all.[120]

Probability
Humanity has never witnessed enormous collapses on La Palma[56] and there is evidence that the western flank of La Palma is currently stable[62] and a collapse in the near future unlikely.[121] A worst-case scenario giant landslide like the one modelled by Ward and Day 2001 is a very low probability event, probably much less common than once per 100,000 years[112] which is the probable occurrence rate of large landslides in the Canary Islands.[6][122] A smaller landslide scenario, which Tehranirad et al. 2015 defined as "extreme credible worst case scenario", has a recurrence rate of about once every 100,000 years.[80] Because of their low incidence probability, the hazard from large flank collapses at La Palma is considered to be low.[120] Return periods are not the only factor involved in estimating risk, as the amount of damage done by an extreme event has to be considered.[122] Globally, the return period of giant landslide-induced tsunamis may exceed one per 10,000 years.[123]

Potential impact
A Cumbre Vieja landslide tsunami may constitute a threat to Brazil,[124] Canada,[125] Caribbean,[126] Ireland,[127] Morocco,[128] the Northeastern United States,[129] Portugal[130] and the United Kingdom.[131] The impact would not be limited to humans.[132]

Aside from the tsunami hazard, the impact of a large collapse on people living on the island would be severe. The communities of El Paso, Fuencaliente, Los Llanos and Tazacorte are located on the unstable block.[133] Cumbre Vieja is largely unmonitored and a flank collapse may begin with little forewarning.[32]









https://en.wikipedia.org/wiki/Cumbre_Vie...ami_hazard

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But huge landslides and the mega-tsunami that they cause are extremely rare - the last one happened 4,000 years ago on the island of Réunion. The growing concern is that the ideal conditions for just such a landslide - and consequent mega-tsunami - now exist on the island of La Palma in the Canaries. In 1949 the southern volcano on the island erupted. During the eruption an enormous crack appeared across one side of the volcano, as the western half slipped a few metres towards the Atlantic before stopping in its tracks. Although the volcano presents no danger while it is quiescent, scientists believe the western flank will give way completely during some future eruption on the summit of the volcano. In other words, any time in the next few thousand years a huge section of southern La Palma, weighing 500 thousand million tonnes, will fall into the Atlantic ocean.

What will happen when the volcano on La Palma collapses? Scientists predict that it will generate a wave that will be almost inconceivably destructive, far bigger than anything ever witnessed in modern times. It will surge across the entire Atlantic in a matter of hours, engulfing the whole US east coast, sweeping away everything in its path up to 20km inland. Boston would be hit first, followed by New York, then all the way down the coast to Miami and the Caribbean.

https://www.bbc.co.uk/science/horizon/20...nami.shtml

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SIMON DAY: About a week after the start of the 1949 eruption something extraordinary happened. There was a series of very strong earthquakes and the west side of the volcano slid downwards and towards the sea by about 4 metres and for about 2 kilometres along the summit of the volcano this fissure opened up. It’s not an ordinary volcanic vent that just opens horizontally and that magma then erupts out as lava. This side has gone down relative to this side by about 4 metres as this area moved off towards the sea and this was something quite unusual, quite unique that you don’t normally see on volcanoes.

NARRATOR: A section of La Palma had started to slide and then abruptly stopped. Simon Day couldn’t be sure what was happening to the volcano and whether it would slide again or even collapse into the sea.

SIMON DAY: The problem was the Cumbre Vieja had erupted many times in its history, but there’d been no previous history of faulting, so what was so special about the 1949 eruption, why had the faulting occurred then?

NARRATOR: To find out Day had to discover what was happening to the rock structure inside the volcano. This might tell him not just why the fault had appeared, but also whether it was the precursor to a giant collapse. The Cumbre Vieja is still active making it hard to know exactly what’s happening inside, but the other volcano on La Palma is extinct and its rock structure is the same as the Cumbre Vieja’s. Here there is a place where geologists can look inside a volcano.

SIMON DAY: These tunnels are an amazing opportunity for geologists because they allow us to look into the interior of the volcanoes, going in several kilometres horizontally and up to 2 kilometres below the surface, so what we can see in here uniquely almost in the world is the inside of a volcano.

NARRATOR: Deep underground lay a clue which began to explain not only what had caused the fault above, but also whether one day the Cumbre Vieja would collapse. For what lies in the heart of these volcanoes is surprising: water. The volcanoes on islands like La Palma are unusual. They are full of water. Much of the rain which has fallen on La Palma for thousands of years has been trapped inside the volcanoes because of their particular rock structure. Deep within the volcanoes on La Palma are two types of rock. One is permeable rubble which allows rain to soak into it, but standing vertically upright within this rubble is the other type of rock, vast walls of cooled lava which form hardened dykes. These are impermeable and act as dams trapping columns of rainwater in the heart of the volcano.

SIMON DAY: What we’re looking at here is one of the two types of rock that we find within the heart of volcanoes like the Cumbre Vieja. It’s very loose, very permeable material, the water can soak straight down through it from the surface, down to this level within the volcano and the second type of rock is this. This is the lava dyke and it’s very hard, it’s formed by volcanic lava forcing its way up through the volcano. Once the eruption’s ended the lava in the dyke solidifies and produces this very hard rock and the important point about this rock is that it’s very impermeable. The water can’t penetrate through it, it’s trapped behind it and these dykes within the middle of each volcano act as a series of dams.

NARRATOR: Simon Day began to wonder if it was the effect of this water on the volcano which could lead to its eventual collapse. He contacted a geologist who studies the forces that build up inside volcanoes, Derek Elsworth. In particular, Elsworth was interested in the effect of water pressure on volcanic collapses.

PROF. DEREK ELSWORTH (Pennsylvania State University): This is a very simple model of how water pressures can cause instability in landslides and we have two inclined bricks. When the bricks are dry with no water pressures acting between the join in these two bricks then just like in a stable volcanic slope there’s no movement.

NARRATOR: If water is added, however, it begins to force the two bricks apart. The pressure of the water actually lifts the top brick off the bottom.

DEREK ELSWORTH: When we add water between these two bricks if the water pressure’s high enough to reduce the strength sufficiently, then the upper brick will slide off.

NARRATOR: Although water pressure is enough to push bricks apart, Elsworth realised that water on its own couldn’t collapse a volcanic island. He discovered that another element needed to be acting on the water: heat. For when this type of volcano erupts heat from the magma has a crucial effect.

DEREK ELSWORTH: This represents what happens to ground water in the Cumbre Vieja trapped between the dykes and magma rises within the upper regions of the volcano. This heated bath represents the magma within the volcano. The red water within the flask, like water within the volcano, expands as it’s heated and as the pressure within the flask increases the only outlet for the water is in this thin tube. This represents what happened within the Cumbre Vieja. As water trapped between the dykes is heated, expands, pressures increase drastically, ultimately causing the flanks of the volcano to collapse.

SIMON DAY: It was tremendously exciting because here was a mechanism that we could use to explain how it was that these enormous masses of rock could be pushed off the side of the islands.

NARRATOR: The heat from an eruption was the final part of the puzzle which explained the forces that would be working in the volcano. When a new column of magma rises and starts erupting water trapped between the dykes will be heated up. This will make it expand, creating enormous pressures within the heart of the Cumbre Vieja. These scientists believe this will trigger the collapse of the western flank of the volcano into the sea.

DEREK ELSWORTH: We found that the relatively small rising temperature in the core of the volcano due to the injection of magma could result in very large changes in water pressures. These water pressures are large enough to produce strength in the flank and result in collapse of the volcano. What this of course means is that the next collapse will ultimately be tied to a future eruption.

NARRATOR: All the conditions for a giant landslide on the Cumbre Vieja are present. It is an active volcano that is full of water. Simon Day needed to find out how big the potential collapse would be and to do that he had to discover the size of the fault within the volcano. He began a detailed survey of all the volcanic vents along the summit to see how extensive the fault was, something no-one had done before.

SIMON DAY: We mapped the volcano from the south to the north and from the south we followed this line of volcanic vents running north up the volcano to here on the summit region. What we found was that the line of vents continued straight off to the north and this told us about how the magma was coming up from deep within the earth up underneath the volcano and erupting at the surface.

NARRATOR: When Day plotted these volcanic vents on a geological map he realised that inside the volcano the fault was far more extensive that it appeared on the surface. It could be as much as 20 kilometres long, dissecting the entire length of the volcano. Potentially one side of the Cumbre Vieja, half a trillion tons of rock, would fall into the sea.

SIMON DAY: When we started analysing the information that we gained by mapping the Cumbre Vieja we found that a change had taken place in the vents of the volcano. The north/south line of vents had extended further to the north with new vents appearing each younger further to the north. This meant that the western side of the volcano was becoming deeply unstable. The whole of this flank was moving towards the sea as a single block.

NARRATOR: The Swiss scientists began to calculate what would then happen. They had to build a new model to estimate the size of the mega-tsunami this event would create. The Cumbre Vieja landslide would be thousands of times larger than any that the scientists had studied before. Because of this, their experiments could only give an approximate figure for the dimensions of the wave.

HERMANN FRITZ: Of course there’s a huge difference in scale between the Cumbre Vieja collapse and its physical model in the laboratory. We’ve tried to err on the side of the caution when we made our calculations using conservative assumptions, but nevertheless what we’ve found when we ran the model was very disturbing.

NARRATOR: The Swiss scientists’ final calculations produced an extraordinary wave.

HERMANN FRITZ: If the Cumbre Vieja were to collapse as one single block it would create a giant mega-tsunami with an initial wave height of 650 metres and a wavelength of 30-40 kilometres travelling westwards across the Atlantic with speeds up to 720 kilometres an hour towards America.

SIMON DAY: The scale of this produced a feeling of unreality as one realised what could happen. This event was so huge that it will affect not only the people on the island but people way, way on the other side of the Atlantic Ocean, people who’ve never even heard of La Palma will be affected by this event.

NARRATOR: There is evidence that seems to show collapses like La Palma create mega-tsunami that really can cross whole oceans and devastate distant continents. Scientists know that one of the last volcanic landslides in the Canaries happened here on a neighbouring island to La Palma. When a section of the island collapsed around 120,000 years ago it launched a mega-tsunami which would have swept across the Atlantic towards the Americas. Simon Day believes that evidence for its destructive power can be seen thousands of miles away in the Bahamas. He believes the huge wave reshaped some of these islands, blasting these shaped chevron ridges up to 10 kilometres long across parts of the Bahamian coastline. The wave also ripped vast boulders from off the ocean floor, some over 1,000 tons in weight and dumped them high above sea-level.

SIMON DAY: This was astonishing. Here was evidence that an event so extraordinary, that it could really only be produced by something as catastrophic as an ocean island collapse.

NARRATOR: So when is the next catastrophic event going to happen? The geologists had now discovered the Cumbre Vieja could collapse during some future volcanic eruption. The difficulty, however, is in knowing when this will happen.

SIMON DAY: We have no idea when the next eruption will occur on the summit of the Cumbre Vieja. In recorded history there have been eruptions in 1949, in 1712, in 1646 so it looks as though there is an eruption up there once every 2 centuries or so, on average. The last eruption was 50 years ago so it is likely that sometime during the next century there’ll be another eruption up there.

NARRATOR: Tourists in America and the Canaries shouldn’t cancel their holidays. The next summit eruption is unlikely to happen for decades and it may take many more eruptions before the flank of the volcano is pushed into the Atlantic. The problem is scientists cannot tell.

BILL McGUIRE: There could be 5 more summit eruptions of the Cumbre Vieja before the western flank collapses, there could be 10, there could be 20. On the other hand, the west flank could collapse during the next eruption. We simply don’t know, but put it this way, if I was living in Miami or New York and I heard that the Cumbre Vieja was erupting I’d be keeping a very close eye on the news.

NARRATOR: The geological evidence now shows that La Palma may well be the next volcanic island to collapse and when it does so it will create a devastating natural disaster.

BILL McGUIRE: The first thing that you’d feel actually would be seismic activity, earthquakes, because the collapse is going to be related to an eruption.

SIMON DAY: As the forces within the volcano built up to, to the point where they would begin to overcome the friction forces holding the flank in place the flank would begin to move towards the sea.

BILL McGUIRE: And then at some point the rock would fail on a major scale and this huge chunk of rock, maybe 20 kilometres long or more, would start to slide into the sea.

SIMON DAY: The waves initially here would be many hundreds of metres high and those waves would all be moving out into the ocean spreading out laterally, but with a lot of the energy heading across the Atlantic towards the coast of the Americas.

BILL McGUIRE: Looking down on it, it’ll look unbelievable, it’ll look as if the island is falling apart generating these huge waves which are fanning outwards to reach the eastern coast of the United States.

SIMON DAY: The waves will take about 8 hours to travel between here and the coast of America just enough time to get the message out to warn people that this event was happening, but unless evacuation plans were incredibly efficient it would not be enough time to get everybody out of the affected areas. The areas at risk include cities like Miami, parts of Boston, the coastal areas and suburbs of New York.

GARY McMURTRY: If you were standing on a beach in what is presently Miami, the very first effects you’d probably see is what we call drawback. The ocean would suddenly just pull away. You’d see a tide, a low tide like you’ve never seen before in your life. It would be actually spellbinding but in the background you’d be seeing this wall and it’d keep coming at you.

BILL McGUIRE: This would be the biggest natural catastrophe in history. There’s a problem with all major natural catastrophes. Because we’ve never experienced these things we don’t think that they’re going to happen to us. We just ignore them, but these sorts of Events have occurred throughout geological history. They’re not going to stop happening just because we’re around. La Palma is going to collapse into the North Atlantic. It’s not a question of if, it’s just a question of when.

https://www.bbc.co.uk/science/horizon/20...ript.shtml

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Courtesy of Involcan.

Translated

''Briefing Update: The seismic swarm continues in the Volcano Vieja Summit (La Palma, Canary Islands) with more than 22.700 low-magnitude earthquakes detected.
From 04:18 p.m. (Canary Time) on Saturday, September 11, 2021, the Canary Islands Seismic Network, which manages the Volcanological Institute of Canary Islands (INVOLCAN), is recording a new swarm of low-magnitude seismic Events in Old Summit Volcano area.
The automatic analysis system, the Canary Seismic Network, which manages the Volcanological Institute of the Canary Islands (INVOLCAN), has been able to detect from 01:00 p.m. Canary time on Friday, September 10 to 11:00 p. m canaria) from today September 18, 2021, over 22.700 earthquakes. It has been possible to locate more than 1200 earthquakes. The maximum magnitude observed so far has been 3,4 on the Richter scale, by an Earthquake recorded last Tuesday, September 14
The following figures show in number of Events detected by each hour, the hypocenters located in the last 24 hours (red) and the seismicity recorded from last Saturday September 11 (in grey).
In recent years, the Volcano of Old Summit has experienced 10 seismic swarms including the one that started this past Saturday (1 in 2017, 1 in the 2018 in 2020 in And 3 in 2021). The earthquakes of the latter swarm are more superficial than previous seismic swarm, where the depth ranged between 20 and 30 km. Without a doubt the current seismic swarm represents a significant change in the activity of the Volcano Old Summit and is related to a process of magmatic intrusion beneath La Palma Island.
INVOLCAN will continue to be updated on the evolution of this new seismic swarm at the Volcano Summit. Remembering that it can't be ruled out to intensify the seismicity felt in the coming days, depending on the evolution of activity.
The current situation of the volcanic traffic light is in AMARILLO for the municipalities of El Paso, Los Llanos de Aridane, Mazo and Fuencaliente de la Palma; therefore, keep an eye on the information provided by the relevant Civil Protection authorities.''

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[jand]

Just reading on the internet a lot of Spanish people do not agree with the Involcan statement the threat of a Tsunami is False many have seen the documentaries and thoughts of other scientists around the world.

Comments have been translated.

I've seen this documentary and it doesn't seem at all a bule!!, another thing is that you don't want to alarm people, but the explanations are very fundamentally,.. Doesn't mean that happens right now, but perhaps a a guy if he can happen,,.. The impossible movie is a great example of what can happen on earth!! 🤷 ♀️🌎
· Reply · See Original (Spanish) · 1h

Tagoror Harimaguada
Not only was universities in England also came from the University of California and talk about the same; you can not try to bulk a scientific hypothesis in any case wish the best or estimate that the chances are low we already have recent experiences of minimizing issues of the Coronavirus like the mask thing.

It wasn't a bull... all geologists who have studied the area have been warning and doing studies and measurements for years
· Reply · See Original (Spanish) ·

1hJose Antonio Donis Farrais
I'm not an expert, so this questions the studies done by the English of BBC. I say this for the documentaries they have done on this issue and everyone says the same thing that if the palm slope in which the tremors are occurring now collapses will occur a tsunami that would reach American shores with catastrophic consequences... And I repeat I am no expert but I am so cool to see documentaries and on this issue has been spoken many times.....

[jand]

Update by Volcano Discovery

La Palma Island (Canary Islands): Earthquake swarm picks up again, deformation reaches 10 cm uplift

The seismic activity under la Cumbre Vieja has picked up again during the past 12 hours, after having decreased significantly during the previous day.
The largest quake was a magnitude 3.2 event at 03:26 (UTC) today, at shallow depth of 0.1 km, and was felt by the population. Up to today moment and since the beginning of the series, 5391 earthquakes have been detected, of which 1102 have been located.
The maximum accumulated vertical deformation is around 10 cm in the area close to the Earthquake swarm and its distribution is still compatible with a center of pressure from a magma intrusion under the same area. These movements have been observed both with the island's GNSS network and through InSAR data (Sentinel-1).

While the seismic swarm is still far from the levels of the first days of the crisis, which had started on 11 Sep, there is a noticeable trend of quakes becoming shallower. Combined with the ongoing deformation, the chances of a new volcanic eruption are gradually becoming larger: it seems that the pulse of new magma intruding underground, causing both the quakes and the uplift of the ground, has not yet stopped.

The link below shows all the Quakes under La Palma during the past 24 hours


https://volcanodiscovery.de/uploads/pics...8sep21.jpg

[jand]

Simulación en #3D de la evolución del enjambre sísmico en La Palma.




https://twitter.com/i/status/1439179984778715138

[jand]

There is going to be a live meeting today at 18:00 Cabildo de La Palma .

We will live stream the meeting to report about the volcanic risk alert to the neighbors and neighbors of Las Manchez de Abajo, San Nicolás, Jedey, La Bulb, El Remo and Puerto de Naos.
🕧 At 18:00 hours
📌 In the Facebook account of the ' Cabildo de La Palma ' or by our YouTube channel ' Cabildo De La Palma live '
#CabildoDeLaPalma #VigilanciaLaPalma
🇬🇧 We will broadcast live the meeting to inform the residents of Las Manchas de Abajo, San Nicolás, Jedey, La Bombilla, El Remo and Puerto de Naos about the volcanic risk alert.
🕧At 18:00 hours
📌 On the Facebook account of the ' Cabildo de La Palma ' or on our YouTube channel ' Cabildo De La Palma live '.