Can a Canarian volcano cause an international catastrophe?

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Can you imagine a wave of biblical proportions capable of flooding and destroying part of Europe and West Africa and the eastern shores of America? This is predicted by a mathematical model published in 2001 by a couple of geologists. This study predicts that such an event could be triggered by a volcano on La Palma which could be more important than we think

Some people believe that our planet takes advantage of certain circumstances to take its revenge against this hairless monkey that has been mistreating it for a long time, that as a living being it would have a kind of immune system that fights to expel from its organism the beings that are decimating it. The responses that this planetary immune system would trigger would be natural catastrophes. On the other hand, others argue that these disastrous events that claim thousands of lives are really processes that must take place following the laws of geophysics and geology that govern our planet. However, regardless of the cause of the natural disasters, the only thing that is certain is that our species, which believes itself to be the leader of the food chain, is defenseless against the inescapable forces of nature, which on several occasions have erased entire civilizations from the face of the planet in the blink of an eye. Such is our futility.

Since the dawn of humanity, we have been aware that there are forces that are beyond us, although in one way or another we have tried to deal with them. At first, we fought them passively, almost submitting to them. We thought they were the furious gods who were executing their wrath against us for not worshipping them properly and we tried to appease them by offering them all kinds of offerings. Today, Homo sapiens is trying to defend himself and to foresee these cataclysms through science and technology, and although we have made great strides, we are still in our infancy. In most cases, natural disasters happen without us being able to prevent them.

One of these catastrophes, which lies in the limbo between plausibility and mere fable, could begin in the Canary archipelago, specifically on La Palma island, where a volcano whose name arouses atavistic fears in many people could once again outwit mankind.

The Cumbre Vieja

The nickname given to this volcanic island lives up to its natural beauty. It is known as “the beautiful island” and is the most northwestern island of the Canary archipelago. It is also a Biosphere Reserve since 2002. But we must not underestimate it, because its surface is sown with volcanoes. The peaks of Taburiente, Fuencaliente, El Charco, etc., rise majestically to the top of the skies of La Palma. But in this post we will focus exclusively on one of them, which we have not yet given the presentation it deserves.

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Aerial view of the island of La Palma, whose surface is dotted with volcanoes. This image shows some of them, including the protagonist of this article. AGU Blogosphere

We are referring to the Cumbre Vieja volcano. It is one of the youngest volcanoes on the island, as the oldest rocks have been dated to about 125000 years ago, and its peak reaches two kilometers above sea level. It is located in the south of La Palma and practically occupies half of it. He is considered one of the most active on the island. In fact, in historical times it has erupted seven times, the last time in 1971. It has been in the news several times recently because of the seismic movements and swarms (earthquakes with several aftershocks) that have been detected in its vicinity. For example, last October, nearly 200 low-intensity earthquakes were detected in the southern part of the island on several consecutive days. This has set off alarm bells in the face of an alleged imminent risk of eruption, which would lead to a disaster of unimaginable proportions. However, experts say it is normal for earthquakes to occur in an active volcano. Even so, fear is not diluted. It is curious, since not as much attention is paid to other similar situations that occur in other parts of the world. Something special has the Cumbre Vieja so that the media and various Internet webs devote so many paragraphs to it. And to understand this, we have to travel in our own particular time machine to the year 2001.

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The Cumbre Vieja volcano in all its extension. El Español

The catastrophic model of Ward and Day

That year, the scientific journal Geophysical Research Letters published a paper whose echo has survived to this day, as it comes back to light every time an earthquake occurs near the volcano. That work was signed by two geologists: Steven N. Ward, from the University of California, and Simon Day, from the University College of London. These authors tried to test a disturbing hypothesis: could the Cumbre Vieja collapse and cause a colossal tsunami that would destroy the eastern coasts of the Americas and the Atlantic coasts of the African and European countries near La Palma? Before answering this question, let’s take this bit by bit.

Why did they focus on the Cumbre Vieja and not on another volcano? As we have already mentioned, the Cumbre Vieja has erupted seven times during the historical period. The last two times were in 1949 and 1971 respectively. However, it was the 1949 eruption that alerted the experts. That event generated a fault or fracture under the western flank of the volcano, making it more unstable. On top of that, the same side was already unstable according to Ward and Day, as it is supported by a platform formed by the unstable accumulation of sediments generated during previous eruptions. For a better visualization, we can imagine a building built on a mountain of uncemented stones.

From these data, Ward and Day developed a mathematical model using a series of equations to evaluate the possibility of collapse and consequent fall into the ocean of the western flank of the volcano and the supposed tsunami that this landslide would cause. They also studied the worst possible scenario which, according to their predictions, would consist of the detachment of no less than 500 km3 of the western flank of the Cumbre Vieja. Their conclusions could not have been more hopelessness: such an event was possible, in fact a future eruption of the volcano could open the underground fault on the western flank completely and throw hundreds of cubic kilometers of material into the water. But the worst of all is what would come next: a titanic tsunami that would initially reach a height of 500 meters and move at more than 800 Km/h. This liquid fortress would wipe out everything in its path and reach some coasts of Africa and the Iberian Peninsula with waves of 5 to 7 meters. Such would be its magnitude that its apocalyptic echoes would reach several beaches in eastern America with waves of 25 meters. The rest is history. Since then, numerous documentaries and headlines have fuelled this study and the fear of the Cumbre Vieja is re-emerging every time there is an earthquake in the area, however small it may be.

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Evolution of the Cumbre Vieja collapse pattern and the “megatsunami” it would cause. The waves would start with heights of several hundred meters, which would decrease as they travel across the Atlantic. The consequences would be unimaginable. Ward and Day, 2001

It might seem a priori that the figures given by the pair of geologists are too exaggerated and that the model does not respond to a real situation. Be that as it may, similar events to the one proposed have occurred in different parts of the world. Let’s look at some of them.

The precedents

Without leaving La Palma, the namesake of the Cumbre Vieja volcano, the Cumbre Nueva volcano, suffered a major landslide on its western side 560000 years ago. It is estimated that 200 km3 were submerged in the ocean, causing a tsunami of significant proportions.

Continuing in Canary Islands, a 2017 survey published in Nature Communications found deposits left by tsunamis on Tenerife island… at 132 meters above sea level. Again, the collapse of a fragment of a volcano caused the waves.

Already in historical times, in 1888 in the east of New Guinea, the Ritter volcano collapsed after a battery of eruptions, sending between 4 – 5 km3 of land into the ocean. It caused a number of tsunamis, some up to 50 feet high. Little is known about their true impacts. Even so, the event must have intimidated the natives of the place, since the phenomenon still lives on in the oral tradition.

On May 18, 1980, a huge mass on the northern flank of Mount St. Helens (Washington) plunged into the surrounding lake, generating waves 250 meters high. In this case, the landslide was caused by an eruption that suddenly melted the polar ice cap at the top. Both the landslide and the tsunamis robbed the lives of 57 people and destroyed substantial material goods.

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Spanish press release about the Mount St Helens disaster. Prensa Libre

Don’t panic!

From what we have seen, it seems that it is common for volcanoes to collapse from time to time and cause tsunamis with great destructive power. As a result, Ward and Day’s model is far from flattering and there seems to be no escaping from the wrath of the Cumbre Vieja. However, there is still a glimmer of hope.

What is scarcely mentioned when talking about the Cumbre Vieja and its fatal prediction is that the geologists’ model has been criticized and refuted on many occasions. First of all because not all the premises on which they base their model are fulfilled. For example, it is proven that the western flank of the mountain is certainly located on an unstable sediment support, but what is still not conclusively proven is that there is an underground crack that crosses this region, according to scientists from the Instituto Vulcanológico de Canarias (Involcán). In addition, we must remember that Ward and Day placed special emphasis on the fact that a future eruption would completely open up the underground crack that generated the 1949 eruption. However, another eruption occurred in the 1970s and nothing happened. Also, the volcano is not as unstable as the pair of geologists proposed. The scientists of Involcán even claim that to reach a remarkable degree of instability, a strong explosive eruption combined with earthquakes of great magnitude would have to occur simultaneously, something that seems unlikely at the moment. On the other hand, it is true that the possibility of landslides and a subsequent tsunami of cyclopean proportions is real, although the probability is rather low. In fact, humanity has attended very few events of this kind.

Other mathematical and computer models have also been developed so far using more refined and effective tools. According to these new models, although the Cumbre Vieja volcano is likely to succumb to the forces of nature (within several centuries), it is unlikely that 500 km3 of the mountain will be detached. In the worst case, a maximum of 80 km3 would be released. The rest of the islands of the Canary archipelago would take the brunt of. At most, waves of 2-3 meters would reach the American coasts.

Regarding the earthquakes that have been recurring for some time at the Cumbre Vieja, experts say that there is nothing to worry about, since it is normal for these geological movements to occur in an active volcano. It can be concluded that it’s not necessary to fear the Cumbre Vieja at the moment, and that we can continue to enjoy the wild and rugged landscapes surrounding the mountain. But we shouldn’t be overconfident either, since nature is still that great unknown that has not yet revealed all its secrets and some kind of terrible surprise may be waiting for us…

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