{Disarmed} The history of the Tenerife tsunamis that were the icing on the cake of a great volcanic event on Teide: rocky landslides, dust clouds and a 132-meter wave

There are natural events so brutal that, even though centuries pass, they are remembered for the direct and indirect consequences they had, such as the Lisbon earthquake that took more than 100,000 lives and that marked the birth of modern seismology in 1755. Others did not leave trace in our civilization because it did not even exist, as with the two tsunamis that originated the nucleus that we now know as Teide, one of them up to 130 meters high .

This is something that happened about 170,000 years ago and what was learned after a study published in Nature . What is the highest peak in Spain (3,718 meters above sea level) is also a volcano that is considered active , with occasional earthquakes and other events that do not become an eruption like the one of this same 2021 on Mount Fagradalsfjall , in Iceland (which ended up being a tourist attraction ), but despite how "calm" it seems, was responsible for that great wave covering a large part of Tenerife millennia ago.

Clues of the pumice stone

In this case, as the researchers explained, the tracks of the tsunamis were given by certain deposits of materials in certain strata of the island of the Canary archipelago, unlike other ancient giant tsunamis that are inferred mainly by simulations, such as the one that it would have caused the meteorite that participated in the extinction of the dinosaurs . Specifically, they referred to marine gravel with pumice stone on the northwestern flanks of Tenerife.

As they describe, the stratigraphy of the tsunami deposits and the characterization of the pumice stone fragments (clasts) found in said deposits make it possible to distinguish at least two successive tsunamis , being able to identify their possible origin and thus demonstrate the association between a massive flank fault and an explosive eruption. Thus, they describe what happened as a complete flank collapse scenario, a large explosive eruption and subsequent tsunamis, one of them reaching 132 meters.

Teide is a book volcanic area. Image: Ronny Siegel.

Reconstruction of the facts

Although it may be familiar to us because it is something recurrent in foot care, pumice or pumice is an igneous rock that sometimes stars in Plinian or Vesuvian-type eruptions (very violent). The researchers saw that there were remains of highly viscous and fibrous and light green pumice stone that were surrounded by gravel, seeing that a layer of coarse sand (40 centimeters) was sandwiched between what was the lava flow and the deposits brought back. by tsunamis.

As we said, the analysis of the substrates and the deposition of materials allows us to reconstruct scenarios from the past, at least roughly. In this case, the tsunami The most recent and highest occurred about 178,000 years ago in Bajo Teno and Playa Arena and was not immediate to a volcanic eruption, while the other was 194,000 years ago in El Puertito.

Tsunami deposits in Teno Bajo and Playa Arena. Image: Raphaël Paris, Juan J. Coello Bravo, María E. Martín González, Karim Kelfoun and François Nauret

In this case, numerical simulations on the faults on the north flank of Tenerife confirm that a large volcanic event triggered a huge avalanche on that flank and that this caused waves high enough to submerge the Taco cone, where the tsunami deposits they have been preserved at an altitude of 132 meters .

The researchers argue that the stratigraphy and composition of the deposits suggest at least two successive tsunamis and highlight the link between the flank fault and the explosive eruption. According to their data, the water would have covered the affected area with a thickness of 50 meters .

Thus, the intense volcanic activity of the moment would have caused a great event that, in turn, created a huge avalanche on the north flank of current Teide. This would have caused the rocky slide to leave deposits that would reach up to 80 kilometers away from the Tenerife coast .

Location and altitude of the tsunami deposits on the northwest coast of Tenerife. Image: Raphaël Paris, Juan J. Coello Bravo, María E. Martín González, Karim Kelfoun and François Nauret

This volcanic event was crowned with a great eruption , violent and capable of covering a large part of the island with lava flows. And not only that, as detailed in Ciencia Canaria also originated the Caldera de Las Cañadas and a valley called La Guancha-Icod.

The consequence of all this in the sea, specifically of seismic movements, would be that monstrous tsunami of more than 130 meters. Therefore, although it is not unusual to find pumice in a volcanic area, the peculiar thing in this case is that it was the enormous torrent of water that was ultimately responsible for these deposits .

The earth is going to keep moving even if the Teide is asleep

Is Tenerife or any of the nearby islands still at risk? The researchers pointed out that studies such as this one can be key to assessing the risk of volcanoes and tsunamis in an integrated manner and alluded to the fact that "monitoring and warning systems are not adequate to face such events", but that the risk of tsunami in The Canarian archipelago is relatively low , but there may be and have been (fortunately, not always 130 meters or much less).

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The first tsunami in the Canary Islands of which there is official record was in 1402, counting a total of eleven according to the Review on historical tsunamis in the Canary Islands: implications for risk reduction (from researchers from the Geological and Mining Institute of Spain (IGME), the Museum of Natural Sciences of Tenerife and the University of La Laguna). Inés Galindo, head of the territorial unit of the IGME in the Canary Islands and one of the authors of this review, commented that there should be more awareness of this risk , without it being a fear that blocks aspects such as normal life or tourism, but simply so that there can be a correct forecast.

Images | Nacho Pintos , Ronny Siegel

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The news The story of the tsunamis in Tenerife that were the icing on the cake of a great volcanic event on Teide: rocky landslides, dust clouds and a 132-meter wave was originally published in xiaomist.com by Anna Martí .