The history 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
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. The one that is the highest peak in Spain (3,718 meters above sea level) is also a volcano that is considered active, with specific earthquakes and other events that do not become an eruption like the one of this same 2021 in Mount Fagradalsfjall, in Iceland (which ended up being a tourist attraction), but that despite how “calm” it seems was responsible for that great wave covered a large part of Tenerife millennia ago.
The 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 fragments (clasts) of pumice stone found in these deposits allow to distinguish at least two successive tsunamis, being able to identify its 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.
Reconstruction of the facts
Although it may be familiar to us because it is something recurrent in foot care, pumice or pumice stone is an igneous rock that sometimes stars in Plinian or Vesuvian-type eruptions (very violent). The researchers saw that there were light green, highly viscous and fibrous pumice stone debris They surrounded themselves with gravel, seeing that a layer of coarse sand (40 centimeters) is sandwiched between what was the lava flow and the deposits brought by the 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 most recent and highest occurred A few ago 178,000 years in Bajo Teno and Playa Arena and it was not something immediate to a volcanic eruption, while the other was 194,000 years ago in El Puertito.
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 tsunami deposits 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 50 meters thick the affected area.
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.
This volcanic event was crowned with a big 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 uncommon to find pumice in a volcanic area, the peculiar thing in this case is that it was the huge torrent of water, the ultimate 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 Canary archipelago is relatively low, but there may be and there have been (luckily, not always 130 meters or much less).
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 yes you should be more aware 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