The black swan theory was developed by the economist and philosopher Nassim Nicholas Taleb to talk about events with a transversal impact on society and which are, in a misleading way, easily explained in retrospect despite their high improbability.
The paradigmatic example of a black swan is the attacks of September 11. The pieces of the puzzle begin to fall into place at the exact moment when the event occurs, but (almost) no one had seen the potential threat with clairvoyance.
Taleb himself has denied that the great recession of 2008-2010 and the Covid-19 pandemic are black swans, not without some controversy about the predictability of these events and their consequences. Where there has been no doubt, on the other hand, has been in the eruption of the Cumbre Vieja volcano, on La Palma, and not only because the island, as well as the Canary archipelago in general, has a great volcanic activity, but because the researchers they had already predicted a “potential eruption” at the beginning of the year. The date was missing.
Between Sherlock Holmes and Minority Report, research led by Jose Fernandez Torres, from the Institute of Geosciences, was on the trail of a ‘crime’ that had not yet been committed. He published his results in Scientific Reports, a magazine of the group Nature, last January, reconstructing step by step the events that would give rise to the eruption that occurred this Sunday in the southern part of the island.
The surprise for Fernández and his team has been another: they did not imagine that it would happen so soon. The investigation itself concludes that they were seeing the “beginning of volcanic disturbances on the island of La Palma, probably decades before a potential eruption“.
Eruptions on La Palma and Cumbre Vieja lava tongue.
Fernández is a researcher at the Institute of Geosciences, a body created in 2011 as a result of the integration of two centers, one dependent on the Superior Council of Scientific Investigations (CSIC) and another from the Complutense University of Madrid.
He specializes in Geodesy and its application to natural hazards, using both terrestrial and space observation techniques. In this way, it creates models applicable to the interpretation of gravity displacements and variations in volcanic and seismic areas, as well as landslides and subsidence of the land.
Fernández is not alone. In this study, he was accompanied by two colleagues from the Institute of Geosciences, Joaquin Escayo and Antonio G. Camacho, as well as Juan F. Prieto, from the Higher Technical School of Topography, Geodesy and Cartography Engineers of the Polytechnic University of Madrid, and the members of the Remote Sensing, Antennas, Microwave and Superconductivity group of the Polytechnic University of Catalonia Zhongbo Hu and Jordi J. Mallorquí.
Eumenius Ancochea, Professor of Petrology at the Complutense University and one of the Spanish eminences on volcanism, completes the Spanish part of the work team, which at an international level included Sergey V. Samsonov, del Canada Centre for Mapping and Earth Observation; Kristy F. Tiampo, from the University of Colorado (USA), and Mimmo Palano, of the Italian National Institute of Geophysics and Volcanology.
A little deformation
“We started doing research on La Palma in 2006”, explains Fernández to EL ESPAÑOL, “when we started to install a GPS network that covered the island.” It was after a series of tremors that occurred at the end of 2017 that the investigations began.
“We were surprised that there had been no deformation [del terreno] and we reviewed all the data we had taken: radar images, gravimetry … We found that yes there had been deformation, but only a few centimeters, and in an area where we had not found it before, the Aridane Valley “.
The valley separates the two volcanic units of the island: the one in the north, geologically older, and the one in the south, where the Cumbre Vieja ‘building’ is located, with a crack that extends for 17 kilometers and ends in the bed oceanic.
These anomalies corresponded with other detected with volcanic gas measurements in 2011, which “corresponded to the passage of magma from the previous year.” In addition, it was corroborated with another chemical anomaly that was detected in the water of a source in 2010.
The magma was rising throughout a period that did not have great seismic activity, using existing fractures since a layer located 25 kilometers deep to another between 8 and 10 kilometers. “The anomalies were a little further north but the magma was coming from the south, taking advantage of unsealed paths from the 1949 eruption and fragile areas that had not been consolidated.”
Fernández’s team was able to detect these changes thanks to the use of new tools that allowed a more exact modeling of the magma’s trajectory, going from a conception in bags of a certain geometric shape to a “fractured, porous material that fills gaps”.
Seismic swarms
The second crucial event for the eruption of the Cumbre Vieja volcano occurred at the end of the last decade, when two seismic swarms were recorded. During the first of them, in October 2017, there were a total of 122 tremors. The second, in February 2018, generated 79.
These events “probably opened new fractures and offered new ascent paths for magmatic gases“, favoring in turn the displacement of the magma towards the surface and towards the south, below Cumbre Vieja.
The distribution and location of the gases and the anomalies in the geochemical measurements carried out by Fernández and his team made it possible to trace the migration of magma “from the south to the central part of the island.”
The professor at the CSIC-UCM Institute of Geosciences and his team closed the study in April 2020. At the same time that they were compiling the information to publish an article, they notified the National Geographic Institute and, through them, the Volcanological Institute of Canarias, Involcan, “since it seemed important to us that they know it.”
Fernández believes that the crisis is being managed “reasonably well. The proof is that there have been no losses and the necessary evacuations are being determined in advance, ensuring that there are no victims“.
The volcanologist is now interested in knowing what has happened between April 2020 and the present, what has been the trajectory of the magma until it rises to the surface, but he is satisfied with how the model that his team published nine months ago has adjusted to the reality. “We got everything to square us without forcing it.”
Regarding the probable anticipation of the eruption “decades before”, Fernández highlights that “the reactivation began 11 years ago” and that they have not been surprised that it happened so ‘soon’: “It looks like the eruption of 49, whose first seismic activity occurred in 36 “.
In any case, he emphasizes that, of these seismic processes, “only 20% lead to an eruption; in the rest, the magma accumulates, stabilizes and solidifies. A reactivation process does not have to end with an eruption”. There are things that cannot be predicted yet. For now
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Reference-www.elespanol.com