Seismic studies underestimated the danger of the Atlas: it rose and narrowed too much

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If in 25 million years there are any of us left here, we would see that Morocco has collided with Andalusia and the Strait of Gibraltar has been closed. The African tectonic plate would continue to push the Eurasian plate and, if geologist Christopher Scotese is right, The Iberian Peninsula will begin to rotate clockwiseand in another 25 million years northern Spain will collide with the French coast.

For now, it is certain that the Eurasian and African plates They have been pushing each other for millions of years, like a plasticine puzzle in which the pieces mix, or rise, or submerge, causing thousands of earthquakes a year. The last one, this weekend in the Atlas mountain range, with the epicenter more than 700 kilometers from the collision of tectonic plates. “It is not predictable, but not impossible“, points out seismologist Juan Vicente Cantavella, from the National Geographic Institute (IGN). The Agadir earthquake, at the oceanic mouth of the mountain range, and even further away from the Plate collision, was 5.8 and in 1960 it stopped at 12,000 to 15,000 fatalities.

At 11:11 p.m. on September 8, the earth shook 60 kilometers to the southwest of Marrakechand in Spain the IGN received more than 500 noticesmostly from Andalusia, but also from Madrid and the islands of La Palma and El Hierro.

According to a study of the Atlas faults published in 2006 by researchers from the Tectonics Laboratory of the Pierre et Marie-Curie University, the Paul Cézanne University of Marseille, the Mohamed V University of Rabat and the Cergy Pontoise, the Atlas faults They had “potential to generate earthquakes of between 6.1 and 6.4″ maximum on the Richter scale. They fell short, making it harder to predict if, when, and of what magnitude there will be more.

Itahiza Domínguez, IGN seismologist, explains on social networks that seismic hazard maps have “a problem”: they are based on knowledge of the past, but if this is limited, or the recurrence times of earthquakes are long, the danger can be “underestimated”. And this is believed to be what happened with the Moroccan earthquake, since the pre-existing map gave a lower probability in the hypocenter area compared to other points in the country, and in North Africa in general. In the Iberian Peninsula, the most dangerous points are in the provinces of Granada and Murcia. In the first one, an earthquake of 6.7 in 1884 with a balance of more than 1,000 deaths. Lorca’s in 2011 was 5.1 and caused 9 deaths and more than 300 injuries. For this reason, Itahiza Domínguez indicates that “it is not ruled out” that a new “destructive” earthquake will occur.

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