The National Geographic Institute has developed a map in which you can see the earthquakes that occur in Spain and the Granada region always appears among the most illuminated sites. It was precisely there that, in 2010, scientists detected unusual seismic waves, which ultimately led to a surprising discovery: an oceanic slab that had completely turned over as she was pushed under her neighbor.
As detailed in a study published in The Seismic Recordthe team discovered that the “Alboran slab”, which meets the Eurasian slab, just east of the Strait of Gibraltar“had made a 180º turn.”
It is the first time that a discovery of this type has been made, say the authors of the study. And it is due to “hydrated magnesium silicates”, approximately 500 kilometers below the surface, indicating that the water on the surface of The slab had not only been pushed down, but had also rotated and dragged under the slab.
The study explains How these fragments of the Earth's crust interact and how they relate to surface seismic activity, as well as giving us a new sense of wonder at the extraordinary geographic wonders of our planet.
Originally, the authors were looking for something completely different when they studied a magnitude 6.3 earthquake beneath Granada in April 2010.
“Initially, we did not intend better understand the mechanisms of deep earthquakes, since several previous studies have studied the source very well – says co-author and seismologist at the University of Science and Technology of China, Daoyuan Sun, in a statement -. Our intention was simply to plot the waveforms out of curiosity, as there is a lot to learn from individual waveforms when one takes the time to observe them closely.”
Low speed vibrations are conventionally the result of waves passing through liquid or molten material. Since subducted slabs often carry water on their surface, they are an excellent explanation for these signals.
“Considering that the bottom of the sea in the western Mediterranean is relatively youngFor the slab to remain cold, the speed of subduction must be quite fast, such as a moderate speed of about 70 millimeters per year – Sun concludes. “In other words, we believe that our study could provide a reasonable lower bound on the subduction velocity in this region.”