An international research team led by the Faculty of Sciences at the University of Lisbon has uncovered a geological process in the Atlantic Ocean that may explain the origin of the devastating Lisbon earthquakes of 1755 and 1969.
The study, published in Nature Geosciences, reveals that the tectonic plate near Cabo de São Vicente is undergoing a process called delamination, where the plate splits into horizontal layers. In this process, the lower part sinks while the upper part remains in place, making the fracture nearly invisible from the seafloor.
Professor João C. Duarte, co-author of the study and researcher at the Instituto Dom Luiz, explained that seismometers placed on the ocean floor for eight months recorded a cluster of deep earthquakes, at depths of 30 to 40 kilometers. These findings point to hidden seismic activity that could generate major earthquakes.
The discovery solves a long-standing mystery in seismology: until now, no fault or tectonic structure large enough had been identified in the region to explain quakes of such magnitude. Researchers stress that this breakthrough underscores the urgent need to better assess Portugal’s seismic risk, as the country remains one of the most earthquake-prone in Europe.
Source: University of Lisbon – Faculty of Sciences
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