A groundbreaking study published in Nature Geoscience suggests that a new tectonic fault may be emerging beneath the Atlantic Ocean, potentially increasing the risk of powerful earthquakes and tsunamis across the basin.
The research, led by Professor João Duarte of the University of Lisbon, aims to explain why Portugal has experienced major earthquakes despite being far from known fault lines. Historic events such as the devastating 1755 Lisbon earthquake, which killed tens of thousands and triggered tsunamis reaching as far as the Caribbean, and the 1969 quake that claimed 25 lives, have long puzzled geologists.
Duarte’s team focused on the Horseshoe Abyssal Plain, a deep-sea region southwest of Portugal. Using seismic data and computer models, the researchers discovered signs of “delamination” – a process in which the Earth’s mantle begins to peel away beneath the crust. This unusual phenomenon, described as the base of the tectonic plate separating “like the sole of a shoe peeling off,” is rarely observed in oceanic crust.
The Atlantic Ocean has traditionally been regarded as geologically stable, with its tectonic plates slowly drifting apart along a mid-ocean ridge. However, the study suggests that water infiltration over millions of years has chemically weakened the crust in this region, allowing parts of the mantle to sink deeper into the Earth. This could signify the birth of a new subduction zone – where one tectonic plate slides beneath another – a process responsible for the world’s most catastrophic earthquakes.
While the formation of a new subduction zone may eventually lead to the creation of a future supercontinent, the immediate concern lies in the increased seismic hazard. Professor Duarte warns that major earthquakes are likely to occur again and could devastate unprepared coastal areas around the Atlantic.
He compares the situation to weather forecasting: “If you see on the forecast that it’s going to rain tomorrow, you take an umbrella… With earthquakes, it’s the same thing; we don’t know when a major one will hit, but we know that one will, so we need to be prepared.”
The findings underscore the importance of readiness in the face of unpredictable but inevitable seismic events, which could have significant human and economic consequences across the Atlantic region.
