Something strange is happening off the coast of Portugal, and scientists have now proposed a groundbreaking explanation.
BY MAYA WEI-HAAS
MAY 6, 2019
For years, João Duarte has puzzled over a seemingly boring underwater expanse off the coast of Portugal. In 1969, this site spawned a massive earthquake that rattled the shore and sparked a tsunami. But you would never know why just from looking at the broad, featureless surface of the seabed. Duarte, a marine geologist from the Instituto Dom Luiz at the University of Lisbon, wanted to find out what was going on.
Now, 50 years after the event, he may finally have an answer: The bottom of the tectonic plate off Portugal’s coast seems to be peeling away from its top. This action may be providing the necessary spark for one plate to start grinding beneath another in what’s known as a subduction zone, according to computer simulations Duarte presented in April at the European Geosciences Union meeting.
If confirmed, the new work would be the first time an oceanic plate has been caught in the act of peeling—and it may mark one of the earliest stages of the Atlantic Ocean shrinking, sending Europe inching toward Canada as predicted by some models of tectonic activity. (Find out what scientists think will happen when Earth’s tectonic plates grind to a halt.)
“It’s certainly an interesting story,” says the University of Oslo’s Fabio Crameri, who was not part of the research team but who attended the EGU lecture. Duarte presented some strong arguments, he says, but he cautions that the model needs further testing—not an easy feat when your data comes from a natural process that works at the speed at which fingernails grow.