Scientists say a slumbering subduction zone beneath the Strait of Gibraltar might be on the verge of awakening and dramatically altering the Atlantic Ocean.
Subduction zones are regions where one tectonic plate dives under another, triggering earthquakes and volcanic eruptions. The zone under Gibraltar, also known as the Gibraltar arc, has been inching westward for 30 million years. Its movement appears to have stalled in the past 5 million years, leading some to believe it's inactive.
A new study published the journal Geology suggests the lull is temporary. Researchers used computer models to simulate the arc's history and future. They found it could break through the Strait and enter the Atlantic in 20 million years, a process called "subduction invasion."
"Subduction invasion is inherently a three-dimensional process that requires advanced modelling tools and supercomputers that were not available a few years ago. We can now simulate the formation of the Gibraltar Arc with great detail and also how it may evolve in the deep future," explains Joao Duarte, first author and researcher at Instituto Dom Luiz, at the Faculty of Sciences of the University of Lisbon.
This wouldn't be the first time the Atlantic has been invaded by subduction. Two such zones already exist. Studying Gibraltar offers a chance to witness this process in its early stages.
The slow movement in recent years explains the region's low earthquake and volcanic activity. The study suggests this is a consequence of the stalled subduction, not a sign of inactivity.
If the Gibraltar arc awakens, it could resemble the Pacific Ocean's Ring of Fire, with subduction zones on both sides of the Atlantic slowly closing the ocean. This future earthquake and volcanic activity are highly unlikely in the near future, with the last major earthquake in the region occurring 250 years ago.
