A change in the tectonic plates off the coast of Spain means a future of earthquakes and heightened plate movement in the region.
A budding subduction zone offshore of Spain heralds the start of a cycle which will one day pull the Atlantic Ocean seafloor into the bowels of the Earth, a new study suggests.
João Duarte is a research fellow at Monash University in Melbourne, Australia, and he has been talking to OurAmazingPlanet magazine.
He explains that Subduction zones are
key players in creating super-continents and opening and closing the Earth’s
oceans.
In a Subduction zone, one of the Earth’s tectonic plates dives beneath another, sinking into the earth’s mantel, which is the layer under the crust. As the crust disappears continents may collide, as has happened numerous times in the history of the planet.
Subduction zones have also led to the biggest earthquakes on the planet.
‘Passive margins’ is where the oceanic and continental crusts make a seamless transition. This is seen in Eastern North American and northern Europe.
But if the north of Europe is stable, it’s different story in the south. Off the SW Spanish coast the seafloor is folded and fractured and is leading scientists to think the earth’s crust could be in for a break.
João Duarte told OurAmazingPlanet, ‘We are precisely in the transition between a passive and active margin. The plate is breaking in two and starting to converge’.
He published that conclusion on June 6 when he and his colleagues placed their research in the Geology journal. It is the result of careful mapping of the underwater faults near Spain and to the west of Gibraltar in the zone called ‘the Southwest Iberia Margin’.
The zone has spawned several large earthquakes such as the 1755 tremor in Lisbon which killed more than 10,000 people, and team has now discovered active thrust faults throughout the supposedly passive margin.
Duarte says that means the margin is not passive anymore and is now being reactivated, i.e. a new convergent plate boundary is forming. This is the beginning of a subduction zone.
The researchers suspect that the new Iberian Subduction zone will get a little help from a tiny ultra-slow subduction zone beneath the Strait of Gibraltar which is attached to the African plate.
Over the next several million years this may roll out towards the Atlantic and merge with the Iberian zone to create an even bigger trench.
Subduction zones take millions of years to form, and they leave few clues as how the process works, most of the clues are left in the mantle.
Duarte says the embryonic subduction zone near Spain suggests that subduction spreads from ocean to ocean.
He and his team are now developing numerical models of subduction to better understand the forces in plate motion.
Making sense of the complex tectonics offshore of Spain and Portugal is also crucial for forecasting the region’s seismic hazard.
‘Despite twenty years of intense investigation, only now are we starting to understand the whole picture’, he said.
In a Subduction zone, one of the Earth’s tectonic plates dives beneath another, sinking into the earth’s mantel, which is the layer under the crust. As the crust disappears continents may collide, as has happened numerous times in the history of the planet.
Subduction zones have also led to the biggest earthquakes on the planet.
‘Passive margins’ is where the oceanic and continental crusts make a seamless transition. This is seen in Eastern North American and northern Europe.
But if the north of Europe is stable, it’s different story in the south. Off the SW Spanish coast the seafloor is folded and fractured and is leading scientists to think the earth’s crust could be in for a break.
João Duarte told OurAmazingPlanet, ‘We are precisely in the transition between a passive and active margin. The plate is breaking in two and starting to converge’.
He published that conclusion on June 6 when he and his colleagues placed their research in the Geology journal. It is the result of careful mapping of the underwater faults near Spain and to the west of Gibraltar in the zone called ‘the Southwest Iberia Margin’.
The zone has spawned several large earthquakes such as the 1755 tremor in Lisbon which killed more than 10,000 people, and team has now discovered active thrust faults throughout the supposedly passive margin.
Duarte says that means the margin is not passive anymore and is now being reactivated, i.e. a new convergent plate boundary is forming. This is the beginning of a subduction zone.
The researchers suspect that the new Iberian Subduction zone will get a little help from a tiny ultra-slow subduction zone beneath the Strait of Gibraltar which is attached to the African plate.
Over the next several million years this may roll out towards the Atlantic and merge with the Iberian zone to create an even bigger trench.
Subduction zones take millions of years to form, and they leave few clues as how the process works, most of the clues are left in the mantle.
Duarte says the embryonic subduction zone near Spain suggests that subduction spreads from ocean to ocean.
He and his team are now developing numerical models of subduction to better understand the forces in plate motion.
Making sense of the complex tectonics offshore of Spain and Portugal is also crucial for forecasting the region’s seismic hazard.
‘Despite twenty years of intense investigation, only now are we starting to understand the whole picture’, he said.
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CREDIT: João Duarte/Geology
