The ground beneath Italy is peeling apart, and scientists think that might explain most of the quakes rattling the Apennine Mountains. A new study finds the lower crust under those peaks is unzipping and dropping into the mantle, a process called delamination that appears to drive seismic activity rather than the usual subduction model.
The research comes from Stefano Tavani, a geoscientist at the University of Florence who led the team. He told Live Science that the Apennines represent the late stage of a long-running geological drama between the African plate and Eurasia. “We are experiencing the very, very late-stage to the subduction, and the tectonics is driven by a different engine, which is this unzipping,” Tavani said.
How the Crust Is Peeling
The Mediterranean region between Africa and Eurasia is a patchwork of tectonic microplates and mountain ranges. The big picture is driven by the African plate pushing northward, squeezing the crust and forcing the ancient Tethys Ocean to sink into the mantle beneath the Apennines. That process has been going on for about 50 million years.
As the African plate subducted under the Eurasian plate, the boundary of that subduction zone marched toward the African plate itself. That motion stretched and thinned the Eurasian crust, creating two large basins: an older one in the Mediterranean west of Corsica and Sardinia, and a younger one, the Tyrrhenian Sea segment, which formed roughly 10 million years ago. Until now, the driver behind those basins and the compression building the Apennines was not fully understood.
Tavani and his colleagues combined earthquake records with ground movements measured by GPS and satellites. They also drew on tectonic models of the plate movements. The result shows that under the Apennines, the lower crust is peeling away and dropping into the mantle. The researchers reported their findings this month in the journal Communications Earth & Environment.
The Late Stage of Subduction
Most earthquakes in the region were assumed to come from subduction — one plate sliding under another. This study suggests otherwise. Delamination, the peeling away of the lower crust, appears to be a major driver of the seismic activity in the Apennines.
In a few million years, Tavani said, the lower crust will finish dropping away and the two plates will weld together. The process is similar to what happens in other places around the world, such as the Hellenic trench south of Greece.
“The findings ‘could be applied to other several systems,’ he said, ‘because in the end, it is a kind of very late-stage plate tectonics.'”
What Comes Next
The study offers a fresh way to understand seismic activity in the region. Rather than waiting for subduction zones to trigger quakes, the focus shifts to the peeling crust itself. The Apennines offer a look into the swan song of subduction, and the unzipping process is visible in the ground movements recorded by GPS and satellites.
The research is a reminder that the ground beneath us is constantly rearranging itself. For now, the message is simple: when you feel the ground shake in Italy, it might not be two plates colliding. It could be the crust itself peeling apart, unzipping layer by layer into the depths below.
Source material: “Earth's crust is 'unzipping' beneath Italy — and that could explain most of the earthquakes in the region,” Live Science.
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