Geologists say that the ground under Spain and Portugal is slowly rotating because of the long, slow clash between Africa and Europe. People can’t see the movement, but it could change how scientists think about earthquakes in the area.
Iberia is not just drifting; it’s twisting.
Schoolbooks have been saying for years that tectonic plates are huge slabs that move past each other slowly, like conveyor belts. That picture works in a lot of places, but the western Mediterranean isn’t following the rules.
A group of geologists recently published a study in the journal Gondwana Research that says the Iberian block, which is basically Spain and Portugal stuck together, is not just moving north with the Eurasian plate. Instead, it is turning to the right, like a huge stone wheel.
The Iberian Peninsula is slowly spinning clockwise because the African and Eurasian plates are hitting each other unevenly.
The speed is very slow. Every year, Africa and Eurasia move closer together by about 4 to 6 millimeters. But the way that movement is spread out over southern Spain, Portugal, and the sea floor nearby makes a subtle twisting effect instead of a clear, straight push.
What makes this part of Europe act differently
At a lot of plate boundaries, things are pretty neat. One plate goes under another, or two plates slide sideways along a fault that is easy to see. That order doesn’t work in the western Mediterranean.
The line between the African and Eurasian plates gets less clear south of Iberia. There isn’t just one clear fault zone; instead, stresses are spread out over a wide area of crust from the Atlantic, through the Strait of Gibraltar, and into the western Mediterranean.
Geologist Asier Madarieta and his team say that some parts of the boundary, like those off the coast of Algeria or in parts of the Atlantic, are very clear. In southern Spain, on the other hand, things are not going well. There are many smaller structures that cut into the rock, and the forces acting on them pull them in different directions.
The Mediterranean pushes Iberia sideways and unevenly compresses it, which causes a torque rather than a straight-line collision.
Think of the peninsula as a stiff book that is being pushed from one corner instead of straight from the front. The book doesn’t slide all the way in one direction; instead, it starts to twist. That seems to be happening to Spain and Portugal on a continental scale.
The Alboran domain and the “hinge” at Gibraltar
The Alboran domain, which is between southern Spain and northern Morocco, is a key part of this story. The African and Eurasian plates are pushing this part of the crust westward, where it is stuck between them.
The Alboran block moves sideways, which changes the shape of the land around the Strait of Gibraltar. That pattern of compression and sideways motion has helped make an impressive arc of mountains over millions of years. It connects Spain’s Betic Cordillera with Morocco’s Rif range. When you put them all together, you get the Gibraltar Arc.
The Alboran domain is being squeezed from the west, which bends the crust into the Gibraltar Arc. This makes the torque that turns Iberia clockwise stronger.
This movement is not the same everywhere. The African plate’s push is strong and direct in some places, causing the crust to crumple. In other cases, some of that energy is redirected sideways, which lets rocks slide past each other instead of hitting each other head-on.
Where the push turns into a twist
The “piston effect” seems to be strongest southwest of the Strait of Gibraltar. The African plate hits the Iberian block more straight on there. The blow to that side makes the peninsula turn, just like a door swings when you push it near the edge instead of the middle.
The result is a complicated pattern of deformation that runs through southern Portugal, Andalusia, the Gulf of Cádiz, and the seafloor nearby. Some areas change shape mostly by being squeezed, while others do so by slipping sideways. All of these changes cause Spain and Portugal to rotate clockwise.
How scientists saw the slow spin
People in Lisbon and Seville won’t feel this rotation. The movement is measured in millimeters per year, which is slower than how fast human nails grow. You need very accurate tools and years of data to find it.
The research team put together two important tools:
GPS satellite measurements: Permanent GPS stations in Iberia and North Africa keep track of how points on the ground move from year to year.
Seismic records show how faults are moving deep down and where stress is building up, even in small earthquakes.
Scientists used GPS to check the ground motion against patterns of seismic activity to figure out how different parts of the crust are being stretched, squeezed, or sheared. The most plausible explanation that accommodates both sets of observations is a gradual, overall clockwise rotation of the Iberian block, superimposed on its general northward drift alongside Eurasia.
What this means for earthquakes in Spain and Portugal
Spain and Portugal aren’t the most seismically active countries in Europe, but they aren’t quiet either. Earthquakes in the past, like the terrible one that hit Lisbon in 1755, show that this area can shake a lot and have a lot of effects.
One puzzle for seismologists is that some earthquakes happen in places where there isn’t a clear major fault on the surface. The new rotational model provides a structure that connects these isolated events.
Researchers get a better picture of hidden areas where damaging earthquakes could start by looking at Iberia as a rotating block under uneven stress.
Madarieta says that many parts of Iberia have changed shape a lot, but there aren’t any clear active structures. Scientists can find the hidden faults that could be dangerous by learning more about how the peninsula bends.
Possible areas of risk
The study emphasizes multiple overarching areas of concern:
| Region | Main tectonic behaviour | Potential implications |
|---|---|---|
| South-west of Gibraltar | Strong compression and twisting | Higher likelihood of moderate to strong offshore quakes |
| Gulf of Cádiz and southern Portugal | Distributed deformation, hidden faults | Shaking from poorly mapped fault systems |
| Southern Spain (Betic Cordillera) | Mix of compression and sideways motion | Frequent small to moderate quakes, complex fault activity |
Scientists still can’t say when a certain earthquake will happen, but a better tectonic model helps planners, engineers, and insurers figure out where stronger building codes or retrofits are needed.
Important geological ideas behind the rotation
For people who aren’t experts, some of the terms used in the research are worth explaining.
The asthenosphere and tectonic plates
The outer shell of the Earth is made up of tectonic plates, which are hard blocks of crust and upper mantle that move over a softer layer below called the asthenosphere. This asthenosphere acts like very thick, warm putty over long periods of time, letting plates “float” and move.
The Iberian block is part of the Eurasian plate on a continental scale. However, on a smaller scale, it acts like a semi-independent mini-plate that reacts to the forces around it in its own way.
Torque and motion that turns
Engineers use the word “torque” to mean a force that twists something, like the one that turns a screwdriver. In tectonics, a similar idea holds: if forces do not align precisely through the center of a block, they can induce rotation.
In Iberia, the pressure from Africa and the push from the western Mediterranean do not cancel each other out. Instead, they make a couple of forces that slowly turn the peninsula to the right.
What a spinning peninsula could mean in the long run
Even a few millimeters a year add up over millions of years. The shape of the coastlines, mountain ranges, and basins around Iberia will keep changing as long as it keeps moving. The Gibraltar Arc may get even tighter, and some parts of the Atlantic margin may stretch or compress slightly.
We can see how realistic the current model is by using computer simulations that predict these movements far into the future. If GPS data continues to show the same rotation pattern over the next few decades, people will be more sure of the long-term predictions. If not, scientists may need to figure out which faults act as hinges and which ones push the hardest.
This slow spin won’t change daily life for people living from Porto to Málaga. The main practical worry is still the risk of earthquakes. Authorities may change the design standards for important infrastructure along the Atlantic and Mediterranean coasts, like bridges, dams, and ports, as hazard maps are updated to show the clockwise rotation.
The Iberian Peninsula’s slight curve is a reminder that even landscapes that seem stable are slowly changing. The ground is slowly and steadily turning beneath the vineyards, beaches, and historic cities of Spain and Portugal. Scientists are only now starting to figure out what this means.
Originally posted 2026-02-16 12:20:00.