Led by Asier Madarieta Txurruka of the University of the Basque Country, the study combines satellite deformation data and decades of seismic records to explain why the peninsula is twisting and what that means for its seismic future. The findings revise long-standing assumptions about tectonic stability in southern Europe.
The research, developed in collaboration with scientists from the University of Palermo and the University of Granada, focuses on the complex and often chaotic boundary between the Eurasian and African tectonic plates. The Iberian Peninsula sits right in the middle of this zone.
While some parts of the boundary, such as those in the Atlantic Ocean or along the Algerian margin, are sharply defined, the area south of Iberia tells a different story. Here, the convergence between the two massive plates becomes a tangled web of interactions, microplates, and hidden faults.
The team analyzed both surface deformation observed from space and stress patterns derived from seismic activity. This approach gave them a high-resolution image of the tectonic forces at work and how they’re distributed across the region.
How Asymmetric Collisions Are Twisting the Peninsula
The key to the rotation lies in the unequal distribution of tectonic force. To the east of the Strait of Gibraltar, a geological structure known as the Gibraltar Arc, formed by the westward-moving Alborán domain, acts as a shock absorber. It reduces the impact of tectonic collision by distributing stress along the Betic and Rif mountains. But west of the strait, no such buffer exists.
In this western sector, the Iberian block, a part of the Eurasian plate, collides more directly with the African plate. This creates a more concentrated transfer of tectonic energy into southwestern Iberia. Because the continental crust in this region is not rigid, the pressure doesn’t just push; it twists.
According to the researchers, this constant mechanical stress is enough to cause a geologically stable landmass to rotate. The motion is slow, just a few millimeters a year, but steady. Over geological time, this produces a clockwise shift of the entire peninsula, something never confirmed at this level of detail until now.
Seismic Blind Spots and the Search for Hidden Faults
One of the study’s most significant contributions is its potential to improve seismic risk models. In regions where tectonic stress is diffuse, like southwestern Iberia, it’s not always clear which faults are active or even where they are. Earthquakes happen, deformation is recorded, but the exact tectonic structures responsible often remain unidentified.
Asier Madarieta explains that the combination of satellite data and seismic records helps geologists narrow down the zones most likely to host these invisible faults. These are areas where future earthquakes could originate. The findings provide a foundation for further investigation, especially in under-studied regions such as the western Gibraltar arc, stretching between Cádiz and Seville.
The research supports efforts like the Iberian Quaternary Active Fault Database (QAFI), which still lacks detailed data in several critical regions. By identifying zones of high deformation with no known faults, the study offers a roadmap for where to look next.
Modern Instruments, Ancient Processes
Although the study is based on state-of-the-art technology, such as radar interferometry (InSAR) and global navigation satellite systems (GNSS), the time frame of the available data remains extremely short. According to La Brújula Verde, the most precise seismic records have only existed since 1980, and the first reliable satellite measurements go back to 1999.
This limitation doesn’t reduce the significance of the findings. Instead, it highlights the importance of combining data sources to create the clearest possible picture of what’s happening underground. By integrating seismology, geodesy, and geology, the researchers have managed to capture a meaningful snapshot of a process that spans millions of years.
Now based at the University of Palermo thanks to a postdoctoral grant from the Basque Government, Madarieta continues to develop this research. The work adds a new layer to the understanding of southern Europe’s geodynamics and underscores the need for further studies to map the region’s tectonic evolution with even more accuracy.