The Alps are a tectonically active region, although they are currently deforming at a comparatively slow and uneven rate. Deep geological processes play a lesser role in this than previously thought. This has been discovered by researchers at Friedrich Schiller University Jena in collaboration with partners from Germany, Italy, Austria, Poland and Slovenia. The team has, for the first time, comprehensively compiled the current state of knowledge on active tectonics in the Eastern and Southern Alps. The new review study has been published in the specialist journal “Tectonics”. The findings help to assess natural hazards in the Alps more realistically and to understand more precisely where earthquakes occur in the Alps and why.

Traces of active tectonics are difficult to detect in the field

The Alps were formed from two primordial oceans and two continents: around 84 million years ago, the Adriatic Plate—part of the African Plate—began to move northwards and collided with the European Plate. The former oceanic crust subducted and the continental crust was compressed. Huge quantities of rock were thus forced upwards, pushed on top of one another, fractured and folded. These plate movements continue to this day. The consequences are earthquakes, although strong quakes are rare.

Until now, it has been unclear which processes within the Earth’s interior are driving the current deformation of the Alps. In recent years, however, thanks to modern geoscientific methods, researchers have been able to gain an increasingly clear picture of the structure of the Earth’s crust and mantle in the Alpine region. "As a result, we now know more precisely than ever before where remnants of subducted plates are located beneath the Alps", says Dr Christoph Grützner from the University of Jena.

However, little research has been carried out to date into whether these so-called slabs are responsible for the current deformation in the Alpine region. Furthermore, the Adriatic Plate and the European Plate are moving towards each other very slowly. This makes it difficult to clearly identify active tectonics in the field. "Traces of tectonic movement are often overlaid or erased by erosion, glaciation and other landscape-shaping processes", explains Christoph Grützner.

Increased tectonic activity, particularly in western Slovenia and on the edge of the Southern Alps

The research team has now analysed the results of several dozen studies conducted over the past few decades and combined various geoscientific datasets and methods. These include seismology, seismic tomography, geodesy, dating of fault zones, historical records of earthquakes, as well as archaeoseismology and palaeoseismology—that is, the analysis of earthquakes in buildings and other archaeological sites, as well as in geological deposits. The researchers have primarily investigated developments over the past million years or so in the Eastern and Southern Alps.

The new review study paints a surprisingly nuanced picture: according to the findings, a significant proportion of the deformation is concentrated along the edge of the Southern Alps. Devastating earthquakes also occur here time and again, most recently in Friuli in 1976. Another zone of heightened activity is found in western Slovenia, where shear movements of around 1.5 millimetres per year have been measured.

Large active fault systems are also present within the Eastern Alps. There, rock material from the Earth’s crust is slowly shifting eastwards—at rates of around 0.5 to 1.0 millimetres per year. This process has been ongoing for millions of years, but has now slowed down considerably. At the same time, there are subject areas that are deforming comparatively little or not at all, such as in the Dolomites.

Combining various geoscientific data and methods reveals slow tectonic processes 

According to the researchers, the strength of the Earth’s crust influences where stresses build up and, consequently, where earthquakes occur and where mountain ranges rise. “Our data show that we cannot simply deduce today’s deformation directly from deep geological processes", says lead author Christoph Grützner. Co-author Gesa Petersen from the GFZ Helmholtz Centre for Geosciences adds: ”The fragmented remnants of the European Plate beneath the Alps do not drive the current deformation. However, we see a clear link between the current uplift and the areas that were once glaciated".

Isostatic balancing movements therefore play an important role: since the end of the last Ice Age, melting glaciers have greatly reduced the weight that previously acted on the Earth’s crust. As the rigid lithosphere floats on the viscous asthenosphere—a layer in the upper mantle—it compensates for this loss of mass by gradually rising. The new study thus also highlights how important the combination of various geoscientific data and methods is in modern geoscience for reliably characterizing slow tectonic processes.

Text: Claudia Hilbert, Dr Christoph Grützner

Original publication:

Grützner, Christoph et al. (2026): Active Tectonics of the Eastern and Southern Alps – Crustal Response to Deep Processes? A Review. Tectonics 45(8), e2025TC009267. DOI: 10.1029/2025TC009267 

The research is part of the priority program 'SPP2017 Mountain Building Processes in 4D (4D-MB)', which was funded by the German Research Foundation (DFG) from 2017 to 2023. For more information, visit: http://www.spp-mountainbuilding.de/

Contact:
Friedrich Schiller University Jena 
Dr. Christoph Grützner
Institut für Geowissenschaften
Burgweg 11
07749 Jena, Germany
E-Mail: Christoph.gruetzner@uni-jena.de
Tel.: +49-(0)3641-948609