Surreal illustration of Zagreb with GPS and radar monitoring overlays.

Is Your City Shifting? How Satellite Tech Keeps Zagreb Safe

Mira Elwood in Science & Nature August 2025 • 3 min read.

"Uncover how GPS and radar technology combine to monitor ground movement in Zagreb, Croatia, protecting its residents and infrastructure."

For eighteen years, scientists have been deeply engaged in monitoring the earth's movements in the region surrounding Zagreb, Croatia. This area, known for its seismic activity, requires constant vigilance. Researchers are employing advanced satellite technology to detect even the slightest shifts in the ground, ensuring the safety and stability of the city.

The area under study spans approximately 800 square kilometers. This extensive monitoring helps scientists understand the dynamics at play beneath the city's surface. By tracking these movements, they can better predict potential hazards and protect the population.

The primary goal is to accurately measure geodynamic movements over extended periods. This involves using a network of specially stabilized points where precise GPS measurements are taken regularly. This geodynamic network, established in 1997, is the foundation for monitoring tectonic activities and seismic events in the Zagreb area.

Why is Zagreb a Key Location for Geodynamic Studies?

Surreal illustration of Zagreb with GPS and radar monitoring overlays.

Zagreb's location makes it a hotspot for geodynamic research. The city is positioned where several major tectonic units converge, creating a complex geological landscape. Branches of the southeast Alps, the Dinarides, and the Pannonian Basin all meet here, resulting in numerous faults that contribute to earthquake activity.

Understanding these tectonic interactions is crucial for assessing and mitigating seismic risks. By continuously monitoring ground movements, scientists can gain insights into the stresses building up beneath the surface. This knowledge is vital for urban planning and infrastructure development.

GPS Technology: Provides precise measurements of ground movement at specific points.
Geological Surveys: Offer a broader understanding of the region's geological structure.
PSInSAR Technology: Uses radar images to detect surface deformations with high precision.

Researchers use specialized software like GAMIT/GLOBK to process GPS data from the geodynamic network. This software employs Kalman filtering, a sophisticated method for estimating velocities at various points. The result is a detailed model of how the ground is moving, both between individual measurement campaigns and cumulatively over the years.

Combining GPS and InSAR for a Clearer Picture

The integration of GPS and InSAR technologies offers a comprehensive understanding of ground deformations in Zagreb. GPS provides precise measurements at specific points, while InSAR delivers detailed surface data across a wider area. Combining these methods enhances the accuracy and reliability of geodynamic models, improving our ability to safeguard urban environments against geological hazards.

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Everything You Need To Know

Why is Zagreb, Croatia, considered a key location for geodynamic studies?

Zagreb's location is crucial for geodynamic research because it lies at the convergence of several major tectonic units, including branches of the southeast Alps, the Dinarides, and the Pannonian Basin. This convergence results in a complex geological landscape with numerous faults, making it prone to earthquake activity. Monitoring these tectonic interactions helps in assessing and mitigating seismic risks, which is vital for urban planning and infrastructure development. Understanding these interactions is crucial. While the text mentions geological surveys, further study of local geology would also enhance results.

How do scientists monitor ground movement in Zagreb, and what technologies are involved?

Scientists monitor ground movement in Zagreb using advanced satellite technology, primarily GPS and PSInSAR. GPS technology provides precise measurements of ground movement at specific, stabilized points within a geodynamic network established in 1997. PSInSAR technology uses radar images to detect surface deformations across a broader area with high precision. The integration of these technologies offers a comprehensive understanding of ground deformations, enhancing the ability to safeguard urban environments against geological hazards. However, the specific types of GPS receivers or radar satellites used are not detailed.

What is the purpose of the geodynamic network in Zagreb, and how does it work?

The geodynamic network in Zagreb, established in 1997, serves as the foundation for monitoring tectonic activities and seismic events in the area. It consists of specially stabilized points where precise GPS measurements are regularly taken. This network helps scientists accurately measure geodynamic movements over extended periods. Data from the network is processed using specialized software like GAMIT/GLOBK, which employs Kalman filtering to estimate velocities at various points and model ground movement. While the text mentions the software used to process the data and Kalman filtering, it does not explain the principles behind this filtering method.

What are the benefits of combining GPS and InSAR technologies for monitoring ground deformations in Zagreb?

Combining GPS and InSAR technologies offers a comprehensive understanding of ground deformations. GPS provides precise measurements at specific points, while InSAR delivers detailed surface data across a wider area. This integration enhances the accuracy and reliability of geodynamic models, improving our ability to safeguard urban environments against geological hazards. PSInSAR technology gives more data and is especially valuable where there are many buildings.

How is the data collected from GPS and InSAR technologies processed and analyzed to understand ground movements in Zagreb?

GPS data from the geodynamic network is processed using specialized software like GAMIT/GLOBK. This software employs Kalman filtering, a sophisticated method for estimating velocities at various points. The result is a detailed model of how the ground is moving, both between individual measurement campaigns and cumulatively over the years. This processed data, combined with the surface deformation data obtained by PSInSAR, enables scientists to create comprehensive geodynamic models that provide insights into tectonic activities and seismic risks. The text does not delve into the specifics of the data fusion process between GPS and InSAR data or the algorithms used to correlate these two disparate datasets.