Scientists from the National Observatory of Athens (NOA), in collaboration with colleagues in New Zealand, have produced a detailed seismic map identifying 892 active fault lines across Greece. The team explains that Greece is “squeezed” between the African plate to the south and the Eurasian plate to the north—a geological pressure that drives seismic activity and has the potential to trigger earthquakes.
Utilizing high-resolution Digital Elevation Models (DEMs) provided by the Hellenic Land Registry, the researchers uncovered hundreds of previously unrecorded faults and refined the mapping of known ones. Their work has resulted in the creation of AFG (Active Faults Greece), the country’s first comprehensive database of active seismic faults. The international team, which includes Dr. John Begg, Dr. Vasiliki Mouslopoulou, Dr. Dave Heron, and Professor Andy Nicol, described the Greek landscape as “a perpetual geological machine.”
“The country, wedged between two continents, is deformed by the ongoing movement of Africa toward the north and Eurasia to the south. Greece’s relief continues to evolve today, primarily through the activity of seismic faults. Many of these faults remain concealed beneath vegetation, within expanding urban areas, or in the complexity of the terrain itself,” the researchers explained.
They emphasized the strategic importance of their findings: “With Greece’s economy increasingly reliant on tourism and with aspirations to become an energy hub in the Eastern Mediterranean, it is essential to understand the distribution of seismic sources throughout the country. This necessitates detailed mapping of active faults, both on land and underwater.” AFG provides the scientific community with the first nationwide map of active faults based on terrain morphology, presented at a consistent scale of 1:25,000.
Active Faults Greece
The AFG seismic map documents 3,815 fault traces, grouped into 892 individual faults, with over half recorded for the first time. The database also includes 35 surface ruptures linked to historical earthquakes.
According to the study, each fault is classified as:
- Active: The relief shows clear signs of recent deformation.
- Possibly active: The fault is visible in the landscape, but evidence of activity is less definitive.
- Uncertain: Additional observations are required to confirm the fault’s existence.
The scientific team further emphasizes classification based on how distinctly faults have shaped the terrain. “Traces resembling ‘stabs’ indicate recent activity, likely within the Holocene—the last 10,000 years—while more rounded traces reflect progressively older seismic events,” it was noted. Overall, over two thousand fault traces in the AFG are characterized as active, with approximately 1,600 deemed possibly active.
The analysis also reveals that over half of Greece’s active faults influence river courses, sediment deposition, and the boundaries between mountains and valleys. These relationships suggest that many active faults remain hidden, “buried” beneath newer sediments, and underscore the ongoing need for detailed seismic mapping.
Advanced methodology
In speaking to the Athens-Macedonian News Agency about Greece’s active faults, the researchers noted that “in recent years, technology has radically transformed the way we ‘see’ the Earth.”
They emphasize that digital elevation models (DEMs) enable scientists to “read” the terrain and its movements with an accuracy previously unattainable. Unlike traditional maps, a DEM is a three-dimensional representation of the Earth’s surface, with each point assigned a specific height. This allows researchers to visualize the terrain in exquisite detail and identify structures otherwise invisible to the naked eye.
For geomorphologists, the Earth’s surface is a narrative of tectonic movement and the passage of time. As the team explains, “in digital models, scientists study the landscape as if stripped of cities or vegetation, searching for systematic signs of active faults.”
However, mapping active faults extends beyond academic research. Mouslopoulou, Principal Researcher at the Geodynamic Institute of the National Observatory of Athens, emphasized the practical importance of this work:
“Understanding the distribution of active seismic sources has direct implications for the safety and resilience of infrastructure. Roads, bridges, dams, and power plants must be designed with knowledge of the faults that can move the ground. When combined with instrumental recordings of earthquakes and ground deformation, the data provided by AFG can significantly enhance seismic hazard models in Greece.”
“Technology is not enough, human experience is needed”
Begg, a key contributor to AFG, told AMNA:
“Technology alone is not enough. Interpreting DEMs requires the experienced eye of a geologist—someone who can distinguish a tectonic front from an erosion surface. Digital indications must be validated by cross-referencing fault activity criteria, on-site observations, and existing studies. The strength of AFG lies in combining advanced technological tools with decades of geological expertise.”
The researchers emphasize that this approach is especially effective in a country with complex terrain like Greece. “Careful observation, paired with the insight of an experienced observer, can separate traces left by earthquakes from those shaped by natural erosion or human activity,” it was explained by the team. “Derived images using special lighting (hillshades) and slope maps reveal unmistakable ‘geomorphological fingerprints’ of past earthquakes along active faults—such as inverted valleys, diverted rivers, or triangular mountain fronts.”
The AFG database is freely accessible to the public. Through an interactive map, engineers, researchers, and citizens can locate active faults in their vicinity and explore their key characteristics. AFG—Active Faults Greece—aims not only to support national efforts to document seismic sources but also to serve as a model for other seismically active countries seeking to leverage digital landscapes in identifying active faults.
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