New mapping of seismic faults
Scientists from the National Observatory of Athens (ΕΑΑ) and from New Zealand, using Digital Elevation Models (DEMs) from the Hellenic Land Registry, have systematically mapped the whole country with the aim of recording the active seismic faults in terrestrial Greece. The scientists discovered hundreds of new seismic faults, while obtaining fuller details of already known ones, creating Active Faults Greece (AFG), the first such database in Greece, which was compiled on the basis of the seismic imprint of faults on the landscape and was published in the authoritative journal Scientific Data.

The team, composed of Dr John Begg, Dr Vasiliki Mouslopoulou, Dr Dave Heron and Prof Andy Nicol, told the Athens-Macedonian News Agency (APE-MPE) that hidden behind the dramatic contrast of the Greek landscape there lies a perpetual geological mechanism: “The country, wedged between two continents, is being distorted by the persistent movement of Africa towards the north and of Eurasia towards the south,” they say. “The relief map of Greece is continuing to change today, chiefly through the movement of active seismic faults. However, many of these faults remain well hidden under vegetation, within the expanding urban landscape or the sheer complexity of the terrain itself.” And they add: “With the economy being increasingly based on tourism, and the country’s ambition to become an energy hub in the Eastern Mediterranean, Greece urgently needs to get a better understanding of the distribution of seismic faults in its territory. And this requires the detailed mapping of the active faults throughout the terrestrial and undersea expanse of Greece.”

The AFG makes available to the scientific community the first Greek map of active faults, based on the morphology of the terrain, on a consistent scale of 1:25,000. The AFG database records 3,815 traces of faults which are grouped into 892 faults, over half of which are mapped for the first time, while it includes 35 surface ruptures which are associated with historical earthquakes.

Each fault is classified by the research as:
– Active, when the terrain appears to have been distorted recently.
– Possibly active, when the fault can be distinguished in the terrain but the data on its activity are less clear.
– Uncertain , when further observation is needed to confirm the existence of a fault.

According to the research team, further classifications include how strongly the faults have left their imprint on the landscape: “Traces like ‘slashes’ indicate recent activity (probably within the Holocene, i.e. in the last 10,000 years), while more rounded traces indicate progressively older earthquakes,” they say.

Active faults
Altogether more than 2,000 traces of faults in the AFG are classified as active, while a further 1,600 are possibly active. Analysis also showed that more than half of the active faults in Greece control the flow of rivers, the deposition of sediments and form the boundaries between mountains and valleys. These relationships, it is stated, demonstrate that inevitably some active faults remain invisible, “buried” under more recent sedimentary deposits.

“During the past few years technological progress has radically changed the way in which we view the Earth,” the team told APE-MPE. The method of Digital Elevation Models (DEMs) used, they said, allow researchers to “read” the terrain and its movements with an accuracy which was not previously possible. They explained that the DEM is not just a map – it is a three-dimensional representation of the surface of the Earth. Each point on the model has a height, allowing researchers to visualise the complexity of the terrain in exceptional detail and to identify features which are invisible to the naked eye.

For the geomorphologist, the Earth’s surface, they emphasise, is a book which narrates the movements of plates and tremors over time, adding that “in the digital models, the scientists can study the landscape denuded of urban development or vegetation, searching for systematic indications of active faults.”

Dr Vasiliki Mousolopoulou, a member of the team, is chief researcher at the Geodynamic Institute of the National Observatory of Athens. She told APE-MPE that mapping active faults is not only of use to science. “It has practical consequences for the safety and sustainability of the country’s infrastructure. Road axes, bridges, dams and power generation units need to be planned in knowledge of the distribution of active seismic sources which could cause movement of the earth’s surface. The information provided by the AFG, when amalgamated with instrumental records of earthquakes, can improve Greek models of seismic risk.”

Her colleague Dr John Begg, the main contributor to the AFG, told APE-MPE that “technology on its own is not enough … The interpretation of DEMs requires the experienced eye of the geologist, who can distinguish a tectonic front from an erosion surface. Digital indications are validated when they check against a series of criteria for fault activity, with on-the-spot observations and comparison with existing studies. The strength of the AFG is guaranteed by the combination of technological tools with decades of geological knowledge,” he said.

Faults in Crete and Chania
According to the data recorded by the scientific team, most of the active faults in Crete are situated in the eastern half of the island. In the nomos of Chania, active faults are chiefly to be found on the Gramvousa and Spatha [Rodopou] peninsulas, in the areas from Falasarna to Gramvousa, from Drapanias to Voulgaro, at Kaliviani in Kissamos, and from Ravdoucha to Menies in the Rodopou area.

Also, an active fault is to be found in the area from Stylos to Tzitzifes in Apokoronas, while “possibly active” faults are found in Vamvakopoulo, Halepa, Pithari and Stavros. In the nomos of Rethymnon, an active fault was located, amongst others, at Spili, which has been studied in detail in the past.

As Dr Mouslopoulou told the Haniotika Nea, “through this research, decades of geological experience has been transferred to Greece from the New Zealand school, of which I am a partial member, which is a pioneer internationally in the mapping and interpretation of seismic faults.”

She added: “With two of the three New Zealand colleagues, we have been working since 2014 in Crete, which we have visited many times, especially Chania…. For Crete the largest number of “red” faults is in the east, chiefly in the nomos of Lasithi. In western Crete and especially in the nomos of Chania, the active faults are concentrated on the Gramvousa and Spatha peninsulas. These active faults have in the post manifested strong earthquakes and we are studying them because they are possible sources of tremors of 6 Richter and above.”

Finally, Dr Mouslopoulou noted that “the seismic risk has not altered – but now we are in a better position to counter it, because we know where the sources of strong earthquakes are in both mainland and insular Greece.”

(Haniotika Nea, 01, 03/12/25)
The original paper published in the journal Scientific Data can be seen here: https://www.nature.com/articles/s41597-025-06283-z