This paper constitutes part of a Technical Report studying soil instabilities and rockfalls that occurred during the heavy rainfall of September 2023, entitled "Daniel,” in a total length of 4.8 km of the provincial road Old Epidaurus-Galata belonging to the municipality of Troizinia-Methana of the Region of Attica in Greece.
The Department of Technical Works of the Piraeus & Islands Regional Unit (Attica, Greece), oversees the restoration of the damage and the removal of risks manifested in the above-mentioned area. On the rocky slopes of the road, as well as in the wider area, during the occurrence of intense rainfall and flooding events in September 2023, were activated instability phenomena which include:
Rock falls in the form of "overturning" and "rock wedge" slides,
Flows and slides of lateral bedrock and material cone bedrock,
Flat slides and slides of the rock masses, and rockslides of boulders and boulder cones.
Slumps and detachments of individual rock fragments
In the present study, the geological and geotechnical characteristics of the conditions and problems of potential instabilities that were activated after the extreme weather phenomena and proposals and immediate measures to address them are presented.
Furthermore, the paper implements two well-known existing rockfall hazard assessment methodologies; a qualitative and a quantitative one that validate the hazard in selected parts of the area under consideration.
Since this section of the provincial road has been closed after the occurrence of the devastating weather event of “Daniel” and because this road is connected with important tourist resorts as well as being the basic road line to many towns and villages in the Piraeus & Islands Regional Unit, the immediate and secure restoration of the described damage and removal of risk are of major importance for the Regional Authority of Attica.