The Roussopouli fault is a large tectonic structure about 10 km long that runs ENE-WSW and connects two different geological formations. The pyroclastic rocks are around 23 million years old (Lower Miocene), while the sedimentary rocks are approximately 33 million years old (Upper Eocene – Lower Oligocene).

The tectonic structure generates an extended terrace on the area’s gentle landscape. It begins at Cape Sagrada, south of the village of Moudros, continues near to the settlement of Roussopouli, and terminates at Cape Kavalaris, in the harbor of Keros.