Stefanos Crater

The creation of the central domes is the latest magmatic activity to occur on Nisyros. All eruptions are hydrothermal (phreatic) and are due to the existence of superheated steam in the subsoil of the island. Temperatures reach 400-500 degrees and enormous pressures are exerted on the overlying rocks, which result in hydrothermal explosions. Thus, 20 craters with a diameter of less than 500 meters were created in the Ramos area, in the southern part of the caldera floor. Ten of them are well preserved and each has its own name. The largest of them is the large Stefanos, with a depth of 27 meters and an ellipsoidal shape with a major axis of 330 meters and a minor axis of 260 meters. Its age is estimated to be between 3,000-4,000 years. Next to it is the small Stefanos. The most numerous and most recent are concentrated in the area of Lofos (large and small Polyvotis, Logothetis).