The Volcano of Nisyros, Greece: Nisyros is the youngest of the large volcanic centers in Greece and is one of the active volcanoes in Greece. The volcano is 160,000 years old, while the youngest, prehistoric rock formations are 15,000 years old and cover the entire island. The island is composed of volcanic rock formations, with swelled elevations that were formed by previous volcanic activities. Thus a major part of the island's soil is volcanic and fertile.
The various rock formations are even used for the construction of various buildings such as the Paleokastro and the bell tower of the Church of Saint John The Theologian just outside Nikea. The base of the island has been formed by lava. The rocks are covered by pyro-clastic deposits and volcanic mud. Two possible eruptions took place several millennia ago, around 25,000 years back. A large depression occurred in the eastern part half way across the island. The western crown of this depression forms the highest peak of the island. The peak of Saint John is in the eastern part of the depression and is about 100m above sea level.
In 1956, schisms emitting smoke were noted in the ground next to the western and southern sides of Ramnos. In 1872, an eruption occurred that was accompanied by earthquakes, backfiring and red flames. Ash and other elements erupted and covered the ground of Ramnos.
During the eruprion of 1872, a crater of about 6 to 7 meters was formed and ash and mud spewed out. The ground of the area of Lakki and Ramnos were transformed into a lake with hot salty water, the water that came me out of the crater. The most recent violent eruption was in 1888 which formed a cylindrical aqueduct of volcanic elements with a diameter of at least 25 meters. The largets crater of the volcano named Polivotis, has a diameter of 260m and 30m depth. Another 5 younger craters in the region, the largest of which is Stefanos with a diameter of 30m and a 30m depth, are also areas of special interest for the tourists.