Different geological researches in Greece have proved that in that place of Aegean Sea of today there was a snore that connected Greece with the minor Asian and Crete. This snore looks the name of Aegiida and consisted of many mountains, plains and lakes. There was also a chain of mountains part of which is the today called prophitis Ilias of Thira.
In the post historic period Aegiida was split to pieces some of them emerged and some of them were sunk. A lot of volcanic phaenomena followed and in the middle of the second millennium P.C. the great volcanic destruction takes place which will cause the thick lay of Kissiris and the complex of the islands Thira, Thirassia and Aspronissi. The activity of the volcano didn't stop exist. From its explosions emerged Palea Kameni and Nea Kameni.
The island complex of Santorini lies in the south end of the Aegean Sea. It is the southwest complex of Cyclades and consists of the island of Thira, Thirassia and Aspronhsi. Those three islands are the remaining of a prehistoric bigger island under the name of Strogilli - from its shape before the destruction - and they are exposed in a shape of a ring around a bassin which was formed from sinking down of the centre of Strogilli, because of an enormous volcanic explosion at 1613 b.C. (±13) which let the sea come in. In this bassin which in the international geographic and geologic science is called Caldera appear two islands Palea and Nea Kameni.
Santorini is after Vesuvius one of the most and best studied volcanoes as very seldom in the construction of a complex a volcano appears so clearly. A tragic irony in the geophysical history of Santorini is that the great destruction, lost in the centuries speeds today its incomparable beauty everywhere. To get aware of it one has to tour the caldera from which he will see its deep blue waters and in a height 200-300 meters the dark colored walls of caldera. The different colors of pyroclastic flow and different kinds of lava are very distinct because of their colors which vary from red to black. Above these colored levels we see the white colored level of the Thiraic earth, having a width of 30-50 meters. This material made the base of economy of this island as the quintiles that were exported even reach the two million tones.
Nowadays the volcano is quite calm. In many a place we can distinguish hot vapours and sulphur from which are formed crystals at Sulphur. The temperature of these gases varies with highest 86 celcious.The whole history of the island is involved with its volcanic activity. This activity has formated Santorini throughout the centuries until its nowadays shape and geological structure.
Today, seven craters are located on the Nea Kameni island and one crater on palea Kameni island, just in the middle of caldera. The craters are still smoking even today. This continious gas expansion decreases the possibility of volcanic eruptions. A submarine volcano named "Columbo" is located in the NW seaside of Santorini, near Oia.