How was the Santorini caldera created?
It might come to you as a surprise that Santorini used to be a larger circular island. In ancient times, the popular Greek holiday destination bore the name Strogili which means round in Greek. However, the devastating 1600 BC volcanic eruption changed the island’s outlook forever by creating its signature caldera.
The famous Santorini caldera consists of a large, mostly submerged caldera, home to the Santorini island group: Thera (more commonly known as Santorini) the main island (75.8 km2), Aspronisi (0.1 km2) and Therasia (9.3 km2) at the periphery and Palea Kameni (0.5 km2) and Nea Kameni (3.4 km2) at the center. Thera was built up by layers of lava created by overlapping shield volcanoes, and it suffered three significant eruptions that formed overlapping calderas or collapsed magma chambers. Around 1620 BC, the fourth and most ‘recent’ eruption created the present-day island and caldera bay of Santorini volcano, as we know it today. The caldera rim is clearly visible even from space in astronaut photographs.
As we already mentioned, a caldera is a large depression formed when a volcano erupts and collapses. Calderas are created the way that magma chambers are partially emptied during large eruptions and the land surface subsides while the area above the shallow magma reservoir collapses. As a result, the sides and top of the volcano collapse inward. Calderas around the world can vary in size from one to 100 kilometers in diameter. The Santorini caldera in particular measures approximately 12 by 7 kilometers, with 300 meters high steep cliffs on three sides.
Caldera-forming eruptions are truly massive, as it was in the case of the 1600 BC catastrophic event that wiped away the former Minoan residents. This devastating event may have been the inspiration for the legend of the “lost continent” of Atlantis. The eruption was rated 7, which is the highest score for a historical eruption. The volcanic complex of Santorini is the most active part of the South Aegean Volcanic Arc which includes the active volcanoes of Methana on the mainland of Greece as well as on the islands of Milos, Santorini and Nysiros. It is formed by the subduction of the African tectonic plate which lies underneath the Aegean subplate of the Eurasian tectonic plate. This tectonic plate moves at a rate of up to 5 cm each year in a northeasterly direction. This subduction can cause earthquakes at depths of 150–170 km.
The most recent volcanic activity in the Kameni islands occurred in 1950 and consisted of some minor explosions and the production of lava. Today, the volcano is classified as dormant and safe to visit. Santorini’s whitewashed villages, scenic views, sunny climate and magnificent sunset have made it a magnet not only for volcanologists but for tourists from all corners of the world. Tens of thousands take a Santorini boat trip every year to explore the dormant volcano and walk around its rim. It is not only a fascinating attraction but also make visitors reflect on the immense power of nature.
