The island group of Santorini — Thira, Thirassia, and Aspronisi — is what was left over from the last major volcanic eruption 3,600 years ago. From time to time, the viscous magma that remained after the destructive eruption of 1630 BC welled up at the center of the huge caldera (a cauldron-like volcanic feature oftenff created by the collapse of land folllowing a volcanic eruption) — formed during the eruption. It poured out at regular intervals until 1950, adding layer upon layer to create a large underwater volcano, whose peaks are the Palea and Nea Kamini islets. These islets are the youngest landform in the eastern Mediterranean.
The Volcano Today
Since the last eruption of Nea Kameni in 1950, the Santorini volcano has remained dormant. The only witnesses to the existence of magma at a depth of a few kilometres under the island are the hot springs that gust out at various parts of the shores, and the hot gases that are emitted from the fumarols of the central craters on the peak of Nea Kameni.
No long term-predictions can be made as to when the next eruption will take place. However, a short-term forecast as to the volcano’s reactivation can be made in a period of a few months to a year prior to an eruption. All measurements recorded in recent years by the monitoring networks have had no drastic changes, implying that the Santorini volcano continues to be dormant.
Extrapolated from various tourist brochures acquired during visit.
[It is interesting to note that swarms of low magnitude, 1.+ to 3.+, have been recorded since January 2011 and are ongoing. There’s no indication that these are indicative of any imminent volcanic activity or substantial earthquake activity, but they are being monitored closely.]