Take the ferry to the beautiful Greek islands of Santorini and you will sail into a truly unique landscape forged by a cataclysm towards the end of the Bronze Age. From either the north or south your ship will leave the brilliant blue seas of the Aegean and enter a natural harbour flanked by majestic cliffs. Ferries pass between the large island of Thira and the smaller island of Thirasia, while straight ahead a small island in the centre of the natural harbour, Nea Kameni, looks like a molehill surrounded by mountains.
It is on Nea Kameni, among hot springs and sulphurous vents, that you can begin to understand the natural history and formation of this island. The harbour, the cliffs, the elegant white houses with blue roofs; all are part of a huge volcano.
Santorini in 3D (image: NASA)
Sometime during the mid-second millennium BC, Santorini erupted. It was one of the biggest volcanic events in human history. In the past 800 years only Mount Tambora in Indonesia has erupted with such force, and Tambora was responsible for a global “year without a summer” in 1816.
The eruption sent devastating tsunamis across the eastern Mediterranean that smashed into the Minoans on Crete, at the time one of the world’s most advanced civilisations.
The Santorini volcano is a caldera, a type of volcano that erupts so violently that its middle collapses in on itself forming a huge crater. How this crater came to be is the focus of a new paper in Nature Communications by Paraskevi Nomikou and colleagues. They have published high-resolution seabed maps and combined these with seismic evidence for what rocks the seabed is made of in the caldera to explain how the volcano collapsed, filled with water and might have produced tsunamis.
Prior to the eruption the modern caldera did not exist. Instead a smaller caldera, from a much older eruption, formed a lagoon at the north of the solitary island. Near the modern town of Akrotiri stood a Minoan settlement, a bustling town with three-storey buildings, narrow streets and courtyards, quite different from the palace complexes found in the Minoan homeland of Crete. The prehistoric Akrotiri may have been home to hundreds or thousands of people, and was probably an important trading port for the eastern Mediterranean.
The eruption first blasted ash high into the sky, which settled back down onto the settlements and farmland. This terrifying but not immediately catastrophic stage might have given the locals early warning and caused them to abandon the island (no bodies have been found among the archaeology, which implies residents probably fled).