Santorini is famous among volcanologists for its Bronze Age eruption in approximately 1600 BC, which might have contributed to the decline of the Minoan civilization on the island of Crete.
Santorini is also home to more than 15,000 residents and attracts around 2 million tourists each year, who Instagram their way around the white- and blue-washed buildings set against the glittering sea.
During an expedition between late 2022 and early 2023, researchers discovered evidence of a previously unknown cataclysm. Half a million years ago, the volcano erupted violently enough to blanket three nearby islands in debris, and it sent underwater currents racing for 70 kilometers. The eruption was much larger than the one in 1600 BC and was one of the biggest ever in this part of the Mediterranean.
The expedition also pulled up evidence that Santorini erupted in the year ad 726 in a blast approximately the size of Mount St Helens’ in Washington in 1980.
No one had understood the scale and scope of these eruptions until now. “The history of Santorini is being written again,” says Paraskevi Nomikou, a marine geologist at the National and Kapodistrian University of Athens in Greece, who was a researcher on the expedition.
Although scientists aren’t expecting similar eruptions to happen any time soon, the findings add to the growing understanding of the volcanic risk at Santorini, which last erupted in 1950. A related volcano, Kolumbo, lies underwater just 7 km away; it last erupted in 1650 and is also considered active.
Both Santorini and Kolumbo are part of the Hellenic volcanic arc, a chain of mostly underwater volcanoes that sit at the junction where the plate of Earth’s crust that carries Africa dives beneath the Aegean Sea plate. With its explosive history and thriving tourist trade, Santorini is one of the most hazardous volcanoes in Europe. Researchers have pieced together much of its eruptive past, by gathering evidence from rocks on land and from cores that could be obtained fairly easily from the top few meters of the Mediterranean Sea floor. But part of Santorini’s history is buried deep beneath the sea floor and had remained inaccessible.
That is, until the drill ship JOIDES Resolution arrived in December 2022 for a 2-month expedition; the researchers drilled 12 holes into the sea floor and pulled up long cores of sediment and rock in and around Santorini and Kolumbo (see ‘Eruption clues’). “By going into the marine realm we can go further back in time,” says Timothy Druitt, a volcanologist at the University of Clermont Auvergne in Clermont-Ferrand, France, and co-chief scientist of the expedition.
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