Geochemistry, Mineralogy, Volcanology News

Podcast: Escape from Thera

A colossal volcanic eruption at Santorini, Greece, 3,600 years ago sent the island’s Bronze Age population fleeing for their lives. Where did the people go?

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In the 1960s, archaeologists uncovered a Bronze Age settlement near the village of Akrotiri on the south side of a popular Mediterranean tourist destination, the Greek island of Santorini. As at the more famous sites of Pompeii and Herculaneum, falling volcanic rock and dust had buried the settlement, preserving multistory buildings, frescoes, tools, furniture, and food during a massive eruption that blew apart the island, then known as Thera, around 1600 BCE.

Unlike the Roman cities destroyed more than a thousand years later, there is no evidence of human remains in ancient Akrotiri. No causalities of the eruption have been found. Archaeologists concluded that Thera gave its inhabitants warning, perhaps in the form of alarming earthquakes, and they sensibly fled by boat.

A Minoan fresco depicting ships traveling between two cities
Detail from a fresco in an excavated room in the Bronze Age settlement of Akrotiri on Santorini, Greece. Credit: smial, Public Domain

Foreign pottery and other domestic items showed that the people of Bronze Age Akrotiri traded widely with other cultures of the Bronze Age Greek archipelago. The island sat in an advantageous location for trade with the powerful Minoan civilization centered on Crete, 120 kilometers (75 miles) to the south.

But traces of the Akrotiris’ own distinctive arts do not appear in the archaeological record on Crete or other nearby islands after the eruption. It’s as if the people just disappeared.

Warning Signs

University of Hawai’i at Mānoa volcanologist Krista Evans thinks the people of Akrotiri most likely responded to a series of minor eruptions preceding the main event. Material from precursory volcanic burps can be found within the archaeological site and in geological deposits around the island.

The geological record implies that Akrotiris would have been accustomed to earthquakes, Evans said, but a 40-kilometer-high eruption column raining pumice and ash likely would have been new and terrifying. Evidence of tidying in some of the buildings suggests some people left, returned to begin cleaning up, and then fled again during a subsequent pulse of volcanic activity.

They were wise to leave. The main volcanic event was one of the largest of the past 10,000 years, on the scale of the 1815 eruption of Mount Tambora, with similar worldwide climate effects. The date of Thera’s eruption, sometimes called the Minoan eruption, has been difficult to pin down, leading to fierce arguments about its place in the historical record. The caldera collapsed and flooded, leaving the island in fragments. As happened during the 1883 eruption of Krakatau, pyroclastic density flows of hot ash and gas hit the water, creating a tsunami that devastated the coast of Crete and may have precipitated the fall of the Minoan civilization.

But it’s another observation by witnesses of the 1883 Krakatau eruption that Evans thinks may be critical to the fate of the Akrotiris: Pyroclastic flows can cross water.

The eruption of Thera created massive amounts of pumice, a volcanic rock light and porous enough to float on water, collecting in dense rafts, like the one above encountered by the yacht Finely Finished in August 2019, near the Vava’u island group in Tonga in the South Pacific Ocean. The people of ancient Akrotiri may have also encountered these floating rocks as they fled the eruption in boats.

In the 33rd episode of Third Pod from the Sun, Evans describes how she thinks the people of Akrotiri likely fled south by boat toward Crete, possibly paddling though inches of floating pumice, and what her eruption models suggest may have been their fate.

—Liza Lester (@LizaLester), Senior Media Relations Specialist, AGU

Citation: Lester, L. (2020), Podcast: Escape from Thera, Eos, 101, https://doi.org/10.1029/2020EO147260. Published on 21 July 2020.
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