Santorini: A Chain of Probable Events Part I

Santorini: A Chain of Probable Events

The Caldera, Santorini

The tension in the air was palpable when Yiannis Paraskevopoulos, co-owner and winemaker of Gaia Estate, arrived at the Heliotopos Hotel in the village of Imerovigli. Paraskevopoulos, who makes wine at Gaia’s Nemean outpost in the Peloponnese as well as on Santorini, was on the island for one of his regular visits, and the hotel is his usual lodging. The front room overlooking the whitewashed terraces of the hotel rooms below and the spectacular volcanic caldera beyond had become the ad hoc headquarters for a group of volcanologists monitoring seismic and volcanic activity on the Aegean Sea floor. The group was huddled around a screen on which Paraskevopoulos could see a large red blip. It was a full red alert.

“We’re quite sure it’s going to blow”, said one of the volcanologists gravely as Paraskevopoulos entered the room. For some days now, pressure had been building beneath the mid-caldera volcanic islands of Palea Kameni and Nea Kameni (“Old” and “new” Kameni), which experience small but regular upheavals causing them to gain a few inches of landmass with alarming regularity. It was now reaching critical levels. The seabed was bubbling up. Pressure sensors embedded on the sea floor and satellite imagery were drawing the red blip on the monitor that was riveting the attention of the scientists, and now Paraskevopoulos, too. The island of Thirasia had moved several inches away the northern tip of the main island of Santorini as the seabed cracked and uplifted between them from gas pressure and the injection of fresh magma into the chamber a couple of miles beneath. The scientists were visibly concerned. “It’s time to call the mayor”, said one of them.

Within minutes the mayor of Santorini was on the phone as the scientists explained the gravity of the situation. “It’s time to distribute the gasmasks”, said another. The mayor paused long and hard as he processed the information. Nothing could be worse for the island then a warning of an impending volcanic eruption, since tourism is the engine that drives Santorini. Without tourists, the economy collapses. This, and the subsequent chain of probable events, flashed through the mayor’s mind. 

Then, calmly, with characteristically Greek, pragmatic, philosophical reasoning, the mayor responded: “we won’t sound the alarm and distribute the masks. Even if this turns out to be a false alarm, the entire tourist season will still be lost from the scare and the economy will be ruined. We’ll all be screwed. On the other hand, if the volcano does erupt, we’re all screwed anyhow. I prefer to do nothing and take my chances.” 

The mayor’s gamble paid off, this time. The science of probability calls for at least a minor eruption in the next three decades, while another major plinian event is due in the next 10,000-20,000 years.

Minoan Eruption of Santorini

There was certainly ample warning before Santorini’s last great Plinian eruption around 1620 BC. The cracked steps and partially crumbled walls buried in the ruins of the city of Akrotiri show the effects of a sizable earthquake that must have occurred a few short weeks or months before the cataclysmic explosion. Citizens had already begun piling rubble and reinforcing weakened structures when the coup de gras came.

Broken steps at Akrotiri, likely caused by an earthquake before the last great eruption in 1620 BC

But unlike Pompeii, for example, where hundreds of cadavers were found, in Akrotiri only a single soul seems to have perished within the city. The fate of the rest is unknown, but what is sure is that, considering the monumental size of the eruption – the largest on the planet in the last 10,000 years, calculated to have emitted 60 cubic kilometers meters (nearly 40 cubic miles) of pyroclastic material – anything and everything within a radius of dozens of miles on land and sea would have been annihilated. A low surge of toxic gas would have instantly killed anyone fleeing by boat, that is, if the tsunamis caused by the eruption hadn’t already. 

3000 year-old wine amphora, Akrotiri

Massive waves reached as far north as the shores of the Peloponnese, and the Minoan civilization on Crete nearly a hundred miles to the south was dealt a decisive blow from which it would never recover. Up to 15 cm of ash even fell in distant Asia Minor, and the climate of the entire Eastern Mediterranean would have been disrupted for several years.

The eruption occurred in several phases, as the visible tephra horizons in many parts of the island reveal. In some areas up to 60 meters (200 feet) of debris accumulated above the older volcanic bedrock (compared to Pompeii’s 6-7m (20-25 feet), ranging from fine ash to lapilli to larger volcanic bombs, and with variable chemical composition. This material formed the black sand beaches of the island, and larger black, red and green rocks used for building walls. 

And the shape of the island itself was dramatically altered. Where once the island was circular, with a fully contained, smaller caldera, the eruption caused the northwest and west sides to collapse and large parts of the island to sink into the emptied magma chamber below. Other parts of the island gained landmass from the accumulation of raining pyroclastic fallout.

Deep banks of wind-sculpted volcanic ash

It would be nearly 4 centuries before Santorini would be re-populated by Phoenician traders in the 12th century BC. But they would discover that, as on Lanzarote in the Canary Islands, the apocalyptic eruption had had unexpected benefits for Santorini’s future winegrowers: it left behind soils suitable for high quality viticulture and fine wine production.

Text and Photos by John Szabo, MS