The volcanic eruption of Thera is also known as the Santorini Eruption or the Minoan Eruption. This historic event made stopping at Santorini one of the most anticipated parts of my trip to Greece. What really got me excited when I read about Thera’s eruption was the magnitude of it and how it affected history. It may have been part of a biblical story and could also have given rise to a famous myth.

As I stood at the crater’s edge, looking down at the sea-filled caldera, I tried to picture what it may have looked like before the historic eruption. Geological studies have shown that it looked as good as it does today.

The caldera, as today, was filled by the sea. However, it was nearly one continuous landmass, rather than five islands surrounding the caldera. There was one small opening at the south end of the ring, the only entrance into the inner harbor. That opening would have been between today’s Thera and Aspronisi islands. At the center of the caldera, as today, would have been a smoldering island volcano that would be the center of the cataclysmic eruption. The Minoans, being people of the sea, were drawn to the protected harbor, making it a perfect place to build one of their main trading ports.

It is believed that the Thera volcano erupted multiple times over several hundred thousand years before the Bronze Age event. It repeated the process of building a volcano, followed by a violent eruption, as the island collapsed into a rough circle and the sea filled the caldera. However, the Minoans were unaware of this process because there were centuries between each of these events.

Around 1627 BCE and 1600 BCE, the new volcano at the center of the caldera became active. First, there were earthquakes. This made the island’s residents aware that something was happening. Studies suggest that there are four phases to the eruption after the earthquakes began. The first was a thin expulsion of ash. This preliminary activity likely gave the population a few months to flee the island. This could be one of the reasons why there are no human remains or valuables found in the buried city of Akrotiri. But did the Minoans flee far enough to save themselves? And what effect the final eruption had on the Minoan civilization and the whole region.

So, how big was the final eruption? To gauge the size of a volcanic eruption, volcanologists use a Volcanic Exclusivity Index or VEI. The Thera eruption is believed to have been a 7 using this index.  So, how does Thera compare to other famous eruptions? Mt. Vesuvius in 79 AD, which buried Pompeii, is rated at a 5. Mt. St. Helens in 1980 is rated at a 4, and the famous 1883 eruption of Krakatoa is rated at a 6. A VEI rating of 7 makes the Thera event one of the largest in history.

The total volume of ejected material is estimated to be approximately 24 cubic miles, projecting an ash plume up to 22 miles into the stratosphere. The final explosion generated a mega-tsunami that is thought to have reached a height of 115 to 492 feet, washing over the coasts and islands of the eastern Mediterranean. The Thera eruption would also have affected the climate of the entire northern hemisphere for years afterward.

This super-eruption has been theorized to have played a role in the Hebrew Exodus from Egypt, contributing to the plagues and the parting of the Red Sea. It is also believed to have led to the collapse of the Minoan civilization, which ended around 1400 BCE. The centers of that civilization could not have withstood the destruction that would have been caused by that eruption. So even if the population of Thera had left before the final blast, they would still have been subjected to the aftermath.

But what fascinated me about this massive eruption was its provable connection to Plato’s Atlantis!  More on that in a later post!