How Was Santorini Formed? The 4 Volcanoes That Shaped a Greek Icon

Santorini—famed for its whitewashed villages, dazzling sunsets, and deep blue seas—owes its iconic beauty to a fiery and explosive past. Over the course of millions of years, a series of powerful volcanic eruptions and seismic shifts transformed this island into the geological marvel we see today.

From underwater volcanoes to massive caldera collapses, here’s how nature’s raw power carved one of the most stunning islands in the Aegean. The Fiery Origins of Santorini

Roughly two million years ago, underwater volcanic activity began just west of present-day Santorini. As lava poured from the seafloor, it slowly built up a landmass—layer upon layer of volcanic rock giving rise to the earliest version of the island.

With each new eruption, the island evolved—shifting, expanding, and taking shape. What began as a cluster of submarine volcanoes would become one of the most famous geological landscapes in the world.

Shaped by Fire: The Four Caldera-Forming Eruptions

Santorini’s dramatic topography is the result of four major volcanic eruptions, each responsible for reshaping the island’s structure and contributing to its iconic caldera:

• Southern Caldera (~180,000 years ago)
  The island’s first massive eruption created a large depression in the southern region—an early glimpse of the caldera to come.

• Skaros Caldera (~70,000 years ago)
  A second significant eruption reshaped the island again, forming the Skaros caldera near modern-day Imerovigli.

• Akrotiri Caldera (~21,000 years ago)
  This eruption laid the groundwork for the current volcanic center, deepening the island’s geological complexity.

• The Minoan Eruption (~3,600 years ago)
  Among the most powerful eruptions in human history, this cataclysmic event hollowed out the island’s heart, creating the present-day caldera and altering the course of Mediterranean history.

The Minoan Eruption: A Blast That Changed History

Around 1600 BCE, the Minoan eruption unleashed between 28 to 41 cubic kilometers of volcanic material—obliterating the central part of the island and sending tsunamis across the Aegean.

Thick layers of ash and pumice buried Santorini, and the resulting environmental impact likely contributed to the decline of the Minoan civilization in Crete. This wasn’t just a geological event—it was a cultural and historical turning point.

After the Ash: Ongoing Volcanic Activity

Volcanic life on Santorini didn’t end with the Minoan eruption. Instead, activity shifted to the Kameni Islands, located in the center of the caldera. Over the centuries, these small islets have grown through successive eruptions, the most recent occurring in 1950.

Today, the Kameni islands remain geologically active, feeding hot springs and reminding visitors that Santorini’s story is still being written—one eruption at a time.

Explore Santorini’s Explosive Past

Want to see how millions of years of eruptions shaped this breathtaking island?
Watch the video below for a journey through Santorini’s fascinating geological history.