Long ago, the volcanic island Santorini (also called Thíra) had a typical conical shape with steep sides. But a series of eruptions over hundreds of thousands of years emptied the Greek island’s magma chamber, which eventually collapsed and created a crater-shaped depression called a caldera. During a particularly cataclysmic eruption about 3,600 years ago, the volcano hurled vast quantities of ash tens of kilometers into the air, unleashed destructive debris flows and tsunamis, and left the caldera hundreds of meters deep and partially flooded by the Aegean Sea.
The caldera is still prominent in modern times. The OLI-2 (Operational Land Imager-2) on Landsat 9 captured this image of Santorini and neighboring islands on December 18, 2024. Overlooking the caldera rim are lines of white-roofed buildings, including the many hotels and guesthouses that cater to millions of travelers who visit the island each year. Firá, Santorini’s largest town, is the island’s modern capital.
The nearby islands of Nisída Thirasía and the smaller Aspronísi are remnants of volcanic deposits and overlapping calderas that formed during a series of older eruptions, including events that occurred 180,000 years ago, 70,000 years ago, and 21,000 years ago. Nisída Néa Kamméni and Nisída Palaiá Kamméni, the small islands in the center of the caldera, are younger features formed by lava domes and flows that occurred during a less explosive eruption beginning about 2,000 years ago.
Archaeological evidence indicates that the eruption 3,600 years ago, sometimes called the Minoan eruption, devastated what had been the thriving Bronze Age settlement, obliterating and flooding whole towns and potentially leading to significant loss of life. However, the eruption also deposited a layer of ash and tephra several meters thick, which buried and preserved in exquisite detail the ancient Minoan town of Akrotiri. Ruins and artifacts include multi-story buildings, roads, irrigation systems, furniture, pottery, and frescoes. Archaeologists have been excavating the site since 1967.
While archaeologists dig for clues to past worlds on land, astrobiologists have looked to the complex underwater terrain and hydrothermal vents found around Santorini and neighboring underwater volcanoes to prepare for future explorations of distant worlds. Woods Hole Oceanographic Institution scientist Richard Camilli, for instance, led an expedition to Santorini to test autonomous robotic submersibles and AI-based systems that helped plan and control the movements of the underwater vehicles and interpret their observations. Learn more about that expedition in the Our Alien Earth episode above.
References & Resources
- Dartmouth College Akrotiri on Thera, the Santorini Volcano and the Middle and Late Cycladic Periods in the Central Aegean Islands. Accessed July 9, 2025.
- Friedrich, W. (2013) The Minoan Eruption of Santorini around 1613 B.C. and its Consequences. In 1600—Cultural change in the shadow of the Thera-Eruption, 9, 37-48.
- Live Science (2023, June 10) The 12 biggest volcanic eruptions in recorded history. Accessed July 9, 2025.
- NASA (2025) Robotically Exploring the Alien World of Earth’s Deep Ocean with Dr. Richard Camilli. Accessed July 9, 2025.
- NASA (2020, January 28) Autonomy Below the Surface of the Aegean Sea. Accessed July 9, 2025.
- NOAA (2024) Significant Volcanic Eruptions 4360 B.C. to A.D. 2023. Accessed July 9, 2025.
- Oceanus (2021, July 15) Spock Versus the Volcano. Accessed July 9, 2025.
- Pennsylvania State University Santorini 1600 BC and the End of Minoan Civilization. Accessed July 9, 2025.
- UC Berkeley (2024, January 16) Historic Santorini eruption pales in comparison to ancient blowout. Accessed July 9, 2025.
- Woods Hole Oceanographic Institution (2020, January 8) WHOI underwater robot takes first known automated sample from ocean. Accessed July 9, 2025.
NASA Earth Observatory image by Wanmei Liang , using Landsat data from the U.S. Geological Survey . Story by Adam Voiland .
