In the heart of the Mediterranean, beneath the waters surrounding the Greek island of Santorini, scientists have made a startling discovery. They have uncovered the remnants of a gigantic volcanic eruption that took place around 500,000 years ago. This eruption, revealed by a layer of pumice and ash up to 492 feet (150 meters) thick, was 15 times more intense than the eruption of the Hunga Tonga-Hunga Ha'apai volcano in 2022.
The island of Santorini emerged due to successive volcanic eruptions.
Santorini Island, which emerged 400,000 years ago following successive eruptions, is today an archipelago formed during the Late Bronze Age (1600 to 1200 B.C.) by the powerful Minoan eruption. Even today, a magma chamber located beneath the Kameni islands, at the center of the Santorini caldera, continues to feed the volcano.
To better understand the volcanic activity of the region, Professor Tim Druitt from the University of Clermont Auvergne, in collaboration with the International Ocean Discovery Program, undertook drilling in the marine sediments around Santorini in late 2022 and early 2023. Sediment cores were extracted up to 2953 feet (900 meters) below the seabed, revealing layers of volcanic sediments, witnesses of past eruptions.
These analyses led to the discovery of an eruption dating back 520,000 years, ejecting at least 55 miles (90 kilometers) of volcanic rock and ash. This eruption demonstrates the Helladic volcanic arc's capacity to produce enormous submarine eruptions.
The eruption occurred from one or more shallow submarine vents of the ancient Akrotiri volcano in the Santorini-Christiana region.
The vent was located in waters shallow enough for magma fragmentation to occur mainly through the exsolution and expansion of magmatic gases. As the gas-particle mixture of the eruptive jet rose through the water column, it ingested water and partially collapsed to form submarine pyroclastic currents. These currents in turn drew in more water and transformed into turbidity currents and flows that spread out across the seabed, depositing a volcaniclastic megaturbidite up to 492 feet (150 meters) thick.
The eruption column's breakthrough of the sea surface also generated subaerial pyroclastic currents that crossed the sea surface and pumice rafts, and deposited thin layers of ignimbrite on the islands (not represented) of Christiani, primitive Santorini, and Anafi.
The drawing is exaggerated vertically, extending several kilometers wide and about a kilometer high.
Although Santorini is not expected to experience an eruption of this magnitude for several hundred thousand years, the magma chamber will continue to fuel lava eruptions and small explosive eruptions for the coming decades, if not centuries.
This discovery signifies a milestone in understanding the volcanic phenomena of the region and their potential impact on our environment.