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Sea Level Drops Trigger for Santorini Volcano Eruptions, No Alarm

SANTORINI — After American and Greek scientists who studied the dormant sunken caldera volcano on an islet off Santorini earlier said there's a risk it could erupt again – 3,666 years after a massive explosion – another review has indicated it would take huge sea level drops to make that happen.

A comparison of the activity of the volcano, which is now partially collapsed, with sea levels over the last 360,000 years reveals that when the sea level dips more than 40 meters (131.23 feet) below the present-day level, it triggers a fit of eruptions. During times of higher sea level, the volcano is quiet, researchers reported online in Nature Geoscience, said Science News.

“It’s hard to see why a coastal or island volcano would not be affected by sea level,” said Iain Stewart, a geoscientist at the Royal Scientific Society of Jordan in Amman, who was not involved in the work. Accounting for these effects could make volcano hazard forecasting more accurate, it was said.

Santorini, one of the world's most popular islands because of its famed sunsets and the volcano, is really a ring of islands surrounding the central tip of the volcano that pokes above the Aegean Sea.

The entire volcano used to be above water, but a violent eruption around 1600 B.C. caused it to partially cave in, forming a lagoon, and looking unlike other volcanoes that rise high above ground.

The report said that researchers created a computer simulation of Santorini’s magma chamber, which sits about four kilometers (2.48 miles) beneath the surface of the volcano.

That showed the trigger point for an eruption being a 40-meter fall which would lead to the crust above the magma chamber splintering and unleashing nuclear-bomb like explosions.

“That gives an opportunity for the magma that’s stored under the volcano to move up through these fractures and make its way to the surface,” said study coauthor Christopher Satow, a physical geographer at Oxford Brookes University in England.

There's no need to worry for some milennia, however, as the report said that it would take about 13,000 years for those cracks to reach the surface and that after it did it would take another 11,000 years for the cracks to close and eruptions to stop.

All but three of the volcano’s 211 well-dated eruptions in the last 360,000 years happened during periods of low sea level, as the simulation predicted. Such periods of low sea level occurred when more of Earth’s water was locked up in glaciers during ice ages.

The last time the sea level was 40 meters below today's level was some 11,000 years ago, and now the seas are expected only to rise because of climate change, although the team did two eruptions happened eons ago during high seas.

In March this year, US and Greek scientists working together to create a geomorphologic map for Santorini to “enhance hazard assessments” on the southeastern Aegean island said it’s “at high risk for volcanically- and seismically-induced hazards.”

The scientists applied planetary geologic mapping methods to submarine data to create an onshore-offshore geomorphologic map of the Christiana-Santorini-Kolumbo Volcanic Group, said Kathimerini.

“Submarine geomorphologic maps are used to provide geologic context and spatial information on landforms and related geo-hazards for risk management,” their abstract said.

The long dormant submerged volcano called Caldera on the Nea Kameni islet across from the main island of Santorini is one of the main attractions and tourists can walk to the top of it.

In 2012, the site Volcano Discovery said that, “There are some (still minor) signs that the volcano of Santorini could wake up in a medium future (months to years.) Predicting IF and if yes, WHEN exactly there will be a new eruption is impossible – volcanoes are and will always be unpredictable.

“It is quite certain, though, that the volcano will erupt in the future again, because it is an active volcano and far from extinct,” the report added, the volcano erupting nine times in 2000 years, the last in 1950.

In February, 2020, an official told the state-run Athens-Macedonia News Agency (ANA-MPA) that the 184-page study named Talio was an Emergency Response and Immediate / Short-Term Impact Management of the Volcanic Activity Event at the Santorini Volcanic Complex.

The document was said to have a high alert level “in view of the imminent danger of volcanic activity in the Santorini volcanic complex, taking into account the alert level designation set by the Hellenic Observatory’s Standing Monitoring Committee”.

Greece's Secretariat said there's no cause for alarm as there's no signs that the Santorini volcano, long dormant, will erupt although there is a second underwater volcano called Colombo about 8.5 kilometers (5.28 miles) from the northeast end of the island that's also known as Thira.

Numerous minor and medium-sized eruptions have built the dark-colored lava shields of Nea and Palea Kameni inside the caldera and the last eruption was in 1950. The volcanic complex has two two active sources, the other being Kameni, between Thira and Thirassia, that's another islet there in the chain.

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