How explosive was the Aegean?

18.04.2017 08:07
Kategorie: News

German-Greek research team investigate Santorini's volcanic past

The Santorini archipelago in the southern Aegean Sea is one of the best spots for an idyllic holiday in the Mediterranean. However, this does not hide the fact that the islands have borne witness to massive volcanic eruptions and strong seismic forces in the past.

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On board the research vessel POSEIDON (from the GEOMAR Helmholtz Center for Ocean Research Kiel), marine scientists from Germany and Greece are studying the seabed around Santorini to find out more about the dangers of volcanism in the region.

In Greek mythology, Poseidon is the god of the sea. The earth trembles and devastating waves are created when he strikes the ground with his trident. This was how the ancient Greeks explained the occurrence of natural catastrophes in the Aegean.

Today, we know better. We know that volcanic eruptions and earthquakes are caused by the African tectonic plate moving beneath the Aegean microplate at about four centimetres a year. Still, many questions about such processes in the seabed remain unanswered.

In an attempt to find out more, the research vessel POSEIDON (aptly named after the mythological god) has been deployed to the southern Cyclades Islands to gather more information. After its first mission, the scientific crew changed in Heraklion (Crete) last weekend before heading back to Santorini.

Together with researchers from the National and Kapodistrian University of Athens, the scientists from Kiel are investigating the history of volcanic activity around the island group. This is of great scientific interest because the present-day islands are what remains after what was possibly the largest volcanic eruption of the past 10,000 years. The eruption took place around 1600 BC, and is linked to the end of the Minoan culture. Volcanoes on Santorini and in the surrounding area are still active today.

The research had started at the beginning of March. During the expedition that spanned three and a half weeks, the autonomous underwater vehicle (AUV) ABYSS was deployed in the waters east of Santorini. It mapped nearly 100 square kilometres of the seabed in search of traces of previous tectonic activity and underwater volcanic eruptions. It also measured the active underwater volcano Kolumbo at a level of accuracy never before achieved.

These processes have been acting on the region for millions of years, and some of the fine structures that we can now see in the AUV maps tell us a great deal about the possible future evolution of the volcanoes”,” said Prof. Dr. Mark Hannington from GEOMAR.

This April, the second team, led by GEOMAR's Dr. Jörg Geldmacher, will collect samples of volcanic rocks from the steep underwater cliffs of Santorini with the remote-controlled dive robot ROV PHOCA. This will be done over the next three weeks, and is expected to yield much information about the early history of the volcanoes and the evolution of the magma.

The ROV will also be used to take thousands of photos for the first high-resolution photomosaics of the volcanoes. With these data, we can produce precise 3D-models of the seafloor,” said Dr. Geldmacher.

Then, in May, Dr. Armin Freundt from GEOMAR will lead a two-week expedition to extract cores of deep-sea sediments that contain a record of highly explosive eruptions that had taken place in the last 160,000 years. These samples will help to quantify the hazards from past eruptions to serve as a gauge of the risk from future volcanic activity.

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