Santorini volcanic eruptions linked to changes in sea level

Santorini volcanic eruptions linked to changes in sea level
Santorini volcanic eruptions linked to changes in sea level
Anonim

Scientists have come to the conclusion that the activity of the volcanoes of Santorini Island is most influenced by the sea level. In antiquity, there was a supervolcano on this island, which supposedly destroyed the Minoan civilization. The research results were published in the scientific journal Nature Geoscience.

"About 3, 6 thousand years ago, a powerful explosion occurred here, as a result of which the central part of the island plunged into the sea. As a result, traces of more than 200 previous eruptions were exposed. Thanks to their study, we found out the connection between the level of the Mediterranean Sea and the eruptions of Santorini," - said one of the authors of the work, researcher at Brooks University (Great Britain) Christopher Satow.

It is believed that before the eruption of the supervolcano, modern Santorini and the small islands surrounding it were a single whole - the island of Thira. As a result of the explosion of a supervolcano in the 17th century BC. in the middle of the island, a notch with a depth of several hundred meters and a volume of 133 km3 was formed. Almost immediately, it was filled with sea waters.

The result was a giant tsunami that flooded neighboring Crete. Fragments of volcanic rocks were at a great distance from the epicenter, and a lot of volcanic ash got into the atmosphere. All this, according to historians, led to a sharp decline in the Cretan-Minoan civilization, influenced the well-being of the inhabitants of Ancient Egypt and other Mediterranean countries, and also gave rise to the legend of Atlantis.

Satou and his colleagues wondered how often this supervolcano erupted in the past and what factors could influence the frequency of such events. To answer this question, experts studied volcanic rocks that formed on the slopes of Santorini over the past 360 thousand years.

These rocks were exposed immediately after the eruption, allowing researchers to study its geological history without resorting to costly and time-consuming drilling. Collecting rock samples, British geologists studied in detail the consequences of 211 volcanic eruptions.

Satou and his colleagues drew attention to the fact that all manifestations of volcanic activity on Santorini occurred when the water level in the Mediterranean Sea was 40-80 meters lower than modern. Only four eruptions of the supervolcano occurred when the sea level was close to modern.

Geologists have modeled how changes in sea level will affect the behavior of magma flows in the depths of Santorini. According to these calculations, when the sea level was several tens of meters below modern, it was easier for molten rocks to move towards the Earth's surface. In addition, new paths were opened up for their ascent.

"This geological mechanism is very simple - a drop in sea level reduces pressure on the Earth's crust and it begins to fragment. Through cracks between these fragments, magma can rise to the surface and feed volcanoes," Satou explained.

Other island volcanoes, which account for about 60% of the known foci of volcanism, behave in a similar way, as geologists suggest. Accordingly, climate fluctuations and associated changes in the area of ​​ice caps can significantly affect the frequency of volcanic eruptions, whose emissions, in turn, affect the climate and temperatures on Earth, the scientists concluded.

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