Geologists have recently unearthed crucial information about the volcanic history of the Greek island, Santorini. The latest research, based on its recent eruptions and ongoing seismic activity, shows that the island, which is partially submerged in the sea, is potentially dangerous. The discovery of the volcano’s active magma chamber makes the monitoring and research of this volatile area crucial.
Santorini’s Volcanic Past
Santorini’s fame as the world’s most romantic get-away is not misplaced. Its steep volcanic cliffs with whitewashed houses perched on their edges make for dreamy locations for honeymooning couples. Its red and black pebbled beaches and a crescent-shaped caldera, half submerged in the sea, are a photographer’s delight. Its sunsets are poetry in motion. However, few are aware that this kaleidoscope of colours cloaks an active volcano, which may explode at any time, turning the transfixing beauty to ashes.
A study of the samples collected from the seafloor surrounding the partially submerged volcano has not only revealed its cataclysmic past eruptions but has also provided insights into potential future threats to communities living in the area.
As per an article published on nature.com, the findings point to a colossal eruption that happened around 520,000 years ago. According to the article, “the volcano erupted violently enough to blanket three nearby islands in debris and it sent underwater currents racing for 70 kilometers.” This makes it the largest volcanic eruption known to geologists in the Mediterranean area, even bigger than the Bronze Age eruption of 1600 BC that destroyed Santorini’s ancient city of Akrotiri and may have led to the decline of the Minoan civilization on the island of Crete.
In AD 726, Santorini erupted again. This eruption, according to the recent discovery, was significantly larger than was previously thought. Researchers are of the view that it was approximately the same size as Mount St. Helens’ in Washington in 1980. Historical accounts reveal that the eruption caused the sea to boil and large blocks of pumice stones that were formed due to the underwater eruption, floated thousands of kilometers.
Santorini forms part of the Hellenic Volcanic Arc, which is one of Europe’s most important volcanic fields. It has seen over 100 eruptions over the past 400,000 years. It is just five miles away from the East Mediterranean’s most active underwater volcano, Kolumbo, which is from the same volcanic system. Submerged in the Aegean sea, Kolumbo has been asleep for the past 400 years. But it is still active and potentially dangerous. Its last eruption was in 1650, which resulted in a 40 foot tsunami, besides toxic gas and plumes of smoke. The eruption killed approximately 70 people. Kolumbo continues to be a threat and is being continuously monitored by scientists and geologists.
The Discovery
A team of researchers drilled the sea floor at 12 different sites near Santorini and, despite many challenges, were able to extract sediments and rocks from deep within the ocean floor. “By going into the marine realm we can go further back in time,” the nature.com article quotes volcanologist Timothy Druitt as saying. The article further states that, “the most significant discovery, however, was a thick layer of the volcanic rock called tuff, which kept appearing in core after core, created by a huge prehistoric eruption. ‘Slowly it began to dawn on us that this was a major [geological] unit we didn’t know anything about,’ says Druitt.
The researchers named it the Archaeos tuff, after the Greek word for ‘ancient’. It formed around 520,000 years ago when Santorini erupted underwater, sending shards of ash and rock racing outwards like giant avalanches, the team reported in January in Communications Earth & Environment.”
Why is the discovery so important?
Till now, all the information about Santorini’s past eruptions was based on the samples gathered from the rocks found on the land and the cores, which were easily accessible. However, unbeknownst to researchers, part of its volcanic history was buried deep under the sea. It is only now that it has come to light and revealed the scale and scope of its eruptions.
Volcanologists have been studying different volcanic systems to understand the behaviour of volcanoes. One such study on the Colli Albani volcano, located 20 km southeast of Rome, delves into the rapid accumulation and ascent of low-viscosity magma preceding caldera-forming eruptions. The research reveals that such a phenomenon occurred on the Colli Albani volcano around 355 thousand years ago. Researchers believe that similar conditions in Santorini may result in short periods of unrest prior to a huge eruption. A comparative study of the two volcanoes, focused on similarities in their magma production and ascent, may give critical insights into the timescales of reactivation of dormant volcanoes, such as Santorini, and for predicting and mitigating the impact of future eruptions.
The study of Santorini’s volcanic past is important to understand the level of destruction the volcano has inflicted on the surrounding areas and the change it has brought to its geological formation. It can provide a key understanding of the nature of volcanoes and give insights as to how they can impact people living in their vicinity. The study also aims to help scientists predict future eruptions and explore links between earthquakes and volcanoes.
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