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Under the region of Tuscany lies a colossal reservoir that scientists say rivals some of the most powerful supervolcanoes on Earth.
Researchers identified a body of molten and partially molten rock containing approximately 6,000 cubic kilometres of magma buried deep beneath the Italian region. According to the team, its volume is comparable to the magma systems beneath Yellowstone in the United States and Lake Taupo in New Zealand.
The find has been published by a team from the University of Geneva, Italy's Institute of Geosciences and Earth Resources, and the National Institute of Geophysics and Volcanology. They believe the finding helps explain why the region has a lot of geothermal activity despite the lack of active volcanoes.
The find was made by a team from the University of Geneva, Italy's Institute of Geosciences and Earth Resources, and the National Institute of Geophysics and Volcanology.
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Using a technique called ambient noise tomography, the team recorded the natural vibrations constantly passing through the ground, often generated by ocean waves, wind, and even human activity. They used a network of around 60 high-resolution seismic sensors spread across the region.
When those vibrations travel underground unusually slowly, it signals molten or partially molten material. By analysing the recordings, the team was able to construct a detailed three-dimensional image of the crust down to a depth of 15 kilometres.
Interestingly, the surface above it shows almost none of the telltale signs that usually point to large magma bodies underground, such as ground deformation and major eruptions.
In fact, the last volcanic eruption in the area was relatively minor and occurred around 300,000 years ago from Mount Amiata.
"We knew that this region, which extends from north to south across Tuscany, is geothermally active, but we did not realise it contained such a large volume of magma, comparable to that of supervolcanic systems such as Yellowstone," said Matteo Lupi, associate professor in the Department of Earth Sciences at the University of Geneva, who led the study.
The magma sits between 8 and 15km below the surface. At its core is an estimated 3,000 cubic kilometres of primarily liquid melt, surrounded by a larger outer shell of roughly 5,000 cubic kilometres of crystal-rich, partially molten rock.
The area beneath Mount Amiata may hold even greater volumes, though the researchers say further analysis is needed before conclusions can be drawn.
Fortunately, the researchers claim that the magma poses no immediate volcanic threat and the melting of the surrounding crustal rocks makes them far less likely to erupt than those found beneath conventional supervolcanoes.
"Such partial melts may help understand the long-term evolutionary processes taking place at volcanic systems that featured super-eruptions and in regional-scale high-enthalpy systems that have not yet erupted," the authors added.
