A disaster could strike Italy if a dormant volcano erupts. A volcano beneath the city of Naples started to show signs of activity.
Researchers have identified the threshold at which rising magma at the Campi Flegrei volcano could trigger an eruption and have found that it is nearing that point.
Lead researcher Giovanni Chiodini, a researcher at Italy’s National Institute of Geophysics and Volcanology in Bologna, said: “Hydrothermal rocks, if heated, can ultimately lose their mechanical resistance, causing an acceleration towards critical conditions.”
The experts are unable to say when the volcano, which is bigger than the nearby Mt Vesuvius that was responsible for the deadly Pompeii incident in 79AD, will erupt.
However, if it were to erupt, “it would be very dangerous” for the 500,000-plus people living locally.
Mr Chiodini said that dense population “highlights the urgency of obtaining a better understanding of Campi Flegrei’s behaviour.”
Scientists first noticed that pressure was building at Campi Flegrei in 2005 and in 2012 they raised the alert level from Green to Yellow – prompting stricter monitoring at the site.
The ancient volcano last erupted in 1538 although it was only minor, lasting for eight days.
However, its formation some 39,000 years ago saw lava and rocks thrown hundreds of kilometres away in what was the most violent eruption in the past 200,000 years in Europe.
The neighbouring Mt Vesuvius has also caused fear among experts and locals in recent times.
The deadly volcano last erupted in 1944 and usually has an eruption cycle of every 20 years, meaning that it has been building up for almost four times that amount.
It is the most densely populated volcanic region in the world, with three million people living in the nearby city of Naples.