Campi Flegrei, the 13-kilometer-wide (8-mile-wide) supervolcano beneath the Bay of Naples, is showing signs of unrest, according to a new study. So perhaps 2016 will literally go out with a bang.

A team of French and Italian geoscientists, including those at the National Institute of Geophysics and Volcanology in Bologna, has concluded that the enormous caldera may be entering a stage wherein it will soon be ready for an eruption, based on the current rate of ground deformation observed at the site.

They have also identified a threshold where, if passed, the supervolcano is likely to commence an eruptive phase. Worryingly, the researchers have concluded that Camp Flegrei’s threshold is being rapidly approached. However, the team warn against making any concrete eruption predictions just yet.

“Additional careful scrutiny of monitoring data in the coming months and years is key,” they write in their study.

Generally speaking, the more trapped gas within a gloopy magma, the more explosive the resulting eruption is. This is because a high gas content increases the pressure inside a magma source, and the greater the pressure difference between the magma and the surface world, the more explosive the resulting decompression will be.

Based on a series of models involving gases and fluids under various pressures, the team have identified something called a “critical degassing temperature” (CDT). This denotes the point at which much of the trapped gas is suddenly released by the magma. When this happens, the surrounding rocks are blasted by superheated gases to a point wherein they may fracture.

These fractures may be significant enough to cause a catastrophic collapse, after which the magma source will explode onto the surface in a powerful eruption. According to recent surface measurements around Naples, Campi Flegrei is approaching the CDT quite quickly, which, of course, is bad news.

^{Solfatara, at Pozzuoli, is an active geothermal area that is fueled by Campi Flegrei's magma source. Landscape Nature Photo/Shutterstock}

This supersized volcano formed around 40,000 years ago, producing an eruption that unleashed 500 cubic kilometers (120 cubic miles) of volcanic debris in mere moments. Some of it was found as far afield as Greenland.

The blast registered as a 6 or 7 on the Volcanic Explosivity Index (VEI) – the most powerful type of eruption. It was, without a doubt, the most powerful volcanic eruption in Europe in the last 200,000 years.

It’s erupted infrequently since then, and scientists are concerned that it may one day cause another VEI 6 event. Vesuvius, the infamous volcano nearby, will look like a firecracker in comparison.

Considering that millions of people live literally within the crater, let alone the millions more living just outside the rim, this make it one of the most dangerous – and heavily monitored – volcanoes in the world.

That’s why, when it was discovered that the ground had risen 0.38 meters (1.25 feet) since 2005, it caused a fair bit of concern. Between 1982 and 1984, the ground moved upwards by 1.8 meters (5.9 feet), about 24 times as fast as the current rate of ascension. Nothing happened, of course, but volcanologists were getting ready to sound the alarm.

^{Nearby Vesuvius has got nothing on Campi Flegrei. S-F/Shutterstock}

There is a huge debate as to why the ground rose, with some thinking that it was, and is, magma infilling into a cavity and causing pressure on the roof. Other studies suggest highly pressurized fluids are butting up against the roof, which although not ideal is better than an accumulation of fresh, eruptible magma.

This new study, published in Nature Communications, appears to buy into the second hypothesis to some degree. So although this unrest is worrying, as any around a volcano would be, there’s absolutely no sign that these fields of fire are about to erupt just yet.

Then again, it is 2016.