Campi Flegrei, an Italian volcanic system near Naples, is continuing to show activity nearly 500 years after its last eruption, according to research cited by The Brighterside. For decades the area has recorded rising ground levels, earthquakes and gas emissions, but no eruption has followed.
The volcano's last eruption was in 1538, when Monte Nuovo formed near the town of Pozzuoli. The ongoing activity in the volcanic system has kept scientists closely monitoring the changes taking place underground.
What the new research found
A study by researchers from University College London and Italy's National Institute of Geophysics and Volcanology found that years of ground deformation have gradually weakened the upper layers of the Earth's crust in the area. The scientists concluded that since around 2020, part of the deformation has resulted from the fracturing and movement of faults rather than simple bending of rock.
According to the researchers' calculations, the strength of rock in the fault zone has dropped by roughly 2.5 to 3 times compared with the period before the 1980s. That means fractures are becoming an increasingly important way the crust responds to pressure building beneath the volcano.
Not a countdown to eruption
The researchers said weakened rock alone does not signal an imminent eruption. The underground processes at Campi Flegrei are complex, with magma, hot gases and fluids all potentially playing a role. If the fractures link up, pressure could partly ease and the ground uplift could stop, and further cycles of rising and sinking ground are also possible.
Later studies have found evidence that the system continues to change, including signs of magma moving from a depth of at least eight kilometres, and some research points to a gas-rich reservoir beneath the surface.
Record earthquake in July
On 31 July 2026, Campi Flegrei experienced its strongest instrumentally recorded earthquake, with a magnitude of 4.7, followed by a series of 169 further earthquakes.
The volcano remains at a yellow alert level. Scientists say the system is genuinely changing, but the weakening of the crust is not a "timer" counting down to an eruption, which is why continued monitoring of earthquakes, gases and ground movement remains essential.
