Italy's Campi Flegrei supervolcano is stirring. Could this seismic giant soon erupt?

Aerial view of the densely inhabited area of Pozzuoli, located within the Campi Flegrei volcanic area. Over half a million people live in this region, which is continuously monitored due to the ongoing volcanic activity.

The volcano near Naples is shaking the ground in a way that scientists say it hasn't for centuries, posing risks for hundreds of thousands of people living in the 8-mile-wide crater left by past eruptions.

(Image credit: Valerio Muscella for NPR)