Decades ago, a series of events made it impossible for the residents of Rione Terra to live there. Rione Terra and the Pozzuoli region are both located in the Phlegraean Fields, an area with about 20 volcanic craters that are on the verge of eruption. This is considered the most dangerous active volcanic region in Europe. About 3,900 years ago, a major eruption in this area sent ash as far as Russia, causing a “volcanic winter” and a drop in global temperatures.

In the Pozzuoli crater, people still see the phenomenon of "slow seismicity" as the rising magma causes the ground to swell and collapse over time. Sometimes people feel like something is boiling underground. The magma seeps into the ground, causing underground rocks to rise and the terrain to crack. On the worst days, this process creates hundreds of low-intensity earthquakes and people can hear "underground rumbling."