Vesuvius is the most problematic because in the past it showed a 25 years cycle between eruptions, but the eruption of ~1975 was missed (last was in 1944 and lava capped the eruptive canal). Anyway, this Vulcanic area is the most populated in the world and evacuating will be a mess.
Every time I hyke to the Vesuvius top, guides explain that there are other active vulcanos in the area; they are all considered active and may harm at any moment. The Phlegraean Fields are problematic because they generate a lot of bradyseism (and in some places the ground went underwater for about 10 meters!), but for now they are considered quiescent.
Ischia island also is a volcano, that has erupted last time around 700 BC. Finally, there's an underwater volcano called Marsilii, that can generate a tsunami.
A couple of years back I was on a flight from the UK to Sicily and it flew down the coast there and so much of what you can see looked volcanic - Ponza in particular.
Every time I hyke to the Vesuvius top, guides explain that there are other active vulcanos in the area; they are all considered active and may harm at any moment. The Phlegraean Fields are problematic because they generate a lot of bradyseism (and in some places the ground went underwater for about 10 meters!), but for now they are considered quiescent. Ischia island also is a volcano, that has erupted last time around 700 BC. Finally, there's an underwater volcano called Marsilii, that can generate a tsunami.
All these volcanos are stricly monitored.