The volcanic activity of Vesuvius volcano is the result of the movement of large crustal plates in the Mediterranean region. The volcano is located in southern Italy where the convergence of the Eurasian plate to the north and the African plate to south produces a subduction zone. Mediterranean seafloor is currently sinking beneath Sicily and Calabria resulting in the formation of the Calabrian volcanic arc. The numbers on the curved lines on the figure to the left indicate the depth to the top of the subducting plate.
Subduction animation from NOAA
Subduction is the process where oceanic crust sinks below either other oceanic crust or more buoyant continental crust. These are some of the most geologically active areas of the planet where both earthquakes and volcanic eruptions are common. Magmas that are generated near the interface between the descending and overiding plate rise to the surface due to buoyancy to feed volcanic eruptions along a narrow arc.