What causes the Pacific Ring of Fire to have so many volcanoes?

The amount of movement of tectonic plates causes the Pacific Ring of Fire to have so many volcanoes.

Explanation:

The ring of volcanoes that is present around the Pacific Ocean which is formed due to the subduction of oceanic plates that lies beneath the lighter continental plates. This region contains most of the volcanoes because of the of the larger part of the subduction zone of the earth.

The plate that is present underneath is pushed down, or subducted by the plate above. As rock is subducted, it melts and becomes magma. The abundance of magma so near to Earth's surface gives rise to conditions ripe for volcanic activity.