High rates of volcanism, earthquakes, and mountain building are the sites of subduction zones. They occur in convergent boundaries found in tectonic plates of both oceanic and continental crusts. Subduction zones occur when one tectonic plate moves under another tectonic plate, sinking into the mantle as the plates converge again.
Regions that are within subduction zones experience an average rate of convergence of 2-8 centimeters per year. They are subject to many earthquakes because of the collisions that occur within the tectonic plates.