A subduction zone forms when continental crust and oceanic crust collide. The continental crust is thicker and more buoyant than the oceanic crust so the oceanic crust subducts beneath the continental crust. ... Volcanoes associated with subduction zones generally have steep sides and erupt explosively.
Subduction zones are formed at convergent boundaries when tectonic plates collide. If one of the plates slides under the other plate, a subduction zone is formed
