Answer:
When two plates collides of varying densities, one tends to subduct introducing volcanic material to the earth surface.
Explanation:
The ring of fire is a geographical area where seismic and volcanic activities are prevalent. This region extend around the edge of the pacific plates and including smaller plates like the Juan de Faca plate, coccus plate and the Philippine plate . The ring of fire is a place known for earthquake and volcanism due to the active plate boundary.
The plate boundaries around the rings of fire are known for subduction activities.
Usually, in a convergence boundary where continental crust collides with oceanic crust the more dense oceanic crust tends to subduct. The continental crust is less dense and possess more buoyancy. The less dense and buoyant nature of the continental crust will cause it to override the oceanic crust.
Generally, when oceanic crust and continental crust collides the oceanic crust subduct reaching the aesthenosphere area, Aesthenosphere material like magma are introduced to the earth surface through the subduction zone. The magma may creep through cracks and fissures or erupt to the earth surface. The subduction zone form trenches which is a prerequisite for creating mountains, volcanisms and earthquakes.