Subduction zones are areas where one tectonic plate moves under another and sinks into the Earth's mantle. This process occurs at convergent plate boundaries, where an oceanic plate typically subducts beneath a continental plate or another oceanic plate. The intense pressure and heat in these zones can lead to volcanic activity and the formation of mountain ranges. As the subducting plate descends, it can create deep ocean trenches, such as the Mariana Trench. Subduction zones are also associated with earthquakes, as the movement of plates can cause stress to build up and release suddenly. This makes them significant in understanding plate tectonics and geological hazards.