Plate boundaries are the weakest points in the Earth's crust, which leads to cracks that allow magma to seep through and develop volcanoes, according to NEWTON. These areas are called "subduction zones." Subduction zones form the Ring of Fire, a volcanic region in the Pacific Ocean, explains Live Science.
As a shifting tectonic plate pushes into the mantle, which is the hot region between the core of the Earth and the crust, fluids inside the tectonic plate are released by the heat. Water, carbon dioxide and other fluids rise up into the upper part of the plate and form magma if they melt the part of the crust they come into contact with. This process occurs along plate boundaries.
San Andreas Fault states that as magma gets closer to the surface of the Earth's crust, hot gases build up and put pressure on the magma. When the magma finally reaches the surface, a volcano is born. Without the shifting of tectonic plates, magma would not form.
Shifting tectonic plates do not always produce volcanoes, according to HowStuffWorks. For example, mountains are formed when tectonic plates collide and one cannot slide beneath the other. However, this boundary can eventually develop into a volcanic subduction zone.