How do tectonic plates create volcanoes?

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volcano Mount St. Helens volcano, viewed from the south during its eruption on May 18, 1980.

Tectonic plates create volcanoes primarily at their boundaries. When plates converge, one plate can slide beneath another in a process called subduction. This descending plate releases water, which lowers the melting point of the overlying mantle rock, forming magma. This buoyant magma rises to the surface, erupting to form volcanoes, often in arcs like the Ring of Fire.123

At divergent plate boundaries, where plates move apart, pressure is released, causing the mantle to melt and form basaltic magma. This magma wells up to create new crust and can erupt as volcanoes, particularly along oceanic ridges. Volcanoes can also form away from plate boundaries at "hot spots," where plumes of hot mantle material rise and melt through the lithosphere.4567