subduction zone graphic

Schematic Cross Section of a Typical Subduction Zone:  When tectonic plates converge (illustrated by the thick black arrows on either side of the image), one plate slides beneath the upper plate, or subducts, descending into the Earth’s mantle at rates of 2 to 8 centimeters (1–3 inches) per year (red-brown slab with skinny arrow shows direction of motion).