Final answer:
A spreading center ridge like the East Pacific Rise explains the existence of the Mariana Trench through subduction at the plate boundary.
Step-by-step explanation:
A spreading center ridge like the East Pacific Rise is responsible for the existence of the Mariana Trench through a process known as subduction.
As tectonic plates move apart at spreading centers, magma rises from the mantle to fill the gap. This creates new oceanic crust, pushing the older crust away. As the older crust moves away, it eventually descends back into the mantle at subduction zones like the Mariana Trench.
The Mariana Trench is located near the western edge of the Pacific Plate, where it is subducting beneath the Mariana Plate. This subduction process is driven by the spreading center ridge and helps explain the existence of the Mariana Trench.
Learn more about Plate tectonics