Mount St. Helens, in the U.S. state of Washington, is an active volcano in the Ring of Fire. Below Mount St. Helens is a convergent boundary between the Juan de Fuca Plate and the North American Plate. The small Juan de Fuca Plate is associated with the massive, heavy Pacific Plate. Both the Juan de Fuca and Pacific plates are being subducted beneath the North American Plate.
A divergent boundary is formed by tectonic plates pulling apart from each other. Divergent boundaries are the site ofseafloor spreading. Seafloor spreading is the process ofmagma welling up in the rift as the old crust pulls itself in opposite directions. Cold seawater cools the magma, creating new crust.
The East Pacific Rise is a site of major seafloor spreading in the Ring of Fire. The East Pacific Rise is located on the divergent boundary between the Pacific Plate and the Cocos Plate (west of Central America), the Nazca Plate (west of South America), and the Antarctic Plate.