Which plates are diverging off the west coast of South America?

Nazca Plateis interacting with the South American Plate off the west coast of South America. In fact, Nazca Plate is a converging plate and not a divergent plate. Diverging plates move away from each other, such as African and Arabian Plates. Converging plates move towards each other, as in this case. The Nazca Plate is undergoing subduction (due to higher density of oceanic plate) and is being pulled under the continental South American Plate....

Nazca Plate is interacting with the South American Plate off the west coast of South America. In fact, Nazca Plate is a converging plate and not a divergent plate. Diverging plates move away from each other, such as African and Arabian Plates. Converging plates move towards each other, as in this case. The Nazca Plate is undergoing subduction (due to higher density of oceanic plate) and is being pulled under the continental South American Plate. This subduction is causing the South American Plate to rise up and this has resulted in Andes Mountains. Another characteristic of this oceanic-continental convergence is the volcanoes that form on the surface of continental plate. Strong earthquakes also result from this subduction, as the fragments of subducting plate gets locked in and are suddenly released. 

Hope this helps.