The relative motions of northwestern South America, the southwestern Caribbean and Panama have been derived from an interpretation of data obtained from three Global Positioning System (GPS) CASA Project measurement campaigns in 1988, 1990 and 1991.

The area of the study is a complex convergent zone for three oceanic plates (Nazca, Cocos and Caribbean) and the South American continental plate. The Nazca-Caribbean-South American triple junction is complicated by two or more microplates (North Andes and Panama-Costa Rica) along the convergent margin, and some of the plate boundaries are still controversial.

The GPS measurements suggest the existence of a Panama-Costa Rica microplate that is moving northward with respect to the Caribbean plate. This motion is supported independently by active folding in the North Panama deformed belt, gravity evidence for oceanic crust dipping beneath the fold belt, and a south-dipping Wadati-Benioff zone beneath Panama. The results also suggest that Panama is still colliding with the North Andes block, at an approximate rate of 10-20 mm/yr, and that the Caribbean plate is being subducted slowly (9-12 mm/yr) beneath the North,Andes microplate. Rapid subduction is taking place at the Middle America (72 mm/yr), Colombia (50 mm/yr) , and Ecuador (70 mm/yr) trenches. Full spreading (70 mm/yr) is occurring at the Galapagos rift.