Wide plate margin deformation, southern Central America and northwestern South America, CASA GPS observations

Global positioning system data from southern Central America and northwestern South America were collected during 1991, 1994, 1996, and 1998 in Costa Rica, Panama, Ecuador, Colombia, and Venezuela. These data reveal wide plate boundary deformation and escape tectonics occurring along an approximately 1400 km length of the North Andes, locking of the subducting Nazca plate and strain accumulation in the Ecuador–Colombia forearc, ongoing collision of the Panama arc and Colombia, and convergence of the Caribbean plate with Panama and South America. Elastic modeling of observed horizontal displacements in the Ecuador forearc is consistent with partial locking (50%) in the subduction zone and partial transfer of motion to the overriding South American plate. The deformation is hypothesized to reflect elastic recoverable strain accumulation associated with the historic seismicity of the area and active faulting associated with permanent shortening of 6 mm/a. Deformation associated with the Panama–Colombia collision is consistent with elastic strain accumulation on a fully locked Atrato–Uraba Fault Zone suture.