Plate Motions and Active Crustal Deformation in the North Andean Region Measured with the Global Positioning System

Abstract

The CASA (Central And South America) Global Positioning System project was inaugurated in 1988 to study plate motions and crustal deformation in Central America and northern South America, a tectonically active area of complex interaction between the Nazca, Cocos, Caribbean and South American plates. Repeated geodetic measurements with the Global Positioning System (GPS) provide direct measurements of displacements due to active plate motions and intraplate deformation, which can provide important constraints on regional kinematic plate motions, and on the active tectonics of the deforming zones of the convergent margins. Dynamic problems such as the relation between the earthquake cycle and large-scale plate motions or intraplate deformation at the convergent margins can be addressed once a sufficiently long span of data has been collected. The CASA network currently consists of 30 primary sites in five countries (Figure 1), most of which have now been reoccupied at least once. This study concentrates on the results from the stations which provide measurements of the relative motions of the major plates over a three year period.