Deformation of convergent plates: Evidence from discrepancies between GPS velocities and rigid-plate motions

Abstract

Systematic discrepancies between the Global Positioning System (GPS) site velocities and those predicted by plate-motion models across the Andes, the Himalayan-Tibetan plateau, and the Taiwan orogen delineate diffuse plate-boundary deformation and significant intraplate deformation, even in the presumably rigid oceanic plates. The relationship between the GPS velocities and the predictions of plate-motion models is illustrated using a simple timescale-dependent mechanical model of plate convergence. A simple stiffness number (Φ), based on the difference between the predictions of plate-motion models and the GPS velocity near plate boundaries, provides a convenient measure of the "plate-like" behavior of convergent plates and strain partitioning between intraplate and interplate deformation.