STRAIN RATE PATTERNS FROM GPS AT CONVERGENT PLATE BOUNDARIES

Satellite based geodetic measurements like GPS provide an outstanding tool to measure crustal motions. They are widely used to derive geodetic velocity models that are applied in geodynamics to determine rotations of tectonic blocks, to localize active geological features, and to estimate rheological properties of the crust and the underlying asthenosphere.

We used GPS velocities to derive the 2d strain rate tensor in continental collision zones like the Kyrgyz Tien Shan and the Alps. A tensor analysis provides strain rate characteristics like dilatation and shear strain rates. These results can be used to set up realistic rheological models and are of importance in the seismic hazard assessment. A novelty of our approach is the determination of confidence intervals for the strain rate tensor. So we assessed the uncertainties of the position measurements, their impact on the velocity estimates, as well as the effect of site distribution on the continuous strain rate tensor.