Analysis of the European velocity and deformation fields by a new approach

Networks of permanent GPS stations provide data which are very dense in time but discrete in space, while the analysis of a velocity and deformation field requires a spatially continuous modelling: therefore, to investigate deformations from permanent network data a time modelling and a spatial interpolation are needed. As time is concerned, the linear model is typically adopted by international agencies to estimate the individual velocities of the stations. Horizontal estimates are more accurate than height estimates: in spatial modelling, the adoption of a two dimensional approach seems justified to investigate geodynamics deformations. The proposed approach models the regional deformation as a stochastic process in space. The displacements and deformations spatial field is predicted by the stations velocities through a collocation approach. Prior trend removal is based on the transformation to a new reference system satisfying a discrete Tisserand principle. In the spatial interpolation, new approaches to model the covariance structure of the displacements and the rigorous estimation of the accuracies of the predicted deformation parameters have been studied. The algorithms and their implementation are presented. As a case study, they have been applied to Europe: official European Permanent Network velocities and covariances of about 260 stations provide input data. The results are discussed.