Impact of loading phenomena on velocity field computation from GPS campaigns: Application to ResPyr GPS campaign in the Pyrenees

Abstract

To quantify the present-day tectonic deformation in the Pyrenees mountain range area where the seismic activity is continuous and moderate, different GPS ResPyr campaigns were performed between 1995 and 2008. Considering the expected rate of deformation of about 1 mm/yr, we can wonder what would be the impact of the different loading effects on velocity field computed from GPS campaigns and therefore on the characterization of the deformation. The data are processed using the GINS software package and we estimated the effect of the loading phenomena on the velocity field resulting from the different campaigns. The final solution uncertainties are of the same order of the expected displacements and we demonstrated the non negligible impact of the various loading phenomena on the velocity field. Indeed, the accumulated loading effect (except tidal ocean load) can reach 0.8 mm/yr on horizontal velocity estimates, which is at the level of the searched signal. © Springer-Verlag Berlin Heidelberg 2012.