Ground uplift in the city of Paris (France) revealed by satellite radar interferometry

We have analyzed a set of ERS-2 images to investigate centimetric surface deformations within the city of Paris (France) using the radar interferometry technique. We show that a large scale uplift phenomenon occurred during the summer 1998 south of the Saint-Lazare railway station (maximum amplitude of 1.3 cm +/- 0.3 cm). This area corresponds to an important underground working site, which required to lower the piezometric level during 1995 and 1997. The uplift correlates in time with the increase of the underground water level at the end of the construction work. The amplitude of the uplift corresponds to the amplitude of a subsidence which was previously observed in the same area, suggesting that the deformation mechanism is elastic and not simply due to compaction.