A ground uplift in the city of Paris (France) detected by satellite radar interferometry

Abstract

We have analyzed a set of ERS-2 images to investigate surface deformation within the city of Paris using the radar interferometry technique (InSAR). 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, where the piezometric level has been lowered during 1995 and 1997. We show that the uplift correlates in time with the increase of the underground water level during the summer 1998, some ten months after the end of the main water pumping work. The amplitude of the uplift corresponds to the amplitude of a subsidence which was previously observed in the same area. This suggests that the deformation mechanism is elastic reversible rather than irreversible. A simple elastic deformation theoretical model matches the InSAR measured surface deformation.