INSAR services for GMES : utilisation of ERS and ENVISAT for pan-European subsidence monitoring
The ESA GMES Services Element (GSE) action looking at Geo-Hazard Land Motion is an activity called TERRAFIRMA that is based upon geo-information services using SAR interferometry that can measure precise ground motions for the purpose of assessing risks associated with urban subsidence and landslides. The need for awareness and control of ground instability is recognised through a variety of statutory instruments. Some, like EC Directives on Landfill or Impact Assessment, offer mandatory guidance at international level. TERRAFIRMA is primarily based on datastacks of ERS SAR and ENVISAT ASAR data that have been regularly collected since 1991 and processed via a network of Value Adding organisations using INSAR techniques. These measurements provide a valuable way to map ground deformations in European cities and in areas exposed to landslide risks and can be integrated into geological modelling for causal analysis in collaboration with geoscience centres and geological surveys. This paper will describe the status of service delivery and feedback from users on the utility of the products alongside with a review of current issues and limitations that are associated with the validation of INSAR based deformation measurements.