This application processes a pair of Envisat ASAR data with ROI_PAC (Repeat Orbit Interferometry PACkage), a software package jointly created by the Jet Propulsion Laboratory division of NASA and CalTech for processing SAR data to create InSAR (Interferometric synthetic aperture radar) images, or ‘interferograms’. This geodetic method uses two or more synthetic aperture radar (SAR) scenes to generate maps of surface deformation or digital elevation models, using differences in the phase of the waves returning to the radar sensor. The technique can potentially measure centimetre-scale changes in deformation over spans of days to years. It has applications for geophysical monitoring of natural hazards, for example earthquakes, volcanoes and landslides, and in structural engineering, in particular monitoring of subsidence and structural stability.