Radar satellite interferometry (InSAR) uses microwave radiation to study the movement of the Earth’s surface. The techniques have been applied to study millimetre level motion derived from repeat observations of the ground surface. It relies on the very precise measurement of the phase difference between two waves to produce exceptionally accurate measurements. The technique is applied by our group to study movement at various locations around the world. These include applications in environmental monitoring for oil and gas fields and mines as well as monitoring urban environments for the settlement of local infrastructure. Recently, we used InSAR to demonstrate the magnitude and extent of the ground changes from the earthquake in Nepal.

The basic physics of interferometry is well understood and under the correct conditions, it can be shown that the techniques provide accuracies to within 2 mm per observation. Challenges in the efficacy of the techniques become apparent when the rate of deformation is high, which may present challenges in phase unwrapping or when the interconnectedness of points in time and space becomes sparse.

The talk will outline the methodology, provide some examples of the success of InSAR in monitoring ground movement and will attempt to describe some challenges that may benefit from the application of graph theoretic methods or other tools to enhance the results that can be achieved.