Insar Imaging of London Surface Movement for Structural Damage Management and Water Resource Conservation

Synthetic Aperture Radar (SAR) Interferometry (InSAR), using data from the European Space Agency satellites ERS1 and ERS2, is being used to image, survey and map surface movement of the London region. Local and regional movement due to shrink and swell of the London Clay geology, tunnelling, and possibly ground water abstraction has been investigated here for the first time by InSAR. Cyclic annual clay shrink/swell of < 50mm causes widespread structural damage to buildings and infrastructure and is a major cause of water main bursts. The phenomenon is well recognised but variability of the actual surface movement across the London Clay has not been comprehensively surveyed before. Ongoing research will produce the first regional shrink/swell maps and model the phenomenon to benefit a diversity of end users and the region’s economy. In particular, engineering solutions may be focused where high shrink/swell susceptibility is identified to efficiently target water main bursts and so conserve water resources.