Satellite SAR Interferometry for Ground Displacement Monitoring
Satellite remote sensing and geospatial technologies have been rapidly advancing, and today space-based earth observation using Synthetic Aperture Radar (SAR) provides an efficient, accurate and low-cost approach for risk and stability monitoring of priority areas such as critical infrastructure, construction sites, mining areas, and oil and gas fields. Spaceborne Differential Interferometry SAR (DInSAR) is a remote sensing technique that is exceptionally useful to measure sudden land deformations at two points in time, such as before and following an earthquake. But when it comes to slow moving ground deformation phenomena such as material compaction, land subsidence or surface creep, it is essential to move to advanced, multi-temporal interferometric stacking techniques that can provide higher accuracies.
In general, there are two kinds of SAR Interferometric Stacking techniques that are applied today. The Persistent Scatterers (PS) method is used for monitoring localized structures (typically man-made features such as buildings, bridges, dams, etc.). The Small Baseline Subsets (SBAS, or Distributed Scatterers) method monitors extended areas like open fields, natural features, or other types of non-geometrically characterized objects. The advanced PS and SBAS Interferometric Stacking techniques analyze time series radar images to obtain a comprehensive overview of the spatial distribution and temporal evolution of slow terrain movements over large areas and long, multi-year periods of time, with millimeter sensitivity.
Unlike passive optical remote sensing sensors that can only operate in daylight when the sun is shining, SAR systems provide their own energy source, allowing them to collect data day and night, and even through clouds. Through the versatile nature of SAR remote sensing technology, it is possible to implement operational land surface monitoring systems for critical sites to precisely observe structural asset conditions at any time.