The potential value of Synthetic Aperture Radar interferometry (InSAR) to detect and quantify Earth surface changes has been recognized for more than 25 years. The European Space Agency (ESA) relatively recently established the Copernicus Program with a satellite constellation that includes a pair of newer satellites, Sentinel-1A and Sentinel-1B. These satellites are in a near-polar, sun-synchronous orbit. They share the same orbital plane with a 180° orbital phasing difference, and carry a C-band synthetic aperture radar active sensor which is applicable for many scientific purposes, including all-weather, day and night data collection. C-band radar sensors have 6-cm wavelength which is suitable for detecting changes as small as ~3 cm per cycle. The pair of satellites are complimentary with one having an ascending view direction and the other a descending view direction, and acquiring repeated 6-m pixel size coverage of the Earth every 12 days.

Satellite radar interferometry is the difference in distance from the satellite to the ground between two radar scenes acquired from the same position on its orbit. An initial data processing step is calculation of a coherence diagram which compares the distance to all pixels in the pair of radar scenes to each other relative to one wavelength (± 3 cm). Interferograms with good coherence are suitable for small-scale distance change detection, whereas poor coherence may indicate large-scale distance changes or some other type of major change, such as a wild fire. Examples of changes suitable for use in pipeline geohazard management that are related to ground surface subsidence over underground potash mines are in the form of areal changes with color bands of distance change, known as fringes, and profiles of distance change extracted from the 6-m pixel interferograms using geographic information system (GIS) utilities.