Dedicated SAR interferometric analysis to detect subtle deformation in evaporite areas around Zaragoza, NE Spain

A high density of local natural and human-induced ground deformation structures resulting from the presence of evaporites occur extensively around Zaragoza (NE Spain), posing risks to infrastructure, buildings and agriculture. We studied the potential of a series of interferograms constructed from 29 European Radar Satellite (ERS)-1/2 images to detect different types of ground deformation related to evaporite dissolution, landslides and mining subsidence. We examined the factors involved in the usefulness and quality of interferograms, especially in relation to coherence and atmospheric circumstances. Favourable conditions were found in desert or developed areas, while agricultural practises caused decorrelation in most sinkhole-prone areas. Results are consistent with previous geomorphological data and indicate that different natural and human-induced deformation phenomena can be detected in a time lag less than 5 years in evaporite areas. Advanced interferometric techniques based on time series of SAR images are needed for precise measurement and monitoring purposes.