SAR interferometric analysis to detect subtle deformation in evaporite 1 areas around Zaragoza , NE Spain

A high density of local natural and human-induced ground deformation 11 structures resulting from the presence of evaporites occur extensively 12 around Zaragoza (NE Spain), posing risks to infrastructures, buildings and 13 agriculture. We studied the potential of a series of interferograms 14 constructed from 29 ERS -1/2 images to detect different types of ground 15 deformation related to evaporite dissolution, landslides, and mining 16 subsidence. We examined the factors involved in the usefulness and quality 17 of interferograms, especially in relation to coherence and atmospheric 18 circumstances. Favourable conditions were found in desert or developed 19 areas, while agricultural practises caused decorrelation in most sinkhole20 prone areas. Results are consistent with previous geomorphological data and 21 indicate that different natural and human-induced deformation phenomena 22 can be detected in a time lag less than 5 years in evaporite areas. Advanced 23 interferometric techniques based on time series of SAR images are needed 24 for precise measurement and monitoring purposes. 25