Monitoring Tianjin Subsidence with the Permanent Scatterers Technique

Many urban areas in China are affected by land subsidence. The Permanent Scatterers (PS) technique [1], [2] is a powerful tool for monitoring terrain motions by means of space-born radar data on a large number of coherent targets. Core idea of the PS technique is the exploitation of a high density of measure points (usually but not necessarily corresponding to man-made objects) in order to estimate and remove atmospheric artifacts that normally prevent a correct displacement analysis. Aim of this paper is the description of the results obtained by means of the PS technique over the area around Tianjin city in the Popular Republic of China, where a subsidence at the present time is active. Furthermore, the dispersion of acquisition parameters like normal baseline and Doppler centroid (DC) frequency has been used for characterizing the physical nature of PS’s, thus providing the first basis for the identification of targets visible by different satellites [4], [5], [6].