Abstract Land Subsidence Monitoring Using Differential SAR Interferometry Technology Jianguo Chen China University of Geosciences Wuhan, China Email: jgchen@cug.edu.cn Guandao Hu, Jianguo Liu Abstract Differential SAR interferometry is based on phase information extracted from SAR complex image pair to retrieve earthĄŻs surface displacement. It is capable of measuring centimetre level land deformation and provides a powerful tool to monitor subsidence. In this paper, the principle of differential SAR interferometry is introduced firstly, and then an approximate formula between surface displacement and the baseline was developed. After that, three ERS SAR scenes of XiĄŻan region were processed using an INSAR processor to generate interferogram of topography (from a tandem pair) and differential interferograms showing possible centimetre level land deformation caused by subsidence. Interferometric fringes were found around XiĄŻan and Weinan in a differential interferogram over two years period. The fringes around Weinan is particularly clear while those in XiĄŻan are rather ambiguous. The phenomena are direct evidences of subsidence.