Analysis of Spatial and Temporal Characteristics of Ground Subsidence in Xiamen Based on PS-InSAR

Xiamen city is located in the east of China and has typical bay-type city characteristics. In this paper, the PS-InSAR technique is used to analyze the 30-view ascending SAR images of Sentinel-1A satellite from 2017-06 to 2022-02. Firstly, image co-registration and interferogram generation are performed on SAR data. Subsequently, stable PS points are selected according to the amplitude dispersion index. GACOS data are introduced to remove the atmospheric delayed phase, and the deformation rate of each PS point is solved after phase unwrapping. Finally, the line-of-sight direction deformation variables are projected to the vertical direction. The results after geocoding show that four major subsidence areas were found on the ground in Xiamen, mainly in Tong’an and Xiang’an districts, with ground vertical deformation rates ranging from -17.5 to 8.5 mm/a. The study provides a reference for future ground subsidence hazard census and early warning by relevant departments.