Ground deformation monitoring of Shenzhen metro area with Interferometric Point Target Analysis

Interferometric Point Target Analysis (IPTA) is a method to exploit the temporal and spatial characteristics of interferometric signatures collected from point targets to accurately map surface deformation histories, terrain heights, and relative atmospheric path delays. In this study, we applied the IPTA technique to monitor the ground deformation of Shenzhen urban area and along the Shenzhen metro lines. The available SAR dataset consists of 20 images from the satellite mission ENVISAT between January 2008 and July 2010. The maximum subsidence rate reaches up to -17.9 to -10 mma^-1. The maximum rise rate reaches up to 6 to 9.8 mma^-1. The Point Target velocity map shows that there is a strong subsidence in Shenzhen urban area, and the subsidence rate is larger than -10 mma^-1. There is also severe subsidence along the metro lines, especially at the stations. The subsidence in the first phase of the Shenzhen metro project is less than the second phase of metro project. The subsidence along the elevated line is less than the underground line. The locations of ground collapse events are mainly distributed at the metro stations.