Land Subsidence Monitoring by Integrating PSI and Geodetic Deformation Measurements

Leveling provides vertical ground deformation and Global Positioning System (GPS) provides three-dimensional (3-D) deformation with subcentimeter accuracy level, but these measurements are point observations. In order to achieve a high spatial resolution, synthetic aperture radar (SAR) is an effective approach. In particular, Persistent Scatterers Interferometry (PSI) can accurately measure wide range of land subsidence by using multi-temporal SAR images. Thus, in this paper, we will merge the results from PSI and geodetic deformation measurements (GPS and leveling) to estimate the 3- D displacement velocities of Kansai International Airport with high spatial reso lution. We apply the least square (LS) approach to combine the interpolated result from GPS and leveling, and estimated results by PSI from SAR images observed on ascending- and descending-orbits. Finally, we compared the estimated results with leveling survey data. The root mean squared error (RMSE) was 18 mm/year, and it was found that the fusion of the results from PSI and geodetic deformation measurements is effective for land subsidence monitoring.