Comparison of Multi-Temporal Differential Interferometry Techniques Applied to the Measurement of Bucharest City Subsidence

Abstract

This paper aims to present some of the most popular multi-temporal differential interferometry (DInSAR) techniques that are used for monitoring surface deformations in different types of areas. We focus on the urban area of Bucharest, where we applied the PS (Persistent Scatterers) and SBAS (Small BAseline Subset) techniques. The PS approach analyzes interferograms generated with a common master image, looking at point targets that remain stable over time, generating signal that remains coherent from an acquisition to another. The SBAS approach relies on small baseline interferograms that maximize the spatial and temporal coherence. In this paper we compare these techniques by applying them to the urban area of Bucharest using TSX data.. Both PS and SBAS methods generate millimetre ground displacement rates. The PS subsidence values range from -22mm/yr to 22mm/yr while the SBAS value rates are lower, from -10mm/yr to 10mm/yr. The subsidence rate maps are compared from a quantitative and qualitative point of view, taking into account also the type of movements that the techniques can derive. The current paper is mainly methodological oriented, aiming to present the PS and SBAS techniques in a comparative way. Less emphasis is put on the initial results, which are presented briefly in order to give an insight about further study directions.