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'Test of applicability of Permanent Scatterers technique to landslide investigations in peri-urban areas'

Janusz Wasowski(1) and Alberto Refice(1)

(1) CNR, CNR-IRPI, c/o Politecnico di Bari, via Orabona 4, 70125 Bari, Italy


This work is concerned with the applicability of the Permanent Scattereres (PS) technique to slope instability investigations in peri-urban areas. We present some results of a case study regarding landslide-prone slopes situated in the municipal territory of Caramanico terme (Abruzzi Apennines, south-central Italy). Because the application of conventional DInSAR methodology did not produce useful results (coherence loss problem), the focus is on the PS technique. A total of 52 ERS images acquired from 1993 to 1999 have been processed using Delft Object-oriented Radar Interferometric Software (DORIS) and performed again the whole interferometric processing in order to produce a reliable stack of differential interferograms as input to the PS processing chain. The analysis of PS posed some problems concerning the application of algorithms in the case where density of PS is low (<5 PS/km2). Due to the scarcity of human artefacts and the presence of vegetation cover, few points show sufficient amplitude/phase stability. Moreover the steep and rough topography introduces errors in the interferometric pre-processing making more difficult the joint estimation of displacements and of DEM errors. Under these conditions the significance of the temporal phase trends of the PS remains uncertain. Nevertheless our results show that several PS targets identified in the landslide-prone area exibit average displacement velocities between 7 and 9 mm/yr. These velocities appear qualitatively compatible with the data on ground surface deformations obtained from the recent GPS topographic surveys conducted in Caramanico. Investigations are still in progress aimed at finding more robust and effective strategies to estimate the Atmospheric Phase Screen (APS) from a limited set of sparse data. In particular, a new Phase Unwrapping algorithm (that takes into account the spectral properties of the atmospheric signal) and a alternative way to perform the joint estimation of DEM error and velocity is being investigated.


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Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry