Nitti, Davide Oscar; Bovenga, Fabio; Refice, Alberto; Wa?sowski, Janusz; Conte, Domenico; Nutricato, Raffaele, 2009, L- and C-Band SAR interferometry analysis of the wieliczka salt mine area (unesco heritage site, poland), 2008 Joint PI Symposium of the ALOS Data, Rodi, Grecia, 2008,
URL: http://www.cnr.it/prodotto/i/170253

This work presents first results of interferometric processing of ALOS PALSAR Single Look Complex SAR images (Stripmap Single Polarization Mode), concerning ground deformations in the Wieliczka Salt Mine area, a few km from Cracow, Poland. It follows a recent Persistent Scatterers SAR Interferometry (PSI) analysis on this area, obtained by processing several tens of ERS satellite images covering the period 1992-2000. The results revealed the presence of a few kilometres long, slowly subsiding zone corresponding very well to the extent of the underground salt mine. The present work aims to extend the analysis by exploiting ALOS-PALSAR data especially for the neighbouring rural areas, relying on the lower sensitivity to temporal decorrelation of L-band w.r.t. C-band radar data. Use of L band data is of interest because it could allow detecting faster ground movements related to sudden subsidence events that have occasionally occurred in the recent past. One such event, reported in the 1990's, caused ground displacements locally exceeding 3 m. Furthermore, with L-band SAR data some useful information can be obtained for the rural areas, which neighbour the salt mine but lack PS. We present results obtained from Fine Beam, HH Single Polarization Mode (FBS), 34.3° Off-Nadir look-angle SAR images. The night acquisition time of FBS PALSAR images mitigates the atmospheric phase screen in each interferogram. No clear evidence of displacements is found on ALOS interferograms spanning about 1 year. The relatively high coherence shown by the interferograms allows easier unwrapping of the differential interferometric phase, aiding further statistical investigations on the spatial properties of the atmospheric signal. We also present considerations concerning some processing aspects of ALOS data, as well as a preliminary comparison between the L-band and C-band differential interferometric phase behaviour.

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