The Valle d’Aosta is the region in the northwest Italy, with an extension of about 3262 km2, sets mainly in the Pennine and Graie Alps. In this context, landslides play an important role in the evolution of the mainly regional territory. In particular, the Valle d’Aosta region is one of the Italian region characterized by higher number of landslides, where landslide affecting an area of 520,35 km2 of the regional territory [Giardino & Ratto, 2007]. The entire territory has been investigated by space-borne technique, using the DInSAR technique by the ESA’s Grid Processing On-Demand (G-POD) service.

Relatively to the Valle d’Aosta region test site, a space-borne analysis, using the DInSAR technique, was done using the ESA’s Grid Processing On-Demand (G-POD) service. The ASAR-Envisat dataset, available through the Virtual Archive 4 of ESA (by the Category-1A project, part of the ESA Geohazard Supersites initiative), was processed by using the G-POD service. The SAR dataset, made of 38 images acquired from ascending orbit (track 301) between June 2004 and November 2010, has been analyzed with the SBAS-DInSAR technique. The ASAR-Envisat satellite acquires images characterized by: - Band acquisition: C Band - Wavelength (cm): 5.6 - Incident angle (°): 23° - Azimuth/ground range resolution (m): ≈ 4/20 - Revisit time (days): 35 - Life status: 2002 – 2010 - Space agency: ESA Regarding the G-POD threshold setting of the SBAS processing, the following parameters were used: - Max Perpendicular Baseline (m): 400 - Max Temporal Baseline (days): 1500 - Ground Pixel Dimension (m): 40 - Coherence Threshold: 0.8 - Area of Interest (AOI): entire frame - REF point: Lat. 45.737049 – Lon. 7.31899 The achieved SBAS measurements are provided in geocoded coordinates (Lat./Lon. and UTM WGS84), and are reported in an ASCII file. The SBAS results, relevant to the entire frame (normally around 100x100 km), have an accuracy of 1 mm/yr concerning the mean velocity measurements, and 5 mm for the deformation measurements [Casu et al., 2006]

The SAR ground deformation time series relevant to Valle d’Aosta region include deformation data obtained from ASAR-Envisat satellite acquisitions (images available in the framework of Category-1A project, part of the ESA Geohazard Supersites initiative), and elaborated by the ESA’s G-POD service with the SBAS technique. In particular, the analysis provided 23634 measure points, for the observed period from April 2004 to November 2010. The analysis provided for each SBAS targets: - East and North UTM WGS84 coordinates (m); - Temporal interferometric coherence [CohT]; - Deformation velocity (cm/year) [Vel.]; - Azimuth and Range coordinates [Az./Rg.]; - Latitude and Longitude coordinates (deg.) [Lat./Lon]; - Topography (m) [RT]; - Deformation Data (cm), related to the acquisition dates of the exploited SAR images. The dataset of the exploited images are expressed as: [year+((month-1)*30+day)/365]. The SBAS results, relevant to the entire frame (normally around 100x100 km), have an accuracy of 1 mm/yr concerning the mean velocity measurements, and 5 mm for the deformation measurements [Casu et al., 2006] The deformation time series present a monthly temporal sampling, and provide long time series of deformation, allowing to follow the evolution of surface displacements over time.