GNGTS 2013 - Atti del 32° Convegno Nazionale

the short-term ones), the two test areas were not well monitored by CGPS stations. ASAR and COSMO-SkyMed InSAR data sets allowed instead to investigate the presence of mid-term transients occurring at the scale of few days to months, giving at the same time the high spatial coverage and resolution needed to distinguish between tectonic and non-tectonic effects. Deformation transients associated to the Pollino seismic sequence. We investigated the presence of deformation transients associated to the area surrounding the Pollino massif, where a seismic swarm is occurring since September 2010. This is an active but slow extensional deforming zone, affected by shallow, normal fault earthquakes, within the diffuse plate boundary between Africa and Eurasia (Sabadini et al. , 2009). In this area the most geologically evident structure is the long-lasting Castrovillari normal fault (Cinti et al. , 1997; Monaco et al. , 2000). Ground deformation occurred before September 2010. We consider both the period prece- ding the inception of the seismic sequence (September 2010), as well as the period preceding the M 5.2 earthquake occurred in October 2012. For the period before September 2010, we had three InSAR data sets. Two ENVISAT data set of 38 ascending and 32 descending ASAR images and a COSMO-SkyMed descending data set of 36 images. A time-series for 38 ascending and 32 descending ASAR Envisat acquisitions respectively, was calculated using the Small Baseline Subset (SBAS) technique of [Berardino et al. , 2002]. The acquisitions span from May, 2003 to September, 2010. The mean-velocity maps derived by SBAS in ascending and descending geometries are shown in Fig.1. Both maps show very low deformation velocities within the noise floor at about +/- 1.5 mm/yr, highlighting a generally low deformation rate for the entire Pollino area. We have validated our results comparing the SAR mean velocities with the corresponding GPS benchmarks velocities (kindly provided by Dr. E. Serpelloni, INGV-Bologna) projected onto the ascending and descending satellite Line of Sights. Due to the characteristics of the Pollino range, showing steep slopes, vegetated areas and presence of snow during the winter season, large decorrelated areas are present in the maps. Fig. 2 – East velocity along the Southern Pollino range slope (red values), preliminary interpreted as due to mainly horizontal downslope sliding of the mid slope part, probably driven by the sliding surface whose main outcropping scarp is indicated with a red line. 203 GNGTS 2013 S essione 1.2