New results on post-seismic deformations over L'Aquila, Italy, by high resolution PSP SAR interferometry

The present work focuses on the analysis of post-seismic surface deformation detected in the region of L'Aquila, Central Italy, after the strong earthquake that hit the city and the surrounding villages on April 6, 2009. The analysis has been carried out thanks to a new dataset of SAR COSMO-SkyMed images, and to the adoption of the Persistent Scatterer Pairs (PSP) approach. This method allow the estimate of surface deformations by exploiting the SAR images at full resolution. Two patterns of subsidence have been identified reaching a maximum value of 45 mm in the northeast area of the L'Aquila town. Here the subsidence is mainly ascribable to the post seismic slip release of the Paganica fault and it does not coincide with the maximum measured coseismic subsidence. The time series of the ground deformations also reveal that a large amount of deformation is released in the first three months after the main shock. The second pattern of deformation interests the Mt. Ocre ridge, where a detailed photogeological analysis allowed us to identify widespread evidence of morphological elements associated with Deep-seated gravitational slope deformation (DGSD). In this sector the observed deformation is mainly ascribable to a gravitative cause.