Investigating the Deformation of Slow Moving Landslides in the Northern Appennines of Italy with Differential Interferometry (InSAR)

The present work addresses different aspects of the analysis of landslide motion in the Northern Apennines of Italy by means of spaceborn radar interferometry (InSAR). Datasets from the satellite systems Envisat, COSMO SkyMed and Sentinel 1A were processed with different open source packages in order to assess technical issues related to different InSAR processing techniques and to obtain precise deformation measurements. One particular technical issue was the influence of the external digital elevation model, that is used to calculate and subtract the topographic phase, on final PS-InSAR and SBAS-results (chapter 3). It is common that different digital elevation models are available for a study area and often differences in final PS-InSAR/SBAS results can be observed. Due to the high landslide density in Northern Apennines, slope instabilities often interfere with man made structures. The case of Ripoli and Santa Maria Maddalena, South of Bologna, show in an interesting way this interaction between human activity and landslide deformation (chapter 4). Here, a double road tunnel was excavated under a slope that hosts several old deep seated landslides. Soon after excavation started in 2011 first deformations and damages on buildings were registered. InSAR derived deformation measurements document the landslide acceleration during the construction phase and show a decrease in displacement rates after the construction ceased. During the years 2013 and 2014 Northern Italy was struck by long enduring persistent rainfalls that caused numerous landslide reactivations. InSAR datasets were used to assess kinematics of 25 landslides during the years 2013 and 2015, hosted either by chaotic clay shales or pelitic turbidites (chapter 5). Deformation responses to precipitation were analysed in detail for eight selected cases, four of which are located in turbidites and four that are hosted by chaotic clay shales. Different deformation responses were discussed in relation to precipitation, morphology and landslide material.