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SAR interferometry has proven capable of measuring surface displacements in various situations including ground-settlement, landslides and excavations. We present a case study that consists of a tunnel excavation under a slope where dormant deep seated landslides are recognized. We take advantage of the high resolution images of the COSMO SkyMed Satellite system, that has a high sampling frequency, to measure the distribution of displacements in space and time. Our results are compared to ground-based InSAR data, surface geophysical techniques, GPS and inclinometer measurements. The data were acquired between 2011 and 2015 during the construction phase of the highway that will connect Bologna with Florence across the Northern Apennines. The tunnel passes under the small villages of Ripoli and Santa Maria Maddalena. The geological conditions are characterized by highly sheared flysch sandstones that belong to the LigurianMonghidoro Formation, a unit that is well known for its poor geomechanical properties and high landslide susceptibility. The work on the tunnel started in 2011 and, with the advance of the tunnel front, severe surface displacements were induced, causing damage to houses and infrastructure. The deformation slowed down after the tunnel was completed in November 2014, and low displacement rates were registered during the spring of 2015. The data illustrate the evolution of ground deformations as the excavation proceeds. In particular the InSAR results obtained with the Stanford Method of Persistent Scatterers (StaMPS) for the X-Band data of COSMO SkyMed give interesting insights into the nature of observed surface deformations that include clear downslope movements. 55 SAR scenes were analyzed that had been acquired in ascending and descending orbits, between December 2012 and February 2015. Together with the new findings from combined HVSR-MASW techniques and a detailed remapping of the area, a new conceptual geological model of the slope is developed.

Extensive landslide occurrences affected the Emilia-Romagna Region (north Apennines, Italy) during March–April 2013 due to a high-intensity precipitations and contemporaneous snow melting. During this period, incessant and intense precipitations characterized by a maximum height equal to 350 mm in the piedmont sector and 700 mm in the inner zones (up to fourfold the amount of predictable rainfalls) occurred. This event produced a relevant economic loss due to damages to several private properties and public infrastructures; in fact, local authorities advised about 1,500 damages. The landslide typologies occurred are generally earth slides and earth flows, even if some rock falls was also documented. Usually, landslides appeared as reactivation of preexisting movements and mainly involved the terrain belonging to the Ligurian Flysch Units, characterized by a stratigraphic succession of sandstones, marls and clays. Landslides advised by local authorities have been verified and successively included in the “Historical database of landslide events” of the Emilia-Romagna Region that presently records about 9,000 events, starting from 1,800 to present days. Major landslides was checked in the field and their geometry systematically updated in the already existing GIS-based “Landslide inventory map” of the Emilia-Romagna Region. The updated landslide data are relevant for immediate planning purposes and remediation strategies at both local and regional scale. They are also significant for subsequent susceptibility modeling and related hazard assessment.