A new appraisal of the Ancona landslide

On the night of December 13th 1982, the city of Ancona suffered the catastrophic reactivation of an old and large landslide located along the coast to the West of the town. According to its morphological and kinematic characteristics, the Ancona landslide can typologically be defined as a deep-seated, multiple, compound and recurrent landslide. After the 1982 event, several geological and geotechnical investigations were carried out; furthermore, a complex network of monitoring instruments has been installed. All these data have been of key importance in identifying the superficial and in depth extension of the landslide, the sliding surfaces, the failure mechanisms, the triggering factors and monitoring the deep on-going deformations. The outcomes of past and new geotechnical investigations and all the data coming from the 30-year readings of the monitoring instruments have been integrated in order to redefine and update the actual location of the sliding surfaces. According to the new analysis, the landslide involves four main sliding surfaces with different extensions and maximum depths. Stability analyses have been performed using the newly derived sliding surface geometries. The analyses have been carried out for five different stratigraphic-geotechnical scenarios, showing in each cases a stability slope condition near the limit equilibrium.