Landslide activity maps for landslide hazard evaluation: Three case studies from Southern Italy

This paper focuses on the application of landslide activity maps for evaluating the mass movement hazard in selected areas of the Southern Apennines of Italy: Bisaccia, Calitri, and Buoninventre. The availability of multi-year aerial photo coverage helped to assess the morphological changes which occurred in the last 40 years. This information, integrated with historical data on slope instability and field checks, were used to produce landslide activity maps. These maps represent a short-cut in the assessment of mass movement hazard, because they focus on the effects of slope instability rather than on the causative conditions and processes; however, if kept simple and prepared at large scale, they may help the local administrators and land-use planners to reduce the socio-economic costs of landslides. Furthermore, the comparative study of landslide activity represents a relatively inexpensive and quick method for evaluating the performance of the engineering control efforts. The quantification of landslide activity in terms of areal frequency can represent an additional step, useful to determine the relative landslide hazard (zonation in more or less hazardous areas). For example, the estimates of areal frequency of active landsliding for the last 40 years demonstrated the great influence of the 1980 Irpinia earthquake (M(s) = 6.9) on the stability of slopes situated close to its epicenter (within a radius of about 20 km).