An approach to join the spatial and temporal components of landslide susceptibility: an application to the Marche region (central Italy)

The paper is focused on the assessment of the landslide susceptibility, defined as the combination of the natural and human factors that make slopes prone to slide, coupled with the observed recurrence of landslide reactivations. The susceptibility (i.e., the spatial component of the landslide hazard) is assessed by taking into account four causative factors chosen looking at the availability of general-purpose datasets commonly available at area-scale: they are lithology, slope aspect, slope gradient and land use, which are representative of the mechanical properties, morphological features, local climatic conditions and human activities, respectively. The temporal component of the landslide susceptibility is assessed through a multitemporal analysis of aerial photographs, spanning a time interval representative of the climate cycles which recursively affect a basin area (typically, 30 to 50 years long). The two components are then joined to provide an overall estimate of the landslide susceptibility in terms of a landslide hazard index.