A proposal for a methodological approach to the characterisation of Widespread Landslide Events: an application to Southern Italy

This paper presents a methodological approach to both identifying and characterising Widespread Landslide Events (WLE), defined as the occurrence of several landslides through wide areas (thousands of square kilometres). This approach is based on a comparative analysis of two historical databases: a rainfall database and a landslide database, both concerning the same period. This methodology was tested on Calabria (Southern Italy) by analysing a period of more than 80 yr. The data allowed the individuation of 25 WLEs generated by the following: (a) a single rainfall event (RE), (b) a few distinct but temporarily close REs, or (c) several consecutive REs occurring over a period of up to two months. An empirical curve, obtained by interpolating the number of landslides occurred during the WLEs and the average values of cumulative rainfall that triggered them enables the individuation of the relationship between rainfall and number of landslides. The proposed methodological approach can be used wherever historical series of both rainfall and landslides are available. The results can be useful for monitoring the development of events and for the planning of emergency management.