“…Mainly based on field geomorphological evidence, some maps are either simple inventories of past events (Highland, 1997;Soldati, 1999), often developed in isopleth maps (Wright et al, 1974;DeGraff, 1985;Guzzetti et al, 1994), or are direct geomorphological maps of landslide-prone areas whose quality strongly depends on the investigator's ability to identify potential slope failures (Humbert, 1977;Dumas et al, 1984;Kienholz et al, 1984;Zimmerman et al, 1986). In order to overcome partly the problem of subjectivity inherent in geomorphological mapping, semi-quantitative hazard maps use a more systematic frame where spatial units of varying nature (catchment and slope unit) are ranked into classes of relative landslide susceptibility on the basis of their environmental characteristics (Hutchinson and Chandler, 1991;Siddle et al, 1991;Moon et al, 1992;Fell et al, 1996) and where GIS and statistical analysis may already be invoked (Carrara et al, 1977(Carrara et al, , 1991Irigaray et al, 1999). Such a statistics-oriented approach finally leads to fully quantitative maps that locate future landslide occurrence as a result of a GIS-based multivariate statistical analysis (Rezig et al, 1996;Leroi, 1997).…”