## 3 Materials and Method
### Distance of Road and River Factor
\begin{table}
\begin{tabular}{c c c c} \hline \hline  & **Factor Class** & **W\({}_{\text{iL}}\)** & **W\({}_{\text{i,PAI}}\)** \\ \hline  & 0–8 & 0.21 & 0.07 \\  & 8.01–18 & 0.15 & 0.15 \\ Slope degree & 18.01–28 & 0.13 & 0.17 \\ \([^{\circ}]\) & 28.01–37 & 0.09 & 0.11 \\  & 37.01–47 & 0.09 & 0.10 \\  & \textless{47} & 0.33 & 0.39 \\ \hline  & Artificial and waterproof surfaces & 0.04 & 0.04 \\ Land Use & \
\begin{tabular}{c} Arabic agricultural areas with sparse vegetation \\ Agroforestry areas with scattered trees and shrubs \\ Wooded areas or areas with important vegetation \\ \end{tabular} & 0.26 & 0.37 \\ \hline  & \textless{100} & 0.19 & 0.10 \\ Elevation & 101–300 & 0.25 & 0.40 \\ \([\text{m}]\) & 301–500 & 0.15 & 0.23 \\  & 501–1000 & 0.27 & 0.21 \\  & \textgreater{1001} & 0.13 & 0.06 \\ \hline  & 0–600 & 0.02 & 0.02 \\ Rainfall & 600–900 & 0.19 & 0.12 \\ \([\text{mm}]\) & 900–1200 & 0.36 & 0.46 \\  & 1200–1500 & 0.25 & 0.29 \\  & \textless{1500} & 0.18 & 0.11 \\ \hline  & Sedimentary deposits & 0.33 & 0.26 \\ Lithology &
\begin{tabular}{c} Clays and sandstones \\ Rocks \\ \end{tabular} & 0.21 & 0.34 \\ \hline  & 0–50 & 0.10 & 0.11 \\ River Distance & 50.01–100 & 0.10 & 0.10 \\ \([\text{m}]\) & 100.01–200 & 0.18 & 0.18 \\  & 200.01–250 & 0.08 & 0.08 \\  & \textless{250} & 0.54 & 0.53 \\ \hline  & 0–100 & 0.10 & 0.14 \\  & 101–200 & 0.08 & 0.11 \\ Road Distance & 201–300 & 0.07 & 0.09 \\ \([\text{m}]\) & 301–400 & 0.06 & 0.07 \\  & 401–500 & 0.06 & 0.06 \\  & \textgreater{}500 & 0.62 & 0.53 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Weight of classes of factor in the landslide areas identified by the PAI. The landslides index for each individual pixel was finally obtained by the weighted sum of the weight determined on the basis of the portion of territory occupied by the factor class (\(\mathbf{W_{i,L}}\)), the weight reached by each factor class in the landslide areas identified by the PAI (\(\mathbf{W_{i,PAI}}\)), and the weight of the same factor obtained from the AHP method (\(\mathbf{W_{i,AHP}}\)). \[\mathbf{LI}=\sum_{i=1}^{n}\mathbf{W_{i,L}}+\mathbf{W_{i,PAI}}+\mathbf{W_{i,AHP}}\]  
The values thus obtained for the assessment of susceptibility were classified into five ranges; in particular, values below 0.17 represent the portions of territory with low risk, values between 0.1701 and 0.25 represent the portions of territory with moderate risk, values between 0.2501 and 0.3 represent the portions of territory with high risk, and values greater than 0.301 represent the portions of the territory with very high risk. The above-mentioned results highlight that 61% of the whole territory of the metropolitan area is affected by a high landslide susceptibility value. In particular, the surface at low risk of landslide is equal to 7% of the entire metropolitan area, at moderate risk is equal to 32%, at high risk is equal to 36%, and at very high risk is equal to 25%. The values obtained for the assessment of susceptibility were classified into five ranges in such a way that, having identified the lower and higher values in each range considered, the number of pixels with respect to the total was equalized between the various classes. This ensures that each class range has approximately the same number of values in each class and that the change between intervals is fairly consistent [40]. From the obtained map (Figure 2), it is possible to notice that the highly and very highly susceptible zones are the hills, i.e., the areas between the coasts and the central part of the province. These areas are particularly relevant because of the connections within the various internal urban areas and the main towns and services located along the coasts. Further, the landslide susceptibility evaluation procedure adopted resulted to be in agreement with the work performed by the Calabria Region Basin Authority: 80% of the highly and very highly susceptible areas coincide with the landslide areas identified by the PAI maps.