*2.3. Susceptibility Models*

Two *S* models are used in this study. The continental-scale *S* model of [45] is calibrated for all landslides regardless of type at a spatial resolution of 0.0033◦. This model is produced through logistic regression using a ~4:1 landslide to no-landslide (L/NL) ratio and is based on four predictor variables: maximum slope (~90 m SRTM [57]), mean local relief (~90 m SRTM [57]), peak ground acceleration [58], and lithology [59]. The landslide inventory used for the model contains more than 18,000 landslides, of which 765 are located in the WEAR. The second *S* model is the regional-scale model of [49] which

was calibrated for a representative part of the WEAR and extrapolated within this study for the entire WEAR. This model includes all landslide types and is trained at a 0.0003◦ resolution using logistic regression with a 1:1 L/NL ratio based on a local inventory and 11 global/continental predictor variables [49]: slope (~30 m SRTM [57]), peak ground acceleration [58], distance to active faults and inactive faults [52,60], lithology [59], land cover [61], distance to drainage network (~30 m SRTM [57]), planar curvature (~30 m SRTM [57]), profile curvature (~30 m SRTM [57]), aspect (~30 m SRTM [57]), and two-day 15 mm rainfall accumulation threshold exceedance [62]. Note that the rainfall predictor was of minor importance in the model and had no significant impact on the susceptibility pattern in the study area [49]. The inventory contained more than 6000 landslides and the regional model shows predictive power and geomorphological plausibility that strongly outperform the continental model [49].

In order to exploit *AR* and *S* data at the same spatial resolution, both *S* models are resampled to the coarser 0.25◦ resolution of TMPA-RT data while assigning the 95th percentile of the original values to the coarser pixels (Figure 1). The *S* range of the continental-scale model for pixels containing calibration (validation) landslides is 0.38–0.97 (0.31–0.97) with mean and standard deviation equal to 0.80 ± 0.15 (0.79 ± 0.16). The regional-scale *S* data range is 0.10–0.72 (0.12–0.72) with mean and standard deviation equal to 0.57 ± 0.14 (0.49 ± 0.15). The difference in the data range between the two *S* models mainly results from their different sampling strategies (L/NL). Furthermore, *S* values are scaled for different geographical extents, with the continental-scale *S* model comprising areas that are not representative for the WEAR.
