## 4 Methodology
### Preparation of the Landslide Causative Factors (LCFs)
Six categories of soil texture (Figure 4j) were mapped i.e., coarse loamy, fine loamy mixed loamy, loamy skeletal, loamy sandy, and loamy. Loamy skeletal to the gravelly loamy texture of soil has more erosion susceptibility as it is found in the regions of higher relative relief and drainage density. Higher soil depth with higher elevation in the slope segment designates a higher possibility of the LS hazard (Figure 4i). Geological factors of the present study are distance to lineaments, geology and earthquake zonation. Areas near to the fault lines are geologically high unstable compared to the distant locations. The lineaments were derived from analyzing satellite images using environment for visualizing images (ENVI) and PCI Geomatica software and from Bhuvan web platform of ISRO. Distances were categorized into five classes (Figure 4k) by applying [PERSON]'s natural breaks classification scheme. The geological distinctions of this district are Chamoli Quartzite, Tourmaline Granite, Chandpur, Nagthat, Tourmaline Granite, Gneiss-Magmata, Granite 500 Ma, Chail-Ramgarh-Amri, and Shalkhalas-Jutogh (Figure 4l). Numerous past landslide events had occurred in Gneiss-Magmata and Chamoli Quartzite category regions. Occurrence of landslides is also influenced by the earthquake events, seismic disturbances,  
Figure 4: Landslide conditioning factors: (**a**) elevation, (**b**) slope steepness, (**c**) slope aspect, (**d**) curvature, (**e**) stream power index, (**f**) rainfall, (**g**) drainage density, (**h**) topographical wetness index, (**i**) soil depth, (**j**) soil texture, (**k**) distance to lineaments, (**l**) geology, (**m**) seismic zone, (**n**) road density, (**o**) NDVI, and (**p**) land use/land cover (LU/LC). mountain slope direction and dip direction near the faults. Therefore, the earthquake zonation of the district was included as an LCF in this research. The zones were categorised according to MSK intensity scale (Medvedev-Sponheuer-Karnik scale) in Figure 4m. This scale (Table 2) helps in evaluating the gravity of the seismic event based on the effect on the district. Human related factor i.e., road density was considered for the landslide susceptibility mapping. Construction of roadways on the steep slopes removes the support of above landmasses. Removal of the landmass across the slope segment interrupts the stability along the gradient resulting in topographic failure event. Therefore, road density is a vital factor in landslide susceptibility mapping. The landslide inventories showed a tendency of taking place alongside the roadways (Figure 4n). Environmental LCFs considered in this study are Normalized Difference Vegetation Index (NDVI) and Land Use/Land Cover (LU/LC). NDVI (Figure 4o) is considered as it is the reflection of diverse character of soil properties i.e., moisture, structural composition, climatic event and vegetation types, which are allied with landmass removal processes [51]. Various LU/LC categories exhibit different role in LS hazard in the downhill such as agriculture area and settlement have a positive relation with the landslide (Figure 4p). The district was classified into several broad LU/LCs which are evergreen forest (47.31%), deciduous forest (8.53%), settlement (1.50%), cropland (5.68%), grazing area (6.53%), barren rocky land (8.76%), perennial water bodies (2.05%), glacier region (1.05%), seasonal water body (0.79%), and permanent snow region (15.27%).