landslides; deep-seated gravitational slope deformations; flysch; Outer Western Carpathians; Czechia

Czech Flysch Outer Western Carpathians (COWC) represent region with the highest density of large landslides and deep-seated gravitational slope deformations (DSGSDs) in Czechia. The region is internally heterogenous in terms of geology (individual flysch nappes with different lithology) and topography (e.g., high monoclinal ridges in the north-eastern part with local relief > 500 m and subdued hilly landscape in the southwest. The region is diverse in the terms of the landslide types, sizes and recent activity as well. Aim of this study is to describe these differences and decipher driving factors, which cause this varied behaviour of mass movements in the region. We mapped 13,721 landslides and DSGSDs in the area of COWC (~7186 km2). We used LiDAR derived DEM and its derivates (hillshade maps, slope map) and mapped landslides as polygons incorporating the detachment and accumulation. We classified landslides into five groups (rotational, translational, debris slide and earthflow), the sixth group consist of DSGSDs. We matched the landslides with individual flysch nappes for further analysis. We analysed clustering of the landslides using L-function which showed, that maximal clustering occurs in the radius ~5 km. We calculated kernel density of the different landslide types. This revealed differences in the concentration of different landslide sizes and types. Whereas the lower and more subdued areas in the southern part are hotspot in terms of total number of landslides, the higher and more topographically pronounced areas in the northeast are affected dominantly by large landslides. Discrepancy also exist in the spatial distribution of different types of landslides. Translational and rotational landslides are dominant in the north-east while complex and earthflows are dominant in the lower regions. We examined frequency-area realtionship of landslides for individual nappes. The ? exponent varies between 2.1 to 3.2 showing different influence of large landslides i