Landslides on the growing folds of the Kura fold-and-thrust belt (Azerbaijan, Georgia)

Rising hillslopes in the active fold-and-thrust regions present new landslide-prone slopes. However, studies investigating landslides in newly formed fold-and-thrust belts are limited. In this research, we analyse landslide occurrences in the Kura fold-and-thrust belt, a geologically active region at the southern edge of the Greater Caucasus. This area has experienced significant tectonic shaping over the last 2-3 million years, affecting Miocene to Quaternary sediments. Using satellite imagery, we identified about 1600 landslides, a quarter of which are active. These landslides, although occupying less than 1% of the land, are predominantly found at higher elevations and areas with greater relief. They mainly occur in regions elevated by tectonic forces, especially on steep anticlines and valley slopes cut by active faults. Our findings lead to a conceptual model for the temporal evolution of landslide patterns in weak sediment-based fold-and-thrust belts: 1) Initially, slow deformations at thrust fronts lead to landslides in deep valleys intersecting the uplifting hanging walls. 2) As anticlines rise and steepen, they become more prone to planar sliding when dip slopes exceed friction angle, and valley development creates additional dip slopes resulting in widespread landslides. 3) Finally, erosion lowers relief, forming badlands and reducing landslide occurence.