Deep-seated gravitational slope deformations; kinematic analysis, electrical resistivity tomography, trenching, Outer Western Carpathians

Deep-seated gravitational slope deformations (DSGSDs) played an important role during the evolution of mountain ridges of the Outer Western Carpathians. Four DSGSD-affected ridges in the highest part of the Czech sector of the OWC have been subjected to multidisciplinary investigation. All the studied DSGSDs are strongly predisposed by regional structural fabric. The area of a single DSGSD can be affected by various types of slope movements. Electrical imaging and trenching revealed that besides these mechanisms, anisotropic flysch massifs formed by thick-bedded sandstones are strongly exposed to subsurface opening of air-filled voids related to widened crevices. Such a process is driven by deep-seated creep and translational sliding of sandstone beds upon plastic claystones whose strength has been reduced to residual values. Performed dating revealed that some of the studied DSGSDs originated in the Holocene period, particularly in the Atlantic and Subboreal chronozones.