Temporal behavior of deep-seated gravitational slope deformations: A review

Kinematic Reconstruction of a Deep-Seated Gravitational Slope Deformation by Geomorphic Analyses

“…Subsurface geometry is often unknown, but the absence of a macroscopically well-denoted slip surface cannot be assumed to be a DSGSD diagnostic feature [6]. In fact, many confined landslides [5,8] do not show a clear or complete sliding surface until final collapse, and, on the other hand, many DSGSDs are characterized by basal sliding surfaces [10,14]; (iv) display gravitational morphostructures (e.g., large scarps and counterscarps or up-hill facing scarps, open or infilled trenches, downthrown blocks, ridge top depressions or toe bulging, open tension cracks, grabens, double or multiple ridges) [4,6,10,13,14] and geomorphological evidence of slope deformation and displacements along individual structures and inherited structural features [4]. Nevertheless, it is not yet clear if tectonic features play an active or passive role in DSGSD movements (i.e., DSGSDs occur in zones of high stress or simply in weak rock) [6] and, therefore, whether the sliding surface is occasionally partially coincident to a pre-existing tectonic surface or whether it must be postulated to justify the DSGSD kinematics [10]; (v) have low displacement rates (mm/year) compared to those of the slopes themselves that are often undetectable because of weathering or erosion [2,6,10,13] and/or because the rates are close to the detection precisions of monitoring instruments [5,9]; and (vi) trigger sudden and rapid secondary minor landslides (rotational and planar slides, falls, topples and debris flows) from the most superficial part [10,15,16] or can evolve in huge landslides of different types after very long evolutionary phases [1], so that DSGSDs can be considered as preparation stages for huge gravitational collapses that, in any event, do not always complete their evolution [1,2].…”

“…The worldwide distribution map of the most significant DSGSDs studied since the 1990s [14] shows that they are not rare in mountain belts. DSGSDs are common in Europe, and there are four main DSGSD published databases [14]: Scottish Highlands (89 landslides), Eastern Pyrennes (30 landslides), European Alps (1033 landslides), and Western Carpathians (more than 100 landslides).…”

“…DSGSDs are common in Europe, and there are four main DSGSD published databases [14]: Scottish Highlands (89 landslides), Eastern Pyrennes (30 landslides), European Alps (1033 landslides), and Western Carpathians (more than 100 landslides). The updated European Alps DSGSD inventory is presented and discussed in [4], together with some general criteria for the generation of a homogeneous and reliable DSGSD inventory.…”

“…Nevertheless, under certain conditions, movements can last for long periods, resulting in large cumulative displacements. However, after periods of inactivity, external agents (exceptionally heavy rainfall periods, groundwater recharge, snow melts, temperature oscillations, and earthquakes) can reactivate them, and they can show episodic accelerations that can sometimes reach alarming levels but then subside to non-critical levels [1,17], evolve into faster mass movements or favour collateral landslide processes [2,14]. Consequently, DSGSDs can also be considered hazardous phenomena because they can cause deformations in structures and infrastructures, i.e., buildings, roads, railway tracks, tunnels, underground caverns, dams, hydroelectric power stations and penstocks [5,6,9,17,18].…”

Landslide Hazard and Risk Management (WCoE 2014–2017)

“…Deep-seated landslides often act as precursors to episodic and potentially catastrophic movements (Pánek and Klimeš 2016). Because of the poor strength and unfavourable hydrological characteristics of mobilized material, they may represent significant obstacles for infrastructure development (Pánek et al 2014).…”