Surface geomorphological features of deep-seated gravitational slope deformations: A look to the role of lithostructure (N Apennines, Italy)

The attention to deep-seated gravitational slope deformations (DSGSDs) has steadily increased in the last few decades, because such features are ubiquitous in mountain areas. Their geomorphological surface expression, especially when related to the effects of lithostructural control in sedimentary stratified bedrocks, is well characterized in theory, but sometimes not as well documented in field cases. In this contribution the investigation of several DSGSDs in the area of the Northern Apennines of Italy is reported. A survey of the area was conducted using fast and low-cost satellite imaging techniques, in order to describe the surface features of selected DSGSDs and verify how their occurrence is linked to the effect of lithostructural constrains such as bedding and folding. Surface features developed in parallel to the strike of the slope are mostly related to the main gravitative strain acting on the deformation. Features along slope dip are instead formed by the release of tension caused by compressive forces at the landslide foot or by the presence of pre-existing weak lines. One example of a DSGSD, formed on the hinge of a vertical fold, shows a corrugated appearance due to the release of vertical fractures that mask most other features usually associated with DSGSDs. This potentially impairs the detection of these landforms during field and remote surveys.