Large rock slope deformations: Evidence of orogen-scale distribution from an original inventory in central Apennines (Italy)

Large rock slope deformations, widely known as Deep-Seated Gravitational Slope Deformations (DSGSDs), are widespread in mountain regions worldwide, yet a comprehensive understanding of their occurrence and distribution remains a complex task. This work presents an inventory of 337 DSGSDs documented in the central Apennines (Abruzzi region, Italy). The dataset was implemented with case histories from former studies and completed after a five-year-long photointerpretation work, combined with field checks. About 260 new sites were documented. DSGSDs morphometric parameters, including areal extent and morphology of the hosting rock slopes, were investigated through statistical analyses. A threshold value of 1 km2 marks the limit of a power law behaviour for the frequency-size distribution of large rock slope deformations. Geospatial analysis reveals significant linear clustering along inherited tectonic lineaments, including Mio-Pliocene thrusts and Plio-Quaternary normal faults. Geolithological conditions also influence DSGSDs spatial distribution and size, as the largest gravity-driven deformations, with areas exceeding 4 km2, are located along thrusts and collapsed backlimbs within carbonate platform sequences. Although structural features and lithology may be regarded as the prevailing conditioning factors, the long-term evolution of the belt, characterized by multi-step thrusting and related uplift, and the bulk topography of the region seem to have played an important role. Apart from linear clustering, the late Messinian portion of the belt presents better conditions for DSGSDs development in terms of localized uplift, local relief, average altimetric range, and slope roughness. Finally, comparison to an inventory from the confining Molise region outlined similar DSGSDs spatial frequency and morphometric values, thus evidencing a homogenous signature in the central Apennine for this kind of geological process. Results of this study provide a basis for further research to unravel the morphogenetic significance of large rock slope deformations in landscape evolution.