###### Abstract  
A pre-existing and inherited geobstructural setting plays a fundamental role in preparing and developing large-scale slope deformational processes. These structures affect the kinematics of the process, the geometrical characteristics, and the geomorphological evolution. In the Apennine Belt, several deep-seated gravitational slope deformations (DSGSDs) that have evolved under a clear structural control have been recognized during the last decades, but none with a continuous and well-defined basal shear zone (BSZ). The structurally-controlled DSGSD of Luco dei Marsi represents the first case of a DSGSD in the Apennine Belt with a well-defined BSZ. Starting from a detailed study of the process and the reconstruction of a morpho-evolutionary model of the slope, a series of numerical modelings were performed for the study of the DSGSD. The analyses allowed us to reconstruct: (i) the mechanism of the process, (ii) the rheological behavior of the rock mass, and (iii) the main predisposing factors of the gravitational deformation. Numerical modeling has demonstrated the significant role played by the inherited structures on the DSGSD and, in particular, the importance of an intensely jointed stratigraphic level in the development of the BSZ. DSGSDs; structural control; slope debuttressing; creep; numerical modeling +
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MRC is driven by the rock mass viscosity, the structural setting of the slopes, the jointing state of rock masses, and the weathering of igneous and metamorphic rocks [4; 10; 12]. Geomechanical conditions and inherited structures can greatly influence the rheological properties of the deformed rock masses and the MRC processes [17]. Nowadays, the role of gestructural elements in slope dynamics is thoughtfully investigated through numerical models. These analyses of DSGSDs were carried out since the 1970s [29]. In more recent years, the growth of new technologies contributes to the increase in the number of numerical modelings on these phenomena [2; 12; 14; 16; 19; 20; 23; 30; 31; 32; 33; 34; 35]. In the last years, some numerical analyses were performed also on large-scale gravitational deformation on the planet Mars [36; 37]. The study area lies in central Italy, within the axial zone of the Apennine Belt and along the western edge of the Fucino Basin, a Quaternary, wide continental depression (Figure 1). Several DSGSDs have been detected and analyzed in the last two decades in the central Apennines, both for scientific purposes and related hazard and risk. Regarding the latter, it is worth underlining how these gravity-induced deformations can evolve as catastrophic rock slope failures, e.g., [25], or be accompanied by secondary landslides threatening infrastructures, roads, villages, and elements of cultural heritage, as it happens [38] in the study area (see insert in Figure 1). The Meso-Cenozoic carbonate sequence outcropping near the village of Luco dei Marsi is affected by an evident DSGSD [39]. The process is revealed by several morphological features, such as grabens, trenches, downhill- and uphill-facing scarps, bulging, and landslides, variously distributed along the slope. The Luco dei Marsi DSGSD shows the first evidence of a clear and well-extended Basal Shear Zone (BSZ) in the central Apennines. This driven element is localized within Middle-Upper Cretaceous, Rudist-bearing massive limestones which underlies a--some meters thick--highly-jointed level (hereafter, HJL) developed into thinly-layered, biodritic limestones featuring the lowermost part of the Upper Cretaceous sequence in the Luco dei Marsi ridge. In this study, sequential numerical modeling was performed to define the main characteristics of the DSGSD evolution. The modeling has been based on the morpho-evolutionary model of the slope, reconstructed since early Pleistocene onward through geological and geomorphological evidence, and on the geomechanical characteristics of the rock masses determined through field measurements and laboratory tests.