## 4 Results
The main instability of the coastal cliff is strictly controlled by lithostructural factors, and just a few and limited zones along the cliff are subjected to the prevailing action of undercutting due to the sea actions. Location and scale of gravity-induced instability processes appear related to the structural settings of the Mt. Conero anticline; in the southern sector, NE-dipping, high-angle bedding conditions the rock mass stability, providing the kinematic arrangement for planar and wedge-sliding, which seasonally affect the coastal slopes by mobilizing block volumes from tens up to hundreds of cubic meters. The repeated rock-block instabilities feed the slope system with a large amount of detritic material, which is mobilized by channelized flows after intense rainfalls. The northern sector is instead featured by an E-ENE dip direction of bedding, resulting from fold-axis plunging and periclinal folding, as identifiable in the east escarpment of the Portonovo landslide. In this area, high-angle preerogenic transtensional faults [41] dissected the anticline forelimb, providing the inherited passive framework where slope-scale deformation evolved [49; 50]. Figure 4: Landforms and deposits due to gravity along the southern portion of the Conero rocky coast. (**A**) Panoramic view of the Due Sorelle cliff. Falls and slides of rock blocks occur in the uppermost cliff portions, characterized by a sharp subvertical escarpment. Bedding attitude coincides with topography along the intermediate slope portion. At the cliff base, thick talus deposits occur, often interested by small debris flows and falls. (**B**) Evidence of a rock-fall detachment zone along the main cliff escarpment. Evidence of slope-scale, gravity-driven processes occur along the entire coast where mesoscale features of MRC processes were surveyed (Figure 5). The structural observations indicate macroscopically ductile features of slope-scale flexural toppling along a steeply dipping and narrow-spaced primary discontinuity set, despite the presence of horizontal cross joints. The latter act as a breakout surface, driving the relative rotation of blocks with respect to a defined hinge surface [51]. These observations lead to a challenging distinction between flexural-toppling and brittle block-toppling [52], thus suggesting a transitional behavior strongly dependent on local lithological and joint density properties of the rock masses. Buckling folds also affect the calcareous bedding at the Vela cliff, causing tension and shearing fractures that can enhance the occurrence of rockfalls. Along the analyzed coastal slope, the slope angle parameter shows a wide range of values (i.e., 0-88\({}^{\circ}\)) and its spatial distribution is good evidence for the subvertical geometry of the upslope zone of the cliff (Figure 6A). In particular, the slope map reveals a very good match between the maximum values and the main rock-block detachment zones and the large landslide scar areas, respectively, in the southern and northern coastal sector. In the latter sector, the lowest slope angle values also appear at the foot of the cliff, delimiting the Portonov landslide toe. Statistics show the prevalence of the highest slope values in the southern sector (Figure 6B), while within the northern sector, the values are distributed heterogeneously (Figure 6C) with a prevalence of the lowest values at the foot of the cliff (Figure 6A,C). Figure 5: Evidence of ongoing gravity-induced deformations along the coastal slope due to the MRC process. (**A**) Buckling folds affecting the calcareous layers at the Vela cliff. (**B**) Flexural toppling south of the Vela cliff. (**C**) Rock fall due to a buckling fold breakout. (**D**) Flexural block-toppling at the Due Sorelle cliff. The surface roughness parameter shows values up to 33 m (Figure 7). The highest values occur along the main rocky scarp, whereas the lowest ones occur in more homogeneous, flat or smoothed zones.