PSI - Issue 84

Antonio Fiorentino et al. / Procedia Structural Integrity 84 (2026) 749–756

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configuration of the affected area, highlighting earthflow-specific morphological features such as slope gradients, elevations, and local changes in relief, and to assume an interpretation of the phenomenon. The geological–structural interpretation is facilitated by evidence of the most recent reactivation, which clearly highlights the three characteristic sectors of the phenomenon: the source area (detachment zone), the flow channel, and the toe (Figs. 1b and 2). The earthflow channel is bounded upslope by a main scarp that undergoes progressive retreat during major reactivation events

Fig. 1 – (a) Excerpt of the geological Map of Italy at 1:50,000 scale, Sheet 523 “Rotondella” (b) Geomorphological Map of the studied area; with some picture highlight the interaction of the earthflow with the viaduct.

Presently, the main scarp is associated with a detachment zone located at an elevation of approximately 350 m a.s.l., (Fig. 2). In earthflows, the movement dynamics may vary significantly between the head and the channel, mainly due to the resistance encountered by the mobilized material. (Guerriero et Al., 2014; Hungr et al., 2001). The earth flow, moved by a gravitational gradient, slides on a slip surface that appears as a series of inclined surfaces (riser) and surfaces with gentle slope (tread) (Guerriero et al., 2014). This flow develops along the channel for a length of about 1000 m, continues up to the beams that support the deck at an elevation of about 275 m a.s.l., and seems to be stabilized beyond the viaduct at an elevation of 200 m. The width of the above-mentioned channel, on the basis of the analysis of the cross sections, is (Fig. 1b) roughly around 50 m, and then increases, as usual, at the toe of the earthflow. This dimension is subject to local variations attributable to the interbedding of material with different geo-structural characteristics, which directly influence the flow trajectory, as well as the velocity.

Fig. 2 - Cross section of the earthflow.