PSI - Issue 84

Nicola Perilli et al. / Procedia Structural Integrity 84 (2026) 805–812

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Figure 2. Logic flow for the determination of the Class of Susceptibility (from LLG 2020). Bassa (Low), Media (Medium), Alta (High). See also Fig. 1 4. Discussion This section translates conceptual understanding into practical application, guiding inspectors from assigning SI Degree and Slope Instability Class (CSI). The inclusion of potentially unstable slopes and incipient landslides . ensure a more accurate representation of the continuum from susceptibility to landslide. These refinements provide reproducible, and actionable field assessments. The main points and methodological implications are summarized below. • Susceptibility – Represents time-independent predisposing conditions and allows areas to be distinguished according to their degree of susceptibility. • SI Degree – Quantifies the current physical state of the slope, enabling detection of active landslides. Field observable metrics derived from P A , P V , and P M support operational decisions (Tabs. 5, 7). SI Degree is assigned only where ongoing or past slope movement is documented. • Slope Instability Class (SIC) – It is evaluated using SI Degreethen modulated by two secondary parameters - Reliability of Primary Parameter Estimation and Status of Mitigation Works . This reduce subjectivity and enhance reproducibility (Tabs. 5, 7). CSI is assigned only where ongoing or past slope movement is documented. It corresponds to Factor of Susceptibility . • Removal of Potential Landslides and Criticality Level (PC) – This solution eliminates sources of operational inconsistency, ensuring P A , P V , and P M are estimated only to active or dormant landslide. • Reliability of Primary Parameter Estimation – Refining this parameter reduces arbitrariness, improves transparency, and strengthens methodological consistency, ensuring SIC assessments are reproducible across sites (Tabs. 6, 7). • Status of Mitigation Works – Redefined with only two options (not involved / involved), enhancing consistency of SIC and enabling inspectors to adjust SI Degree efficiently (Tabs. 6, 7). • Potentially unstable slopes vs Incipient Landslides - Potentially unstable slopes: areas with high susceptibility but no evidence of active movement, where predisposing factors indicate possible instability. - Incipient landslides: slopes showing precursory signals or initial deformation, without measurable mass movement. It provides an intermediate classification between high susceptibility -i.e. potentially unstable slopes