## 2 The Stage-Wise Methodology for the GHM Characterization of the Landslide Mechanisms
\begin{table}
\begin{tabular}{l l l l l l} \hline  & **Balance** & **Variables** & **Physical Laws and** & **Boundary** \\  & **Equations** & **(Unknowns)** & **Constitutive Properties** & **Conditions** \\ \hline  & Mass balance of & & & \(\bullet\) & [PERSON]’s law & \\  & liquid: liquid & & \(\bullet\) & [PERSON]’s law & \\  & water and air & & \(\bullet\) & [PERSON]’s law & \\  & dissolved in & & \(\bullet\) & Psychrometric law & \\  & water & & \(\bullet\) & Ideal gas law & /Meteorological \\  & & & \(\bullet\) & Retention curve & \\  & & & \(\bullet\) & Conductivity functions & \\  & & gas: water & \(\bullet\) & Diffusion/Dispersion & \\  & vapour and air & & & coefficients & \\  & & & & & \\  & & & & & \\  & & & & & \\  & Internal energy & & \(\bullet\) & [PERSON]’s law & \\  & balance & T & & \(\bullet\) & Thermal conductivity & \\  & & & & \(\bullet\) & Density variation with T & \\  & & & & & \\  & & & & & \\  & & & & & Soil constitutive model & \\  & balance & u & & and corresponding & \\  & & & & & \\  & & & & & \\  & & & & & \\  & & & & \\ \end{tabular}
\end{table} 
Table 1: Laws and equations controlling the thermo-hydro-mechanical state of the soils in the slope (after [20] modified). _Two Examples of the Application of the Stage-Wise Methodology_  
Hereafter, the application of the stage-wise methodology to diagnose landslide mechanisms is presented for two case studies, the Pisciolo and the Tolve landslides. In both cases, the landslides are part of a landslide basin, including multiple rototranslational, slow-moving landslide bodies, of medium to high depth [15]. These examples are presented to exemplify how to apply the stage-wise methodology, which is the key pivot to gather GHM characterization data aimed at a comprehensive diagnosis of any landslide mechanism. At Pisciolo, the landslide involved fissured clays incorporating floating fractured rock blocks, whereas at Tolve, it involved stiff, highly overconsolidated and locally weathered clays, as shown in Figures 6 and 7, respectively. At both sites, the study was started according to the prescriptions for stage I of the methodology in Figure 5, i.e., carrying out geological and geomorphological field surveys of the whole landslide basin, multitemporal photointerpretation of the hillslope, investigation of the slope at depth through continuous coring and undisturbed geotechnical sampling down to large depth, geophysical surveys (in particular geoelectric tomography), analysis of the soil corings and of the results of geotechnical laboratory tests on the undisturbed soil samples, and topographic monitoring. These activities allowed us to phenomenologically interpret the slope instability processes at the sites. Thereafter, in stage II, a back-analysis of the limit equilibrium of the different active sliding bodies (safety factor F = 1) was carried out, implementing the geological, geotechnical and piezometric data stage I, in order to check the stage I phenomenological interpretation of the landslide, in particular, deriving a hierarchy of instability among the different landslide bodies. Finally, the diagnoses of the landslide mechanisms were verified by means of coupled hydro-mechanical modelling (using the finite element method, FEM) of the slope, according to stage III of the methodology. Such numerical analyses allowed us to verify the landslide diagnoses achieved through stages I and II, and to define a slope model for use in the design of mitigation measures.