3D limit equilibrium analysis: an opportunity for quantitative landslide susceptibility assessment at the scale of the urban area

Landslide susceptibility assessment at scales wider than the single slope has been so far carried out mainly through heuristical/geomorphological and/or statistical methods, except for applications limited to shallow landslide predictions by means of infinite-slope limit equilibrium models (Godt et al. 2008). Owing to the complexity of developing quantitative deterministic susceptibility models at wide scales, taking into account also deep and complex landslide mechanisms, the application of limit equilibrium methods as well as numerical stress-strain methods have been historically limited to the scale of the single slope. However, the increased availability of powerful computational tools as well as the existence of detailed geological and geotechnical databases at scales that are intermediate between the single slope and the regional scales, as for example the scale of a single urban centre, allow for extending the application of three-dimensional limit equilibrium analysis to the assessment of landslide susceptibility at such scale, also taking into account the failure susceptibility of deep and complex landslide mechanisms. This contribution presents a physically-based methodology aimed at assessing landslide susceptibility at the urban area scale, for both shallow and deep instability processes involving urbanized areas that are diffusely affected by landsliding processes (Ugenti et al. 2025). The proposed methodology has been applied to the municipality of Carlantino (Daunia Apennines, Southern Italy) as a test case study, using the available geological and geomorphological datasets as well as the soil geotechnical property data. Based on a three-dimensional geotechnical model, 2.5 km² wide, a three-dimensional limit equilibrium analysis has been develop to obtain a mechanically-based map of the safety factors at the urban area scale, assuming different scenarios related to the groundwater table depth, which has been validated against geomorphological evidence and remote sensing data. The proposed approach, which is supposed to be exportable to other geological environments, provides a valuable tool for quantitative assessment of the slope stability conditions of an overall urban area to be used for a more rational approach of urban planning policies and risk management activities.

 

References:

Godt J.W., Baum R.L., Savage W.Z., Salciarini D., Schulz W.Z., Harp  E.L. (2008). Transient deterministic shallow landslide modeling: requirements for susceptibility and hazard assessments in a GIS framework. Engineering Geology, 102 (3-4), 214-226.

Ugenti A., Mevoli F.A., de Lucia D., Lollino P., Fazio N.L. (2025). Moving beyond single slope quantitative analysis: a 3D slope stability assessment at urban scale. Engineering Geology, 344, 107841, doi: 10.1016/j.enggeo.2024.107841.