Exploring Temperature-Shear Strength Dynamics: A Spatial Modelling Approach for Clay Landslide Susceptibility in Italy

The influence of temperature as a key factor in slope stability, particularly in temperate regions, remains insufficiently explored. This study investigates the thermo-hydro-mechanical (THM) response of expansive soils, focusing on the thermally-induced activity in clay landslides.

Establishing a representative thermal variable for broad-scale assessments poses challenges due to material heterogeneities and the intricate nature of THM processes. Our research employs landslide spatial modelling in Italy, concentrating on clay-rich areas with shallow landslides on gentle slopes. Utilizing geo-lithological and geological maps and the Italian National Inventory (IFFI), we apply a Generalized Additive Model (GAM) based on slope units to capture nonlinearities in the temperature-shear strength relationship. A decade-long dataset of Land Surface Temperature (LST) from MODIS, accessible in Google Earth Engine, serves as a key input.

The study produces spatial probability maps for clay deposits across Italy, revealing a positive correlation between landslide occurrence and LST on warmer, gentle slopes, especially in Southern Italy. This aligns with the observation that higher temperatures reduce soil and water viscosity, amplifying shear creep rates in clay-rich materials. By elucidating the temperature-slope stability relationship, this study contributes to understanding landslide dynamics in temperate climates, facilitating the development of effective risk recognition strategies.