Mapping landslide susceptibility through physically-based modeling

Landslide susceptibility is the likelihood of a landslide occurring in a specific area based on the local terrain conditions. Susceptibility does not take into account the size, duration, or frequency of occurrence of landslides. Different approaches and methods have been proposed to determine the likelihood of occurrence of landslides: geomorphological mapping, analysis of landslide inventories, heuristic terrain zoning, statistically-based classifications and physically based numerical modelling (Aleotti and Chowdhury, 1999; Guzzetti et al., 1999). The last two approaches are preferred for assessing susceptibility in quantitative terms. Today, statistically based methods are preferred for small-scale landslide susceptibility zonations. Performing this task by using physically-based approaches is more challenging, as the performance of numerical analyses usually requires detailed geomechanical and hydrological data, whose collection demands significant time and costly efforts.However, this work is primarily motivated by the following question: Can landslide susceptibility maps at smaller scales than detail-scale truly not be attained through the application of physically-based approaches?The authors show their first attempt in answering the question through the combined application of Geographic Information Systems (GIS) and a 2.5D Limit Equilibrium Method (LEM) implemented using the SSAP software (Borselli, 2023). The results obtained in a study area in Southern Italy and the physically-based landslide susceptibility map derived at basin-scale are presented and discussed. This preliminary but yet reproducible analysis allows to drive future efforts in physically-based susceptibility zonation. ReferencesAleotti, P., & Chowdhury, R. (1999). Landslide hazard assessment: summary review and new perspectives. Bulletin of Engineering Geology and the environment, 58, 21-44. DOI: https://doi.org/10.1007/s100640050066Borselli L. (2023). "SSAP 5.2 - slope stability analysis program". Manuale di riferimento. Del codice ssap versione 5.2. Researchgate.   DOI: https://dx.doi.org/10.13140/RG.2.2.19931.03361Guzzetti, F., Carrara, A., Cardinali, M., & Reichenbach, P. (1999). Landslide hazard evaluation: a review of current techniques and their application in a multi-scale study, Central Italy. Geomorphology, 31(1-4), 181-216. DOI: https://doi.org/10.1016/S0169-555X(99)00078-