Landslide susceptibility assessment of Western Ghats of Karnataka region in India: A case study of Ankola landslide

Recurring and frequent landslides in the Western Ghats of India pose major socio-economic challenges by interrupting the infrastructure development and daily life. The present study evaluates the landslide susceptibility of the region using a hybrid approach. Data from various sources including satellite images, past landslide records, geological, topographical and hydrological datasets was utilised to develop landslide inventory and the causative factors of the study area. The adopted hybrid approach integrates the analytic hierarchy process (AHP) and relative frequency ratio. The model demonstrated excellent discriminatory ability with an area under the ROC curve (AUC) of 0.902. The Uttara Kannada district has been identified as most susceptible to landslide in Karnataka. Further, recently Ankola landslide in the highly susceptible Uttara Kannada was taken for a detailed case study. The field observations, geotechnical characterization, and rainfall details of the landslide site suggest that the anthropogenic activity and heavy rainfall were the reasons for triggering the landslide. The landslide event was back-analysed using pore water pressure factor ( R u ) to simulate pore-water pressure development during rainfall. The R u factor of 0.4 was identified as critical threshold for initiating slope failures, providing a quantitative basis for early warning systems for the region. The susceptibility model and the R u factor threshold found in the study offer essential information for the enhancement of risk mitigation efforts in the Western Ghats. • Landslide susceptibility of the Western Ghats region in Karnataka state is mapped. • The model demonstrated excellent performance with an AUC value of 0.9. • Uttara Kannada district in Karnataka identified as most susceptible to landslides. • The paper documented a recent landslide (Ankola) in the highly susceptible zone of the study area (Uttara Kannada). • Pore-water pressure factor of 0.4 was critical for triggering landslides in Ankola.