Study of qualitative stability analysis and rainfall thresholds for possible landslide occurrence: a case study of Sikkim Himalaya

Landslide hazard characterization in the Setijhora landslide, located near Kalijhora village, along National Highway 10, was carried out a qualitative way using Rock Mass Rating (RMR), Continuous Slope (CSMR) and Geological Strength Index (GSI). CSMR data helped understanding of slope failures (wedge, planner, rotational toppling), while RMR & GSI provides better rock mass quality its deformation. observed between 10–49 dry season 1–39 monsoon season. Kinematic/stereographic analyses indicate vulnerability to wedge failure, ranges from 13.84 50.85 (class III class V). Rainfall threshold shows cumulative rainfall more than 111.3 mm over 20 days 222 month indicating high probability landslides occurrence. Data generated study will be very useful for developing landslide early warning area.