Hazard evaluation of progressive Pawari landslide zone, Satluj valley, Himachal Pradesh, India

The Pawari landslide zone, located in the Satluj valley, Himachal Pradesh (India), is a progressive complex landslide zone that is ~ 900 m long and ~ 4000 m wide and encompasses an area of ~ 6 km2. It is observed that the frequency of the slope failure in the landslide zone and dimension of the landslide area have increased considerably in the last decade that pose threat to the human population of about 6000 residing in the vicinity of the landslide zone. The finite element method (FEM) and kinematic analysis are used for stability analyses, while high-resolution imagery, slope failure data and rain-gauge-based rainfall data are used to infer landslide activity. The FEM analysis involved numerical simulation of two slope models, i.e. S-1 (rockmass only) and S-2 (rockmass overlain by debris) that were chosen along the width of the landslide zone. The shear strength reduction method was incorporated in FEM to quantify the existing slope strength and to infer pattern of strain and displacement. The analyses results show that the main scarp of the landslide zone has increased ~ 7% between 2005 and 2014, and presently, major as well as minor scarps accommodate maximum shear strain (0.001–0.006) and displacement (0.08–0.20 m). The kinematic analysis reveals wedge failure in the rockmass that corroborates with the field evidences of rock failure. The present work intends to evaluate the hazard of landslide zone by analysing landslide activity pattern and determining shear strain and displacement of the slope.