Search

The paper describes the recent devastating landslide of Kotrupi, Himachal Pradesh in India which had claimed many human lives and properties along its course on 13 August 2017. This event was the third reactivation of the slide as per data available. The study for this landslide involves a preliminary investigation of the site and comparison of pre- and post-event slope stability analysis. Other than rainfall, the combined effect of differential weathering rate of the debris and soil layers, low material strength, and the presence of a fault zone was found to be the primary cause of instability. The analysis was carried out with the geotechnical investigation and numerical modeling with the help of finite element model-based Phase 2 simulator. The significant findings of this paper include numerical simulation of pre- and post-event slide as stated under unsaturated and saturated condition. The study finds a low factor of safety of the present slope. The unstable condition of the slope may trigger another event of the same intensity shortly. [ABSTRACT FROM AUTHOR]

Landslides are the most common hazards which modify the surface morphology of the orogenic belts. Structural conditions and nature of slope forming material play a vital role in the development of surface morphology. The paper highlights the influence of structure on slope morphology and consequent instability pattern in Sukhidang-Ladhiya section in Eastern Kumaun Himalaya. Rocks of lesser Himalayan sequences, Siwalik Group and veneer of Quaternary deposits occur in the area. The area is punctuated by many landslides of various dimensions affecting all the lithological units present; however, study is based on three major landslides occurring along the Main Boundary Thrust (MBT) and Himalayan Frontal Thrust (HFT) zone. Structural data shows that thrusts environment has manifested in crushing and shearing of rocks, which play an important role in landslide proneness along with the rainfall intensity. Evidences of active tectonics such as triangular facets (flatirons), tilting river terraces and active landslides zones have been noticed in the study area. Limited data on temporal details of landslide morphology (perimeter and area) from remote sensing and topographical sheets indicate that perimeters and area of active scars of landslides in the area are gradually expanding, probably associated with tectonic movements in proximal areas of thrusts. [ABSTRACT FROM AUTHOR]

Landslides are the most established geological hazards in the Siwalik and Murree strata of Jammu region. The prolonged rainfall in the area frequently trigger landslides and has become a common phenomenon in hilly areas of Jammu region due to over saturation of slope forming material and cause considerable damage to life and property. The landslide that occurred on the Katra-Qazigund railway track alongside of portal (P2) of tunnel-47 on 25 September 2010 at village Dharam in Sangaldan area of Ramban district caused extensive damage to buildings. The water sensitive lithology (alteration of sandstone and mudstone beds) within the Murree thrust zone has made the area more vulnerable to landslides. Most of the landslides in the area are activated mainly during prolonged rainfall due to increase in pore water pressure as a result of seepage. The present paper is an attempt to study various geological factors along with physio-mechanical properties of slope forming materials to understand their role in failure mechanism. [ABSTRACT FROM AUTHOR]

Landslides cause extensive loss of life and property in the Nepal Himalaya. Since the late 1980s, different mathematical models have been developed and applied for landslide susceptibility mapping and hazard assessment in Nepal. The main goal of this paper is to apply fuzzy logic to landslide susceptibility mapping in the Ghurmi-Dhad Khola area, Eastern Nepal. Seven causative factors are considered: slope angle, slope aspect, distance from drainage, land use, geology, distance from faults and folds, soil and rock type. Likelihood ratios are obtained for each class of causative factors by comparison with past landslide occurrences. The ratios are normalized between zero and one to obtain fuzzy membership values. Further, different fuzzy operators are applied to generate landslide susceptibility maps. Comparison with the landslide inventory map reveals that the fuzzy gamma operator with a γ-value of 0.60 yields the best prediction accuracy. Consequently, this operator is used to produce the final landslide susceptibility zonation map. [ABSTRACT FROM AUTHOR]