Earthquake-induced landslide mapping in the western Himalayas using medium resolution ASTER imagery

Abstract

On 8 October 2005, a devastating earthquake struck northern Pakistan and several parts of Pakistani- and Indian-controlled Kashmir. The severely hit areas lie in close proximity to the most tectonically active region of the western Himalayas. The earthquake destroyed close to 400 000 houses and over 75 000 people lost their lives. The intensity of the earthquake was such that it triggered widespread landslides, which caused considerable destruction of the area's forests, and blocked the mountain roads and rivers. Satellite imagery-based analysis can be effectively used to provide critical geologic information for determining the causes of earthquakes, mapping of faults and lineaments, as well as for hazards and damage assessment mapping. In this study, Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) imagery acquired on 27 October 2005 was analysed to assess earthquake-induced land cover changes in severely hit areas. Image analysis techniques including intensity hue and saturation (IHS), principal component analysis (PCA), Normalized Difference Vegetation Index (NDVI) and Iterative Self-Organizing Data Analysis Technique (ISODATA) were applied on VNIR–SWIR bands of ASTER for the purpose of identification and mapping of landslides triggered by the earthquake in areas of northern Pakistan and Pakistani-controlled Kashmir. The techniques proved effective in identifying freshly exposed surfaces on mountain slopes, landslide scars and debris deposits. Accurate identification and mapping of landslides and slope failures can play an important role in post-earthquake damage assessment and hazards mapping in earthquake-prone mountainous areas.