Earthquake-Induced Landslide Hazard Assessment of Chamoli District, Uttarakhand Using Relative Frequency Ratio Method

Landslides are a natural hazard that affects at least 15% of the land area of India (>0.49 million km(2)). Landslide induced due to earthquake is one of the most prevalent seismic hazards, which claims hundreds of lives in the Himalayan hilly terrains of India. Uttarakhand state is among the most seismically active parts of India. The objective of this study is to prepare an earthquake-induced landslide hazard map for the Chamoli district, Uttarakhand. Then, compare and validate with existing landslide database. Relative frequency ratio (RFR) method is used to identify the correlation between landslide occurrence and landslide controlling factors. Landslide hazard index (LHI) is calculated by the weighted linear combination of weight of factors. A total five factors, viz. slope angle, slope aspect, slope curvature, normalized difference vegetation index (NDVI) and PGA, are used as input geo-factors. CartoDEM and Landsat 8 TM images are considered as basic data source for generating these layers. To assess the earthquake-induced landslide in the considered region, these factors along with landslide inventory are used to calculate ratings and weights. The rating maps were integrated in geographic information system (GIS) to obtain the landslide hazard map. A final landslide hazard map showing five categories, namely very low hazard (VLH), low hazard (LH), moderate hazard (MH), high hazard (HH) and very high hazard (VHH), is presented. The results are important for regional land use planning and disaster risk reduction strategies. The hazard map provides useful information for hazard mitigation and to minimize the impact of earthquake for landslide and efficient planning for evacuation during the disaster. It is the first comprehensive attempt to produce the earthquake-induced landslide hazard map of complete district based on the earthquake-induced landslide inventory using relative frequency ratio method.