EARTHQUAKE-INDUCED LANDSLIDE HAZARD ASSESSMENT OF UTTARKASHI DISTRICT, USING MULTI CRITERIA DECISION MAKING (MCDM) TECHNIQUE

Abstract

Earthquake has played a major role in the current landslide scenario of Uttarkashi in the past few decades. Moreover, Uttarkashi lies in the seismically active part of India i.e. the seismic zone IV and V as per the Indian seismic zonation map IS 1893(Part 1): 2002. Hence it has become necessary to determine the landslides induced by earthquake with increasing magnitude and area of the earthquake. The main aim of this research is to prepare an earthquake-induced landslide susceptibility map using Analytical Hierarchal Process (AHP) and Relative frequency ratio (RFR) for Uttarkashi district, Uttarakhand. Over 65 Earthquake epicenters (ranging from a magnitude of 3.5 to 6.8) along with landslide points in and around the study area have been considered. Further, 11 factors are taken into consideration including tectonic framework, earthquake magnitude distribution, fault mechanism, topography along with other landslide factors. The consistency ratio (CR) determined for AHP is 0.075(<0.1), which indicates an acceptable preference matrix for the associated factors. The weights assigned to AHP for the above factors are validated using the RFR method. Earthquake-induced landslide susceptibility map is prepared, and the zones are classified accordingly. These maps were then validated by the area under the curve (AUC) method.