Seismic risk zonation using the geospatial tool: A case study over East and South district of Sikkim

Abstract

Seismic risk assessment in the high mountains of Himalaya is necessary toaccommodate safe and suitable sites for homing with also to direct the pathway of plan and policyfor development sustainably. The continuous orogeny results often earthquakes, mostly, the areaaround fault lines as have been documented by USGS. Hence, to prepare the vulnerability andsusceptible zonation in East and South Sikkim districts Analytical Hierarchy Process (AHP)technique has been adopted. LANDSAT 8 onboard OLI multispectral data is used to prepare theLand-use Land-cover map of study area using supervised classification techniques, whileCartoSAT-1 version 2 DEM is used to look into the physiographical aspects of this region. Withalso, Geological Survey of India prepared soil and geological map is used to prepare the soil andlineament map. Not only that, ground motion data of four different parameters, have also beenacquired form USGS on about of an earthquake event on 18th September 2011, which hadepicenter at 27.730°N, 88.155°E. Certainly, it has been achieved that, area with soil type ofudorthents entisol in the 10 km buffer zone from the major faults victimized of seismic hazardmostly. By the AHP comparison matrix, proximity of any area to the fault lines found to be mostinfluential followed by the ground motion vectors while the LULC categories are the leastinfluential. Using the weighted overlay analysis, area along the western boundary of East districtand north-west of South district in Sikkim found to be under high seismic risk zone. Risk zones hasbeen verified with the help of archive earthquake data from USGS and approximately 22% area inthese two districts comes under high risk zone.