Seismic Hazard Zonation Mapping of Gangtok Block, Sikkim, India

Earthquake are the common disastrous events in the study area, Gangtok Block, Sikkim; it shows a historical record in the study area. The heavy loadings of slopes by the residential as well as commercial buildings, construction work leads seismic activities, resulting in great loss of human lives and properties due to collapse building which is mainly constructed in local materials such as wood, bricks, and stone. Communication network is also disrupted due to these seismic activities. Therefore, it is necessary to prepare the seismic hazard or earthquake hazard zonation map of the study area to mitigate or manage the loss and damages. The objective of this present study is to prepare a seismic hazard zonation map. The present study has been carried out by using secondary sources of data. A total of 14 earthquake location since 1985–2015 have been collected from the Geological Survey of India. In this study, the four most causative parameters have been taken such as land-use/land-cover, slope, soil and geology. The hazard zonation map has been done with the technique of frequency ratio model. Application of GIS techniques allowed to insert, extract, handle, and analyze the data for the zoning of seismic map. The end-product consists of information layers such as maps of earthquake intensity, the expected damage, and hazard involved, as well as numerical tables associated to maps. The seismic hazard zonation map was developed using ARC GIS 10.4 software and is structured in thematic vector and raster layers. Therefore, the results of this study also reveal that the final map of hazard zonation can be useful for mitigating the hazard and is very helpful to planners and engineers for determining the safe and suitable locations to continue the developmental works. The present study may focus on the changes of landscape which is a part of man-made activities. The changes of land-use/land-cover can bring the stress, and it is related to the magnitude of earthquake though it is a slow process but continuous too. So it can be recommended to give more emphasis on the landscape changes for further research. It is also recommended to focus on the awareness of local people, technical skill, application of engineering tools, and also developmental research work on the particular area. It is necessary to modify the developmental structural parameters which would be more genuine for the further seismic vulnerability mapping of the study area.