Study of effect of seismic displacements on landslide susceptibility zonation (LSZ) in Garhwal Himalayan region of India using GIS and remote sensing techniques

Abstract

Landslides are the most damaging and threatening aftereffect of seismic events in Garhwal Himalayas. It is evident from past seismic events in Uttarakhand, India that no other phenomena can produce landslides of so great in size and number as a single seismic event can produce.Landslide inventories are produced for the study area before and after the occurrence of Chamoli Earthquake using Panchromatic (PAN) sharpened Linear Imaging Self Scanning-III (LISS-III) images. A sudden increase in number of landslides after the earthquake is observed. Further, two Landslide Susceptibility Zonation (LSZ) maps have been derived using pre- and post-Chamoli Earthquake landslide inventories. The difference of two LSZ indicates that landslides are very complex phenomenon and are affected by static factors in seismic conditions also.An attempt has been made to estimate the seismic displacements using Differential Synthetic Aperture Radar Interferometry (DIn SAR). European Remote Sensing Satellite-1/2 (ERS-1/ 2) SAR images have been used for preparing differential interferogram. Geometric and temporal decorrelation in SAR images is very high in the study area, which limits the use of DInSAR for displacement estimation. Theoretical displacement has been estimated using fault displacement modeling parameters for Chamoli earthquake. Post-Chamoli earthquake landslide inventory is overlaid over displacement map for understanding the impact of seismic displacement pattern with other static factors on the occurrence of landslides. It is observed that distribution and size of landslides is affected by displacement pattern controlled by other static factors also.