In order to comprehend the inter-seismic and co-seismic deformation pattern and to analyse the post-seismic crustal adjustment following the Sikkim earthquake (MW 6.9) on 18 September 2011, GPS data was gathered from the DSH and surrounding foothills for four years, from 2009–10, 2010–12, 2012–13 and 2013–14. During the inter-seismic interval, strain analysis reveals compressional strain linked to reversal faults and extensional strain linked to transverse faults. In contrast to the inter-seismic interval, strain is released during the co-seismic period. Since considerable strain build-up has been discovered, overall displacement behaviour and strain patterns suggest the probability of future strain release towards the eastern half of the DSH, primarily the area between the west of the Tista River and the south of the Rangit River. A portion of the accumulated strain in the eastern sector may have been relieved by the 2011 Sikkim earthquake, but further crustal movement is probably going to increase the strain there. Furthermore, all thrust planes—MCT, MBT and MFT—as well as the main transverse lineaments—aside from the MCT of the eastern Sikkim dome—are discovered to be differentially active and to have experienced significant post-seismic changes.