A destructive Gorkha earthquake of M-w 7.8 took place on April 25, 2015 in Nepal Himalaya region in the Indian-Eurasian collision zone and led to a largest aftershock M-w 7.3 on May 12, 2015. The main event occurred in the historical earthquake of the M-w 8.5 (1100) rupture zone. To understand and assess the aftershock activity, the Coulomb stress changes (CSC) are modelled along the plate interface. Generally, the magnitude and the number of aftershock activity decrease with time and follow the modified Omori's law and the magnitude of aftershocks is less than one-unit magnitude and the largest aftershock takes place within 1 week. But the largest aftershock M(w )7.3 occurred on May 12, 2015, in the southeast of the mainshock region of the Gorkha earthquake after 17 days. slightly enhanced CSC region, in the high topographic gradient region in the Indian-Eurasian collision zone. The deviatoric stress similar to 98 MPa per unit area is produced by high gradient of gravitational potential energy (GPE) due to the Mount Everest region and its surrounding facilitates a distinctive aftershock of Mw 7.3 occurred on May 12, 2015, in the east of the mainshock.