The massive Mw = 7.8 earthquake which rocked the Nepal Himalaya on 25 April 2015 is the largest to have occurred in this region in the past 81 years. This event occurred by slip on a ~150 km long and 55 km wide, shallow dipping (~5) segment of the Main Himalayan Thrust (MHT), causing the Himalaya to lurch southwestward by 4.8  1.2 m over the Indian plate. The main shock ruptured the frictionally locked segment of the MHT, initiating near the locking line and rupturing all the way updip close to its surface expression near the foothills of the Himalaya.