A major earthquake occurred in Nepal on 12 May 2015 at 12:50 pm local time (07:05 UTC) with a moment magnitude of 7.3, 18 km (11 mi) southeast of Kodari. The epicenter was on the border of Dolakha and Sindhupalchowk, two districts of Nepal. This earthquake occurred on the same fault as the larger magnitude 7.8 earthquake of 25 April, but further east than the original quake. As such, it is considered to be an aftershock of the 25 April quake. It struck at a depth of 18.5 kilometres (11.5 mi). Shaking was felt in northern parts of India including Bihar, Uttar Pradesh and West Bengal. Tremors were felt as far as about 2400 kilometers away from the epicenter in Chennai.

Minutes later, another 6.3 magnitude earthquake hit Nepal with its epicenter in Ramechhap, east of Kathmandu. The earthquake was felt in Bangladesh, China and many other states in India. The impact of these tremors was felt even 1,000 kilometres away in the Indian capital New Delhi, where buildings shook and office workers evacuated.

The aftershock caused mass panic as many people were living in the open air after the 25 April quake.  "For the first seconds, it was complete silence. By the fifth second, everybody started to scream", said an eyewitness. "It was really, really intense. Even when the shaking stopped, people were still screaming". The tremor caused fresh landslides, and destroyed some buildings which survived the first quake.

In Nepal, at least 153 people were killed by the earthquake and more than 3,200 people were injured, primarily in mountain regions of the northeast. As of 15 May, 1,700 people were still receiving treatment for their injuries. Thirty-two of the nation's seventy-five districts were affected by the quake. In Kathmandu, the streets were quickly filled as people fled buildings. Within hours of the quake, tents began to fill open areas of the city as residents were afraid to go back inside. The district of Sindhupalchowk, which was also hit hard in the original quake, was among the worst affected areas. Between the two quakes, 95% of the areas houses were destroyed. Areas around Mount Everest also saw fresh damage.