Officials said at least 16 people had been killed in the new quake, which the USGS initially reported as magnitude 7.1, before later upgrading it to magnitude 7.3.
The quake, which struck 18km southeast of Kodari, near the base camp for Mt Everest, was measured at a shallow depth of about 18km. A series of aftershocks - including one 6.3 magnitude tremor - later hit in the same area, the USGS reported.
The Ministry of Home Affairs reported that at least 16 people have been killed in the quake.
Among those, four people were killed in Kathmandu, two were killed in Sindhupalchowk district, eight were killed in Dolakha district and two people died in Sindhuli district.
At least 641 people were injured in the Kathmandu Valley, police said, and at least four buildings are believed to have collapsed in the east of Kathmandu.
Police issued a public warning, calling for people to stay in open areas and to send text messages instead of making calls, to prevent the network from becoming jammed.
'Utter panic'
Al Jazeera's Annette Ekin, reporting from Kathmandu, said that there was "utter panic" in the capital following the quake.
"The earth just started rolling. Everyone ran out onto the streets and all of the shops are now shuttered," she said, adding that the quake seemed to last about 30 seconds.
A woman who works for a finance company in Thamel, in Kathmandu, told Al Jazeera that she had clung on to a pillar inside her building when the quake struck.
"I was screaming. It felt like the house was falling," she said.
Al Jazeera's Andrew Simmons, also reporting from Kathmandu, said the quake was so powerful that it made the building he was in "feel like jelly".
Tremors were felt in northern parts of neighbouring India, Afghanistan and Indonesia.
Two hours after the quake struck, our correspondent Ekin said that no one in Kathmandu appeared willing to go back indoors.
"Everyone is outside in the streets. At my hotel, all of the staff and guests are sitting around outside, waiting for more information," she said.
Kathmandu's airport has been closed, following the quake.
A 7.8-magnitude earthquake struck on April 25, killing at least 8,046 people and injuring more than 17,800.
More to come ...
Source: Al Jazeera
