The US Geological Survey initially said the quake was 7.1 in magnitude, but then swiftly upgraded it to 7.3.
Tuesday's disaster hit near the Chinese border between the capital of Kathmandu and Mount Everest, with at least four confirmed dead.
Devastation was reported in the Katmandu, which is still reeling after buildings were flattened and sacred sites destroyed after the 7.8 earthquake of 25 April that wiped out whole villages nearby.
Buzzfeed's deputy news director Jon Passantino said there were "multiple landslides, building collapses and bodies being pulled out after latest Nepal quake."
"Shopkeepers closed their shops and the streets were jammed with people rushing to check on their families," tweeted Reuters journalist Tony Tharakan. "Parents could be seen clutching children tightly and hundreds of people were frantically trying to call relatives on their mobile phones."
The quake was followed closely by at least five aftershocks measuring from magnitude 5.6 to magnitude 6.3.
Jack Board, at Katmandu airport, tweeted: "The walls inside the international terminal at Kathmandu airport started to crumble. I can [see] big plumes of dust looking back over the city."
The international airport, which has become a transport hub for international aid, was closed temporarily, while the streets were blocked with traffic in the chaos.
A Save The Children UK operations base - being used to help people affected by the first quake - was also damaged.
source: Reuters