A tremor hit the northern province of Lao Cai early Sunday morning as an aftershock of a 4.7 magnitude earthquake in China's Yunan province.
Tran Phuc Thanh, director of the Sa Pa Geophysics Station, said the quake's epicenter was about 100 kilometers to the north of Lao Cai.
There was no information immediately available about any damage caused by the quake.
In Vietnam, the aftershock shook buildings in Lao Cai town and Bat Xat District within five to six seconds, Luu Minh Hai, deputy director of the Lao Cai Hydrometeorology Center, was quoted as saying by the Saigon Tiep Thi newspaper.
No damages were reported, Hai said.
This was the third time this year that Lao Cai has been affected quakes in adjacent areas in China and Myanmar.