Park officials said lava was moving slowly and should not pose a threat to humans or wildlife.
“The little threat we have is that every time the Nyamulagira erupts it emits volcanic ash. We have to watch out for that,” said Deogratias Kavotha Kalenda, an expert at Goma Volcanic Observatory.
Nyamulagira has erupted recently about once every two years and can spew for days, weeks or even months.
It is the most active volcano in Africa and last erupted in January 2010.
In 2002, nearby Mount Nyirangongo volcano sent a flow of lava through the heart of the city of Goma.
Photo: Virunga National Park