Congolese authorities on Thursday ordered the partial evacuation of Goma, a city that has been rocked by hundreds of earthquakes and seen large cracks appear in the earth in the aftermath of a volcanic eruption on its doorstep at the weekend.
More than 20,000 people are homeless and 40 still missing following Saturday evening's eruption, which sent rivers of lava flowing toward Goma, killing at least 31 and destroying more than 3,000 homes, according to the United Nations.
The lava from Mount Nyiragongo stopped just 300 metres short of Goma airport, the main hub for aid operations in eastern Democratic Republic of Congo.
Seismic and ground deformation data indicates the presence of magma under Goma, extending under Lake Kivu, said Ndima Kongba, the military governor of North Kivu province.
"Given these scientific observations, an eruption on land or under the lake cannot be ruled out at present, and it could occur with very little or no warning," Kongba said.
Ten neighborhoods of the city needed to evacuate to Sake, another lakeside town around 13 miles (21km) northwest, he said.
"Evacuation is compulsory, those who do not adhere swiftly, carry unnecessary risks. A return home can only take place on the recommendation of the provincial authority."
On Wednesday the UN said it was temporarily relocating around 250 non-essential staff, around half of its aid workers, and about 1,500 of their dependents to the city of Bukavu, around 50 km (30 miles) south.