Thousands of people have fled the Congolese city of Goma, some picking their way across landscapes scarred with lava, after officials said a second volcanic eruption could happen at any time.

Thirty-one people were killed on Saturday evening when Mount Nyiragongo, one of the world’s most active volcanoes, sent a wall of orange lava downhill towards the city, destroying 17 villages on the way. The lava stopped just 300 metres short of Goma airport, the main hub for aid operations in the eastern part of the Democratic Republic of the Congo