When Mount Nyiragongo erupted in the Democratic Republic of Congo in January 2002 it seemed like a disaster.Molten lava plunged down the hillside and poured into nearby Lake Kivu.
Many died, and much of the city of Goma was destroyed. In fact, the local people were lucky.
Had the eruption spread to one of the many volcanic faults under Lake Kivu, it could have unleashed one of the most terrifying of all natural phenomena – lake overturn.
The Nyos disaster promoted a survey of deep lakes in Africa and Indonesia to see where else lake overturn could happen. All seem to be safe, except one – Lake Kivu, in Rwanda.