Nyiragongo
The Congolese volcano cradling one of the world's great lava lakes
Above the city of Goma in the eastern Democratic Republic of the Congo broods one of the most dangerous volcanoes on Earth. Nyiragongo holds within its summit crater a churning lava lake, at times the largest on the planet, a cauldron of molten rock glowing red against the night. What makes it so lethal is the chemistry of that lava: unusually fluid and poor in silica, it can race downhill at the speed of a car, far faster than the sluggish flows of most volcanoes, leaving little time for the two million people in its shadow to escape.
Nyiragongo rises about 3,470 metres in the Virunga Mountains, part of the East African Rift, where the continent is slowly tearing apart and magma wells up through the thinning crust. Its main crater is roughly a kilometre wide, and for much of the past century it has held a persistent lava lake whose level rises and falls with the volcano's moods. The deadly speed of its eruptions comes from its alkaline, silica-poor magma, which flows like hot syrup. When the crater walls fracture, as they did in 1977 and again in 2002, the lake can drain in hours, sending torrents of lava straight into Goma.
The 2002 eruption buried much of Goma's downtown and displaced hundreds of thousands, and in 2021 another flank eruption again sent lava toward the city, killing dozens. Monitoring is perilously difficult in a region beset by conflict, and the volcano sits within Virunga National Park, Africa's oldest, also home to endangered mountain gorillas. Scientists and a small band of volcanologists have braved its crater to study the lava lake up close, drawn by a rare window into the inner workings of the Earth, even as the people of Goma live with a threat that can erupt with terrifying speed.