This Volcano Both Captivates and Concerns Scientists: Home to the World’s Largest Lava Lake

Nyiragongo dominates the region by its imposing silhouette and vapor plumes. Each night, its caldera kisses red glows, a reflection of a large lava lake constantly agitation. This hypnotic spectacle attracts looks, but hides an internal mechanics capable of rushing a disaster. In 2002, a crack opened by an earthquake allowed Torrents de lava to descend the slopes of the volcano, destroying part of the city of Goma and leaving more than one hundred thousand homeless people, as the UNOPS recalls in its summary of the surveillance project led with the European Union. Since this eruption, the volcano has never stopped recharging.

Its modest altitude for an active volcano, at 3,470 meters, in no way has no destructive power. The neighboring city has however densified at a sustained pace, going from 400,000 to more than 1.5 million inhabitants in two decades. The volcanologist Dario Tedesco, a privileged witness to this evolution, compared Goma to one of the cities most exposed to natural risks on the planet, in a region already marked by armed conflicts, deadly gas pockets in the soil and regular earthquakes.

A lava with unique and murderous properties

The main danger of nyiragongo does not come from its size, but from the very nature of its lava. Unlike other more viscous volcanoes, it produces an extremely fluid basalt magma. During the 2002 eruption, the lava reached speeds estimated at 60 kilometers per hour, making it one of the rare volcanoes whose flows can compete with a moving vehicle. This behavior is explained by a low concentration in silica, which makes the lava more mobile, warmer, and therefore much more difficult to flee.

The Nyiragongo lava lake, considered the largest in the world in permanent activity, acts as an unstable reservoir. Researchers see it as a direct indicator of the internal pressure. The more the level of the lake rises, the more the risk of violent eruption increases. In 2020, a team led by Dario Tedesco observed an accelerated rise in the lake level, reaching a flow equivalent to an Olympic swimming pool filled every ten minutes, according to data published in the journal Science. These observations let fear a possible rupture of the internal walls of the crater if an earthquake came to shake the area.

The consequences of such a flaw would be immediate for the city of Goma, already marked by episodes of collective panic with each visible sign of volcanic activity. In June 2024, an intense flame appeared at the top of the volcano caused a movement of panic among the inhabitants. Faced with uncertainty, an emergency unit was set up by the local volcanological observatory to assess the risks.

Pending lives in the face of insufficient alert means

As the threat grows, the surveillance means fall asleep. For several years, the Goma volcanological observatory has faced financing cuts, the deterioration of its sensors, and a regional instability which sometimes prevents its teams from operating in complete safety. The Science article already underlined in 2020 the loss of support from the World Bank, leaving the only network of sensors at the mercy of vandalism, bad weather and armed conflicts.

Recently installed seismometers with the help of Belgian researchers have made it possible to detect several swarms of earthquakes, signs of magmatic movements in depth. But without regular maintenance or staff trained in sufficient numbers, this data often remains unusable in real time. The UNOPS had tried to structure a real community alert network, by forming teachers, by broadcasting messages on local radio and organizing educational competitions in the schools of Goma. These efforts have made it possible to educate part of the population, but cannot replace functional sensors and an operational evacuation system.

In a city where rumor circulates faster than scientific information, confidence in local institutions plays a crucial role. As long as the volcano remains active, vigilance must remain constant. This fragile balance between natural beauty and latent danger continues to define the daily life of the inhabitants of Goma.