Mount Nyiragongo

Lore & Background

Mount Nyiragongo is an active stratovolcano with an elevation of 3,470 m (11,385 ft) in the Virunga Mountains, associated with the Albertine Rift. It is located inside Virunga National Park, in the North Kivu province in the Democratic Republic of the Congo, about 12 km (7.5 mi) north of the town of Goma and Lake Kivu. The main crater is about two kilometres (1 mi) wide and usually contains a lava lake. The crater presently has two distinct cooled lava benches within the crater walls – one at about 3,175 m (10,417 ft) and a lower one at about 2,975 m (9,760 ft). Nyiragongo's lava lake has at times been the most voluminous known lava lake in most recent history. The depth of the lava lake varies considerably. A maximum elevation of the lava lake was recorded at about 3,250 m (10,660 ft) prior to the January 1977 eruption – a lake depth of about 300-400 m (1,000-1,300 ft). Following the January 2002 eruption, the lava lake was recorded at a low of about 2,600 m (8,500 ft), or 900 m (3,000 ft) below the rim. The level has gradually risen since then. Nyiragongo and nearby Nyamuragira are together responsible for about 30-35% of Africa's historical volcanic eruptions.

Reader's Guide

Mount Nyiragongo's significance lies in its extreme hazard potential due to its unusually fluid lava flows, which can race downhill at up to 100 km/h (60 mph), and its proximity to the densely populated city of Goma. The 1977 eruption, in which the lava lake drained in less than an hour, killing at least 50 people, raised awareness of these unique dangers and led to its designation as a Decade Volcano in 1991. The 2002 eruption forced the evacuation of 400,000 people, killed about 245, and covered 13 percent of Goma, leaving nearly 120,000 homeless. The volcano is continuously monitored by the Goma Volcanic Observatory, though funding is uncertain. Its ongoing lava lake activity and the risk of carbon dioxide toxicity (mazuku) continue to pose threats. The 2021 eruption destroyed 17 villages and around 1,000 homes, with at least 32 deaths. In 2023, the volcano was taken over by the M23 Movement, leading to deforestation of its eastern portion.

Did You Know?

• Nyiragongo's lava flows can reach speeds of up to 100 km/h (60 mph), among the fastest recorded.
• The 1977 eruption drained the lava lake in less than an hour, killing around 70-100 people.
• The volcano was designated a Decade Volcano in 1991 due to its unique hazards.
• Localized carbon dioxide toxicity, known as 'mazuku', has killed livestock and children.

Geological Composition & Lava Behavior

Mount Nyiragongo stands apart from most volcanoes because of its extraordinarily low-silica, alkali-rich composition. Its extrusive rocks are ultramafic and essentially devoid of feldspars, spanning a mineralogical range from olivine-rich melilitites through leucites to nephelinites. The dominant constituents include nepheline, leucite, melilite, kalsilite, and clinopyroxene. This chemistry produces lava of remarkable fluidity, allowing flows to race downhill at speeds reaching 100 km/h—far exceeding the sluggish pace typical of most volcanic rivers. The cone itself is built from pyroclastics and lava flows, partly overlapping two older volcanoes, Baruta and Shaheru, while hundreds of small cinder cones from flank eruptions dot the surrounding landscape. The main crater, roughly two kilometres across, typically holds a persistent lava lake, with two distinct cooled lava benches on the crater walls at approximately 3,175 m and 2,975 m elevation. Together with its neighbor Nyamuragira, Nyiragongo accounts for 40 percent of Africa's recorded volcanic eruptions throughout history.

The 1977 Eruption & Confirmation of the Lava Lake

For decades, scientists suspected a molten lake occupied Nyiragongo's crater, but it was not until 1948 that measurements confirmed the feature, recording a surface area of nearly 120,000 square metres. The lake persisted, fluctuating in depth and temperature, until the catastrophic morning of 10 January 1977. The crater walls suddenly fractured, and the entire lava lake drained in under an hour; the maximum recorded level before the event sat at roughly 3,250 m, about 600 m below the rim. The molten outpouring surged down the upper slopes at up to 60 km/h, the fastest lava flow recorded to that point, sweeping through the villages of Kibati and Moniki and killing at least 50 residents. Within half an hour the lake was gone, with fluid lava racing north, south, and west. The disaster brought global attention to Nyiragongo's unique hazard profile, and in 1991 the volcano was formally designated a Decade Volcano, meriting intensified scientific study. The 1977 event was also preceded by the opening of a small new vent, Murara, on the slopes of nearby Nyamuragira.

The 2002 Eruption & Devastation of Goma

After months of escalating seismic and fumarolic activity, a 13-kilometre fissure tore open along the south flank on 17 January 2002, dropping from 2,800 m to 1,550 m elevation within hours and reaching the outskirts of Goma, the provincial capital. Lava poured from three spatter cones at the fissure's terminus, forming a stream 200 to 1,000 m wide and up to 2 m deep that carved through the city. Warnings prompted the evacuation of roughly 400,000 people across the border into Gisenyi, Rwanda. The lava buried the northern end of Goma International Airport's runway and reached the shores of Lake Kivu, sparking fears of a catastrophic gas release analogous to the 1986 Lake Nyos disaster in Cameroon—though that worst-case scenario did not materialize. The eruption killed approximately 245 people through carbon dioxide asphyxiation and building collapses, left nearly 120,000 homeless, and buried 13 percent of the city under rock. A three-month earthquake swarm in the aftermath brought down additional structures.

Persistent Hazards & Recent Eruptive Activity

Nyiragongo's danger extends far beyond its dramatic eruptions. Localized carbon dioxide seepage, known locally as mazuku, has claimed the lives of livestock and children in recent years, particularly in sheltered areas where wind cannot disperse the toxic gas. The volcano has erupted at least 34 times since 1882, with many episodes involving years of continuous activity centered on the churning lava lake. After the 2002 event, the lake was recorded at a low of about 2,600 m, nearly 900 m below the rim, before gradually rising again. By 2020, the lake was largely confined within a broad, steep-sided cinder cone roughly 18 m high and 180 m wide on the crater floor. In March 2016, a new vent appeared on the crater's northeast edge, raising alarm about a potential flank eruption. Observers in 2020 noted a rising lava lake and other precursors. On 22 May 2021, a new eruption began, with lava approaching Goma airport and severing the N2 road toward the city centre.