Lava flows in town: the 17 January 2002 Nyiragongo eruption
Nyiragongo is a 3470 m high volcano located in the western branch of the East African Rift in the Democratic Republic of Congo (DRC), close to the border with Rwanda. It has a 1.3 km wide summit crater that has been filled with an active lava lake since 1894. The area is affected by frequent damaging tectonic earthquakes and by permanent passive degassing of carbon dioxide (CO2). Fatal concentrations of CO2 can accumulate in low-lying areas, threatening the permanent population and internally displaced persons (IDPs) in refugee evacuation centres.
On 17 January 2002 fractures opened on Nyiragongo's upper southern flanks triggering a catastrophic drainage of the lava lake (Figure 11.1). An estimated 25 million cubic metres of lava erupted from many vents along the fractures, which rapidly propagated South towards and into the city of Goma located 17 km away on the shores of Lake Kivu. A small volume of lava entered the lake, which contains deep CO2 and CH4 (methane) gas-charged waters. This raised concerns of a potential overturn of the lake, generating lethal gas flows, but the lake was not disturbed. Nyiragongo volcano is responsible for 92% of global lava-flow related fatalities (ca. 824) since 1900. The eruption was accompanied by an unprecedented level of felt earthquakes (Allard et al., 2002, Komorowski et al., 2002/2003, Tedesco et al., 2007b).
Two main lava flows entered the city producing major devastation, and forcing the rapid exodus of most of Goma's 300,000 to 400,000 inhabitants across the border into neighbouring Rwanda. There were international concerns about the evacuation causing an additional humanitarian catastrophe exacerbating the ongoing regional ethnic and military conflict. Lava flows destroyed about 13 % of Goma, 21% of the electricity network, 80% of its economic assets, 1/3 of the international airport runway and the housing of 120,000 people. The eruption caused about 470 injuries and about 140 to 160 deaths mostly from CO2 asphyxiation and from the explosion of a petrol station near the active hot lava flow (Komorowski et al., 2002/2003, Baxter et al., 2003).