Nyiragongo (3470 m a.s.l.) is by shape a stratovolcano which is located in the Virunga (North Kivu, D.R. Congo) volcanic province of the western branch of the East African Rift. The main volcanic edifice is composed by a 1.3 km wide central crater surrounded by two main adventive cones, the Baruta on the northern flank and the Shaheru on the southern flank.
Eruptive activity of Nyiragongo is caracterized by the presence of a (semi-)permanent active lava lake inside the main crater. This ~200 m wide lava lake is currently the largest on Earth. A SO2-rich gas plume is continuously released from the lava lake and frequently causes important acidic rainfalls that affect vegetation, crops, human infrastructures, surface water quality and also probably human health. Two historical flank eruptions are known and occurred on 10th January 1977 and 17th January 2002. These eruptions correspond to long and very fast lava flows associated to the lava lake drainage, which come from eruptive fissures on the volcano flanks. Both 1977 and 2002 events caused casualties and huge damages to the Goma region. In January 2002, 100 to 150 persons were killed, more than 100 000 persons became homeless and at least 10 % of the city of Goma were destroyed by lavas. This eruption caused a huge humanitarian and economical impact, which affected the whole Great Lake Region.
The current activity of the Nyiragongo lava lake is marked by -sometimes large- level oscillations and frequent lava overflows on the lower platform of the crater, which progressively rises tens of meters per year. This rise of the lava lake and lower platform levels contribute to the instability of the whole volcanic edifice and the amount of lava available in case of flank eruption.
