Report on Nyiragongo (DR Congo) — 31 July-6 August 2002
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 31 July-6 August 2002
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2002. Report on Nyiragongo (DR Congo). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 31 July-6 August 2002. Smithsonian Institution and US Geological Survey.
1.52°S, 29.25°E; summit elev. 3470 m
All times are local (unless otherwise noted)
A helicopter flight over Nyiragongo on 1 August revealed a thick, dense plume rising from the crater at a high velocity. The inner crater was completely filled with dispersed gas, preventing visibility of any fresh lava that may be in the crater. No red glow has been seen during recent nights, but the permanent sustained tremor recorded on all stations confirmed that the volcano remained active with magma moving beneath it. Some individual shocks were recorded around the SW flank of Nyiragongo. The Alert Level remained at Yellow.
Geologic Background. One of Africa's most notable volcanoes, Nyiragongo contained a lava lake in its deep summit crater that was active for half a century before draining catastrophically through its outer flanks in 1977. In contrast to the low profile of its neighboring shield volcano, Nyamuragira, 3470-m-high Nyiragongo displays the steep slopes of a stratovolcano. Benches in the steep-walled, 1.2-km-wide summit crater mark levels of former lava lakes, which have been observed since the late-19th century. Two older stratovolcanoes, Baruta and Shaheru, are partially overlapped by Nyiragongo on the north and south. About 100 parasitic cones are located primarily along radial fissures south of Shaheru, east of the summit, and along a NE-SW zone extending as far as Lake Kivu. Many cones are buried by voluminous lava flows that extend long distances down the flanks, which is characterized by the eruption of foiditic rocks. The extremely fluid 1977 lava flows caused many fatalities, as did lava flows that inundated portions of the major city of Goma in January 2002.