Report on Nyiragongo (DR Congo) — 17 July-23 July 2002
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 17 July-23 July 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, 17 July-23 July 2002. Smithsonian Institution and US Geological Survey.
1.52°S, 29.25°E; summit elev. 3470 m
All times are local (unless otherwise noted)
During the previous several weeks, long and significant episodes of volcanic tremor had been recorded at several seismometers near Nyiragongo. Inclement weather conditions prevented visual observations of the volcano from the city of Goma. A team that climbed the volcano on 16-17 July observed a plume rising above the volcano and smelled SO2. Around 1800 on the 16th, lava fountains were observed rising ~100 m above the crater floor. During the night, large amounts of ash continuously fell on the upper part of the volcano. By morning, ash fall had ceased and a white plume rose above the crater. Observers could not see the bottom of the crater clearly, but due to visible activity on the lower and central parts of the crater they suspected that a new lava lake had formed.
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. The steep slopes of a stratovolcano contrast to the low profile of its neighboring shield volcano, Nyamuragira. 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.
Sources: Observatoire Volcanologique de Goma (OVG), UN Office for the Coordination of Humanitarian Affairs (OCHA)