Report on Nyiragongo (DR Congo) — 30 April-6 May 2003
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 30 April-6 May 2003
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2003. Report on Nyiragongo (DR Congo). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 30 April-6 May 2003. Smithsonian Institution and US Geological Survey.
1.52°S, 29.25°E; summit elev. 3470 m
All times are local (unless otherwise noted)
UN peace keepers in the Democratic Republic of Congo provided volcanologists an early May helicopter flight. This presented very clear views of Nyiragongo, including the scene inside the active crater. Viewers reported seeing a significant plume containing gas and ash rising high above the volcano. Such activity is typical at Nyiragongo, with its restless lava lake. The lake's molten surface appeared slightly larger than when seen during a field excursion to the crater rim during 22-24 April. The field excursion measured the plume at 5-6 km a.s.l. The also noted 5 distinct vents, almost continuous emissions of scoria, an agitated molten-lake surface that included emerging gas, and splashing lava thrown 50-60 m high. Occasional waves of lava rolled across portions of the crater floor and walls. Excursion members also witnessed crater-wall collapses taking place along the NW and S fracture zones. Widely felt earthquakes also continued in the region, presumably related to extension along the massive East African rift system.
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.
Sources: Goma Volcano Observatory (GVO), The Open University Volcano Dynamics Group