Report on Nyiragongo (DR Congo) — 24 November-30 November 2004
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 24 November-30 November 2004
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2004. Report on Nyiragongo (DR Congo). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 24 November-30 November 2004. Smithsonian Institution and US Geological Survey.
1.52°S, 29.25°E; summit elev. 3470 m
All times are local (unless otherwise noted)
The Goma Volcano Observatory reported that during 10-17 November continuous volcanic tremor was recorded at all seismic stations located around Nyiragongo. Visual observation of the volcano's summit on 12 and 13 November revealed that the lava lake surface had widened considerably, with strong lava fountains. Numerous Pele's hairs and scoriae were seen on the cone's S, W, and N sides. A gas plume and incandescence were visible rising above the volcano. All fractures that opened during the 2002 eruption on the volcano's S flank had widened slightly and showed minor temperature increases.
During 18-29 November, continuous banded tremor at high amplitudes occurred beneath the volcano, but the amplitudes seemed to be lower that those recorded during 9-18 November. Visual observations at the summit on 25 and 26 November revealed a slight decrease in the level of the lava lake, although there continued to be strong lava fountains and a high flux in lava and gases. Pele's hair, scoriae, a gas plume, and incandescence were all still present. Measurements of the fractures on the volcano's slopes showed that they remained stable. The Alert Level at Nyiragongo 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.
Source: Goma Volcano Observatory (GVO)