Report on Nyiragongo (DR Congo) — 15 May-21 May 2002
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 15 May-21 May 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, 15 May-21 May 2002. Smithsonian Institution and US Geological Survey.
1.52°S, 29.25°E; summit elev. 3470 m
All times are local (unless otherwise noted)
On 17 January 2002, during the eruption of Nyiragongo, all lava drained from the volcano's summit, leaving a 700-m-deep empty crater. In late April harmonic tremor began to be registered at two seismic stations on Nyiragongo's S flank, and increased irregularly in amplitude until mid-May. Anomalous clouds had been noticed above the crater twice since 1 May, but no incandescence had been visible at night. No eruptive activity was visible 14 May during an overflight, but increasing tremor amplitude suggested that magma was moving within the summit area. On 17-18 May a small lava fountain was seen on the floor of the crater along the same fissure that apparently drained the crater in January. The lava fountain was 12 m high, no lava lake was forming in the crater, and small incandescent vents on the crater floor ejected hot gases. The Goma Volcano Observatory stated,"this is a normal development in Nyiragongo's historical eruptive pattern, and is no cause for immediate concern."
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)