Report on Nyiragongo (DR Congo) — 1 April-7 April 2009
Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 1 April-7 April 2009
Managing Editor: Sally Sennert.
Please cite this report as:
Global Volcanism Program, 2009. Report on Nyiragongo (DR Congo) (Sennert, S, ed.). Weekly Volcanic Activity Report, 1 April-7 April 2009. Smithsonian Institution and US Geological Survey.
1.52°S, 29.25°E; summit elev. 3470 m
All times are local (unless otherwise noted)
A recent report from Goma Volcano Observatory (GVO) noted a seismic swarm from Nyiragongo and Nyamuragira in January and increased seismicity along the East African Rift since then. Gas plumes from Nyiragongo were frequently emitted and contributed to acid rain that fell on inhabited areas. On 22 March, tremor was detected on nearby seismic networks. Scientists who visited the summit crater on 22 and 24 March observed active fumaroles along a fissure connecting the Shaheru (S flank) and Nyiragongo craters. Strong methane concentrations were detected. The lava lake level had dropped 20 m compared to 27 February. A small area of the lava lake was active and lava fountains were seen. The temperature of some fissures had increased by 4 degrees Celsius since 27 February.
Geological Summary. 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.