Report on Nyiragongo (DR Congo) — 16 January-22 January 2002
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 16 January-22 January 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, 16 January-22 January 2002. Smithsonian Institution and US Geological Survey.
1.52°S, 29.25°E; summit elev. 3470 m
All times are local (unless otherwise noted)
According to reports from news and government agencies, the eruption at Nyiragongo that began on 17 January appeared to have stopped by 21 January. During the eruption lava flowed from fissures on the volcano's S and E flanks, moving towards the S. Lava flows cut directly through the city of Goma (~10 km S of the volcano) and continued onward to enter Lake Kivu. A 100-m-wide delta formed where lava entered the lake. Various reports estimated that lava flows had destroyed 25-75% of the city including ~10,000 homes. The buildings at the Goma airport remained intact, but lava covered ~80% of the airstrip rendering the airport inoperable.
Residents of Goma were evacuated after the eruption was underway. Reports of the number of deaths and injuries vary; most reports state ~45 people died, possibly as a result of remaining in their homes which burned or collapsed. In addition, 50-100 people were killed when hot lava caused gas station tanks to explode at 0830 on 21 January. A total of ~400 people suffered from injuries including burns. Beginning around 19 January many Goma residents returned to the city; field reports from USAID/OFDA staff stated that on the morning of the 20th more than 15,000 people per hour returned, while only 3,000 people per hour fled the city. By the 21st there were ~12,000 homeless families in Goma.
Press accounts indicated that volcanologists tentatively suggested that Nyiragongo's volcanism was due to seismicity producing fissures up to several km in length along the E African rift, allowing magma to reach the surface. After observing the volcano on 21 January volcanologists stated, "The current phase of the active eruption is finished. The volcano is quiet." Although no new lava flows were threatening the city, some scientists feared that lava entering the lake or seismic activity could perturb the lake sufficiently to release significant amounts of carbon dioxide and methane gas lying at the bottom of the lake. On the other hand, news interviews quoted Jaques Durieux, a French volcanologist working with the UN, as saying, "There is no reason for the methane and carbon dioxide to rise to the surface."
According to Bruce Presgrave of the USGS, National Earthquake Information Center there have been an unusual number of tectonic earthquakes in the Goma-Nyiragongo region since ~9 hours after Nyiragongo's alleged initial lava flows at 0500 local time on 17 January. The sequence included ~100 earthquakes of M 3.5 or larger. The largest earthquake to date was M 5; it struck around 1.76°S, 29.08°E at 0014 on 20 January. According to news reports, several earthquakes were of sufficient magnitude to have been felt in the Goma region.
As of 22 January, no new lava flows had been reported, although lava slowly flowed into Lake Kivu and seismic activity continued. In addition, analysis of lake chemistry found the city's main water supply had remained potable.
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: ReliefWeb, UN Office for the Coordination of Humanitarian Affairs (OCHA), US Agency for International Development / Office of US Foreign Disaster Assistance, US Geological Survey Earthquake Hazards Program