Report on Nyamuragira (DR Congo) — 24 July-30 July 2002
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 24 July-30 July 2002
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2002. Report on Nyamuragira (DR Congo). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 24 July-30 July 2002. Smithsonian Institution and US Geological Survey.
1.408°S, 29.2°E; summit elev. 3058 m
All times are local (unless otherwise noted)
An eruption began at Nyamuragira on the evening of 25 July that produced a cloud composed of steam, gas, and ash, 100- to 200-m-high lava fountains, and lava flows down the volcano's N and S flanks. According to the seismic record, the eruption began on the 25th at about 1310. National Park guards saw "smoke" rising above the volcano about an hour earlier. Around 1700, lava was seen pouring out of a fracture. Scientists who visited the crater later that day saw that the crater had been cut in two parts by a fracture: NW and SE. Sustained 100- to 200-m-high lava fountains were visible along the fracture. One lava flow traveled to the N from the several-km-long fracture, while a smaller one traveled to the S. On the 27th the lava flows were 6-7 km long and ~1 km wide. Neither flow was a threat to inhabited areas, but they caused large amounts of damage to vegetation within the National Park.
Volcanic clouds produced during the eruption were detected by several satellites. Beginning on 26 July around 0000, a steam-and-ash plume was visible on METEOSAT satellite imagery, below 6 km a.s.l., drifting to the WSW. From the 26th to the 28th TOMS detected 125 to 330 kt of SO2 in a cloud that may have come from the neighboring volcano Nyiragongo, but is believed to be from Nyamuragira. A NASA satellite detected a very large plume that was 400 km long, 300 km wide, and extended to the WSW. Nyamuragira is ~20 km NW of Nyiragongo and 40 km NW of the city of Goma, which was devastated by an eruption at Nyiragongo in January 2002. Scientists do not think the eruption of Nyamuragira is a threat to residents of Goma, but the ash cloud may cause respiratory problems, and threaten animals and crops in its path.
Geologic Background. Africa's most active volcano, Nyamuragira, is a massive high-potassium basaltic shield about 25 km N of Lake Kivu. Also known as Nyamulagira, it has generated extensive lava flows that cover 1500 km2 of the western branch of the East African Rift. The broad low-angle shield volcano contrasts dramatically with the adjacent steep-sided Nyiragongo to the SW. The summit is truncated by a small 2 x 2.3 km caldera that has walls up to about 100 m high. Historical eruptions have occurred within the summit caldera, as well as from the numerous fissures and cinder cones on the flanks. A lava lake in the summit crater, active since at least 1921, drained in 1938, at the time of a major flank eruption. Historical lava flows extend down the flanks more than 30 km from the summit, reaching as far as Lake Kivu.