Report on Nyamuragira (DR Congo) — 12 May-18 May 2004
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 12 May-18 May 2004
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2004. Report on Nyamuragira (DR Congo). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 12 May-18 May 2004. Smithsonian Institution and US Geological Survey.
1.408°S, 29.2°E; summit elev. 3058 m
All times are local (unless otherwise noted)
During a flight over Nyamuragira on 12 May scientists noted that volcanic activity remained strong, but stable. The lava lake at the volcano's summit was in a ~15-m-deep pit and its activity had greatly decreased in comparison to observations on 9 May. The lake's surface had crusted over, with three vents exhibiting Strombolian activity (lava spattering and overflows producing short lava flows). In addition, the eruptive fracture on the volcano's NNW flank had four main cones with very active lava fountains reaching heights of 30-50 m. Small lava flows from the cones coalesced into one wide lava flow, covering a large area to a distance of ~12 km. The TOMS (Total Ozone Mapping Spectrometer) Volcanic Emissions Group reported that sulfur-dioxide clouds were visible on TOMS satellite imagery since the eruption began on 8 May, although some of the gas may be attributed to emissions from neighboring Nyiragongo (~13 km SE from Nyamuragira).
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.
Sources: Observatoire Volcanologique de Goma (OVG), OMI Sulfur Dioxide Group