Report on Nyamuragira (DR Congo) — 29 June-5 July 2005
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 29 June-5 July 2005
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2005. Report on Nyamuragira (DR Congo). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 29 June-5 July 2005. Smithsonian Institution and US Geological Survey.
1.408°S, 29.2°E; summit elev. 3058 m
All times are local (unless otherwise noted)
GVO reported that a significant seismic crisis occurred at Nyamuragira during several days in late June. The crisis consisted of swarms of mainly long-period earthquakes, which increased in number daily and peaked on 26 and 27 June. The swarms were recorded by the entire seismic network at the volcano, as far away as 90 km S of the volcano. Most of the events occurred within a 10 km radius around Nyamuragira's summit caldera and were aligned roughly N-S. The depths of the earthquakes ranged from 0 to 30 km, with two main areas of concentration; one between 15 and 25 km deep, and the other between 0 and 4 km. Based on precursory activity before previous historical eruptions at Nyamuragira, GVO reported that a new eruption might occur in the next 2-4 months. They stressed that an eruption from Nyamuragira would not threaten the city of Goma or other inhabited areas.
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), Jacques Durieux, UN Program Manager