Report on Nyamuragira (DR Congo) — 31 July-6 August 2002
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 31 July-6 August 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, 31 July-6 August 2002. Smithsonian Institution and US Geological Survey.
1.408°S, 29.2°E; summit elev. 3058 m
All times are local (unless otherwise noted)
Helicopter flights on 1 and 3 August revealed that the eruption that began on 25 July at Nyamuragira continued at a high rate. Two volcanic cones were visible growing on the eruptive fracture. The cones were built by the accumulation of spatter and ash from two very active 100- to 200-m-high lava fountains. Two large lava flows moved quickly and joined below the lowest cone to form a main flow. The main flow (estimated to be 15 km long) moved toward the NNE and changed direction after a few kilometers to move toward the NE. Many lateral overflows were visible on the E side of the main flow. The front of the main flow appeared to be very wide and lava covered a wide area, though it remained within the National Park boundaries. Permanent tremor was registered. The Alert Level remained at Yellow.
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.