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.

Geological Summary. Africa's most active volcano, Nyamulagira (also known as Nyamuragira), is a massive high-potassium basaltic shield about 25 km N of Lake Kivu and 15 km NE of the steep-sided Nyiragongo volcano. The summit is truncated by a small 2 x 2.3 km caldera that has walls up to about 100 m high. Documented eruptions have occurred within the summit caldera, as well as from the numerous flank fissures and cinder cones. A lava lake in the summit crater, active since at least 1921, drained in 1938, at the time of a major flank eruption. Recent lava flows extend down the flanks more than 30 km from the summit as far as Lake Kivu; extensive lava flows from this volcano have covered 1,500 km2 of the western branch of the East African Rift.

Source: UN Office for the Coordination of Humanitarian Affairs (OCHA)