Satellite images acquired on 20 and 25 February showed continuing activity at Nyamuragira. A thermal anomaly just NE of the central part of the summit crater was visible in the 20 February image, along with smaller thermal anomalies to the NE and SW. Thermal anomalies near the distal end of the lava flow on the WSW flank possibly indicated that it continued to advance; the flow was about 3.3 km long, measured from the W crater rim. Another anomaly was visible about 780 m W of the crater rim. Most of the summit crater and lava-flow field was obscured by weather clouds in the 25 February image, though the end of the active lava flow was visible and had advanced about 80 m.

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 13 km NNW 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: Copernicus