Satellite images from 13 and 18 September indicated continuing activity at Nyamuragira. The end of the NNW lava flow was about 7.6 km from the crater rim based on a 13 September satellite image and had advanced a short distance by 18 September. Lava had branched from the flow in an area about 1.3 km upslope from the end of the flow and traveled about 1.6 km NE. Lava flows that had breached the NNW crater rim traveled W and SW. The farthest end of the W flow was about 5 km from the crater rim and the end of the SW flow was about 3 km from the crater rim. Small thermal anomalies were visible near the ends of the NNW flow and in areas along the W and WSW flows. A larger thermal anomaly was present the part of the eastern crater floor. An 18 September image showed that the thermal anomaly in the main crater had shifted to the NW part of the crater. Scattered thermal anomalies on the flow fields indicated breakouts in areas along the margins of the NNW, W, and SW. Weather clouds slightly obscured the crater and flow field in the 13 September image but obscured most of the flow field and part of the crater in the 18 September image.

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