Mount Karisimbi

Karisimbi is a complex basanitic-to-trachytic volcano with a symmetrical sharp-peaked summit. The 2-km-wide Branca caldera, located SE of the summit, is filled by viscous lava flows and two explosion craters. The large 1.2-km-wide Muntango pit crater is located south of the summit. A broad lava plain, formed from lava flows erupted within the caldera and along a chain of cones, extends SW. More than 100 cones erupted along a NNE-SSW zone that extends to the shores of Lake Kivu. The youngest Potassium-Argon date obtained is about 10,000 years before present (de Mulder, 1985). The youngest eruptions produced a group of dome-shaped vents east of the caldera, which fed viscous lava flows that traveled as far as 12 km E, and lava flows from the SW-flank lava vents.