Musanze - main segment (Ubuvumo bwa)

Michael Laumanns - 29/11/2015

(North province, Virunga mountains, Musanze district) Co-ordinates (taken where the main tarred road from Ruhengeri towards Gisenyi crosses over the cave): S 01"30,212°; E 029°36,783°. Alt. ca. 1,870 m. The segmented lava tube was partly surveyed by a team from the Centre Routièr Spéléo Belgique in 1975 to a length of 1,600 m (main segment) (Martin 1978). They were followed by Barcelonan cavers who surveyed Ubuvumo bywa Musanze in 1977 to a length of 4,560 m and a depth of -210 m. However, they added several independent tube segments to the overall length: i, 176 m of the total passage length is open to the surface and 2,960 m of the total length comes from segments that are not physically connected to the longest segment. The cave consists of a main gallery that is well proportioned with an average diameter between 10 and 15 m. Side passages exist mainly in the longest (middle) segment of the lava tube but they are generally insignificant. The lava stream that forms the cave came from the Bisoke-Sabyinyo volcano. The gallery is mainly filled with boulders but rainstorms have washed in sediments from the surface at some places. The cave has 31 entrances in total, the easiest to locate being one above the longest (middle) section of the cave immediately alongside the main road between Ruhengeri and Gisenyi near a school. Most of the entrances are roof collapses. Ubuvumo bya Musanze is by far the most famous cave currently known in Rwanda (MontoriolPous 1978a, Montoriol-Pous 1978b, Montserrat i Nebot & Montoriol-Pous 1978; Montserrat i Nebot 1978; Montserrat i Nebot 1979). It is mentioned in most travelling guides on Rwanda. However, the cave is closed by the military at the moment due to many human skeletons still wrapped in their clothes inside the cave, being probably remains of post 1994 clashes. There are large bat roosts in some parts of the cave. Hutson & Wilson (1992) found about 40,000 Rousettus aegyptiacus in the main entrance chamber. Survey according to Montserrat i Nebot & Montoriol-Pous (1978).