Waw an Namus (also spelled Wau-en-Namus, Arabic: واو الناموس) is a volcano in Libya. Of either Pleistocene or Holocene age, it is located within the eastern Fezzanregion. The origin of the volcanism there and at Al Haruj farther north is not clear. Radiometric dating has yielded an age of about 200,000 years ago, but other circumstantial evidence points to a Holocene or even historical formation of the volcano.
Waw an Namus is characterized by a caldera surrounded by an apron of dark tephra, which has a notable colour contrast to the surrounding desert terrain of the Sahara. A smaller crater lies northwest of the Waw an Namus caldera. The caldera itself contains a scoria cone. Several small lakes and associated vegetation are located within the caldera.
It is also known as Uaw en Namus, Uau en Namus, Wau-en-Namus and Wau Sqair. It means "Oasis of mosquitoes", a reference to the small lakes around itand the numerous mosquitoes that exist at Waw an Namus.
The volcano lies within the Sahara, in the eastern Fezzan and was discovered a few decades before 1951. The caravan route between Kufra and Sabha passes by the volcano. Ancient graves have been found at Waw an Namus, the oasis was probably visited by herders and hunters and may have been the source of raw materials, but the place is otherwise uninhabited. The landscape around Waw an Namus has been described as "very beautiful".
Waw an Namus is a 100 metres (330 ft) deep and 4 kilometres (2.5 mi) wide caldera, which has a small relief outwards but a steep margin inwards. Its formation involved the removal of over 800,000,000 cubic metres (2.8×1010 cu ft) of rock. Another crater lies 5 kilometres (3.1 mi) northwest from Waw an Namus, that vent is formed by overlapping craters which feature no volcanic rocks and have produced salty mud; this may be a site of phreatic activity.
Within the caldera lies a 140 metres (460 ft) high and 1.3 kilometres (0.81 mi) wide scoria cone constructed out of phreatomagmatic material with a 80 metres (260 ft) deep and 150 metres (490 ft) wide crater. Another crater, now reduced to remnants, is located west of the summit crater of the cone. The cone is modified by gullies.
