Haruj is not located close to a plate boundary. Rather, volcanism there and in other African volcanic fields which are located on top of crustal domes, has been explained by the presence of hotspots, but in the case of Haruj a mantle plume is considered unlikely. Alternatively, volcanism at Haruj may be the consequence of the intersection of three geological structures of Paleozoic to Tertiary age and melting of the shallow mantle, or of the rifting process of the Sirte Basin. Wau an Namus is sometimes considered to be part of the field, other volcanic fields in Libya are Gharyan, Gabal as Sawada, Gabal Nuqay and Tibesti some of which belong to a long line known as the Tibesti lineament. Volcanism in general has shifted southward over time, although more recent radiometric dating efforts indicate that volcanic activity in the fields was more contemporaneous than thought.