The name Rū is the Māori word for earthquakes, itself derived from Rūaumoko the deity of earthquakes (also known as Whakaruaimoko, Rūamoko, Rūaimoko, Whakarūamoko, Rūaimokoroa).
In Māori tradition, earthquakes are caused by Rūaumoko, the son of Ranginui (the Sky-father) and his wife Papatūānuku (the Earth-mother). Rangi had been separated from Papa by one of their sons Tānenuiarangi, and because they pined for one another so much, producing clouds, rain, mist, frost and snow, their sons resolved to turn their mother face downwards, away from Rangi towards Rarohenga, the underworld. When Papatūānuku was turned over Rūaumoko was still at her breast and was carried to the world below where he was given fire – te ahi komau to provide warmth and comfort for his mother. To avenge the ill-treatment of his parents, Rūaumoko constantly battles humankind, physically manifested by earthquakes and volcanoes. Although a geological interpretation of the ultimate explanations of why we experience earthquakes and volcanoes differs fundamentally from that given above, some interesting commonalities exist, most notably that earthquakes and volcanoes are caused by the same processes – heat causing earthquakes and volcanoes.