Krafla, (818 m) a tuff mountain north of Námafjall. Considerable geothermal heat on the west side of Krafla with fumaroles and mud-springs (solfataras). At the northwest side is Víti, ("Hell") an ex plosion crater, 300 m in diameter with green water in the bottom. Leirhnjúkur ("Clay peak"), is west of Krafla and on the southeast side is Hrafntinnu hryggur, ("Raven flint (i.e. obsidian) ridge") where pure obsidian is to be found. Construction of a geothermally powered electric plant started in 1974. Its first stage has been completed and provides 30 MW. From 1975-84 there was a series of tremors and eruptions in the area, 9 eruptions altogether along a 7,5 km long fissure. These originated in the old volcano Kröfluaskja.