1. a Bureau de Recherches Geologiques et Minieres, Direction de la Recherche, Departernent Geophysique et Imagerie geologique , Orleans, Cedex 2, BP 6009 45060, France
2. b Geography Department, University of Auckland, Private Bag , Auckland, 92019, New Zealand
3. c Institute of Geological and Nuclear Sciences, Wairakei Research Centre, State Highway 1, Wairakei, Private Bag , Taupo, 2000, New Zealand
4. d Geothermal Institute, University of Auckland, Private Bag , Auckland, 92019, New Zealand