Topography As A Major Influence On Geothermal Circulation In The Taupo Volcanic Zone, New Zealand

Geothermal systems are an important resource in the global effort to reduce fossil fuel use. They are formed by convection of water heated at depth, but without external controls convection is unstable and upflows move or dissipate. In the central Taupo Volcanic Zone in New Zealand, the geothermal systems have been in the same locations for more than 50 kyr. We created heat and fluid flow models with uniform geology and basal heat which showed that the known topography localizes convective upflows. Fourteen out of 19 known geothermal systems in the model area were correctly located beneath topographic lows. Even at 3 km depth, inclusion of topography in our models improved agreement between the locations of upflows and low-resistivity zones derived from 3-D inversion of magnetotelluric data. Therefore, while topography is not the only factor that influences geothermal convection, its contribution is on a larger scale than is generally assumed.