Shallow Resistivity of the Taupo Volcanic Zone, New Zealand

Abstract

All publicly available dc resistivity data are being combined to produce a new map series that covers the Taupo Volcanic Zone (TVZ) at a scale of The two maps in this new series incorporate data with nominal Schlumbergerarray spacings of 500m and These maps show that the shallow (less than 1 depth) resistivity structure of the TVZ is dominated by short-wavelength, high-amplitude anomalies. The central portion of the TVZ consists of two parallel zones of mostly low resistivity, oriented at about Nearly all high temperature geothermal fields are found within these low resistivity zones. An area of high resistivity between the low resistivity zones coincides with the Taupo Fault Belt - a region of active surface faulting. Other parameters can be derived from the resistivity data, such as the vertical resistivity gradient and the extrapolated resistivity at any depth. The TVZ exhibits a generally positive resistivity gradient (increasing resistivity with depth) while areas surrounding the have negative gradients (decreasingresistivity with depth).