The ups and downs of the TVZ: Geodetic observations of deformation around the Taupo Volcanic zone, New Zealand

Abstract

The 300 km long Taupo Volcanic Zone (TVZ) formed as a result of back-arc rifting associated with subduction of the Pacific Plate beneath the Australian Plate, with current extension rates of 8-15 mm yr−1. Using GPS and interferometric synthetic aperture radar (InSAR) data, collected by the European (ESA) and Japanese (JAXA) space agencies, we present ground deformation observations from 2003 to 2011. Both InSAR and vertical GPS data show widespread subsidence across the central TVZ at rates of up to 20 mm yr−1. Using simple elastic dislocation models to represent the contraction of a sill like body at 6 km depth, we predict an annual volume change of 0.011-0.016 km3 beneath the central TVZ. We suggest that the majority of the observed subsidence is a result of the cooling and subsequent contraction of magma within the shallow crust.