A multi-disciplinary investigation into the distribution of melt along 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. The TVZ is home to two of the most active rhyolitic calderas in the world, Taupo and Okataina, and is thought to have erupted more than 10,000 km³ of predominately rhyolitic magma, with ~640 km³ of material over the past 61 ka from Taupo and Okataina alone. 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 and show widespread subsidence across the central TVZ at rates of up to 20 mm/yr. Using simple elastic dislocation models to represent the contraction of a sill like body, we predict an annual volume change of up to 0.016 km³ beneath the central TVZ and suggest that the majority of the observed subsidence is a result of the cooling and subsequent contraction of magma within the shallow crust. Furthermore, with New Zealand volcanoes now added to the GEO’s Geohazard Supersites and Natural Laboratories initiative, we will detail our attempts at integrating geodetic, magnetotelluric and petrological datasets to image the plumbing system beneath the TVZ.