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Deformation at Taupo volcano, New Zealand, measured by InSAR, lake levelling and GPS

Jessica K. Hole(1), Jessica K. Hole(2), Bradley J. Scott(3), John Beavan(4), Geoff Wadge(1) and Nicola F. Stevens(5)

(1) Environmental Systems Science Centre, Harry Pitt Building, Reading, RG6 6AL, United Kingdom
(2) NPA Group, Crockham Park, Edenbridge, TN8 6SR, United Kingdom
(3) GNS Science, Wairakei Research Centre, Taupo 3377, New Zealand
(4) GNS Science, 1 Fairway Drive, Avalon, Lower Hutt 5010, New Zealand
(5) Ministry for the Environment, Environment House, Wellington 6011, New Zealand

Abstract

Taupo volcano is a major young caldera system in the Taupo Volcanic Zone (TVZ), New Zealand, an area of active back-arc extension. Taupo caldera is mostly filled by Lake Taupo, which since 1979, has been routinely monitored for vertical deformation using a portable lake levelling survey technique. Over the last century, there have been three major periods of seismic unrest at Taupo volcano; the most recent in 1983 was accompanied by up to 50 mm of deformation. In this paper, the use of InSAR to measure deformation at Taupo volcano has been investigated. Using descending ERS and ascending and descending Envisat data from 1996 to 2006, deformation in the area to the north of Lake Taupo has been measured by distributed interferogram stacking and persistent scatter InSAR. Temporal and spatial variations in deformation have been identified that agree well with the coeval lake levelling data. A broad area of ongoing uplift has been identified from west to east across the lake with its maximum at Acacia Bay, near the main urban area of Taupo. Changes in the rate of uplift were measured that coincided with the onset of an earthquake swarm in mid-2004. It is suggested that this uplift may be caused by changes in hydrothermal fluid pressure, driven by hot magma at depth. Horizontal velocity data for the same area, derived from multiple GPS campaigns carried out from 1991 to 2005, showed extension across the north of the lake from west to east of ~8 mm/year, that occurred predominantly in the Taupo Fault Belt (TFB). A small number of the stations in the TFB experienced a slight westward component of motion, which is unexpected in this extensional setting, and may be related to localised fault movement or the uplift described above.

 

Workshop presentation

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry