Abstract
Taupo Volcano, located in the central part of the TVZ (Taupo volcanic
Zone), North Island of New Zealand, is one of the most productive
Rhyolitic centres in the world. Although its last eruption occurred
about 1800 years ago, 16 periods of unrest have been identified
including surface deformation, hydrothermal eruptions, and seismic
swarms since 1870. The town of Taupo lies on the north-eastern shore of
the lake filling the caldera of the volcano and is located close to
recent seismic swarms and local surface deformation episodes highlighted
in this report. The aim of this work is to study the different periods
of episodic deformation, contrasting with the long-term deformation of
the Taupo region, in order to constrain the sources generating local
deformation. For this, an analysis of GPS (continuous and campaign
stations) and InSAR data (from two satellites, EnviSAT and ALOS) was
conducted. After correcting the data for several external factors such
as subsidence generated by water pumping in the Wairakei-Tauhara
geothermal station and displacements associated with slow slip events
along the Hikurangi subduction interface, periods of local deformation
have been identified. We highlight two periods of uplift with rates of
10 mm/yr in 2004-2008 and in 2011-2013 accompanied by more or less rapid
horizontal deformation punctuated by seismic swarms. The geodetic data
were inverted to characterize the deformation sources using the GBIS
software, allowing the use of different analytical models. In order to
explain the different periods of deformation over time, at least three
sources at different locations are needed, revealing the presence of
different processes at depths ranging from ∼ 10 km to ∼ 0.5 km and whose
causes can vary given the complexity of the tectonic context
characterizing the region.