InSAR observations over the Taupō Volcanic Zone's cone volcanoes: insights and challenges from the New Zealand volcano supersite
Launched in 2015, the New Zealand volcano supersite provides regular radar acquisitions covering all the major calderas and cone volcanoes which form the Taupō Volcanic Zone (TVZ). This paper documents new InSAR (Interferometric Synthetic Aperture Radar) observation of deformation over the cone volcanoes within the TVZ including the Tongariro Volcanic complex (TVC) and White Island. Observations over White Island support earlier observations indicating that the stability of the crater wall is controlled, at least in part, by the water level in the crater lake with downslope motion of ∼50 mm/yr observed during the latest period of lake drop in early 2019. Deformation over the TVC is dominated by the continued subsidence above the 2012 Te Maari eruption site at rates of ∼30 mm/yr with no evidence of deformation elsewhere. Synthetic models, used to test the potential detectability of magma movement beneath Ruapehu and White Island, suggest that for small volumes (<0.005–0.02 km3), intruded over short periods of time, it would be difficult for InSAR data alone to identify their accumulation. These challenges are not unique to New Zealand's volcanoes and are likely to be faced at other volcanic systems globally.
