ALOS PALSAR interferometry of Taupo Volcanic Zone, New Zealand

Sergey Samsonov(1) and John Beavan(1)

(1) GNS Science, 1 Fairway Drive, Avalon, Lower Hutt, 5010, New Zealand


We present results from interferometric studies of the Taupo Volcanic Zone (TVZ), New Zealand. Past attempts to use C-band data in New Zealand for deformation monitoring were mostly unsuccessful due to temporal decorrelation in the highly-vegetated environment. L-band data from ALOS PALSAR has substantially expanded the possibilities. We acquired 30 ALOS PALSAR images in raw format across the TVZ region between December 2006 and April 2008, and performed interferometric processing using GAMMA software. For this region PALSAR interferograms were coherent for time periods longer than one year and perpendicular baselines smaller than 2000 meters. Atmospheric and orbital errors were widely observed and corrected where possible. Some “deformation-like” signals due to local soil response (probably due to water content) and residual topography significantly complicates the interpretation. Large scale subsidence with rates of 2-4 cm/year is observed around Lake Taupo, but its magnitude varies temporally. We observe small scale subsidence at a rate of 10-20 cm/year around the Wairakei geothermal field. A few other localized subsidence signals are observed throughout the area but at present their cause is uncertain. Backscatterer intensity and coherence images also reveal a signal related to the lahar that occurred at Mt. Ruapehu (southern end of TVZ) in March 2007.


Symposium presentation


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