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Published byDavid Cox Modified over 9 years ago
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InSAR measurements around Alpine Fault, South Island of New Zealand
(ALOS-2 PI Project Title: Measurements and understanding of strain concentration around active faults) Yo Fukushima Disaster Prevention Research Institute, Kyoto University PAC AUS
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Acknowledgements This study has been partially conducted under the ALOS PI RA3 project (#591) of JAXA, and a cooperative research contract with ERI, Univ. Tokyo. The ownership of PALSAR data belongs to the Ministry of Economy, Trade and Industry and JAXA. The the ALOS/PALSAR data used in this study were obtained through the ALOS PI framework and PIXEL (PALSAR Interferometry Consortium to Study our Evolving Land surface) shared archive. I would be grateful to Dr. Laura Wallace for the GPS velocity data used in this study.
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The alpine Fault Right-lateral strike-slip fault that runs through the South Island of NZ Previously shown that it accommodates at least 70–75% of the relative plate motion (~25- 30mm/year, geologic & geodetic) Ideal geometry for studying with InSAR LOS (asc.)
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Motivations Campaign GPS surveys have revealed the long- scale deformation With InSAR TS analysis, we can further investigate on the… temporal variations deformation in finer scale GPS data: courtesy of L. Wallace
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Why is finer scale deformation important?
(Model of Savage and Prescott, 1978) Displacement 〜x km (up to ~20km) 〜x km Stick (and slip) Steadily slipping The locking depth x ≈ future earthquake rupture depth → helps evaluation of future earthquake size & damage
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GPS: interval of > 10km
Locked 10 km 20 km 10 km Locked Upper layer 50% coupled
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GPS: interval of > 10km
Upper layer completely locked (100% coupled) Upper layer 50% coupled
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DATA: ALOS/PALSAR FBS&FBD Jan. 2007 – Feb. 2011 (~4yrs)
334 335 336 337 338 339 340 341 342 343
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Processing Raw -> Interferograms: GAMMA® w/SRTM DEMs
Heavily multi-look to make the ifgs coherent (px interval ~400m) Remove outliers (heavy ionospheric noise etc) SBAS Time-Series analysis -> Obtain the average velocity
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Path 334 334 335 336 337 338 339 340 341 342 343
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Path 335 334 335 336 337 338 339 340 341 342 343
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Path 336 334 335 336 337 338 339 340 341 342 343
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Path 337 334 335 336 337 338 339 340 341 342 343
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Path 338 334 335 336 337 338 339 340 341 342 343
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Path 339 334 335 336 337 338 339 340 341 342 343
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Path 340 334 335 336 337 338 339 340 341 342 343
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Path 341 334 335 336 337 338 339 340 341 342 343
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Path 342 334 335 336 337 338 339 340 341 342 343
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Path 343 334 335 336 337 338 339 340 341 342 343
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Result: Whole Area
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comparison w/gps vel (qualitative & rough)
InSAR GPS
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Summary Average velocity map along the Alpine Fault (South Island of NZ) is obtained from ~200 ALOS/PALSAR images of 10 paths. The plate relative motion is successfully captured by the InSAR TS analysis. The InSAR result appears to show along- fault variation in the fault locking depth and strain partitioning on multiple fault strands.
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Future Plans More data to process to cover the entire fault
Validation of the results Compare and calibrate with GPS displacements Check the consistency of the results of adjacent paths (they overlap) Tectonic interpretation Locking depth Strain partitioning in the north ALOS-2!! (especially looking fwd to the frequent ScanSAR) and other places!
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