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Limitations in one-dimensional (an)elastic Earth models for explaining GPS-observed M$_2$ Ocean Tide Loading displacements in New Zealand
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  • Bogdan Matviichuk,
  • Matt A King,
  • Christopher Stephen Watson,
  • Machiel Simon Bos
Bogdan Matviichuk
University of Tasmania, University of Tasmania

Corresponding Author:[email protected]

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Matt A King
University of Tasmania, University of Tasmania
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Christopher Stephen Watson
University of Tasmania, University of Tasmania
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Machiel Simon Bos
University of Beira Interior, Institute D. Luis, University of Beira Interior, Institute D. Luis
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Abstract

GPS observations of ocean tide loading displacements can help infer the regional anelastic properties of the asthenosphere. We estimate M2 ocean tide loading displacements at 170 GPS sites in New Zealand and compare these to modeled values using a range of numerical tide and radially symmetric (1D) elastic and anelastic Earth models. Regardless of the model combination we are unable to reduce the strong spatial coherence of the M2 residuals across the North Island where they reach 0.4 mm (2%). The best fit in the North Island is obtained when combining the FES2014b tide model with spatially-variable ocean density and water compressibility, and the STW105 Earth model. The residuals exhibit a change of ~0.3 mm in magnitude between the Taupo Volcanic Zone and the east coast (~100 km), suggesting that this region’s laterally-varying, shallow rheological structure may need to be considered to explain these observations.
Jun 2021Published in Journal of Geophysical Research: Solid Earth volume 126 issue 6. 10.1029/2021JB021992