Evaluating the utility of gravity gradient tensor components Mark Pilkington Geological Survey of Canada

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Evaluating the utility of gravity gradient tensor components Mark Pilkington Geological Survey of Canada Slide 2 Tensor component choice Txx TxyTxz Tyz Tyy Tzz Single components Combinations Concatenations Which to use? Qualitative interpretation Quantitative interpretation Slide 3 Tensor component choice Quantitative interpretation [Inversions] (T xx, T xy, T xz, T yy, T yz )Li, 2001 (T uv, T xy ), T zz Zhdanov et al., 2004 (T xz, T yz, T zz, T uv )Droujinine et al., 2007 (T uv, T xy )Li, 2010 (T uv, T xy ), T zz, (T zz, T uv, T xy )Martinez & Li, 2011 T zz, (T xz, T yz, T zz), (T xz, T yz, T xz, T yy, T xx )Martinez et al., 2013 Rating the solutions: goodness of fit sharp/smooth close to geology Slide 4 Inversion versus component combinations Martinez et al., 2013 T zz T xz, T yz, T zz T xz, T yz, T xz, T yy, T xx T xz, T yz, T xz, T zz, T yy, T xx Components inverted: RMS error Txx Txy Txz Tyy Tyz Tzz 1-C 23.9 23.2 31.8 23.1 26.1 16.5 3-C 17.5 16.0 15.9 16.0 12.4 22.5 5-C 16.6 12.6 16.3 15.8 12.2 24.3 6-C 15.7 13.0 17.9 13.8 13.8 21.4 Slide 5 Outline Aim: quantitative rating of component/combinations Approach: inversion using a simple model estimate parameter errors Method: linear inverse theory analyse model/data relations Slide 6 Inversion method used Inversion Parametric [underdetermined inversion problem] n data m parametersm >> nm