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GEOPHYSICAL RESEARCH LETTERS,
VOL. 31,
L07503,
doi:10.1029/2004GL019617,
2004
Assessing the resolution-dependent utility of tomograms for geostatistics
F. D. Day-Lewis
Office of Ground Water, Branch of Geophysics, U.S. Geological Survey, Storrs, Connecticut, USA
J. W. Lane Jr.
Office of Ground Water, Branch of Geophysics, U.S. Geological Survey, Storrs, Connecticut, USA
Abstract
Geophysical tomograms are used increasingly as auxiliary data for geostatistical modeling of aquifer and reservoir properties.
The correlation between tomographic estimates and hydrogeologic properties is commonly based on laboratory measurements, co-located
measurements at boreholes, or petrophysical models. The inferred correlation is assumed uniform throughout the interwell region;
however, tomographic resolution varies spatially due to acquisition geometry, regularization, data error, and the physics
underlying the geophysical measurements. Blurring and inversion artifacts are expected in regions traversed by few or only
low-angle raypaths. In the context of radar traveltime tomography, we derive analytical models for (1) the variance of tomographic
estimates, (2) the spatially variable correlation with a hydrologic parameter of interest, and (3) the spatial covariance
of tomographic estimates. Synthetic examples demonstrate that tomograms of qualitative value may have limited utility for
geostatistics; moreover, the imprint of regularization may preclude inference of meaningful spatial statistics from tomograms.
Received 30
January
2004;
accepted 17
March
2004;
published 13
April
2004.
Index Terms: 0910 Exploration Geophysics: Data processing; 0915 Exploration Geophysics: Downhole methods; 1829 Hydrology: Groundwater hydrology; 1869 Hydrology: Stochastic processes; 3260 Mathematical Geophysics: Inverse theory.
Read Full Article (file size: 594855 bytes) Cited by
Citation: Day-Lewis, F. D., and J. W. Lane Jr.
(2004),
Assessing the resolution-dependent utility of tomograms for geostatistics,
Geophys. Res. Lett.,
31,
L07503,
doi:10.1029/2004GL019617.
This paper is not subject to U.S. copyright. Published in 2004 by the
American Geophysical Union.
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