Variogram analysis of helicopter magnetic data to identify paleochannels of the Omaruru River, Namibia

Maus, Stefan; Sengpiel, Klaus-Peter; Röttger, B.; Siemon, B.; Tordiffe, E. A. W.

doi:10.1190/1.1444588

Cited by 15 publications

(7 citation statements)

References 13 publications

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“…These findings were further confirmed by the authors in another publication (Pilkington and Todoeschuck 1995). Maus et al (1999) conducted variogram analysis on magnetic data in Canada and found the data to exhibit scaling behavior as function of the horizontal distance. Studies in the soil science field have shown that the soil pore structure is fractal (Perrier et al 1996;Baveye et al 1998).…”

Section: Multifractal Modeling and Magnetic Datasupporting

confidence: 67%

Multifractal Characterization of Geologic Noise for Improved UXO Detection and Discrimination

Nyquist¹,

Boufadel²

2008

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This document has been approved for public release. Report Documentation PageForm Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. Executive SummaryPushing sensors and algorithms to the limit to minimize the chance of overlooking unexploded ordnance (UXO) increases the chance that noise will be misidentified as signal and money wasted excavating scrap metal or chucks of magnetic rock. Approaches to improve the signal to noise ratio typically follow one of three tracks: (1) development of new sensors that are either more sensitive, or less noisy; (2) fusion of data from multiple sensors so that the chances of confounding all of the det6ectors simultaneously is reduced; or (3) development of computer algorithms to extract the signal(s) from the noise. In the case of wide-area surveys that use methods such as helicopter-borne magnetometry, the battle against noise has focused primarily on instrument noise (e.g., thermal noise), platform noise (e.g., magnetic noise created by the helicopter), or interference created by multiple UXO targets in cluttered settings. What has been largely ignored is the "noise" created by the rock and soil that surrounds the buried ordnance.The goal of this pilot project was to investigate a new approach to the characterization and simulation of geologic noise using multifractal analysis that captures the scale-dependent variability arising from geologic heterogeneity in different environments. By combining geologic noise simulations with models for the geophysical signatures of UXO, the researchers aim to create synthetic datasets that can be used both to test and improve UXO discrimination algorithms developed by other researchers, and to develop more reliable estimates of the ratio of false positives to false negatives for a particular geologic environment.In this report we discuss the multifractal methodology and its application to three data sets: Isleta Pueblo, NM; Fort Ord, CA; and the Sierra Army Depot, CA, The S1 site at the Isleta Pueblo, which is underlain by volcanic rock, typifies a UXO site with high magnetic noise. Fort Ord is underlain by sedimentary rock that is largely non-magnetic, but apparently magnetic sediments have washed into topographic drainages, creating moderate levels of geologic noise distributed...

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Section: Multifractal Modeling and Magnetic Datasupporting

confidence: 67%

Multifractal Characterization of Geologic Noise for Improved UXO Detection and Discrimination

Nyquist¹,

Boufadel²

2008

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show abstract

“…These findings were further confirmed by the authors in another publication (Pilkington and Todoeschuck 1995). Recently, Maus et al (1999) conducted variogram analysis on magnetic data in Canada and found the data to exhibit scaling behavior as function of the horizontal distance.…”

Section: Introductionsupporting

confidence: 69%

“…Prior studies Todoeschuck 1993, 1995;Pilkington et al 1994;Maus et al 1999) found that the spatial distribution of magnetic data exhibit monofractal scaling. Our approach is more general because it allows for multifractality, while treating monofractality as a particular case.…”

Section: Discussionmentioning

confidence: 99%

Multifractal characterization of airborne geophysical data at the Oak Ridge facility

Tennekoon

Boufadel

Nyquist

2005

Stoch Environ Res Ris Assess

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Scaling analyses on geophysical measurements of electrical conductivity, gamma radiation, and magnetic fields, at the Oak Ridge Reservation were conducted. The electrical conductivity and magnetic data exhibited multifractality in the north-south and eastwest directions. The radiation data were observed to be non-scaling; a variogram with a sill was found to be more appropriate. The scaling of the EC and magnetic was generally within a range smaller than the maximum distance selected, as periodicity dominated at the larger distances. The electrical conductivity had anisotropy in the scaling of their variograms. But the magnetic data appear to have an isotropic scaling. The underlying statistics of the fields were near Gaussian for the electrical conductivity, but essentially Gaussian for the magnetic data. In environmental hydrogeology, knowledge of the spatial distribution of the intrinsic permeability, K, is very helpful in understanding the transport and spreading of contaminant plumes. Our previous studies have shown that the subsurface permeability, K, is multifractal. Detailed measurement of K is costly. Hence, large data sets of value collected both on a fine scale and over large distances are rare. In this study, we hypothesize that geophysical data could be used indirectly as a surrogate measurement for K, for obtaining statistical information on scale limited K data, and perhaps, directly at sites where K and electrical conductivity are correlated.

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“…He described that the power spectrum of gravity anomaly is given by the product of functions that describe source parameters depth, thickness horizontal dimensions and density contrast of the causative body. Maus (1999) and Maus et al (1999) showed that model variograms describe the space domain statistics of gravity and magnetic data. They proposed variogram analysis of gravity and magnetic data as an alternative to power spectrum method.…”

Section: Methodsmentioning

confidence: 99%

New techniques for estimation of source parameters: Applications to airborne gravity and pseudo-gravity gradient tensors

Beiki

2011

GEOPHYSICS

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Variogram analysis of helicopter magnetic data to identify paleochannels of the Omaruru River, Namibia

Cited by 15 publications

References 13 publications

Multifractal Characterization of Geologic Noise for Improved UXO Detection and Discrimination

Multifractal Characterization of Geologic Noise for Improved UXO Detection and Discrimination

Multifractal characterization of airborne geophysical data at the Oak Ridge facility

New techniques for estimation of source parameters: Applications to airborne gravity and pseudo-gravity gradient tensors

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