The theory of the Bouguer gravity anomaly: A tutorial

Chapin, David A.

doi:10.1190/1.1437341

Cited by 40 publications

(36 citation statements)

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“…The Bouguer anomaly is used primarily in the modeling and map interpretation of land gravity anomalies. Isostatic gravity anomalies are used in interpreting regional gravity anomalies, especially in map form, although care must be taken to consider the potential problems in the calculation of this anomaly derived from the assumption of isostatic compensation associated with local topographic variations (Simpson et al, 1986;Chapin, 1996b). This anomaly is calculated by adding the effect of the isostatic compensation effect to the Bouguer gravity anomaly.…”

Section: Gravity Anomaliesmentioning

confidence: 99%

“…In local surveys, this value is determined by the density of the geological materials between the survey and the local vertical datum. However, in regional and continental databases, a mean density is used for the spherical cap, typically 2670 kg/m 3 for the solid earth (Chapin, 1996b;Hinze, 2003), 1027 kg/m 3 for sea water, 1000 kg/m 3 for fresh water, and 917 kg/m 3 for ice. In the future, as more definitive information is obtained on the density of solid-earth materials subjacent to gravity stations, it may be desirable to use a density appropriate for the station location rather than the 2670 kg/m 3 average value (Hackney and Featherstone, 2003;Hinze, 2003).…”

Section: Bouguer Correctionmentioning

confidence: 99%

“…As more accurate gravity anomalies have become of interest, especially regional anomaly compilations and observations in rugged topography, modifications to reduction procedures have been investigated (e.g., Olivier and Hinze, 1986;LaFehr, 1991aLaFehr, , b, 1998Chapin, 1996a;Talwani, 1998;Li and Götze, 2001) and implemented on a limited basis, but they have not been used generally and have not been used to prepare national and North American gravity databases. Use of these modifications has received impetus from the availability of improved terrain and geoid databases, enhanced computational power, and increased use of global positioning system (GPS) technology to establish the location and heights of gravity stations (e.g., Fairhead et al, 2003;Hackney and Featherstone, 2003).…”

Section: Introductionmentioning

confidence: 99%

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New standards for reducing gravity data: The North American gravity database

et al. 2005

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The North American gravity database as well as databases from Canada, Mexico, and the United States are being revised to improve their coverage, versatility, and accuracy. An important part of this effort is revising procedures for calculating gravity anomalies, taking into account our enhanced computational power, improved terrain databases and datums, and increased interest in more accurately defining long-wavelength anomaly components. Users of the databases may note minor differences between previous and revised database values as a result of these procedures. Generally, the differences do not impact the interpretation of local anomalies but do improve regional anomaly studies. The most striking revision is the use of the internationally accepted terrestrial ellipsoid for the height datum of gravity stations rather than the conventionally used geoid or sea level. Principal facts of gravity observations and anomalies based on both revised and previous procedures together with germane metadata will be available on an interactive Web-based data system as well as from national agencies and data centers. The use of the revised procedures is encouraged for gravity data reduction because of the widespread use of the global positioning system in gravity fieldwork and the need for increased accuracy and precision of anomalies and consistency with North American and national databases. Anomalies based on the revised standards should be preceded by the adjective "ellipsoidal" to differentiate anomalies calculated using heights with respect to the ellipsoid from those based on conventional elevations referenced to the geoid.

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Section: Gravity Anomaliesmentioning

confidence: 99%

Section: Bouguer Correctionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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New standards for reducing gravity data: The North American gravity database

et al. 2005

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“…Central to both the geophysical and geodetic views is the requirement to algebraically consider the gravitational effects of the topographic masses. While the general definition of the Bouguer gravity anomaly (either geophysical or geodetic) does not contain any approximation, the gravitational effect of the topographic masses is frequently approximated, thus leading to different variants of the Bouguer gravity anomaly (e.g., Heiskanen & Moritz 1967;Ervin 1977;Chapin 1996;Vaníček et al 2001;2004).…”

Section: Introductionmentioning

confidence: 99%

“…The Bouguer gravity anomaly is frequently used in geophysics to infer geological information from observed gravity (e.g., Ervin 1977;Chapin 1996) and in geodesy to provide boundary values on the geoid, which have been reduced by the gravitational attraction effect of all masses above the geoid (e.g., Heiskanen & Moritz 1967;Vaníček et al 2004). Central to both the geophysical and geodetic views is the requirement to algebraically consider the gravitational effects of the topographic masses.…”

Section: Introductionmentioning

confidence: 99%

Complete spherical Bouguer gravity anomalies over Australia

Kühn

Featherstone

Kirby

2009

Australian Journal of Earth Sciences

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We have computed complete (or refined) spherical Bouguer gravity anomalies for all 1,095,065 land gravity observations in the June 2007 release of the Australian national gravity database. The spherical Bouguer shell contribution was computed using the supplied ground elevations of the gravity observations. The spherical terrain corrections, residual to each Bouguer shell, were computed on a 9 arc-second grid (~250 m by ~250 m spatial resolution) from a global Newtonian integration using heights from version 2.1 of the GEODATA digital elevation model (DEM) over Australia and the GLOBE and JGP95E global DEMs outside Australia. A constant topographic massdensity of 2670 kg/m 3 was used for both the spherical Bouguer shell and spherical terrain correction terms. The difference between the complete spherical and complete planar Bouguer gravity anomaly exhibits an almost constant bias of about -18.7 mGal over areas with moderate elevation changes, thus verifying the planar model as a reasonable 2 approximation in these areas. However, the results suggest that in mountainous areas with large elevation changes, the complete spherical Bouguer gravity anomaly should be selected in preference over the less rigorous complete planar counterpart.

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