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Eigenvector analysis of gravity gradient tensor to locate geologic bodiesPrimeFaces.cw("AccordionPanel","widget_formSmash_some",{id:"formSmash:some",widgetVar:"widget_formSmash_some",multiple:true}); PrimeFaces.cw("AccordionPanel","widget_formSmash_all",{id:"formSmash:all",widgetVar:"widget_formSmash_all",multiple:true});
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PrimeFaces.cw("AccordionPanel","widget_formSmash_responsibleOrgs",{id:"formSmash:responsibleOrgs",widgetVar:"widget_formSmash_responsibleOrgs",multiple:true}); 2010 (English)In: Geophysics, ISSN 0016-8033, Vol. 75, no 6, L37-49 p.Article in journal (Refereed) Published
##### Abstract [en]

##### Place, publisher, year, edition, pages

2010. Vol. 75, no 6, L37-49 p.
##### National Category

Geophysics
##### Research subject

Geophysics with specialization in Solid Earth Physics
##### Identifiers

URN: urn:nbn:se:uu:diva-165274DOI: 10.1190/1.3484098OAI: oai:DiVA.org:uu-165274DiVA: diva2:472747
#####

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Available from: 2012-01-04 Created: 2012-01-04 Last updated: 2012-02-15Bibliographically approved

We^{ }have developed a new method to locate geologic bodies using^{ }the gravity gradient tensor. The eigenvectors of the symmetric gravity^{ }gradient tensor can be used to estimate the position of^{ }the source body as well as its strike direction. Fora given measurement point, the eigenvector corresponding to the maximumeigenvalue points approximately toward the center of mass of the^{ }causative body. For a collection of measurement points, a robust^{ }least-squares procedure is used to estimate the source point as^{ }the point that has the smallest sum of square distances^{ }to the lines defined by the eigenvectors and the measurement^{ }positions. It's assumed that the maximum of the first vertical^{ }derivative of the vertical component of gravity vector *g*_{zz} is^{ }approximately located above the center of mass. Observation points enclosed^{ }in a square window centered at the maximum of *g*_{zz}are used to estimate the source location. By increasing the^{ }size of the window, the number of eigenvectors used in^{ }the robust least squares and subsequently the number of solutions^{ }increase. As a criterion for selecting the best solution from^{ }a set of previously computed solutions, we chose that solution^{ }having the minimum relative error (less than a given threshold)^{ }of its depth estimate. The strike direction of the source^{ }can be estimated from the direction of the eigenvectors correspondingto the smallest eigenvalue for quasi 2D structures. To study^{ }the effect of additive random noise and interfering sources, the^{ }method was tested on synthetic data sets, and it appears^{ }that our method is robust to random noise in the^{ }different measurement channels. The method was also tested on gravity^{ }gradient tensor data from the Vredefort impact structure, South Africa.^{ }The results show a very good agreement with the available^{ }geologic information.

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