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APPARENT RESISTIVITY, ANISOTROPY AND STRIKE MEASUREMENTS *
Author(s) -
HABBERJAM G. M.
Publication year - 1975
Publication title -
geophysical prospecting
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.735
H-Index - 79
eISSN - 1365-2478
pISSN - 0016-8025
DOI - 10.1111/j.1365-2478.1975.tb01525.x
Subject(s) - anisotropy , electrical resistivity and conductivity , depth sounding , geology , square (algebra) , field (mathematics) , earth's magnetic field , measure (data warehouse) , vertical electrical sounding , geophysics , orientation (vector space) , mineralogy , condensed matter physics , geometry , physics , electrical engineering , geotechnical engineering , magnetic field , optics , mathematics , aquifer , computer science , engineering , groundwater , oceanography , quantum mechanics , database , pure mathematics
A bstract In the search for a descriptive system capable of accounting for the wide variations of earth resistance with orientation of electrode array, which can occur in field measurements, a modified measure of apparent resistivity, based on an anisotropic earth, is proposed. This measure requires the sampling of earth resistance in, at least, three orientations. A practical system, the crossed square array, which effectively samples in four, is considered in detail. A system of reduction of field observations yields, besides the apparent resistivity, apparent measures of anisotropy and strike. Field trials show that the anisotropic analysis not only accounts for the major part of the observed orientational variations in resistance, but also yields sounding curves of resistivity, anisotropy and strike, which vary systematically with electrode spacing. The effects and limitations of applying such techniques in regions of pronounced two dimensional structure are examined. Finally, to avoid unnecessary labour in deploying the crossed square sounding technique at sites where it is not required, a modified single square technique is proposed, which will normally serve but will also alert the observer when crossing is required.