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Telluric currents and magnetic anomalies
Author(s) -
Cull J. P.,
Tucker D. H.
Publication year - 1986
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl013i009p00941
Subject(s) - geology , magnetic anomaly , geophysics , aquifer , current (fluid) , remanence , groundwater , trough (economics) , artesian aquifer , geomorphology , oceanography , magnetic field , magnetization , physics , quantum mechanics , economics , macroeconomics , geotechnical engineering
Current densities of 2.5*10 −4 amp/m² can be generated by constant groundwater migration in artesian aquifers. These DC currents are sufficient to generate magnetic anomalies exceeding 200 nT in both the Menindee Trough (Australia) and the Karoo Basin (South Africa). Telluric currents associated with ionospheric activity can be detected by variations in magnetic induction but constant offsets associated with streaming potentials and geochemical activity (SP anomalies) are obscured by noise. Consequently some regional magnetic anomalies may be wrongly attributed to variations in magnetic susceptiblity with residuals explained by remanence.