TY - CONF
T1 - Investigation of MT static shift correction methods
AU - Sternberg, Ben K.
AU - Washburne, James
AU - Anderson, Robert G.
N1 - Funding Information:
One of us (C.F.) was supportedd uring the courseo f this research by a scholarshipo f the Consejo National de Ciencia y Tecnologia, Mexico, and additionally by a U. of Toronto Open Fellowship and grants of the Natural Sciencesa nd Engineering ResearchC ouncil of Canadat o R. N. Edwardsa nd R. C. Bailey. S. Cheesmanc ontributedt o the algorithm developmenta s part of his MSc. thesis, supportedb y an Ontario GeosciencesR esearch Fund.
Publisher Copyright:
© 1985 SEG Annual Meeting, SEG 1985.All right reserved.
PY - 1985
Y1 - 1985
N2 - Very small scale inhomogeneities (that is, with dimensions much less than a skin depth at the highest recorded frequency) can lead to severe problems in the interpretation of magnetotelluric (MT) data. These small-scale inhomogeneities can produce a shift of the MT apparent resistivity sounding curve such that the shifted curve is parallel to the undistorted curve on a log apparent resistivity versus log frequency plot. This parallel shift is commonly referred to as a static shift. The amount of static shift of the MT curves cannot be determined directly from conventionally recorded MT data. The most practical method for measuring the static shift appears to be a controlled-source measurement of the magnetic field, since magnetic fields, unlike electric field measurements, will be relatively unaffected by small scale inhomogeneities. The relative strengths and weaknesses of a number of magnetic field controlled-source methods are compared for this application, including central-loop frequency-domain sounding, central loop time-domain sounding, and far-field loop-loop sounding. The controlled-source sounding (which may be a relatively shallow sounding and made with lightweight equipment) can be combined in a joint inversion with a deep MT sounding to obtain a complete, undistorted model of the earth.
AB - Very small scale inhomogeneities (that is, with dimensions much less than a skin depth at the highest recorded frequency) can lead to severe problems in the interpretation of magnetotelluric (MT) data. These small-scale inhomogeneities can produce a shift of the MT apparent resistivity sounding curve such that the shifted curve is parallel to the undistorted curve on a log apparent resistivity versus log frequency plot. This parallel shift is commonly referred to as a static shift. The amount of static shift of the MT curves cannot be determined directly from conventionally recorded MT data. The most practical method for measuring the static shift appears to be a controlled-source measurement of the magnetic field, since magnetic fields, unlike electric field measurements, will be relatively unaffected by small scale inhomogeneities. The relative strengths and weaknesses of a number of magnetic field controlled-source methods are compared for this application, including central-loop frequency-domain sounding, central loop time-domain sounding, and far-field loop-loop sounding. The controlled-source sounding (which may be a relatively shallow sounding and made with lightweight equipment) can be combined in a joint inversion with a deep MT sounding to obtain a complete, undistorted model of the earth.
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U2 - 10.1190/1.1892688
DO - 10.1190/1.1892688
M3 - Paper
AN - SCOPUS:85026598074
SP - 264
EP - 267
T2 - 1985 Society of Exploration Geophysicists Annual Meeting, SEG 1985
Y2 - 6 October 1985 through 10 October 1985
ER -