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Accession number;02A0508681
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| Title;A simple method for deriving the uniform field MT responses in auroral zones. |
| Author;
JONES A G
(Geological Survey Of Canada, Ontario, Can)
SPRATT J
(Geological Survey Of Canada, Ontario, Can)
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Journal Title;Earth, Planets Space
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Journal Code:G0106B
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ISSN:1343-8832
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VOL.54;NO.5;PAGE.443-450(2002)
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| Figure&Table&Reference;FIG.12, TBL.1, REF.41 |
| Pub. Country;Japan |
| Language;English |
| Abstract;Source field effects in magnetotelluric data acquired at high geomagnetic latitudes can result in erroneous interpretations of Earth conductivity structure deep within the mantle. This paper describes a simple technique most appropriate for a region that is dominantly one-dimensional(1-D) and uses the vertical magnetic field variations for identifying intervals of likely low contamination by non-uniform sources. Times are chosen when the variations stay within prescribed limits defined on the basis of a histogram of the variations for the whole recording interval. An example is given showing application of the method for data from a site under the auroral oval at a time when solar activity was at its lowest for the last solar cycle. A model derived from the responses obtained by processing all available data implies a decrease in resistivity at about 350km to about 100.OMEGA.m. In contrast, the model obtained from low activity interval responses shows a less rapid decrease in resistivity, without a change at around the 410km phase boundary. The responses obtained from all data can be explained by the influence of a source with an average wavelength of 3,000km. (author abst.) |
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