Magnetotelluric tensor decomposition: Part II, Examples of a basic procedure
نویسنده
چکیده
The decomposition procedure suggested for magnetotelluric (MT) data in a companion paper is illustrated by examples. Adjacent pairs of stations are examined to test for common features in their MT response. The method analyzes the real and quadrature parts of an impedance tensor separately, and the results for the real and quadrature parts are compared, and in some cases combined, at the end. Values are obtained which are interpreted directly in terms of nearest 2-D principal impedances, local geologic strike, and regional geologic strike. The requirement for valid data derived in the companion paper, that Zxyr Z yxr < Zxxr Z yyr together with Zxyq Z yxq < Zxxq Z yyq , is shown to be a useful criterion in the winnowing of erroneous data. The examples presented typically show the direction interpreted as local geologic strike to be well determined, period independent, and consistent between real and quadrature MT matrices. In these examples, however, the direction interpreted as regional geologic strike is period dependent and not in good agreement between real and quadrature MT matrices. These results suggest caution is desirable in the use of period-independent galvanic distortion models, which should be checked first with regional strike determinations.
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