TERRAPUB Earth, Planets and Space

Earth Planets Space, Vol. 51 (No. 10), pp. 1059-1065, 1999

A new approach in the determination of characteristic directions of the geoelectric structure using Mohr circles

John Makris, Nikos Bogris, and Kostas Eftaxias

Solid Earth Physics Institute, University of Athens, Panepistimiopolis, Zografos, 15784, Greece

(Received November 2, 1998; Revised February 23, 1999; Accepted April 12, 1999)

Abstract: The use of Mohr circles into magnetotelluric (MT) intepretation was introduced by Lilley (Lilley, 1976). By plotting Zxx-rotated versus Zxy-rotated (real and imaginary parts) important information on the conductivity structure is obtained. In this paper Mohr circles are employed to reveal the directions of polarisation of the electric field. Furthermore, the following procedure for Mohr circle analysis is suggested: plotting Zxx-rotated versus Zyx-rotated (instead of Zxy-rotated) the principal axes system i.e., the strike angle, of the regional 2D structure can be resolved in some cases. The latter analysis is implemented to MT data from Ioannina area, in NW Greece. Results from other intepretation techniques applied to the same dataset, such as decomposition methods, tipper and induction arrows analysis, provide support for the validity of the conclusions reached.

Corresponding author E-mail: nbogris@atlas.uoa.gr

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