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A field test of imaging properties of rotational invariants of the magnetotelluric impedance tensor
Author(s) -
Szarka László,
Ádám Antal,
Menvielle Michel
Publication year - 2005
Publication title -
geophysical prospecting
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.735
H-Index - 79
eISSN - 1365-2478
pISSN - 0016-8025
DOI - 10.1111/j.1365-2478.2005.00477.x
Subject(s) - magnetotellurics , geology , basement , borehole , tensor (intrinsic definition) , electrical resistivity and conductivity , electrical impedance , geophysics , seismology , geometry , physics , geotechnical engineering , mathematics , civil engineering , quantum mechanics , engineering
A part of the Békés Basin (an extensional sub‐basin of the Pannonian Basin, where the basement under thick Pannonian sediments is well known from deep boreholes and from seismic measurements, and where many magnetotelluric (MT) soundings have been carried out for frequencies ranging from 1 to 10 −3 Hz) was selected as a test area to assess the imaging performances of various apparent‐resistivity definitions computed with rotational invariants of either the real part of the complex impedance tensor, or its imaginary part, or both. A comparison (based on earlier 3D numerical studies) has been made between the magnetotelluric images obtained in this way and the depths to the high‐resistivity basement, as known from boreholes and seismic investigations. The correlation coefficient between the series of basement depth values at 39 MT sites and the apparent‐resistivity values was found to be stronger and high correlation appeared at a shorter period when it was computed with apparent resistivities based on the real tensor rather than with apparent resistivities based on the imaginary tensor. In the light of our studies, ρ Re Z and the impedance phase seem to be more informative than any other combination of magnetotelluric interpretation parameters.