Understanding 1D magnetotelluric apparent resistivity and phase

ABSTRACT

A novel approach is applied on 1D magnetotelluric problem, based purely on physical considerations of processes on a layered half-space. Relations for apparent resistivity and impedance phase as functions of frequency were derived on grounds of knowledge of a given model. These are considered to be the best benefit coming from the analysis. Two different systems of a layered half-space were examined theoretically and the results were compared with those gained by the traditionally used recursion formula. The obtained dependences faithfully reflect all prescribed physical features. Understanding of these behaviours can significantly contribute to correct interpretation of measured data. Inflection points of the impedance phase appeared to be the proper diagnostic tool for detection of transitions in conductivity. They provide the pairs frequency – apparent resistivity as an input for inversion. It relies on the derived formulas and for well localized changes gives output in the form of layers' thicknesses and their resistivities.

KEYWORDS:

• 1D magnetotellurics
• layered half-space
• apparent resistivity
• impedance phase

Acknowledgements

The author would like to thank to Dr Josef Pek with whom this study was discussed.

Disclosure statement

No potential conflict of interest was reported by the author.

Additional information

Funding

This work was supported by the Slovak Research and Development Agency under the contract No. APVV-16-0482.

Notes on contributors

Alexandra Marsenić

Alexandra Marsenić, graduated in Physics in 2003 from the Comenius University, Faculty of Mathematics, Physics and Informatics. I continued in their Department of Astronomy, Physics of the Earth and Meteorology, where I obtained my PhD in 2010. In October 2006 I was employed as a scientific worker at the Geophysical Institute of the SAS, which became a part of the Earth Science Institute of the SAS in June 2015. The period October 2011–2013 I spent on a PostDoc-position at the Institute of Geophysics of the CAS, Prague. My research interest was originally focused in the magnetohydrodynamics of the Earth's core. In 2015 I discovered that cosmic magnetic fields cannot be produced by the dynamo process as it is described and one year later I developed my own theory of their generation. It, however, was not met with understanding of the scientific community and I did not succeed to publish it. Then I turned my interest into the field of magnetotellurics.