Comment on 'Definitions of apparent resistivity for the presentation of magnetotelluric sounding data' by A.T. Basokur1

One method to determine the resistivity structure of the earth, the magnetotelluric (MT) sounding method (Cagniard, 1953; Vozoff, 1972), is widely used especially for deep sounding. The surface impedance of the earth is measured for natural electromagnetic (EM) waves, and the apparent resistivity is calculated as a function of frequency. The MT sounding curve is a plot of the apparent resistivity with respect to the frequency. This representation of the sounding curve at larger abscissa (higher frequency) shows the shallower structure. Sometimes the sounding curve is plotted with respect to the period (the inverse of the frequency), so that the larger abscissa (longer period) corresponds to the deeper structure, as is the case for the Schlumberger sounding curve.

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THE INVERSE PROBLEM OF MAGNETOTELLURIC SOUNDING

Geophysics ◽

10.1190/1.1439991 ◽

1968 ◽

Vol 33 (6) ◽

pp. 972-979 ◽

Cited By ~ 33

Author(s):

Francis T. Wu

Keyword(s):

Inverse Problem ◽

Apparent Resistivity ◽

Least Squares Method ◽

Nonlinear Least Squares ◽

Initial Guess ◽

Magnetotelluric Sounding ◽

Partial Derivatives ◽

Linearly Independent ◽

Nonlinear Least Squares Method ◽

Derivatives Of

Based on the model of a flat layered earth, a nonlinear, least‐squares method is used to invert magnetotelluric sounding curves to obtain the layer resistivities and thicknesses. Partial derivatives of the apparent resistivity with respect to layer parameters show the manner in which the layer parameters are contrbuting to the apparent resistivities. Uniqueness of the inversion is not guaranteed, but when the partial derivatives are linearly independent and the relative magnitudes of the layer resistivities of the initial guess are not too far from the correct ones, the convergence of the method to the correct values seems to be ensured.

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ANALYSIS OF GEOPHYSICAL PARAMETERS VARIATIONS AND SEISMIC EVENTS AT THE POINT OF DEEP MAGNETOTELLURIC SOUNDING

Interexpo GEO-Siberia ◽

10.33764/2618-981x-2021-1-144-150 ◽

2021 ◽

Vol 1 ◽

pp. 144-150

Author(s):

Vitalii E. Matiukov ◽

Kseniia S. Nepeina

Keyword(s):

Apparent Resistivity ◽

Magnetotelluric Sounding ◽

Energy Class ◽

Seismic Events ◽

Electromagnetic Parameters ◽

Magnetotelluric Soundings ◽

Tidal Deformations ◽

The Relationship ◽

Endogenous Component

The paper considers the results of processing and analysis of data from deep magnetotelluric soundings (DMT) performed in 2018. Comparison of variations in apparent resistivity, the endogenous component of the magnetotelluric field, lunar-solar tidal deformations and seismic events that were recorded during the research. The objective of the study is to detect the relationship between the appearance of variations in electromagnetic parameters of the data of magnetotelluric monitoring from the occurred earthquakes, their distance, energy class and position, relative to the DMT point.

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ANALYSIS OF GEOPHYSICAL PARAMETERS VARIATIONS AND SEISMIC EVENTS AT THE POINT OF DEEP MAGNETOTELLURIC SOUNDING

Interexpo GEO-Siberia ◽

10.33764/2618-981x-2021-2-2-174-180 ◽

2021 ◽

Vol 2 (2) ◽

pp. 174-180

Author(s):

Kseniia S. Nepeina ◽

Vitalii E. Matiukov

Keyword(s):

Apparent Resistivity ◽

Magnetotelluric Sounding ◽

Energy Class ◽

Seismic Events ◽

Electromagnetic Parameters ◽

Magnetotelluric Soundings ◽

Tidal Deformations ◽

The Relationship ◽

Endogenous Component

The paper considers the results of processing and analysis of data from deep magnetotelluric soundings (DMT) performed in 2018. Comparison of variations in apparent resistivity, the endogenous component of the magnetotelluric field, lunar-solar tidal deformations and seismic events that were recorded during the research. The objective of the study is to detect the relationship between the appearance of variations in electromagnetic parameters of the data of magnetotelluric monitoring from the occurred earthquakes, its’ distance, energy class and position, relative to the DMT point.

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