The theory of magnetotelluric methods when the source field is considered

Price, A. T.

doi:10.1029/jz067i005p01907

Cited by 187 publications

(69 citation statements)

References 8 publications

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“…For example, E from Eq. (1) becomes This equation thus gives an expression for 01G1(0) in terms of the complex ratio Hz/Hx, and v. Equation (11) has been the basis of what might be termed traditional geomagnetic depth sounding, as developed for example by PRICE (1962), WHITHAM (1963), CANER et al (1967), COCHRANE and HYNDMAN (1970), and CANER (1971. Often the modulus of both sides of Eq.…”

Section: Running Wavesmentioning

confidence: 99%

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Running Waves and Standing Waves in Geomagnetic Depth Sounding

Lilley

1975

J. geomagn. geoelec

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The process of electromagnetic induction in a layered half-space depends on the horizontal scale-length of the source field, whether it has the form of a running wave or a standing wave, and whether it consists of mixed modes. The theory as traditionally applied to geomagnetic depth sounding depends on approximating natural source-fields by single-mode running waves.Magnetometer array data can be interpreted to show whether source fields are in fact running waves or standing waves. Phase maps of array data give wave-length estimates for running waves; amplitude maps of array data give field gradients (but usually not wave-length estimates) for standing waves. Commonly superpositions exist of both running waves and standing waves, indicating possible errors in traditional depth-sounding estimates which are based on the theory of a single-mode running wave.Lack of source-field knowledge is a more serious disadvantage in traditional geomagnetic depth-sounding than it is in a newer method, which involves the ratio of vertical component to horizontal gradient measured from array data.

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Section: Running Wavesmentioning

confidence: 99%

“…This paper draws on the theory of electromagnetic induction in a horizontally layered half-space as developed by PRICE (1950PRICE ( , 1962, WHITHAM (1963), andSRIVASTAVA (1965). The notation and units of Price will be used.…”

Section: Introductionmentioning

confidence: 99%

Running Waves and Standing Waves in Geomagnetic Depth Sounding

Lilley

1975

J. geomagn. geoelec

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“…8) have been included to show the E/B ratio at the surface of an ocean overlying a uniform half space. They are two of a series computed by Swift and Hessler (1964) from the formulae of Price (1962), for a range of ocean depth, d, and source dimension, L. The latter is related to Price VOL. 14 Using equation (1), pa was computed fOir the two ellipse mDdel and is shown as the lower (dashed) curve Qf Fig.…”

Section: Observationsmentioning

confidence: 99%

Magneto-telluric results from Scott Base

Gill

1971

New Zealand Journal of Geology and Geophysics

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The amplitude ratio E/B for the earth current and magnetic variations at Scott Base has been determined over the period range of 30s to 30,000s. The distortion of the electric field by the land and sea in the neighbourhood of Scott Base is estimated and an equivalent E/B curve is derived for a horizontally uniform medium. A magnetotelluric interpretation of this curve gives the thickness of the poorly conducting outer layer of the earth as 100 km, but other evidence suggests that this is an underestimate.

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“…The Sopron group started investigations of the source effect in induction parameters in the late sixties, following the ideas of Price (1962) on the dimension of the inducing (source) field A structure similar to the field-line resonance, i.e. E-W direction elongated, namely the auroral electrojet has been studied from an induction point of view by Mareschal, 1981;Pirjola, 1982, etc.…”

Section: Introductionmentioning

confidence: 99%

Solar eclipse effect on geomagnetic induction parameters

2005

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Abstract. The 11 August 1999 total solar eclipse had been studied using a large array of stations in Central Europe (Bencze et al., 2005). According to the result of this study, the amplitudes of the field line resonance (FLR)-type pulsations decreased in and around the dark spot by about a factor of 2, and this decrease moved with the velocity of the dark spot in the same direction. This decrease was interpreted as a switch-off of the FLR-type pulsations, due to a change in the eigenperiod of the field line as a consequence of a change in the charged particle distribution along the field line. An effect was also found in the phase of the (magnetic or electric) perpendicular components.At the Nagycenk (NCK) observatory lying in the zone of totality, both magnetic and electric records were available. The magnetotelluric (MT) sounding curve computed by the usual method for the eclipse interval (08:00-14:00 UT) fits the previously known standard curve extremely well. During the eclipse, however, impedance values in the FLR period range were highly scattered. The scatter remained as long as the eclipse lasted. Coherence values between magnetic and electric components decreased significantly. In contrast, an earlier similar switch-off of the FLR-type activity on the same day did not cause a similar scatter, in spite of a comparably low coherence. Thus, the lack of FLR-type activity disturbed the usual MT connection between the magnetic and electric components during the eclipse.The induction vector (tipper), especially its real part, shows a clear effect of the eclipse in the FLR period range (24-29 s), too. Both at NCK and at Bad Bergzabern (BBZ, westernmost station and longest FLR period)), a definite decrease in the real tipper was ascertained during the totality. The average direction of the tipper did not change.Concerning both parameters, a random effect cannot fully explain the observed phenomena. The scatter of the EM induction parameters is most likely due to the switch-off of the FLR activity. The possibility of such an effect should Correspondence to: A.Ádám (adam@ggki.hu) be considered in induction studies. Pilipenko and Fedotov (1993) supposed an opposite effect and emphasised lower quality data, if resulting from FLR-type pulsations, while we claim high quality data just from such an activity.

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The theory of magnetotelluric methods when the source field is considered

Cited by 187 publications

References 8 publications

Running Waves and Standing Waves in Geomagnetic Depth Sounding

Running Waves and Standing Waves in Geomagnetic Depth Sounding

Magneto-telluric results from Scott Base

Solar eclipse effect on geomagnetic induction parameters

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