# Classic MT Publications

Papers that are listed here are the Classics of Magnetotellurics that everyone in the field should read.

This list represents the personal bias of Alan Jones, and should not be taken as representative of the views of the MT community. Papers appearing here do so because of their influence, as measured in terms of influencing Jones or influencing the community (determined broadly, but not exclusively, using citation statistics).
This should **NOT** be thought of as an exclusive list, more of an indicative one that is **very** incomplete.
Students/practitioners of MT should know all of these papers at a minimum, and a whole lot of others.

Scans of papers for which there isn't a PDF are very gratefully received.

(Suggestions for inclusions on this list, except self-promotions, are also very gratefully received...)

**Theory****Instrumentation****Processing****Analysis**- Response Function Appraisal
- Impedance Invariants
- Current Chanelling
- Galvanic Distortion
*Galvanic Distortion - General**Galvanic Distortion - 1D**Galvanic Distortion - 2D**Galvanic Distortion - 3D**Galvanic Distortion including magnetic effects*- Static Shift
- 2D modelling/interpretation of 3D data
**Induction Vectors (Vertical Field Transfer Functions)****Modelling****Inversion**- Inversion - Uniqueness
- Inversion - Approximate Methods
- Inversion - 1D
- Inversion - 2D
- Inversion - 3D
- Inversion - Joint-Inversion
**General****Laboratory measurements****Modelling/interpretation of MT data with other data**

## Theory

- Rikitake, T., 1948.
1. Notes on electromagnetic induction within the Earth.
*Bull. Earthquake Res. Inst.*,**24**, 1-9. - Tikhonov, A.N., 1950.
On determining electrical characteristics of the deep layers of the Earth's crust,
*Doklady*,**73**, 295-297. - Cagniard, L., 1953.
Basic theory of the magnetotelluric method of geophysical prospecting,
*Geophysics*,**18**, 605-635.**Note:**See the Acknowledgements of this paper where Cagnaird states that he developed the MT technique "some time ago" and recognises the independent work of Russian (Tikhonov) and Japanese (Rikitake, Kato & Kikuchi) scientists.

- Wait, J.R., 1954.
On the relation between telluric currents and the Earth's magnetic field,
*Geophysics*,**19**, 281-289.**Note:**Includes historical correspondence between Professors Cagniard and Wait on the general applicability of the MT method.

- Madden, T., and P. Nelson, 1964. A Defense of Cagniard's Magnetotelluric Method, Geophysics Laboratory, ONR NR-371-401, Final Report, MIT, Cambridge, USA, 7 pp.
- Weaver, J.T., 1963.
A discussion of the "fault" and "dyke" problems in magnetotelluric theory,
*Geophysics*,**19**, 487-490.**Note:**This is a very nice and informative discussion of two papers, one by d'Erceville and Kunetz (1962) on the fault model, and the other by Rankin (1962) on the dyke model. It includes their replies.

- Jones, F.W., and A.T. Price, 1970.
The perturbations of alternating geomagnetic fields by conductivity anomalies,
*Geophysical Journal of the Royal Astronomical Society*,**20**, 317-334.**Note:**Excellent presentation of EM fields for 2D structures, including boundary conditions.

- Jones, F.W., and A.T. Price, 1971.
Geomagnetic effects of sloping and shelving discontinuities of Earth conductivity,
*Geophysics*,**36**, 58-66.**Note:**See discussion of the physics of this paper by Hermance, 1971, and the elegant reply by F.W. Jones and A.T. Price.

- Schmucker, U. and P. Weidelt, 1975. Aarhus Lecture Notes, 182 pp.
- Dmitriev, V.I., and M.N. Berdichevsky, 1979.
The fundamental model of magnetotelluric sounding,
*Proceedings IEEE*,**67**, 1034-1044. - Weaver, J.T., B. V. Le Quang and G. Fischer, 1985.
A comparison of analytic and numerical results for a two-dimensional control model in electromagnetic induction - I. B-polarization calculations,
*Geophysical Journal of the Royal Astronomical Society*,**82**, 263-277. - Weaver, J.T., B. V. Le Quang and G. Fischer, 1986.
A comparison of analytic and numerical results for a two-dimensional control model in electromagnetic induction - II. E-polarization calculations,
*Geophysical Journal of the Royal Astronomical Society*,**87**, 917-948.**Note:**The above two papers by John Weaver and colleagues detail analytical solutions for the dyke problem that should be used to test all numerical forward codes.

- Weidelt, P., 2005.
The relationship between the spectral function and the underlying conductivity structure in 1-D magnetotellurics,
*Geophysical Journal International*,**161**, 566-590. - Parker, R.L., 2011.
New analytic solutions for the 2-D TE mode MT problem,
*Geophysical Journal International*,**186**, 980-986, doi: 10.1111/j.1365-246X.2011.05091.x.

### Coast Effect

- Parkinson, W.D., and F.W. Jones, 1979.
The Geomagnetic coast effect,
*Reviews of Geophysics*,**17**, 1999-2015. - Fischer, 1979.
Electromagnetic induction effects at an ocean coast,
*Proceedings of the IEEE*,**67**, 1050-1060. - Ravel et al., 1981.
The ocean-coast effect re-examined.
*Geophysical Journal of the Royal Astronomical Society*,**67**, 115-123. - Fischer, G., and J.T. Weaver, 1986.
Theoretical investigation of the ocean-coast effect at a passive continental margin,
*Physics of the Earth and Planetary Interiors*,**42**, 246-254. - Weaver, J.T., and T.W. Dawson, 1992.
Adjustment distance in TM mode electromagnetic induction,
*Geophysical Journal International*,**108**, 293-300.

## Instrumentation

### Instrumentation - Electrodes

- Petiau, G., and A. Dupis, 1980.
Noise, temperature coefficient, and long time stability of electrodes for telluric observations,
*Geophysical Prospecting*,**28**, 792-804. - Petiau, G., 2000.
Second generation Lead-Lead Chloride electrodes for geophysical applications,
*Pure and Applied Geophysics*,**157**, 357-382.

### Instrumentation - Magnetometers

- Korepanov, V., and A. Marusenkov, 2012.
Flux-gate magnetometers design peculiarities,
*Surveys in Geophysics*,**33**, 1059-1079, doi: 10.1007/s10712-012-9197-8.

## Processing

- Sims, W.E., F.X. Bostick, and H.W. Smith, 1971.
The estimation of magnetotelluric impedance tensor elements from measured data,
*Geophysics*,**36**, 938-942.**Note:**Biases that could be introduced by auto-power spectral bias was known in other fields much earlier, particularly in economic theory (Reiersol, O., 1941, Confluence analysis by means of lag moments and other methods of confluence analysis, Econometrica, 9, 1-22; and independently by Geary, R.C., 1943, Relations between statistics: The general and the sampling problem when the samples are large, Proc. Roy. Irish Acad., 49, 177-196.)

- Wight, D.E., F.X. Bostick, and H.W Smith, 1977.
Real time Fourier transformation of magnetotelluric data,
*Electrical Geophysics Research Laboratory Technical Report*, pp. 98.**Note:**This report details the cascade decimation processing technique used by Phoenix Geophysics.

- Gamble, T.D., W.M. Goubau, and J. Clarke, 1979.
Magnetotellurics with a remote magnetic reference,
*Geophysics*,**44**, 53-68.**Note:**The concept of using a "remote" signal to remove auto-power spectral bias was used in other fields much earlier, again particularly in economic theory (Gini, C., 1921, Sull'interpolazione di una retta quando i valori della variabile indipendente sono affetti da errori accidenteli, Metton, 1, 63-82; reviewed in Reiersol, O., 1950, Identifiability of a linear relation between variables which are subject to error, Econometrica, 18, 375-389.

- Jones, A.G., Chave, A.D., Auld, D., Bahr, K. and Egbert, G., 1989.
A comparison of techniques for magnetotelluric response function estimation,
*Journal of Geophysical Research - Solid Earth*,**94**, 14,201-14,213. - Parker, R.L., 2010.
Can a 2-D MT frequency response always be interpreted as a 1-D response?
*Geophys. J. Int.*,**181**, 269-274, doi: 10.1111/j.1365-246X.2010.04512.x.

## Analysis

### Response Function Appraisal

- Weidelt, P., 1972.
The inverse problem of geomagnetic induction,
*J. Geophys. (Z. Geophysik)*,**38**, 257-289.**Note:**Lists inequality constraints that must be obeyed for a 1-D response function.

- Boehl, J.E., F.X. Bostick Jr., and H.W. Smith.
An application of the Hilbert Transform to the magnetotelluric method,
*Electrical Geophysics Research Laboratory Technical Report*, pp. 103. - Jones, A.G., 1980.
Geomagnetic Induction Studies in Scandinavia. I. Determination of the Inductive Response Function from the Magnetometer Array Data.
*J. Geophys. (Z. Geophysik)*,**48**, 181-194.

**Note:**Lists more inequality constraints provided by Peter Weidelt to Alan Jones and tests whether constraints are met in both time and frequency domains.

- Weidelt, P., 1986.
Discrete frequency inequalities for magnetotelluric impedances of one-dimensional conductors,
*J. Geophys. (Z. Geophysik)*,**59**171-176. - Parker, R.L., and J.R. Booker, 1996.
Optimal one-dimensional inversion and bounding of magnetotelluric apparent resistivity and phase measurements,
*Physics of the Earth and Planetary Interiors*,**98**, 269-282.**Note:**Rho+ test.

### Impedance Invariants

- Weaver, J.T., A.K. Agarwal and F.E.M. Lilley, 2000.
Characterization of the magnetotelluric tensor in terms of its invariants,
*Geophys. J. Int.*,**141**, 321-335. - Marti, A., P. Queralt, A.G. Jones and J. Ledo, 2005.
Improving Bahr's invariant parameters using the WAL approach,
*Geophys. J. Int.*,**163**, 38-41. - Marti, A., P. Queralt, and J. Ledo, 2009.
WALDIM: A code for the dimensionality analysis of magnetotelluric data
using the rotational invariants of the magnetotelluric tensor,
*Computers Geosci.*,**35**, 2295-2303. **Note:**Code available from Source Codes page

### Current Chanelling

- Jones, A.G., 1983.
The problem of "current channelling": a critical review,
*Geophys. Surv. (now Surv. Geophys.)*,**6**, 79-122.

### Galvanic Distortion

#### Galvanic Distortion - General

- Berdichevsky, M., and V.I. Dmitriev, 1976.
Distortion of magnetic and electrical fields by near-surface lateral inhomogeneities,
*Acta Geod. Geophys. Mont., Acad. Sci. Hung.*,**11**, 447-483.**Note:**Review paper presented at Third EM Induction Workshop, Sopron, Hungary, June, 1976.

#### Galvanic Distortion - 1D

- Larsen, J.C., 1977.
Removal of local surface conductivity effects from low frequency mantle response curves,
*Acta Geod. Geophys. Mont., Acad. Sci. Hung.*,**12**, 183-186.

#### Galvanic Distortion - 2D

- Richards, M.L., U. Schmucker, and E. Steveling, 1982. Entzerrung der Impedanzkurven von magnetotellurischen Messungen in der Schwabischen Alb, In: Protokol uber das Kolloquium "Elektromagnetische Tiefenforschung", 27–40.
- Bahr, K., 1984. Elimination of local 3D distortion of the magnetotelluric tensor impedance allowing for two different phases, Presented at Seventh Wkshp. Electromagnetic Induction in the Earth and Moon.
- Bahr, K., 1988.
Interpretation of the magnetotelluric impedance tensor, regional induction and local telluric distortion,
*Journal of Geophysics (Zeitschrift fuer Geophysik)*,**62**, 119–127. - Zhang, P., R.G. Roberts, and L.B. Pedersen, 1987.
Magnetotelluric strike rules,
*Geophysics*,**52**, 267-278. - Bailey, R.C., and R.W. Groom, 1987.
Decomposition of the magnetotelluric impedance tensor which is useful in the presence of channeling,
*SEG Published Abstract*, 154-156. - Groom, R.W., and R.C. Bailey, 1989.
Decomposition of magnetotelluric impedance tensors in the presence of local three-dimensional galvanic distortion,
*J. Geophys. Res.*,**94**, 1913-1925. - Groom, R.W., and R.C. Bailey, 1991.
Analytic investigations of the effects of near-surface three-dimensional galvanic scatterers on MT tensor decompositions,
*Geophysics*,**56**, 496-518. - Groom, R.W., Kurtz, R.D., Jones, A.G. and Boerner, D.E., 1993.
A quantitative methodology for determining the dimensionality of conductivity structure and the extraction of
regional impedance responses from magnetotelluric data,
*Geophysical Journal International*,**115**, 1095-1118. - McNeice, G.W., and A.G. Jones, 2001.
Multi-site, multi-frequency tensor decomposition of magnetotelluric data.
*Geophysics*,**66**, 158-173.

#### Galvanic Distortion - 3D

- Utada, H., and H. Munekane, 2000.
On galvanic distortion of regional three-dimensional magnetotelluric impedances,
*Geophys. J. Int.*,**140**, 385-398. - Garcia, X. and A.G. Jones, 2002.
Decomposition of three-dimensional magnetotelluric data,
In: Three-Dimensional Electromagnetics, edited by M.S. Zhdanov and P.E. Wannamaker,
publ. by Elsevier, Methods in Geochemistry and Geophysics (ISBN 0 444 50429 X),
**35**, 235-250. - Caldwell, T.G., H.M. Bibby, and C. Brown, 2004.
The magnetotelluric phase tensor,
*Geophys. J. Int.*,**158**, 457–469. - Moorkamp, M., 2007.
Comment on "The magnetotelluric phase tensor",
*Geophys. J. Int.*,**171**, 565-566. - Weaver, J.T., A.K. Agarwal, and F.E.M. Lilley, 2006.
The relationship between the magnetotelluric tensor invariants and the phase tensor of Caldwell, Bibby, and Brown,
*Explor. Geophys.*,**37**, 261-267. - Jones, A.G., 2011.
Three-dimensional galvanic distortion of three-dimensional regional conductivity structures: Comments on "Three-dimensional joint
inversion for magnetotelluric resistivity and static shift distributions in complex media" by Y. Sasaki and M.A. Meju (2006).
*Journal of Geophysical Research - Solid Earth*,**116**, B12104, doi: 10.1029/2011JB008665.

#### Galvanic Distortion including magnetic effects

- Chave, A.D., and A.G. Jones, 1997.
Electric and magnetic field distortion decomposition of BC87 data.
*J. Geomagn. Geoelectr.*,**49**, 767-789.

### Static Shift

Static Shift is a sub-set of Galvanic Distortion, but papers published on identifying Static Shifts and their removal in MT are worth highlighting.- Jones, A.G., 1988.
Static shift of magnetotelluric data and its removal in a sedimentary basin environment,
*Geophysics*,**53**, 967-978.

### 2D modelling/interpretation of 3D data

- Ledo, J., P. Queralt, A. Marti and A.G. Jones, 2002.
Two-dimensional interpretation of three-dimensional magnetotelluric data: an example of limitations and resolution,
*Geophys. J. Int.*,**150**, 127-139. - Ledo, J., 2006.
2-D Versus 3-D magnetotelluric data interpretation,
*Surv. Geophys.*,**27**, 511-543.**Note:**This is the corrected version. The originally published version was missing author's corrections and some figures were displayed incorrectly.

## Induction Vectors (Vertical Field Transfer Functions)

- Parkinson, W.D., 1959.
Directions of rapid geomagnetic fluctuations,
*Geophysical Journal of the Royal Astronomical Society*,**2**, 1-14. - Parkinson, W.D., 1962.
The influence of continents and oceans on geomagnetic variations,
*Geophysical Journal of the Royal Astronomical Society*,**6**, 441-449. - Wiese, H., 1962.
Geomagnetische Tiefentellurik Teil II: Die Streichrichtung der Untergrundstrukturen des elektrischen Widerstandes, erschlossen aus
geomagnetischen Variationen,
*Pure and Applied Geophysics*,**52**, 83-103. (In German) - Gregori and Lanzerotti, 1980.
Geomagnetic depth sounding by induction arrow representation - A review,
*Reviews of Geophysics and Space Physics*,**18**, 203-209.- Jones, A.G., 1981.
Comment on "Geomagnetic depth sounding by induction arrow representation - A review",
*Reviews of Geophysics and Space Physics*,**19**, 687-688.

- Jones, A.G., 1981.
Comment on "Geomagnetic depth sounding by induction arrow representation - A review",
- Jones, A.G., 1986.
Parkinson's pointers potential perfidy?,
*Geophysical Journal of the Royal Astronomical Society*,**87**, 1215-1224.

## Modelling

### Modelling - 1D

### Modelling - 2D

- Jones, F.W. and L.J. Pascoe, 1971.
A general computer program to determine the perturbation of alternating electric currents in a Two-Dimensional Model of a
region of uniform conductivity with an embedded inhomogeneity,
*Geophysical Journal of the Royal Astronomical Society*,**24**, 3-30.**Note:**Although there were a number of problems with the implementation, particularly the FD equations (see Williamson et al., 1974 and Brewitt-Taylor and Weaver, 1976), this was the first code to be made freely available to the community for 2D forward modelling and provided a great service.

- Madden, T.R., 1972.
Transmission systems and network analogies to geophysical forward and inverse problems,
MIT Technical Report,
**72-3**, (N000-14-67-A-0204-0045 371-401/05-01-71), 49 pp. - Brewitt-Taylor, C.R. and J.T. Weaver, 1976.
On the Finite Difference solution of two-dimensional induction problems,
*Geophysical Journal of the Royal Astronomical Society*,**47**, 375-396. - Rodi, W.L., 1976.
A technique for improving the accuracy of Finite Element solutions for magnetotelluric data,
*Geophysical Journal of the Royal Astronomical Society*,**44**, 483-506.

### Modelling - 3D

- Weidelt, P., 1975.
Electromagnetic induction in three-dimensional structures,
*Journal of Geophysics (Zeitschrift fuer Geophysik)*,**41**, 85-109. - Ting, S.C., and G.W. Hohmann, 1981.
Integral equation modeling of three-dimensional magnetotelluric response,
*Geophysics*,**46**, 182-197. - Wannamaker, P.E., G.W. Hohmann, and S.H. Ward, 1984.
Magnetotelluric responses of three-dimensional bodies in layered earths,
*Geophysics*,**49**, 1517-1533. - Mackie, R.L., T.R. Madden, and P.E. Wannamaker, 1993.
Three-dimensional magnetotelluric modeling using difference equations - Theory and comparisons to integral equation solutions,
*Geophysics*,**58**, 215-226. - Weiss, C.J., and G.A. Newman, 2002.
Electromagnetic induction in a fully 3-D anisotropic earth,
*Geophysics*,**67**, 1104-1114.

## Inversion

### Inversion - Uniqueness

- Bailey, R.C., 1970.
Inversion of the geomagnetic induction problem,
*Proc. Roy. Soc. London A*,**315**, 185-194.

### Inversion - Approximate Methods

- Jones, A.G., 1983.
On the equivalence of the "Niblett" and "Bostick" transformations in the magnetotelluric method,
*J. Geophys. (Z. Geophysik)*,**53**, 72-73. - Gomez-Trevino, E., 1996.
Approximate depth averages of electrical conductivity from surface magnetotelluric data,
*Geophys. J. Int.*,**127**, 762-772. - Rodríguez, J., F.J. Esparza, and E. Gomez-Trevino, 2010.
2-D Niblett-Bostick magnetotelluric inversion,
*Geologica Acta*,**8**, 15-31.

### Inversion - 1D

- Weidelt, P., 1972.
The inverse problem of geomagnetic induction.
*J. Geophys. (Z. Geophysik)*,**38**, 257-289. - Parker, R.L., 1980.
The inverse problem of electromagnetic induction: Existence and construction of solutions based on
incomplete data.
*J. Geophys. Res.*,**85**, 4421-4428.**Note:**D+ paper. Gives the minimum possible misfit. Code available.

- Parker, R.L., 1983.
The magnetotelluric inverse problem.
*Geophys. Surv.,*(now titled*Surv. Geophys.*),**6**, 5-25.**Note:**Presented as a review paper at the 1982 EM Induction Workshop in Victoria, Canada.

- Weidelt, P., 1985.
Construction of conductance bounds from magnetotelluric impedances,
*Journal of Geophysics (Z. Geophysik)*,**57**: 191-206.**Note:**This is an important paper for testing impedance response for 1D validity.

- Constable, S.C., R.L. Parker, and C.G. Constable, 1987.
Occam's inversion: A practical algorithm for generating smooth models from electromagnetic sounding data,
*Geophysics*,**52**, 289-300. - Smith, J.T., and J.R. Booker, 1988.
Magnetotelluric inversion for minimum structure,
*Geophysics*,**53**, 1565-1576. - Weidelt, P., 1995.
Bounds on local averages of one-dimensional electrical conductivity distributions,
*Geophysical Journal International*,**123**, 683-714.

### Inversion - 2D

- deGroot-Hedlin, C., and S. Constable, 1990.
Occam's inversion to generate smooth, two-dimensional models from magnetotelluric data,
*Geophysics*,**55**, 1613-1624. - Rodi, W., and R.L. Mackie, 2001.
Nonlinear conjugate gradients algorithm for 2-D magnetotelluric inversion,
*Geophysics*,**66**, 174-187.

### Inversion - 3D

### Inversion - Joint-Inversion

## General

- Swift, C.M., 1967.
A magnetotelluric investigation of an electrical conductivity anomaly in the south-western United States,
PhD thesis, Massachusetts Institute of Technology, Cambridge, MA, U.S.A., 211 pp.
**Note:**This is deservedly the most-referenced PhD thesis on MT. This thesis influenced the MT method for over a decade.

- Keller, G., 1968.
Electrical prospecting for oil.
*Quarterly Journal of the Colorado School of Mines*, vol.**63**, No. 2. - Vozoff, K., 1972.
The magnetotelluric method in the exploration of sedimentary basins,
*Geophysics*,**37**, 98-141.- Erratum
- Jupp, D.L.B., and K. Vozoff, 1976.
Discussion of "The magnetotelluric method in the exploration of sedimentary basins",
*Geophysics*,**41**, 325-328. - Esparza, F.J., and E. Gomez-Trevino, 1997.
Discussion of "The magnetotelluric method in the exploration of sedimentary basins",
*Geophysics*,**62**, 691-692.

## Laboratory measurements

## Modelling/interpretation of MT data with other data

- Gough, D.I., 1986.
Seismic reflectors, conductivity, water and stress in the continental crust,
*Nature*,**323**, 143-144.**Note:**Ian Gough brings together seismic reflection and electrical conductivity observations, and inferences about the stress and saline water distributions, in a model for the crust.

- Nelson, K.D., Wenjin Zhao, L.D. Brown, J. Kuo, Jinkai Che, Xianwen Liu, S.L. Klemperer, Y. Makovsky, R. Meissner, J. Mechie, R. Kind, F. Wenzel, J. Ni, J. Nabelek, Leshou Chen, Handong Tan, Wenbo Wei, A.G. Jones, J. Booker, M. Unsworth, W.S.F. Kidd, M. Hauck, D. Alsdorf, A. Ross, M. Cogan, Changde Wu, E. Sandvol, M. Edwards, 1996.
Partially molten middle crust beneath southern Tibet: an initial synthesis of Project INDEPTH results,
*Science*,**274**, 1684-1688.**Note:**This paper on the INDEPTH Phases I & II results is the most cited multi-disciplinary project involving MT (850+ citations). The MT results were crucial to the interpretation of a partially-molten mid-crustal layer beneath the Tibetan Plateau, and has since initiated and driven "Channel Flow" simulation by geodynamic modellers.