The Perturbations of Alternating Geomagnetic Fields by Conductivity Anomalies

Jones, F. W.; Price, A. T.

doi:10.1111/j.1365-246x.1970.tb06073.x

Cited by 150 publications

(66 citation statements)

References 4 publications

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“…The period dependence of RIKITAKE's model has been examined on the basis of a numerical method of determining the perturbation of alternating electric currents by conductivity anomalies in a two-dimensional structure (JONES and PRICE, 1970;RIKITAKE and HONKURA, 1973). According to the result, the effect of the central Japan anomaly is still seen for long periods toward the Pacific Ocean as far as around Hachijo-jima Island.…”

Section: Discussion and Concluding Remarksmentioning

confidence: 99%

Geomagnetic variation anomaly on Hachijo-jima Island.

Honkura

Oshima²,

Kondo³

1974

J. geomagn. geoelec

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Time-varying magnetic fields were recorded during the winter of 1972 with an array of 5 flux-gate magnetometers on Hachijo-jima Island. The observed records show a typical island effect, e.g, a reversal of sign of the vertical magnetic fields between the northern and southern observation points on the island when the inducing field varies in the north-south direction. The period dependence of the anomaly is examined for a period range from 5 to 240 min by making use of the transfer function technique. A uniform period dependence is seen throughout the stations for periods longer than 30min or so. As a result it is shown that the geomagnetic variation anomaly on Hachijojima Island is accounted for by the central Japan anomaly superposed on the island effect, and the strong period dependence is due to the central Japan anomaly.A numerical calculation of induced electric currents and magnetic fields is made on the basis of a non-uniform thin sheet model representing the island. As for transfer function Au, the calculated values are about twice as large as the observed ones as is the case for Miyake-jima Island (HONKURA, 1971). It is concluded, therefore, that a highly conducting layer must lie very close to the earth's surface underneath Hachijo-jima Island.

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Section: Discussion and Concluding Remarksmentioning

confidence: 99%

Geomagnetic variation anomaly on Hachijo-jima Island.

Honkura

Oshima²,

Kondo³

1974

J. geomagn. geoelec

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“…This equation may be solved for Ex for a given model over the region of interest in accordance with the boundary conditions which have been outlined by JONES and PRICE (1970). PASCOE (1971) andJONES (1972) have given general computer programs which can be used to solve the equations for arbitrary conductivity distributions.…”

Section: The E-polarization Casementioning

confidence: 99%

“…When Maxwell's equations are applied to a two-dimensional problem (that is, one in which there is no variation in one of the directions) the equations separate (JONES and PRICE, 1970), and for the E-polarization case become:…”

Section: The E-polarization Casementioning

confidence: 99%

Investigation of the Coastal Effect by Three Numerical Models

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Ainslie

Jones

1973

J. geomagn. geoelec

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The geomagnetic effects of a coastline are investigated for the E polarization case. Calculations of the amplitudes and phases of the surface electric and magnetic field components are given for three different two-dimensional models. The calculated values for these models show the effects of electric currents in the ocean and in the mantle. Two different frequencies of the sinusoidally time varying fields are used, and so skin effects are also shown in the results. The results show the similarity of a coastal effect due to the ocean alone and a coastal effect due to the ocean and mantle.

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“…Jones and Price, 1969;Coggon, 1971;Hohmann, 1971;Swift, 1971;Weaver and Brewitt-Taylor, 1978;Kuo and Cho, 1980;Hermance, 1982;Goldman and Stoyer, 1983). Again, a range of numerical techniques has been applied to this problem including the finite difference method (e.g.…”

Section: Introductionmentioning

confidence: 99%

Modelling of 3-D electromagnetic responses using the time-wavenumber method

Lee¹

1991

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The Perturbations of Alternating Geomagnetic Fields by Conductivity Anomalies

Cited by 150 publications

References 4 publications

Geomagnetic variation anomaly on Hachijo-jima Island.

Geomagnetic variation anomaly on Hachijo-jima Island.

Investigation of the Coastal Effect by Three Numerical Models

Modelling of 3-D electromagnetic responses using the time-wavenumber method

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