Electromagnetic induction in New Zealand: analogue model and field results

Chen, J.; Dosso, H. W.; Ingham, M.

doi:10.1016/0031-9201(90)90170-3

Cited by 10 publications

(8 citation statements)

References 30 publications

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“…The alternative approach of using laboratory scale models has been carried out by CHEN et al (1990). Results for North Island have been reported but not in a format convenient for comparison with our data.…”

Section: Resultsmentioning

confidence: 99%

“…They have been discussed by INGHAM (1987) and were compared with laboratory scale models by CHEN et al (1990). These studies revealed several highly anomalous areas.…”

Section: Further Discussionmentioning

confidence: 99%

“…A number of magnetovariational studies and magnetotelluric studies have been carried out in North Island (MIDHA, 1979;INGHAM, 1985aINGHAM, , b, 1988 which were compared with laboratory scale model studies by CHEN et al (1990). These studies showed that the ocean effect dominated the results and no unambiguous evidence was found for a subducted plate under North Island (INGHAM, 1988).…”

Section: Introductionmentioning

confidence: 99%

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A New Zealand Wide Magnetometer Array Study.

Chamalaun

McKnight

1993

J. geomagn. geoelec

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An array of three-component magnetometers was operated across the whole of New Zealand from November 1991 till April 1992, and the transfer functions have been computed for 34 sites. The results show that the ocean effect dominates the induction arrows. An attempt to remove the ocean effect by means of a thin sheet numerical model has not produced unambiguous evidence for induction effects associated with the underlying subduction zones. If such effects are present then they are small compared with the ocean effect and a much finer numerical grid with very detailed bathymetry is required to detect them.

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Section: Resultsmentioning

confidence: 99%

“…They have been discussed by INGHAM (1987) and were compared with laboratory scale models by CHEN et al (1990). These studies revealed several highly anomalous areas.…”

Section: Further Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A New Zealand Wide Magnetometer Array Study.

Chamalaun

McKnight

1993

J. geomagn. geoelec

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“…This also results in the observed variation in angles with period and controls the implied orientations of fields to which the current is most sensitive. Previously, Chen et al () had modeled electromagnetic induction in the New Zealand region using an analogue model. The results of this showed that the principal direction of the induced electric field is generally perpendicular to the local coastline.…”

Section: Discussionmentioning

confidence: 99%

“…At the time there was no generalized theory for calculating GIC in pipelines, and the conclusion was that the observed variations in PSP were largely the result of variations in the induced telluric field perpendicular to the pipeline. The original report noted that modeling showed that induced electric fields in the North Island of New Zealand were largest around and to the north of Auckland (Chen et al, ), the region in which the 2017 pipeline failure occurred. This region was consequently deemed to be at very high risk of corrosion in the event of a break in pipeline insulation.…”

Section: Introductionmentioning

confidence: 99%

Telluric Field Variations as Drivers of Variations in Cathodic Protection Potential on a Natural Gas Pipeline in New Zealand

Ingham

Rodger

2018

Space Weather

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A study of variations in cathodic protection potential on a natural gas pipeline in the North Island of New Zealand is reported. Both the measured pipe‐to‐soil potential (PSP) and the current measured through an installed defect in the pipeline coating show strong correlations with variations in measured magnetic and telluric fields. Contrary to predictions from distributed‐source transmission line theory, analysis shows that the closest correlations of PSP and current are with the component of telluric field perpendicular to the pipeline. This orientation is close to perpendicular to major electrical conductivity contrasts associated with both the local coastline and with on‐shore Earth conductivity structure. It is therefore inferred the variations in PSP which drive the variations in defect current are the result of changes in the local Earth potential. While reporting on specific observations from New Zealand, these results should be applicable across a wide range of middle and high‐latitude global locations. Estimates of possible corrosion rates for the pipeline in question suggest that such enhancement of telluric field variations by conductivity structure may pose significant risk to pipelines in the event of defects in the pipeline coating.

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Tectonic interpretation of regional conductivity anomalies

Brown

1994

Surv Geophys

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Electromagnetic induction in New Zealand: analogue model and field results

Cited by 10 publications

References 30 publications

A New Zealand Wide Magnetometer Array Study.

A New Zealand Wide Magnetometer Array Study.

Telluric Field Variations as Drivers of Variations in Cathodic Protection Potential on a Natural Gas Pipeline in New Zealand

Tectonic interpretation of regional conductivity anomalies

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