The quiet daily variation in the total magnetic field: Global curves

Hitchman, Adrian; Lilley, F. E. M.; Campbell, Wilbur H.

doi:10.1029/98gl51332

Cited by 29 publications

(16 citation statements)

References 8 publications

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“…For the 54 magnetics crossover errors the RMS was 39 nT, with 90% of the data falling between-56 and 84 nT. We attribute some of the magnetics variability to diurnal variation, which reaches 20 nT in this area at this time of year [Hitchman et al, 1998], and some to the very high magnetic field gradients associated with the shallow topography and recent volcanism of the ASP Plateau.…”

Section: Data Setmentioning

confidence: 99%

Anomalous seafloor spreading of the Southeast Indian Ridge near the Amsterdam‐St. Paul Plateau

Scheirer¹,

Forsyth²,

Conder³

et al. 2000

J. Geophys. Res.

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Abstract. The Amsterdam-St. Paul Plateau is bisected by the intermediate-rate spreadingSoutheast Indian Ridge, and numerous geophysical and tectonic anomalies arise from the interactions of the Amsterdam-St. Paul hotspot and the spreading center. The plate boundary geometry on the hotspot platform evolves rapidly (on timescales <1 Myr), off-axis volcanism is abundant, the seafloor does not deepen away from the axis, and transform faults do not have fracture zone extensions. Away from the hotspot platform the ridge-transform geometry is typical of mid-ocean ridges globally. In contrast, the Amsterdam-St. Paul Plateau spreading segments are shorter, they often overlap each other significantly, and the intervening discontinuities are smaller, more ephemeral, and more migratory. Abyssal hills are smaller and less uniform on the hotspot platform than on neighboring spreading segments. From gravity and isostasy analysis the average thickness of the platform crust is -10 km, approximately 50% thicker than that of typical oceanic crust. Most of the isostatic compensation of the hotspot plateau occurs at the Moho or within the lower crust, and the effective elastic thickness of the plateau lithosphere is -1.6 km, less than half that of adjacent spreading segments. Away from the platform some transform faults contain intratransform spreading centers; on the platform the two transform faults have valleys which may be depocenters for abundant axial or off-axis volcanism and mass wasting. Although not wellconstrained by magnetics coverage, the Amsterdam-St. Paul hotspot appears to have been "captured" by the Southeast Indian Ridge, enhancing crustal production at the ridge since about 3.5 Ma. Prior to this time the hotspot formed a line of smaller, isolated volcanoes on older Australian plate. The underlying cause for the present-day crustal accretion anomalies is the effect of melt generation from separate sources of mantle upwelling (due to plate spreading and the hotspot) which has a consequent effect of weakening the lithosphere.

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Section: Data Setmentioning

confidence: 99%

Anomalous seafloor spreading of the Southeast Indian Ridge near the Amsterdam‐St. Paul Plateau

Scheirer¹,

Forsyth²,

Conder³

et al. 2000

J. Geophys. Res.

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“…Magnetic disturbances are usually defined as the difference between the real variations and the ''quiet day curve'' (QDC), which represents the daily magnetic variation, observed at the particular station during extremely quiescent days (Chapman and Bartels, 1940;Matsushita and Maeda, 1965;Campbell, 1979;Hitchman et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

Determination of the running quiet daily geomagnetic variation

Janzhura

Трошичев

2008

Journal of Atmospheric and Solar-Terrestrial Physics

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“…This latitudinal dependence is typically characterized in the three traditional components of magnetic variation, H (magnetic north), D (magnetic east) and Z (vertically down), and it is also present in the total‐field amplitude, F . Hitchman et al (1998a) gave the global latitudinal dependence to be expected for S q in the total field, and Hitchman et al (1998b) gave its dependence for Australia in particular.…”

Section: Resultsmentioning

confidence: 99%

Electromagnetic induction information from differences at aeromagnetic crossover points

Hitchman

Lilley

Milligan

2001

Geophysical Journal International

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SUMMAR YThis paper describes an investigation of the use of aeromagnetic crossover misfits as a source of geological information. The misfits occur when, at a crossover point of an aeromagnetic survey, the separate measurements of the Earth's magnetic field are not the same. Misfits are mainly the result of time-dependent field changes and, in this paper, are analysed as indicators of electromagnetic induction in the Earth, and thus of electrical conductivity structure. The method derives estimates of a magnetic diurnal variation function both for cells within the surveyed area and for a reference base station. Normalizing the former by the latter gives extra information from the aeromagnetic data. A case history from Australia is presented of the method applied to an aeromagnetic survey conducted in a region containing a known electrical conductivity structure. The presence of the conductivity anomaly is evident in the aeromagnetic misfit results.

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The quiet daily variation in the total magnetic field: Global curves

Cited by 29 publications

References 8 publications

Anomalous seafloor spreading of the Southeast Indian Ridge near the Amsterdam‐St. Paul Plateau

Anomalous seafloor spreading of the Southeast Indian Ridge near the Amsterdam‐St. Paul Plateau

Determination of the running quiet daily geomagnetic variation

Electromagnetic induction information from differences at aeromagnetic crossover points

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