Journal of geomagnetism and geoelectricity
Online ISSN : 2185-5765
Print ISSN : 0022-1392
ISSN-L : 0022-1392
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Volume 41, Issue 6
Displaying 1-5 of 5 articles from this issue
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  • Calibration of the Balloon-Borne NO Instrument
    Yutaka KONDO, Noriji TORIYAMA, W. Andrew MATTHEWS, Patrick AIMEDIEU
    1989 Volume 41 Issue 6 Pages 507-523
    Published: 1989
    Released on J-STAGE: September 14, 2010
    DOIhttps://doi.org/10.5636/jgg.41.507
    JOURNAL FREE ACCESS
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    The precision of balloon-borne NO measurements using chemiluminescent instruments critically depends on the precision in estimating the flow rates of sampled air and calibration gas, as well as the concentration of NO in the calibration gas. These parameters have now been measured in the laboratory with more precision than was done for our previous work. The NO data we obtained from balloon observations in the past has been revised in light of these new laboratory calibration data.
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  • Periodicities in the Time-Series of Geomagnetic Inclination during the Last 9000 Years, Recorded in Sediment Cores from Lake Kasumigaura, Japan
    R. P. KANE
    1989 Volume 41 Issue 6 Pages 525-532
    Published: 1989
    Released on J-STAGE: September 14, 2010
    DOIhttps://doi.org/10.5636/jgg.41.525
    JOURNAL FREE ACCESS
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    A power-spectrum analysis of the Geomagnetic Inclination data time-series for the last 9000 years as obtained from studies of sediment cores from Lake Kasumigaura, Japan, revealed highly significant periodicities of about 900, 1900 and 3200 years and less significant periodicities of about 375, 450 and 650 years.
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  • Paleomagnetism of Miocene Sedimentary Rocks around Matsushima Bay, Northeast Japan and Its Implication for the Time of the Rotation of Northeast Japan
    Toshitsugu YAMAZAKI
    1989 Volume 41 Issue 6 Pages 533-548
    Published: 1989
    Released on J-STAGE: September 14, 2010
    DOIhttps://doi.org/10.5636/jgg.41.533
    JOURNAL FREE ACCESS
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    A paleomagnetic study of sedimentary rocks distributed in the Matsushima area, Northeast Japan, was conducted. Samples were collected from the Ajiri, Matsushima and Otsuka Formations of the early to middle Miocene Matsushimawan Group. The stability of remanence was investigated by the progressive thermal demagnetization method. The magnetization of the Matsushima and Otsuka Formations was grouped into two antipodal directions close to north-south. Its magnetic reversal sequence is correlative with that of the standard time-scale of around 16Ma (from the Polarity Chron 5C to 5P of HARLAND et al. (1982)) on the basis of diatom biostratigraphy. It has been proposed by previous works that the counter-clockwise rotation of Northeast Japan occurred in the early to middle Miocene with the opening of the Japan Sea. I conclude that the rotation had completed before 16Ma. On the other hand, eastward-deflected paleomagnetic directions have been reported from the strata in Southwest Japan which are precisely correlative with the Matsushima and Otsuka Formations by both biostratigraphy and magnetostratigraphy. This implies that the rotation of Northeast Japan took place earlier than that of Southwest Japan.
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  • An Attempt to Obtain a Detailed Declination Chart from the United States Magnetic Anomaly Map
    Leroy R. ALLDREDGE
    1989 Volume 41 Issue 6 Pages 549-563
    Published: 1989
    Released on J-STAGE: September 14, 2010
    DOIhttps://doi.org/10.5636/jgg.41.549
    JOURNAL FREE ACCESS
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    Modern declination charts of the United States show almost no details. Greater detail may be of value to surveyors trying to follow old land deed descriptions, or to pilots of small planes or small pleasure boats operating in inland waterways. It would be extremely expensive to make adequate declination measurements needed for such a chart. It was hoped that declination details could be derived from the information contained in the existing magnetic anomaly map of the United States. This could be realized only if all of the survey data were corrected to a common epoch, at which time a main-field vector model was known, before the anomaly values were computed. Because this was not done, accurate declination values cannot be determined. In spite of this conclusion, declination values were computed using a common main-field model for the entire United States to see how well they compared with observed values. The provisional geomagnetic reference field for 1978.5 was used as the main-field model. The computed detailed declination values were found to compare less favorably with observed values of declination than declination values computed from the IGRF 1985 model itself. This result indicates that the computed anomaly elements or their combination with main-field values cannot be used as accurate anomaly values, but they may be used as an indication of where anomalies probably occur.
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  • Novel Views of the Geomagnetic Field
    Leroy R. ALLDREDGE
    1989 Volume 41 Issue 6 Pages 565-571
    Published: 1989
    Released on J-STAGE: September 14, 2010
    DOIhttps://doi.org/10.5636/jgg.41.565
    JOURNAL FREE ACCESS
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