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北海道大学地球物理学研究報告 = Geophysical bulletin of Hokkaido University >
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Title: 道東地域の地磁気永年変化と三成分絶対測量
Other Titles: Geomagnetic secular changes in eastern Hokkaido
Authors: 橋本, 武志1 Browse this author
茂木, 透2 Browse this author
西村, 三治3 Browse this author
有田, 真4 Browse this author
清水, 淳平5 Browse this author
井, 智史6 Browse this author
源, 泰拓7 Browse this author
長町, 信吾8 Browse this author
Authors(alt): Hashimoto, Takeshi1
Mogi, Tohru2
Nishimura, Mitsuharu3
Arita, Shin4
Shimizu, Junpei5
I, Tomofumi6
Minamoto, Yasuhiro7
Nagamachi, Shingo8
Issue Date: 19-Mar-2012
Publisher: 北海道大学大学院理学研究院自然史科学部門(地球物理学)
Journal Title: 北海道大学地球物理学研究報告
Journal Title(alt): Geophysical bulletin of Hokkaido University
Volume: 75
Start Page: 117
End Page: 132
Abstract: Localized geomagnetic secular changes have been reported in the eastern Hokkaido, previously by repeat surveys, and more recently, by continuous recording. Some previous studies discuss the piezo-magnetic field due to stress accumulation by plate subduction. To elucidate the nature of such “anomalous” secular changes in the total field, we started geomagnetic three-component absolute measurements. Firstly, we estimated the so-called orientation effect which may be contained in the simple differential total field, by using the results of the absolute measurements. At some stations this effect has been found to be non-negligible.   While correcting the orientation effect, we assessed an effect of global-scale secular changes by using the IGRF-11 model. This effect contributes much to regional-scale secular changes in the eastern Hokkaido. As a result, considerable part of the observed differential total field can be explained by this component. Then, residuals which deviated from the global secular field are obtained, which showed relatively good agreement with the predicted piezo-magnetic field. However, it is still uncertain that the residual field is significant or not, as well as its origin.   Our analysis has also revealed an “anomalous” decreasing trend in the total field in the late 90s at NIB station which is located at the eastern side of Kussharo caldera. We speculate that this anomalous magnetic change may have some relation to the elevated signature of volcanic unrest at Atosanupuri where seismic swarm was followed by significant ground deformation in the mid 90s. 
Type: bulletin (article)
Appears in Collections:北海道大学地球物理学研究報告 = Geophysical bulletin of Hokkaido University > 第75号

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