Japan Geoscience Union Meeting 2014

Presentation information

Print

Oral

Symbol M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS28_1AM1] Extremely severe geomagnetically induced currents in Japan

Thu. May 1, 2014 9:00 AM - 10:45 AM 313 (3F)

Convener:*Shigeru Fujita(Meteorological College, Japan Meteorological Agency), Ryuho Kataoka(National Institute of Polar Research), Ikuko Fujii(Kakioka Magnetic Observatory, Japan Meteorological Agency), Shinichi Watari(National Institute of Information and Communications Technology), Chair:Ikuko Fujii(Kakioka Magnetic Observatory, Japan Meteorological Agency), Shigeru Fujita(Meteorological College, Japan Meteorological Agency)

10:00 AM - 10:15 AM

[MIS28-05] Magnetotelluric method and the source field with finite wave number

*Yasuo OGAWA1 (1.Volcanic Fluid Research Center, Tokyo Institute of Technology)

Keywords:magnetotelluric method, source field

Magnetotelluric method is now widely used for mapping the crustal and upper mantle structure in three-dimensions. In magnetotelluric method, we normally assume the source field as a plane wave. However, if the source field has a finite wave length, the impedances (apparent resistivity, and impedance phase) and the geomagnetic transfer functions will be affected. In a simple case with uniform earth where the source field has a wave number is considered. The apparent resistivity inferred from the impedance (ratio of horizontal electric field to the orthogonal horizontal magnetic field), by assuming a plane wave source will be biased downward and impedance phase will be biased upward. Also the geomagnetic transfer function will have phase of pi/4, even without any lateral heterogeneity.Some magnetotelluric studies at the high latitude and under the magnetic equator will be reviewed.