title: Time variation of the electromagnetic transfer function of the earth estimated by using wavelet transform.
abstract: In order to accurately estimate the geomagnetic transfer functions in the area of the volcano Mt. Iwate (IWT), we applied the interstation transfer function (ISTF) method to the three-component geomagnetic field data observed at Mt. Iwate station (IWT), using the Kakioka Magnetic Observatory, JMA (KAK) as remote reference station. Instead of the conventional Fourier transform, in which temporary transient noises badly degrade the accuracy of long term properties, continuous wavelet transform has been used. The accuracy of the results was as high as that of robust estimations of transfer functions obtained by the Fourier transform method. This would provide us with possibilities for routinely monitoring the transfer functions, without sophisticated statistical procedures, to detect changes in the underground electrical conductivity structure.
authors: Department of Earth and Environmental Sciences, Graduate School of Environmental Studies, Nagoya University, Aichi, Japan . ; Earthquake Research Institute, University of Tokyo, Tokyo, Japan .
authors: Noriko
authors: N
authors: Suto
authors: Venture Business Laboratory, Chiba University, Chiba, Japan .
authors: Makoto
authors: M
authors: Harada
authors: Institute of Oceanic Research and Developments, Tokai University, Shizuoka, Japan .
authors: Jun
authors: J
authors: Izutsu
authors: Institute of Oceanic Research and Developments, Tokai University, Shizuoka, Japan . ; Institute of Oceanic Research and Developments, Tokai University, Shizuoka, Japan .
authors: Toshiyasu
authors: T
authors: Nagao
keywords: Interstation transfer function; ULF geomagnetic field change; conductivity anomaly; earthquake-related electromagnetic phenomena; wavelet transform