Transfer function approach to signal discrimination of ULF geomagnetic data

Abstract In order to study earthquake-related ULF geomagnetic field changes, it is important to discriminate the noises such as magnetic pulsations originated from solar–terrestrial interactions and artificial noises from DC-driven trains and factories. For this aim, the interstation transfer functions and wavelet transform method have been proposed and applied to the data obtained at the ULF electromagnetic sensor array at the Boso Peninsula, Japan. It is concluded that this interstation transfer function approach has a capacity for signal discrimination; that is, it shows effectiveness to eliminate noises originated from the external ionospheric sources and its secondary effects.

[1]  Masashi Hayakawa,et al.  Ultra-low-frequency magnetic fields during the Guam earthquake of 8 August 1993 and their interpretation , 1998 .

[2]  M. Farge.  Wavelet Transforms and their Applications to Turbulence , 1992 .

[3]  T. Rikitake.  The undulation of an electrically conductive layer beneath the islands of Japan , 1969 .

[4]  L. Mansinha,et al.  On the principle of maximum entropy and the earthquake frequency—magnitude relation , 1983 .

[5]  Gary D. Egbert,et al.  Robust multiple‐station magnetotelluric data processing , 1997 .

[6]  早川 正士,et al.  Seismo electromagnetics : lithosphere-atmosphere-ionosphere coupling , 2002 .

[7]  J. Morlet,et al.  Wave propagation and sampling theory—Part I: Complex signal and scattering in multilayered media , 1982 .

[8]  Ulrich Schmucker,et al.  Anomalies of geomagnetic variations in the Southwestern United States , 1970 .

[9]  Yu. A. Kopytenko,et al.  Results of ULF magnetic field measurements near the epicenters of the Spitak (Ms = 6.9) and Loma Prieta (Ms = 7.1) earthquakes: Comparative analysis , 1992 .

[10]  Masashi Hayakawa,et al.  Generation of ULF electromagnetic emissions by microfracturing , 1995 .

[11]  Kiyohumi Yumoto,et al.  Results of ultra-low-frequency magnetic field measurements during the Guam Earthquake of 8 August 1993 , 1996 .

[12]  K. Gotoh,et al.  Principal component analysis of ULF geomagnetic data for Izu islands earthquakes in July 2000 , 2002 .

[13]  K. Hattori,et al.  ULF Magnetic Anomaly Preceding the 1997 Kagoshima Earthquakes , 2002 .

[14]  Satoshi Furwara,et al.  Geomagnetic transfer functions in Japan obtained by first order geomagnetic survey , 1996 .

[15]  M. Ladd,et al.  Low‐frequency magnetic field measurements near the epicenter of the Ms 7.1 Loma Prieta Earthquake , 1990 .

[16]  Yu. A. Kopytenko,et al.  Detection of ultra-low-frequency emissions connected with the Spitak earthquake and its aftershock activity, based on geomagnetic pulsations data at Dusheti and Vardzia observatories , 1993 .

[17]  H. Tanaka,et al.  Electric and magnetic phenomena observed before the volcano-seismic activity in 2000 in the Izu Island Region, Japan , 2002, Proceedings of the National Academy of Sciences of the United States of America.

[18]  早川 正士,et al.  Electromagnetic phenomena related to earthquake prediction , 1994 .

[19]  Kiyohumi Yumoto,et al.  ULF electromagnetic precursors for an earthquake at Biak, Indonesia on February 17, 1996 , 2000 .

[20]  Masashi Hayakawa,et al.  Atmospheric and ionospheric electromagnetic phenomena associated with earthquakes , 1999 .

[21]  Alan D. Chave,et al.  On the robust estimation of power spectra, coherences, and transfer functions , 1987 .

[22]  C. Torrence,et al.  A Practical Guide to Wavelet Analysis. , 1998 .