OJER  Vol.4 No.2 , May 2015
On the Anomalies in ULF Magnetic Field Variations Prior to the 2008 Sichuan Earthquake
Abstract: There have been reported several papers on the ionospheric F region perturbations prior to the 2008 Sichuan earthquake (EQ) (magnitude 8.0), but it seems that very few reports have been published on the characteristics of ground-based ULF (ultra low frequency) magnetic field variations for this EQ. This paper deals with two different aspects of ground-based ULF magnetic field variations: 1) ULF radiation from the lithosphere, and 2) depression of ULF horizontal magnetic field as a signature of lower ionospheric perturbations. ULF data from two Chinese stations [Chengdu (epicentral distance, 80 km) and Xichang (about 300 km away from the EQ epicenter)] are analyzed, with paying attention to the local nighttime period (LT = 22 h to 02 h, UTC = 14 h to 18 h) in order to avoid man-made noise. We have analyzed powers of the horizontal component (H2), vertical component (Z2), polarization as their ratio (Z2/H2), depression of the horizontal component (as an inverse of horizontal magnetic field component power, 1/H2) and δDep as a variation of depression at a particular frequency of 0.01 - 0.02 Hz (10 - 20 mHz). It is then found that there seems no clear signature of lithospheric ULF radiation. Whilst, the most evident fact is the finding of depression of ULF horizontal magnetic field at Chengdu a few days before the Sichuan EQ, which suggests that the lower ionosphere was perturbed before the EQ. The characteristics of the lower ionospheric perturbations are compared with those of upper ionospheric perturbations reported before.
Cite this paper: Li, Q. , Schekotov, A. , Asano, T. , Hayakawa, M. (2015) On the Anomalies in ULF Magnetic Field Variations Prior to the 2008 Sichuan Earthquake. Open Journal of Earthquake Research, 4, 55-64. doi: 10.4236/ojer.2015.42005.

[1]   Hayakawa, M. and Molchanov, O.A. (2002) Seismo Electromagnetics: Lithosphere-Atmosphere-Ionosphere Coupling. TERRAPUB, Tokyo, 477 p.

[2]   Pulinets, S. and Boyarchuk, K. (2004) Ionospheric Precursors of Earthquakes. Springer, Berlin, 315 p.

[3]   Molchanov, O.A. and Hayakawa, M. (2008) Seismo-Electromagnetics and Related Phenomena: History and Latest Results. TERRAPUB, Tokyo, 189 p.

[4]   Hayakawa, M. (2009) Electromagnetic Phenomena Associated with Earthquakes. Transworld Research Network, Trivandrum, 279 p.

[5]   Hayakawa, M. (2012) The Frontier of Earthquake Prediction Studies. Nihon-Senmontosho-Shuppan, Tokyo, 794 p.

[6]   Hayakawa, M. (2013) Earthquake Prediction Studies: Seismo Electromagnetics. TERRAPUB, Tokyo, 168 p.

[7]   Hayakawa, M., Kasahara, Y., Nakamura, T., Muto, F., Horie, T., Maekawa, S., Hobara, Y., Rozhnoi, A., Solovieva, M. and Molchanov, O.A. (2010) A Statistical Study on the Correlation between Lower Ionospheric Perturbations as Seen by Subionospheric VLF/LF Propagation and Earthquakes. Journal of Geophysical Research, 115, A09305.

[8]   Liu, J.Y. (2009) Earthquake Precursors Observed in the Ionospheric F-Region. In: Hayakawa, M., Ed., Electromagnetic Phenomena Associated with Earthquakes, Transworld Research Network, Trivandrum, 187-204.

[9]   Zhao, B., Wang, M., Yu, T., Wan, W., Lei, J., Liu, L. and Ning, B. (2008) Is an Unusual Large Enhancement of Ionospheric Electron Density Linked with the 2008 Great Wenchuan Earthquake? Journal of Geophysical Research, 113, A11304.

[10]   Liu, J.Y., Chen, Y.I., Chen, C.H., Liu, C.Y., Chen, C.Y., Li, J.Z., Xia, T.Q., Oyama, K.I., Hattori, K. and Lin, C.H. (2009) Seismoionospheric GPS Total Electron Content Anomalies Observed before the 12 May 2008 Mw 7.9 Wenchuan Earthquake. Journal of Geophysical Research, 114, A04320.

[11]   Liu, C.Y., Liu, J.Y., Chen, W.S., Li, J.Z., Xia, Y.Q. and Cui, X.Y. (2010) An Integrated Study of Anomalies Observed before Four Major Earthquakes: 2004 Sumatra M9.3, 2006 Pingtung M7.0, 2007 Chuetsu Oki M6.8, and 2008 Wenchuan M8.0. Journal of Asian Earth Sciences, 41, 401-409.

[12]   Pulinets, S.A., Boudur, V.G., Tsidilina, M.N. and Gaponova, M.V. (2010) Verification of the Concept of Seismoionospheric Coupling under Quiet Heliogeomagnetic Conditions, Using the Wenchuan (China) Earthquake of May 12, 2008, as an Example. Geomagnetism and Aeronomy, 50, 231-242.

[13]   Klimenko, M.V., Klimenko, V.V., Aakharenkova, I.E., Pulinets, S.A., Zhao, B. and Tsidilina, M.T. (2011) Formation Mechanism of Great Positive TEC Disturbances Prior to Wenchuan Earthquake on May 12, 2008. Advances in Space Research, 48, 488-499.

[14]   Zhang, X., Shen, X., Liu, J., Ouyang, X., Qian, J. and Zhao, S. (2009) Analysis of Ionospheric Plasma Perturbations before Wenchuan Earthquake. Natural Hazards and Earth System Science, 9, 1259-1266.

[15]   Sarkar, S. and Gwal, A.K. (2010) Satellite Monitoring of Anomalous Effects in the Ionosphere Related to the Great Wenchuan Earthquake of May 12, 2008. Natural Hazards, 55, 321-332.

[16]   Blecki, J., Parrot, M. and Wronowski, R. (2010) Studies of the Electromagnetic Field Variations in ELF Frequency Range Registered by DEMETER over the Sichuan Region Prior to the 12 May 2008 Earthquake. International Journal of Remote Sensing, 31, 3615-3629.

[17]   Walker, S.N., Kadirkamanathan, V. and Pokhotelov, O.A. (2013) Changes in the Ultra-Low Frequency Wave Field during the Precursor Phase to the Sichuan Earthquake: DEMETER Observations. Annales Geophysicae, 31, 1597-1603.

[18]   Ryu, K., Parrot, M., Kim, S.G., Jeong, K.S., Chae, J.S., Pulinets, S. and Oyama, K.I. (2014) Suspected Seismo-Ionos- pheric Coupling Observed by Satellite Measurements and GPS TEC Related to the M7.9 Wenchuan Earthquake of 12 May 2008. Journal of Geophysical Research, 119, 10305-10323.

[19]   Huang, Q.H. (2011) Retrospective Investigation of Geophysical Data Possibly Associated with the Ms 8.0 Wenchuan Earthquake in Sichuan, China. Journal of Asian Earth Sciences, 41, 421-427.

[20]   Kopytenko, Y.A., Matiashvily, T.G., Voronov, P.M., Kopytenko, E.A. and Molchanov, O.A. (1990) Discovering of Ultra-Low-Frequency Emissions Connected with Spitak Earthquake and Its Aftershock Activity on Data of Geomagnetic Pulsations Observations at Dusheti and Vardzija. IZMIRAN Preprint N3, 888, 27 p.

[21]   Molchanov, O.A., Kopytenko, Y.A., Voronov, P.M., Kopytenko, E.A., Matiashvili, T.G., Fraser-Smith, A.C. and Bernardy, A. (1992) Results of ULF Magnetic Field Measurements near the Epicenters of the Spitak (Ms = 6.9) and the Loma-Prieta (Ms = 7.1) Earthquakes: Comparative Analysis. Geophysical Research Letters, 19, 1495-1498.

[22]   Fraser-Smith, A.C., Bernardy, A., McGill, P.R., Ladd, M.E., Helliwell, R.A. and Villard Jr., O.G. (1990) Low-Frequency Magnetic Field Measurements near the Epicenter of the Ms 7.1 Loma-Prieta Earthquake. Geophysical Research Letters, 17, 1465-1468.

[23]   Hayakawa, M., Kawate, R., Molchanov, O.A. and Yumoto, K. (1996) Results of Ultra-Low-Frequency Magnetic Field Measurements during the Guam Earthquake of 8 August 1993. Geophysical Research Letters, 23, 241-244.

[24]   Hayakawa, M., Hobara, Y., Ohta, K. and Hattori, K. (2011) The Ultra-Low-Frequency Magnetic Disturbances Associated with Earthquakes. Earthquake Science, 24, 523-534.

[25]   Hattori, K. (2013) ULF Geomagnetic Changes Associated with Major Earthquakes. In: Hayakawa, M., Ed., Earthquake Prediction Studies: Seismo Electromagnetics, TERRAPUB, Tokyo, 129-152.

[26]   Schekotov, A., Molchanov, O.A., Hattori, K., Fedorov, E., Gladyshev, V.A., Belyaev, G.G., Chebrov, V., Sinitsin, V., Gordeev, E. and Hayakawa, M. (2006) Seismo-Ionospheric Depression of the ULF Geomagnetic Fluctuations at Kamchatka and Japan. Physics and Chemistry of the Earth, 31, 313-318.

[27]   Schekotov, A., Fedorov, E., Molchanov, O.A. and Hayakawa, M. (2013) Low Frequency Electromagnetic Precursors as a Prospect for Earthquake Prediction. In: Hayakawa, M., Ed., Earthquake Prediction Studies: Seismo Electromagnetics, TERRAPUB, Tokyo, 81-99.

[28]   Hayakawa, M., Rozhnoi, A., Solovieva, M., Hobara, Y., Ohta, K., Schekotov, A. and Fedorov, E. (2013) The Lower Ionospheric Perturbation as a Precursor to the 11 March 2011 Japan Earthquake. Geomatics, Natural Hazards and Risk, 4, 275-287.

[29]   Schekotov, A., Fedorov, E., Hobara, Y. and Hayakawa, M. (2013) ULF Magnetic Field Depression as a Possible Precursor to the 2011/3.11 Japan Earthquake. Journal of Atmospheric Electricity, 33, 41-51.

[30]   Schekotov, A., Izutsu, I. and Hayakawa, M. (2015) On Precursory ULF/ELF Electromagnetic Signatures for the Kobe Earthquake on April 12, 2013. Journal of Asian Earth Sciences, in Press.

[31]   Currie, J.L. and Waters, C.L. (2014) On the Use of Geomagnetic Indices and ULF Waves for Earthquake Precursor Signatures. Journal of Geophysical Research: Space Physics, 119, 992-1003.

[32]   Hayakawa, M. and Ida, Y. (2008) Fractal (Mono- and Multi-) Analysis for the ULF Data during the 1993 Guam Earthquake for the Study of Prefracture Criticality. Current Development in Theory and Applications of Wavelets, 2, 159-174.

[33]   Varotsos, P.A. (2005) The Physics of Seismic Electric Signals. TERRAPUB, Tokyo, 338 p.

[34]   Eftaxias, K., Potirakis, S.M. and Chelidze, T. (2013) On the Puzzling Feature of the Silence of Precursory Electromagnetic Emissions. Natural Hazards and Earth System Science, 13, 2381-2397.

[35]   Hayakawa, M., Schekotov, A., Potirakis, S. and Eftaxias, K. (2015) Criticality Features in ULF Magnetic Fields Prior to the 2011 Tohoku Earthquake. Proceedings of the Japan Academy: Series B, 91, 25-30.

[36]   Onishi, T., Berthelier, J.J. and Kamogawa, M. (2011) Critical Analysis of the Electrostatic Turbulence Enhancements Observed by DEMETER over the Sichuan Region during the Earthquake Preparation. Natural Hazards and Earth System Science, 11, 561-570.

[37]   Saradjian, M.R. and Akhoonzadeh, M. (2011) Prediction of the Date, Magnitude and Affected Area of Impending Strong Earthquakes Using Integration of Multi Precursors Earthquake Parameters. Natural Hazards and Earth System Science, 11, 1109-1119.

[38]   Kamiyama, M., Sugito, M., Kuse, M., Schekotov, A. and Hayakawa, M. (2014) On the Precursors to the 2011 Tohoku Earthquake: Crustal Movements and Electromagnetic Signatures. Geomatics, Natural Hazards and Risk.