Four ULF (0.01 Hz - 20 Hz) electromagnetic stations had been gradually
established and put into service from 2010 to 2011 in Zhaotong area, Yunnan
province. Two stations of Qiaojia and Yongshan have been running with
continuous and high quality recordings and free of influence of solar
activities, like magnetic storms. In this investigation, daily recordings from
1 January 2020 to 22 May 2021 have been examined of these both stations. The
results show that weak anomalous signals appeared at the beginning of March
2021 with relative low magnitudes of 0.6 nT at Qiaojia station and 0.3 nT at
Yongshan station. At the end of this month, the emissions gained an abrupt
increase and the amplitudes reached up to 3.8 nT at Qiaojia station and 1.2 nT
at Yongsha station. Then, the amplitude decreased to be 0.5 - 1.5 nT and 0.6 -
1.3 nT respectively at both stations but with a high variation frequency in all
components. This situation lasted till the Yangbi MS 6.4 earthquake happened on May 21, 2021, more than
300 km away from these two ULF observing stations. Totally, the ULF magnetic
emissions had been characterized by a synchronous variation in all components
at two observing stations.
References
[1]
Fraser-Smith, A., Bernardi, A., McGill, P., Ladd, M., Helliwell, R. and Villard, O. (1990) Low-Frequency Magnetic Measurements Near the Epicenter of the MS 7.1 Loma Prieta Earthquake. Geophysical Research Letters, 17, 1465-1468. https://doi.org/10.1029/GL017i009p01465
[2]
Bernardi, A., Fraser-Smith, A., McGill, P. and Villard, O. (1991) Magnetic Field Measurements near the Epicenter of the MS 7.1 Loma Prieta Earthquake. Physics of the Earth and Planetary Interiors, 68, 45-63. https://doi.org/10.1016/0031-9201(91)90006-4
[3]
Molchanov, O., Kopytenko, Y., Voronov, P., Kopytenko, E., Matiashvili, T., Fraser-Smith, A. and Bernardi, A. (1992) Results of ULF Magnetic Field Measurements near the Epicenters of the Spitak (MS 6.9) and Loma Prieta (MS 7.1) Earthquakes: Comparative Analysis. Geophysical Research Letters, 19, 1495-1498. https://doi.org/10.1029/92GL01152
[4]
Kopytenko, Y., Matiashvili, T., Voronov, P., Kopytenko, E. and Molchanov, O. (1993) 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. Physics of the Earth and Planetary Interiors, 77, 85-95. https://doi.org/10.1016/0031-9201(93)90035-8
[5]
Hayakawa, M., Kawate, R., Molchanov, O. and Yumoto, K. (1993) Results of Ultra-Low-Frequency Magnetic Field Measurements during the Guam Earthquake of 8 August 1993. Geophysical Research Letters, 23, 241-244. https://doi.org/10.1029/95GL02863
[6]
Hayakawa, M., Itoh, T., Hattoti, K. and Yumoto, K. (2000) ULF Electromagnetic Precursors for an Earthquake at Biak, Indonesia on February 17, 1996. Geophysical Research Letters, 27, 1531-1534. https://doi.org/10.1029/1999GL005432
[7]
Prattes, G., Schwingenschuh, K., Eichelberger, H., Magnes, W., Boudjada, M., Stachel, M., Vellante, M., Villante, U., Wesztergom, V. and Nenovski, P. (2011) Ultra Low Frequency (ULF) European Multi Station Magnetic Field Analysis before and during the 2009 Earthquake at L’Aquila Regarding Regional Geotechnical Information. Natural Hazards and Earth System Sciences, 11, 1959-1968. https://doi.org/10.5194/nhess-11-1959-2011
[8]
Li, M., Lu, J., Parrot, M., Tan, H., Chang, Y., Zhang, X. and Wang, Y. (2013) Review of Unprecedented ULF Electromagnetic Anomalous Emissions Possibly Related to the Wenchuan MS = 8.0 Earthquake, on 12 May 2008. Natural Hazards and Earth System Sciences, 13, 279-286. https://doi.org/10.5194/nhess-13-279-2013
[9]
Singh, R., Mishra, P. and Singh, B. (2001) Anomalous VLF Electric Field Perturbations Associated with Chamoli Earthquakes of March/April 1999. Currentence, 80, 1416-1421.
[10]
Fujinawa, Y., Takahashi, K., Matsumoto, T. and Kawakami, N. (1997) Experiments to Locate Sources of Earthquake-Related VLF Electromagnetic Signals. Proceedings of the Japan Academy Ser. B Physical & Biological Sciences, 73, 33-38. https://doi.org/10.2183/pjab.73.33
[11]
Li, M., Li, W., Zhao, H., Zhang, L., Zhang, P., Zhang, X. and Yu, C. (2019) Electromagnetic Abnormity Recorded by Borehole TOA Installment during the Mojiang MS 5.9 Earthquake on September 8, 2018. Earthquake Research in China, 33, 17-29.
[12]
Li, M., Yu, C., Zhang, Y., Zhao, H.X., Zhang, X.H., Li, W.X., Zhang, P. and Zhang, L. (2020) Electromagnetic Emissions Recorded by a Borehole TOA Installment before Four Huge Destructive MS ≥ 8.0 Earthquakes in Asia. Open Journal of Earthquake Research, 9, 50-68. https://doi.org/10.4236/ojer.2020.92004
[13]
Fraser-Smith, A.C., McGill, P.R., Helliwell, R.A. and Villard Jr., O.G. (1994) Ultra-Low Frequency Magnetic-Field Measurements in Southern California during the Northridge Earthquake of 17 January 1994. Geophysical Research Letters, 21, 2195-2198. https://doi.org/10.1029/94GL01984
[14]
Qian, S., Hao, J., Zhou, J. and Gao, J. (2001) Comparing Rock Pressure Experiment Results with ULF Abnormal Signals Recorded before the Chi-Chi MS 7.4 Earthquake, on September 21, 1999. Earthquake Science, 23, 322-327. (In Chinese)
[15]
Qian, S., Hao, J., Zhou, J., Gao, J., Wang, M. and Liang, J. (2003) ULF and VLF Electromagnetic Precursory Signals Produced by Rock Pressure Experiment. China Earthquake, 19, 109-116. (In Chinese)
[16]
Hao, J., Qian, S., Zhou, J., Gao, J. and Zhu, T. (2003) Ultra Low Frequency Electromagnetic Abnormality Produced during Rock Rupture. Earthquake Science, 25, 102-111. (In Chinese)
[17]
Freund, F. (2002) Charge Generation and Propagation in Igneous Rocks. Journal of Geodynamics, 33, 543-570. https://doi.org/10.1016/S0264-3707(02)00015-7
[18]
Freund, F. (2009) Stress-Activated Positive Hole Charge Carriers in Rocks and the Generation of Pre-Earthquake Signals. In: Hayakawa, M., Ed., Electromagnetic Phenomena Associated with Earthquakes, Transworld Research Network, Trivandrum, Vol. 3, 41-96.
[19]
Freund, F. (2010) Toward a Unified Solid State Theory for Pre-Earthquake Signals. Acta Geophysica, 58, 719-766. https://doi.org/10.2478/s11600-009-0066-x
[20]
Freund, F. and Wengeler, H. (1982) The Infrared Spectrum of OH¯ Compensated Defect Sites in C-Doped MgO and CaO Single Crystals. Journal of Physics and Chemistry of Solids, 43, 129-145. https://doi.org/10.1016/0022-3697(82)90131-7
[21]
Freund, F. and Sornette, D. (2007) Electro-Magnetic Earthquake Bursts and Critical Rupture of Peroxy Bond Networks in Rocks. Tectonophysics, 431, 33-47. https://doi.org/10.1016/j.tecto.2006.05.032
[22]
Scoville, J., Sornette, J. and Freund, F. (2015) Paradox of Peroxy Defects and Positive Holes in Rocks Part II: Outflow of Electric Currents from Stressed Rocks. Journal of Asian Earth Sciences, 114, 338-351. https://doi.org/10.1016/j.jseaes.2015.04.016
[23]
Draganov, A.B., Inan, U.S. and Taranenko, Y.N. (1991) ULF Magnetic Signatures at the Earth Due to Groundwater Flow: A Possible Precursor to Earthquakes. Geophysical Research Letters, 18, 1127-1130. https://doi.org/10.1029/91GL01000
[24]
Park, S.K. (1996) Precursors to Earthquakes: Seismo-Electromagnetic Signals. Surveys in Geophysics, 17, 493-516. https://doi.org/10.1007/BF01901642
[25]
Fenoglio, M.A., Johnston, M.J.S. and Byerlee, J.D. (1995) Magnetic and Electric Fields Associated with Changes in High Pore Pressure in Fault Zones: Application to the Loma Prieta ULF Emissions. Journal of Geophysical Research, 100, 951-958. https://doi.org/10.1029/95JB00076
[26]
Egbert, G.D. (2002) On the Generation of ULF Magnetic Variations by Conductivity Fluctuations in a Fault Zone. Pure and Applied Geophysics, 159, 1205-1227. https://doi.org/10.1007/s00024-002-8678-y
[27]
Simpson, J.J. and Taflove, A. (2005) Electrokinetic Effect of the Loma Prieta Earthquake Calculated by an Entire-Earth FDTD Solution of Maxwell’s Equations. Geophysical Research Letters, 32, L09302. https://doi.org/10.1029/2005GL022601
[28]
Yang, J.Y., Wen, Y.M. and Xu, C.J. (2021) The 21 May 2021 MS 6.4 Yangbi (Yunnan) Earthquake: A Shallow Strike Slip Event Rupturing in a Blind Fault. Chinese Journal of Geophysics, 64, 3101-3110. (In Chinese)
[29]
Li, C.Y., Zhang, J.Y., Wang, W., Sun, K. and Shan, X.J. (2021) The Seismogenic Fault of the 2021 Yunnan Yangbi MS 6.4 Earthquake. Seismology and Geology, 43, 706-721. (In Chinese)
[30]
Li, M., Yao, L., Wang, Y.L., Parrot, M., Hayakawa, M., Lu, J., Tan, H.D. and Xie, T. (2019) Anomalous Phenomena in DC-ULF Geomagnetic Daily Variation Registered Three Days before the 12 May 2008 Wenchuan MS 8.0 Earthquake. Earth and Planetary Physics, 3, 330-341. https://doi.org/10.26464/epp2019034
[31]
Xu, X.W., Jiang, G.Y., Yu, G.H., Zhang, J.G. and Li, X. (2014) Discussion on Seismogenic Fault of the Ludian MS 6.5 Earthquake and Its Tectonic Attribution. Chinese Journal of Geophysics, 57, 3060-3068. (In Chinese)
[32]
Bortnik, J., Bleier, T.E., Dunson, C. and Freund, F. (2010) Estimating the Seismotelluric Current Required for Observable Electromagnetic Ground Signals. Annals of Geophysics, 28, 1615-1624. https://doi.org/10.5194/angeo-28-1615-2010
[33]
Li, M., Tan, H. and Cao, M. (2016) Ionospheric Influence on the Seismo-Telluric Current Related to Electromagnetic Signals Observed before the Wenchuan MS 8.0 Earthquake. Solid Earth, 7, 1405-1415.
