SLF/ELF电磁接收机研究及观测试验
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摘要
大功率、人工源的超低频/极低频电磁波技术已经成为当今国际地球物理学界瞩目的一个新兴研究领域,采用此方法计算获得的地下介质电性结构具有很高的精度和稳定性,特别适用于地震预测等需要精确观测数据的研究。在中国,从20世纪90年代末开始,开展了基于大功率人工源超低频/极低频技术的方法研究,也开展了该方法在地震监测领域的应用研究,然而对于适用于地震监测应用的观测系统的研究进展比较缓慢。文中介绍了专门用于地震监测应用的超低频/极低频电磁接收机的研发,详细说明了仪器的硬件系统组成、主要技术指标及其关键技术。试验观测结果表明该仪器能满足目前0.1～300Hz频段人工源电磁信号观测的需求。
The electromagnetic method plays an important role in seismic activity monitoring and earthquake prediction and has become one of the important ways for earthquake prediction.During the past decades,many electromagnetic anomalous phenomena at available frequency bands(ELF,VLF,ULF,LF,FM etc.),especially at SLF and ELF bands were observed by scientists before earthquakes,which show that the electromagnetic effects do exist before shocks.Major earthquake may be predicted accurately if the corresponding relation between these electromagnetic anomalies and the physical process in the crust can be proved.In these studies,the objective is the natural electromagnetic field.Because its signal is characterized by instability,low precision and prone to influence of disturbance,especially at the sites with strong noise,the observational data often have low signal-tonoise ratio(SNR).Therefore,its applications are greatly limited.In order to improve the capability of identifying earthquake electromagnetic precursors,researchers must find a new source whose signal has higher stability and precision and wider coverage.In recent years,great progress has been made in the study.Russian scientists firstly applied the artificial SLF/ELF signal to probing the electrical structure of the crust in 1990s,since then,this technique has attracted much attention of geophysicists.Because the artificial SLF/ELF signal can be transmitted high precisely at each frequency under control and has the advantages of strong power,less influence of ionosphere,vast coverage,stable transmission and continuous observation,and the observed data can be analyzed by the correlation analysis technique,the SNR and precision of observed data,even in areas of strong noise,can be greatly enhanced.Measurement results show that in the same setting,the observed signal from SLF/ELF transmitter facility is much stronger than that from natural one,and the apparent resistivity obtained by the former has much higher precision than that by the latter.Therefore,this technique is very suitable for those studies requiring high-precision observational data,especially for earthquake monitoring and prediction.In our country,the study of the SLF/ELF technique started since late 1990s.In this paper,a newly developed SLF/ELF receiver's hardware system scheme,principle,main technical specifications and key technology are introduced in details.Results from a series of tests in lab and in field have shown that the SLF/ELF receiver can be used for observing the artificial SLF/ELF signal with frequency range from 0.1 to 300Hz.
The electromagnetic method plays an important role in seismic activity monitoring and earthquake prediction and has become one of the important ways for earthquake prediction.During the past decades,many electromagnetic anomalous phenomena at available frequency bands(ELF,VLF,ULF,LF,FM etc.),especially at SLF and ELF bands were observed by scientists before earthquakes,which show that the electromagnetic effects do exist before shocks.Major earthquake may be predicted accurately if the corresponding relation between these electromagnetic anomalies and the physical process in the crust can be proved.In these studies,the objective is the natural electromagnetic field.Because its signal is characterized by instability,low precision and prone to influence of disturbance,especially at the sites with strong noise,the observational data often have low signal-tonoise ratio(SNR).Therefore,its applications are greatly limited.In order to improve the capability of identifying earthquake electromagnetic precursors,researchers must find a new source whose signal has higher stability and precision and wider coverage.In recent years,great progress has been made in the study.Russian scientists firstly applied the artificial SLF/ELF signal to probing the electrical structure of the crust in 1990s,since then,this technique has attracted much attention of geophysicists.Because the artificial SLF/ELF signal can be transmitted high precisely at each frequency under control and has the advantages of strong power,less influence of ionosphere,vast coverage,stable transmission and continuous observation,and the observed data can be analyzed by the correlation analysis technique,the SNR and precision of observed data,even in areas of strong noise,can be greatly enhanced.Measurement results show that in the same setting,the observed signal from SLF/ELF transmitter facility is much stronger than that from natural one,and the apparent resistivity obtained by the former has much higher precision than that by the latter.Therefore,this technique is very suitable for those studies requiring high-precision observational data,especially for earthquake monitoring and prediction.In our country,the study of the SLF/ELF technique started since late 1990s.In this paper,a newly developed SLF/ELF receiver's hardware system scheme,principle,main technical specifications and key technology are introduced in details.Results from a series of tests in lab and in field have shown that the SLF/ELF receiver can be used for observing the artificial SLF/ELF signal with frequency range from 0.1 to 300Hz.
引文
关华平,张洪魁,鲁跃.1999.怀来台震前超低频电场与地震关系研究[J].地震,19(2):142—148.GUAN Hua-ping,ZHANG Hong-kui,LU Yue.1999.Study of electromagnetic radiation measured at Huailai station,He-bei Province and its correlation to earthquake[J].Earthquake,19(2):142—148(in Chinese).
郭自强.1994.地震低频电磁辐射研究[J].地球物理学报,37(增刊Ⅰ):261—267.Guo Zi-qiang.1994.Investigation on low-frequency seismoelectromagnetic emission[J].Acta Geophysica Sinica,37(SupplⅠ):261—267(in Chinese).
郝建国,李德瑞,张云福,等.1995.震前极低频电磁异常及其频谱特征[J].地震学报,17(1):81—88.HAO Jian-guo,LI De-rui,ZHANG Yun-fu,et al.1995.ELF electromagnetic abnormity and its spectral characteristic be-fore earthquake[J].Acta Seismologica Sinica,17(1):81—88(in Chinese).
侯朝焕,阎世尊,蒋银林.1990.实用FFT信号处理技术[M].北京:海洋出版社.HOU Chao-huan,YAN Shi-zun,JIANG Yin-lin.1990.The Applied Techniques for FFT Signal Processing[M].Ocean Press,Beijing(in Chinese).
毛桐恩.1989.中国震前电磁波观测与试验研究[J].地球物理学报,32(专辑Ⅰ):500—504.MAO Tong-en.1989.Experimental study on electromagnetic observation before earthquake in China[J].Chinese Jour-nal of Geophysics,32(SpecialⅠ):500—504(in Chinese).
钱家栋,曹爱民.1998.1976年唐山7.8级地震的电阻率和地下水前兆综合物理机制研究[J].地震,18(增刊):1—9.QIAN Jia-dong,CAO Ai-min.1998.Research on comprehensive mechanism of precursors in apparent resistivity and wa-ter table associated with1976Tangshan earthquake(M=7.8)[J].Earthquake,18(Suppl):1—9(in Chinese).
王祥书.2001.大地电阻率在超低频/极低频电波传播技术中的作用[J].地震地质,23(4):574—580.WANG Xiang-shu.2001.Effect of earth resistivity on SLF/ELF transmission technique[J].Seismology and Geology,23(4):574—580(in Chinese).
应启珩,冯一云,窦维蓓.2001.离散时间信号分析和处理[M].北京:清华大学出版社.YING Qi-heng,FENG Yi-yun,DOU Wei-pei.2001.Analysis and Processing on Discrete Time Signal[M].Tsinghua U-niversity Press,Beijing(in Chinese).
赵国泽,陆建勋.2003a.利用人工源超低频电磁波监测地震的试验与分析[J].中国工程科学,5(10):27—32.ZHAO Guo-ze,LU Jian-xun.2003a.Monitoring and analysis of earthquake phenomena by artificial SLF waves[J].En-gineering Science,5(10):27—32(in Chinese).
赵国泽,汤吉,邓前辉,等.2003b.人工源超低频电磁波技术及在首都圈地区的测量研究[J].地学前缘,10(特刊):249—255.ZHA0Guo-ze,TANG Ji,DENG Qian-hui,et al.2003b.Artificial SLF method and the experimental study for earthquake monitoring in Beijing[J].Earth Science Frontiers,10(Special):249—255(in Chinese).
赵国泽,王立凤,汤吉,等.2010.地震监测人工源极低频电磁技术(CSELF)新试验[J].地球物理学报,53(3):479—486.ZHAO Guo-ze,WANG Li-feng,TANG Ji,et al.2010.New experiments of CSELF electromagnetic method for earthquake monitoring[J].Chinese Journal of Geophysics,53(3):479—486(in Chinese).
Fraser-Smith A C,Bannister P R.1998.Reception of ELF signals at antipodal distances[J].Radio Sciences,33(1):83—88.
HUANG Q H,Nagao Toshiyasu.2002.Seismic quiescence before the2000M=7.3Tottori earthquake[J].Geophysical Research Letter,29(12):191—194.
Saraev A K,Pertel M I,Parfentev V E,et al.1999.Experimental study of the electromagnetic field from a VLF radio set for the purposes of monitoring seismic activity in the North Caueasus[J].Physics of the Solid Earth,35(2):101—108.
Zhao G Z,Zhan Y,Wang L F,et al.2009.Electromagnetic anomaly before earthquakes measured by EM experiment[J].Earthquake Science,22:395—402.
郭自强.1994.地震低频电磁辐射研究[J].地球物理学报,37(增刊Ⅰ):261—267.Guo Zi-qiang.1994.Investigation on low-frequency seismoelectromagnetic emission[J].Acta Geophysica Sinica,37(SupplⅠ):261—267(in Chinese).
郝建国,李德瑞,张云福,等.1995.震前极低频电磁异常及其频谱特征[J].地震学报,17(1):81—88.HAO Jian-guo,LI De-rui,ZHANG Yun-fu,et al.1995.ELF electromagnetic abnormity and its spectral characteristic be-fore earthquake[J].Acta Seismologica Sinica,17(1):81—88(in Chinese).
侯朝焕,阎世尊,蒋银林.1990.实用FFT信号处理技术[M].北京:海洋出版社.HOU Chao-huan,YAN Shi-zun,JIANG Yin-lin.1990.The Applied Techniques for FFT Signal Processing[M].Ocean Press,Beijing(in Chinese).
毛桐恩.1989.中国震前电磁波观测与试验研究[J].地球物理学报,32(专辑Ⅰ):500—504.MAO Tong-en.1989.Experimental study on electromagnetic observation before earthquake in China[J].Chinese Jour-nal of Geophysics,32(SpecialⅠ):500—504(in Chinese).
钱家栋,曹爱民.1998.1976年唐山7.8级地震的电阻率和地下水前兆综合物理机制研究[J].地震,18(增刊):1—9.QIAN Jia-dong,CAO Ai-min.1998.Research on comprehensive mechanism of precursors in apparent resistivity and wa-ter table associated with1976Tangshan earthquake(M=7.8)[J].Earthquake,18(Suppl):1—9(in Chinese).
王祥书.2001.大地电阻率在超低频/极低频电波传播技术中的作用[J].地震地质,23(4):574—580.WANG Xiang-shu.2001.Effect of earth resistivity on SLF/ELF transmission technique[J].Seismology and Geology,23(4):574—580(in Chinese).
应启珩,冯一云,窦维蓓.2001.离散时间信号分析和处理[M].北京:清华大学出版社.YING Qi-heng,FENG Yi-yun,DOU Wei-pei.2001.Analysis and Processing on Discrete Time Signal[M].Tsinghua U-niversity Press,Beijing(in Chinese).
赵国泽,陆建勋.2003a.利用人工源超低频电磁波监测地震的试验与分析[J].中国工程科学,5(10):27—32.ZHAO Guo-ze,LU Jian-xun.2003a.Monitoring and analysis of earthquake phenomena by artificial SLF waves[J].En-gineering Science,5(10):27—32(in Chinese).
赵国泽,汤吉,邓前辉,等.2003b.人工源超低频电磁波技术及在首都圈地区的测量研究[J].地学前缘,10(特刊):249—255.ZHA0Guo-ze,TANG Ji,DENG Qian-hui,et al.2003b.Artificial SLF method and the experimental study for earthquake monitoring in Beijing[J].Earth Science Frontiers,10(Special):249—255(in Chinese).
赵国泽,王立凤,汤吉,等.2010.地震监测人工源极低频电磁技术(CSELF)新试验[J].地球物理学报,53(3):479—486.ZHAO Guo-ze,WANG Li-feng,TANG Ji,et al.2010.New experiments of CSELF electromagnetic method for earthquake monitoring[J].Chinese Journal of Geophysics,53(3):479—486(in Chinese).
Fraser-Smith A C,Bannister P R.1998.Reception of ELF signals at antipodal distances[J].Radio Sciences,33(1):83—88.
HUANG Q H,Nagao Toshiyasu.2002.Seismic quiescence before the2000M=7.3Tottori earthquake[J].Geophysical Research Letter,29(12):191—194.
Saraev A K,Pertel M I,Parfentev V E,et al.1999.Experimental study of the electromagnetic field from a VLF radio set for the purposes of monitoring seismic activity in the North Caueasus[J].Physics of the Solid Earth,35(2):101—108.
Zhao G Z,Zhan Y,Wang L F,et al.2009.Electromagnetic anomaly before earthquakes measured by EM experiment[J].Earthquake Science,22:395—402.
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