震前特大地磁异常及其短临预警意义
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摘要
对地磁记录分析的结果显示,大地震前强烈的地磁异常现象反复出现;在震中附近极震区临震前36h至十几分钟,地磁场的特大异常数值随震级增大而增大。归算到距震中1 km处,Ms=6.0～9.5级破坏性地震的磁场异常值约为102～105 nT,异常强度甚至超过地球磁场量级5.5×104 nT。根据其强度特性及时空分布,这种临震前在震中附近的ULF磁场异常,表现为一种"磁间隙喷发"。由此地磁异常的特性,提出利用大地震前短临地磁异常作为预警信号进行防震预警的探讨,由地磁预警突破目前地震预测预报难的现实困境,有望收到防震减灾的新效果。
Strong magnetic anomalies repeatedly took place before big earthquakes.Based on geomagnetic record analysis results,we discussed a possible pattern of the magnetic anomalies prior to earthquake.In meizoseismal area or epicenter,in a time period of 36 hours to 10s minutes before earthquake,the exceptional big geomagnetic change increases with the magnitude of earthquake.We calculated that,in a place of 1 km from the epicenter,the magnetic anomaly before destructive earthquakes of Ms 6.0～9.5 can reach to 102～105 nT(the magnitude of earth's magnetic field is 5.5×104 nT),rather than the magnitude of 101 nT from seismomagnetic effect theories since 1964.From this we speculated the abnormal magnetic ULF near epicenter before earthquake seems to be an "intermittent magnetic eruption".Accordingly,we proposed that geomagnetic induction earthquake pre-warning can be a new early warning method to surmount hardship in solving the puzzledom of earthquake imminent prediction.
Strong magnetic anomalies repeatedly took place before big earthquakes.Based on geomagnetic record analysis results,we discussed a possible pattern of the magnetic anomalies prior to earthquake.In meizoseismal area or epicenter,in a time period of 36 hours to 10s minutes before earthquake,the exceptional big geomagnetic change increases with the magnitude of earthquake.We calculated that,in a place of 1 km from the epicenter,the magnetic anomaly before destructive earthquakes of Ms 6.0～9.5 can reach to 102～105 nT(the magnitude of earth's magnetic field is 5.5×104 nT),rather than the magnitude of 101 nT from seismomagnetic effect theories since 1964.From this we speculated the abnormal magnetic ULF near epicenter before earthquake seems to be an "intermittent magnetic eruption".Accordingly,we proposed that geomagnetic induction earthquake pre-warning can be a new early warning method to surmount hardship in solving the puzzledom of earthquake imminent prediction.
引文
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[12]Fraser-Smith A C,Bernardi A,McGill P R,et al.Low-fre-quency magnetic field measurements near the Epicenter of the Ms7.1 Loma Prieta Earthquake[J].Geophysical Research Letters,1990,17:1465-1468.
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[14]Freunf Friedemann.Toward a unified solid state theory for pre-earthquake signals[J].Acta Geophysica,2010,58(5):719-766.
[15]郑吉盎.加强震磁关系研究开发地磁预警产品实现有效防震减灾//高建国.综合风险鉴别与防范技术研究——灾害预测方法集成[M].北京:气象出版社2,010:65-69.
[2]Max Wyss.Cannot earthquakes be predicted[J].Science,1997,278:487-490.
[3]Ian Main.Long odds on prediction[J].Nature,1997,385:19-20.
[4]胡锦涛.中国科学院和中国工程院两院院士大会讲话[R].北京,2008.
[5]The New York Times.Earthquake in Portugal:graphic descriptionof a recent earthquake[N].1858-10-25.
[6]Stacey F D.The seismomagnetic effect[J].Pure Appl Geophys,1964,58:5-22.
[7]Nagata T.Tectonomagnetism[J].IAGA Bull,19692,7:12-43.
[8]Sasai Yoichi.Tectonomagnetic modeling based on the piezomag-netism:a review[J].Annali Di Geofisica,2001,44(2):361-368.
[9]Fitterman D V.Theory of electrokinetic-magnetic anomalies in afaulted half-space[J].J Geophys Res1,979,84(B11):6031-6040.
[10]Zeng Xiaoping,Liu Zhengyan,Lin Yunfang,et al.The possibleconnection of the mantle plume phenomenon with the seismo-hydromagnetic effect prior to earthquakes-seismo-hydromag-netic effect and a plannar current model[J].Earth ScienceFrontiers2,001,8(2):253-258.
[11]Moore G W.Magnetic disturbances preceding 1964 Alaska Earth-quake[J].Nature1,964,203:508-509.
[12]Fraser-Smith A C,Bernardi A,McGill P R,et al.Low-fre-quency magnetic field measurements near the Epicenter of the Ms7.1 Loma Prieta Earthquake[J].Geophysical Research Letters,1990,17:1465-1468.
[13]Uyeda S.Electric and magnetic phenomena observed before thevolcano-seismic activity in 2000 in the Izu Island Region,Japan[J].PNAS,20029,9:7352-7355.
[14]Freunf Friedemann.Toward a unified solid state theory for pre-earthquake signals[J].Acta Geophysica,2010,58(5):719-766.
[15]郑吉盎.加强震磁关系研究开发地磁预警产品实现有效防震减灾//高建国.综合风险鉴别与防范技术研究——灾害预测方法集成[M].北京:气象出版社2,010:65-69.
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