地震电离层VLF电磁场频谱特征研究
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摘要
对2006年3月—2009年2月DEMETER卫星VLF电磁场频谱数据的分析发现,全球地震电离层电磁场频谱有以下特征:50～300 Hz为地震电离层效应的优势频段;距离地震空间位置越近,地震异常越显著;不同半球的地震,异常方向和方位不同;对地磁夏季北半球地震的研究表明,海洋地震主要为正异常,陆地地震为负异常;地磁夏季,不同半球地震的磁场频谱异常显著不同,北半球的正异常偏南,而负异常偏北,南半球的负异常偏东北,而正异常偏西南。
By analyzing the electromagnetic spectrum data observed by DEMETER satellite during the time interval between March 2006 and February 2009,it is found that the characteristics of electric field power spectrum of global ionosphere in DEMETER altitude are as follows:the 50-300 Hz frequency band about earthquake ionospheric effect are the dominant frequency the closer,the distance to seismic spatial position,the more significant seismic anomaly;indifferent hemispheres of the earthquake,abnormal azimuthal direction is different.The studies on the events in northern hemisphere in geomagnetic summer show that the anomaly corresponding marine quakes occured in geomagnetic summer the frequency spectrum anomaly of geomagnetic field basically were positive and these land negative and corresponding the quakes in different hemisphere were significantly different:these in the northern hemisphere were positive and meridional,and negative anomaly of north but negative anomaly opposite in the southern hemisphere,the negative anomaly were northeast and positive ones southwest.
By analyzing the electromagnetic spectrum data observed by DEMETER satellite during the time interval between March 2006 and February 2009,it is found that the characteristics of electric field power spectrum of global ionosphere in DEMETER altitude are as follows:the 50-300 Hz frequency band about earthquake ionospheric effect are the dominant frequency the closer,the distance to seismic spatial position,the more significant seismic anomaly;indifferent hemispheres of the earthquake,abnormal azimuthal direction is different.The studies on the events in northern hemisphere in geomagnetic summer show that the anomaly corresponding marine quakes occured in geomagnetic summer the frequency spectrum anomaly of geomagnetic field basically were positive and these land negative and corresponding the quakes in different hemisphere were significantly different:these in the northern hemisphere were positive and meridional,and negative anomaly of north but negative anomaly opposite in the southern hemisphere,the negative anomaly were northeast and positive ones southwest.
引文
1 Gokhberg,et al.Experimental measurement of electromagnet-ic emissions possibly related to earthquakes in Japan[J].JGeophys Res.,1982,87(B9):7 824-7 828.
2 Parrot M and Mogilevsky M M.VLF emissions associatedwith earthquakes and observed in the ionosphere and themagnetosphere[J].Physics of The Earth and Planetary In-teriors,1989,(1-2):86-99.
3 Parrot M.Statistical study of ELF/VLF emissions recordedby a low-altitude satellite during seismic events[J].J Geo-phys Res.,1994,99(A12):23 339-23 347.
4 Molchanov,et al.Observation by the Intercosmos-24 satelliteof ELF-VLF electromagnetic emissions associated with earth-quakes[J].Ann Geophys.,1993,11:431-440.
5 He Yufei,et al.SNR changes of VLF radio signals detectedonboard the DEMETER satellite and their possible relation-ship to the Wenchuan earthquake[J].Sci.China Ser D-Earth Sci.,2009,52(6):754-763.doi:10.1007/s11430-009-0064-5.
6曾忠超,等.利用DEMETER卫星数据分析汶川地震前的电离层异常[J].地球物理学报,2009,52(1):11-19.(Zeng Zhongchao,et al.The analysis of ionospheric varia-tions before Wenchuan earthquake with DEMETER data[J].Chinese Journal of Geophysics,2009,52(1):11-19)
7朱涛.DEMETER卫星观测的LF/MF电场频谱特征的初步研究[J].地震学报,2010,32(4),476-489.(ZhuTao.A preliminary study on characteristics of average powerspectrum density of LF/MF electric field observed by DEME-TER satellite[J].Acta Seismologica Sinica,2010,32(4),476-489)
8张学民,等.DEMETER卫星观测到得智利7.9级地震前的电离层电磁扰动[J].地球物理学进展,2009,24(4):1196-1203.(Zhang Xuemin,et al.Ionospheric electromag-netic disturbances observed on DEMETER satellite before anearthquake of M7.9 in Chile[J].Progerss in Geophysics,2009,24(4):1 196-1 203)
9安张辉,等.汶川地震前DEMETER卫星探测的离子温度变化分析[J].地震学报,2010,32(6):753-758.(AnZhanghui,et al.Analysis on ion temperature variation detec-ted by DEMETER before 2008 Wenchuan Ms8.0 earthquake[J].Acta Seismologica Sinica,2010,32(6):753-758)
10姚丽,刘晓灿,何宇飞.全球电离层VLF电场功率谱特征[J].地震地磁观测与研究,2011,32(4):27-34.(Yao Li,Liu Xiaocan and He Yufei.The global character-istics of VLF electric field frequency spectrum in ionosphere[J].Seismological and Geomagnetic Observation and Re-search,2011,32(4):27-34)
11 Němec F,et al.Decrease of intensity of ELF/VLF wavesobserved in the upper ionosphere close to earthquakes:Astatistical study[J].J Geophys Res.,2009,114:A04303.
12 Haiyan Y,Zhou H and Qiao X.Propagation analysis of ELFelectromagnetic emission below the cut-off frequency in ion-osphere[J].PCSPA,2010,9:799-802.
13 Zhao S,et al.Penetration characteristics of VLF wave fromatmosphere into the lower ionosphere[J].Earthquake Sci-ence,2010,23(3):275-281.
2 Parrot M and Mogilevsky M M.VLF emissions associatedwith earthquakes and observed in the ionosphere and themagnetosphere[J].Physics of The Earth and Planetary In-teriors,1989,(1-2):86-99.
3 Parrot M.Statistical study of ELF/VLF emissions recordedby a low-altitude satellite during seismic events[J].J Geo-phys Res.,1994,99(A12):23 339-23 347.
4 Molchanov,et al.Observation by the Intercosmos-24 satelliteof ELF-VLF electromagnetic emissions associated with earth-quakes[J].Ann Geophys.,1993,11:431-440.
5 He Yufei,et al.SNR changes of VLF radio signals detectedonboard the DEMETER satellite and their possible relation-ship to the Wenchuan earthquake[J].Sci.China Ser D-Earth Sci.,2009,52(6):754-763.doi:10.1007/s11430-009-0064-5.
6曾忠超,等.利用DEMETER卫星数据分析汶川地震前的电离层异常[J].地球物理学报,2009,52(1):11-19.(Zeng Zhongchao,et al.The analysis of ionospheric varia-tions before Wenchuan earthquake with DEMETER data[J].Chinese Journal of Geophysics,2009,52(1):11-19)
7朱涛.DEMETER卫星观测的LF/MF电场频谱特征的初步研究[J].地震学报,2010,32(4),476-489.(ZhuTao.A preliminary study on characteristics of average powerspectrum density of LF/MF electric field observed by DEME-TER satellite[J].Acta Seismologica Sinica,2010,32(4),476-489)
8张学民,等.DEMETER卫星观测到得智利7.9级地震前的电离层电磁扰动[J].地球物理学进展,2009,24(4):1196-1203.(Zhang Xuemin,et al.Ionospheric electromag-netic disturbances observed on DEMETER satellite before anearthquake of M7.9 in Chile[J].Progerss in Geophysics,2009,24(4):1 196-1 203)
9安张辉,等.汶川地震前DEMETER卫星探测的离子温度变化分析[J].地震学报,2010,32(6):753-758.(AnZhanghui,et al.Analysis on ion temperature variation detec-ted by DEMETER before 2008 Wenchuan Ms8.0 earthquake[J].Acta Seismologica Sinica,2010,32(6):753-758)
10姚丽,刘晓灿,何宇飞.全球电离层VLF电场功率谱特征[J].地震地磁观测与研究,2011,32(4):27-34.(Yao Li,Liu Xiaocan and He Yufei.The global character-istics of VLF electric field frequency spectrum in ionosphere[J].Seismological and Geomagnetic Observation and Re-search,2011,32(4):27-34)
11 Němec F,et al.Decrease of intensity of ELF/VLF wavesobserved in the upper ionosphere close to earthquakes:Astatistical study[J].J Geophys Res.,2009,114:A04303.
12 Haiyan Y,Zhou H and Qiao X.Propagation analysis of ELFelectromagnetic emission below the cut-off frequency in ion-osphere[J].PCSPA,2010,9:799-802.
13 Zhao S,et al.Penetration characteristics of VLF wave fromatmosphere into the lower ionosphere[J].Earthquake Sci-ence,2010,23(3):275-281.
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