玉树地震前电离层VLF信号信噪比变化
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摘要
2010年4月13日23点49分38秒(世界时),青海省玉树县发生了MS7.1地震.根据法国DEMETER卫星电场探测仪(ICE)实验数据,研究震区上空半径500km范围内电离层10—20kHz甚低频(VLF)电场频谱信噪比发现,玉树地震前3个不同频率的地面VLF发射站信号对应的信噪比均出现相同的变化特征,即震前DEMETER卫星1个重访周期内的平均信噪比明显减弱,而2009年相同时段和区域的平均信噪比并未出现相似变化趋势.分析认为,玉树地震孕震期信噪比衰减现象很可能是由地震-电离层耦合所致.
In Yushu, Qinghai province, a strong earthquake took place at 23:49:38 UT on April 13, 2010, with a magnitude MS7.1. Based on ICE experiments onboard the DEMETER satellite, the VLF signal in 10—20 kHz radiated by three ground transmitters and received on board of DEMETER satellite revealed the attenuation of the signal to noise ratio averaged value in the region with a radius of 500 km from the earthquake epicenter in a revisited period of DEMETER just prior to the mainshock. On the other hand, there were no similar phenomena in 2009; on the contrary we found an ascending SNR in the corresponding time interval and spatial position. These ionospheric anomalies before the Yushu earthquake are highly regarded as resulting from the seismo-ionospheric coupling.
In Yushu, Qinghai province, a strong earthquake took place at 23:49:38 UT on April 13, 2010, with a magnitude MS7.1. Based on ICE experiments onboard the DEMETER satellite, the VLF signal in 10—20 kHz radiated by three ground transmitters and received on board of DEMETER satellite revealed the attenuation of the signal to noise ratio averaged value in the region with a radius of 500 km from the earthquake epicenter in a revisited period of DEMETER just prior to the mainshock. On the other hand, there were no similar phenomena in 2009; on the contrary we found an ascending SNR in the corresponding time interval and spatial position. These ionospheric anomalies before the Yushu earthquake are highly regarded as resulting from the seismo-ionospheric coupling.
引文
何宇飞,杨冬梅,陈化然,钱家栋,朱荣,Parrot M.2009.DEMETER卫星探测到可能与汶川地震有关的地面VLF发射站信号的信噪比变化[J].中国科学:D辑,39(4):403--412.
Erthelier J J,Godefroy M,Leblanc F,Malingre M,Menvielle M,Lagoutte D,Brochot J Y,Colin F,Elie F,LegendreC,Zamora P,Benoist D,Chapuis Y,Artru J,Pfaff R.2006.ICE,the electric field experiment on DEMETER[J].Planet Space Sci,54(5):456--471.
Inan U S,Helliwell R A.1982.DE-1observations of VLF transmitter signals and wave-particle interaction in the magne-tosphere[J].Geophys Res Lett,9(9):917--920.
Molchanov O A.2004.On the origin of low-and middle-latitude ionospheric turbulence[J].Phys Chem Earth,29(4--9):559--567.
Molchanov O A,Rozhnoi A,Solovieva M,Akentieva O,Berthelier J J,Parrot M,Lefeuvre F,Biagi P F,Castellana L,Hayakawa M.2006.Global diagnostics of the ionospheric perturbations related to the seismic activity using the VLFradio signals collected on the EMETER satellite[J].Nat Hazards Earth Sys,6(5):745--753.
Erthelier J J,Godefroy M,Leblanc F,Malingre M,Menvielle M,Lagoutte D,Brochot J Y,Colin F,Elie F,LegendreC,Zamora P,Benoist D,Chapuis Y,Artru J,Pfaff R.2006.ICE,the electric field experiment on DEMETER[J].Planet Space Sci,54(5):456--471.
Inan U S,Helliwell R A.1982.DE-1observations of VLF transmitter signals and wave-particle interaction in the magne-tosphere[J].Geophys Res Lett,9(9):917--920.
Molchanov O A.2004.On the origin of low-and middle-latitude ionospheric turbulence[J].Phys Chem Earth,29(4--9):559--567.
Molchanov O A,Rozhnoi A,Solovieva M,Akentieva O,Berthelier J J,Parrot M,Lefeuvre F,Biagi P F,Castellana L,Hayakawa M.2006.Global diagnostics of the ionospheric perturbations related to the seismic activity using the VLFradio signals collected on the EMETER satellite[J].Nat Hazards Earth Sys,6(5):745--753.
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