汶川大震前数字地震仪位移地脉动低频异常现象研究
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摘要
选取了2008年4月25日至5月12日间的四川台网14个台宽频带地震仪记录到的地脉动波形资料,把速度波形做适当的数据校正和滤波处理后,经积分转换成位移波形。频谱分析结果表明:地震发生前存在低频异常颤动,地震前2～3天开始0.1～0.3Hz频段傅里叶谱幅值逐渐增大;各个台的位移振幅值逐渐增强。其中靠近龙门山断裂带的台站记录到的地脉动变化较明显。
Through selection the broadband digital seismic data from April 25,2008 to May 12,2008,recorded by fourteen seismic stations in Sichuan province,the microtremor wave form records are transformed to displacement wave forms after the data correction and filtering.The results of Fourier analysis indicate that before the earthquake occurred the low-frequency abnormal quiver is found;Fourier spectrum value at 0.1~0.3 Hz band is increased in two to three days.Amplitude values of displacement waves are gradually increased at every seismic stations.The microtremor records change greater at stations near the Longmenshan fault zone.
Through selection the broadband digital seismic data from April 25,2008 to May 12,2008,recorded by fourteen seismic stations in Sichuan province,the microtremor wave form records are transformed to displacement wave forms after the data correction and filtering.The results of Fourier analysis indicate that before the earthquake occurred the low-frequency abnormal quiver is found;Fourier spectrum value at 0.1~0.3 Hz band is increased in two to three days.Amplitude values of displacement waves are gradually increased at every seismic stations.The microtremor records change greater at stations near the Longmenshan fault zone.
引文
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[13]Linde A T,Gladwin M T,Johnston M J S.A slow earthquakesequence on the San Andreas fault[J].Nature,1996,383:65-68.
[14]HasselmannK A.A statistical analysis of the generation ofmicroseisms[J].Rev.Geophys.,1963,1:177-209.
[15]胡小刚,赫小光.强台风对汶川大地震和昆仑山大地震“震前扰动”影响的分析[J].地球物理学报,2009,5(7):1363-1375.
[2]Longuet-Higgins M S.A theory of the origin of microseisms[J].Phil.Trans.R.Soc.London,1950,A 243:1-35.
[3]Robert K Cessaro.Sources of Primary and Secondary Micro-seisms[J].Bulletin of the Seismological Society of America,1994,84(1):142-148.
[4]王迪晋,李正媛,吕品姬.慢地震研究综述[J].大地测量与地球动力学,2007,27:21-25.
[5]杨又陵,赵根模,高国英,等.2001年11月14日昆仑山口西M8.1地震前的缓慢地震事[J].国际地震动态,2003,(9):1-4.
[6]杨立明.汶川地震临震地脉动记录特殊频率波动现象及其重现性初究[J].国际地震动态,2009,(1):14-19.
[7]杨立明,王建军,冯建刚,等.汶川地震前地脉动低频波动现象及其应用的初步研究[J].中国地震,2009,25(4):356-366.
[8]陈运泰,吴忠良,王培德,等.数字地震学[M].北京:地震出版社,2000:16-18,52-53,57-59.
[9]李鸿吉.用FFT和现代控制论方法恢复地面位移[J].地球物理学报,1992,35(1):37-43.
[10]周云好,陈章立,缪发军.2001年11月14日昆仑山口西MS8.1地震震源破裂过程研究[J].地震学报,2004,26(7):9-20.
[11]许昭永,杨润海,胡毅力.慢地震慢机制的研究[J].地震,2003,23(2):12-20.
[12]张晁军,石耀霖,马丽.慢地震研究中的一些问题[J].中国科学院研究生学报,2005,22(3):258-269.
[13]Linde A T,Gladwin M T,Johnston M J S.A slow earthquakesequence on the San Andreas fault[J].Nature,1996,383:65-68.
[14]HasselmannK A.A statistical analysis of the generation ofmicroseisms[J].Rev.Geophys.,1963,1:177-209.
[15]胡小刚,赫小光.强台风对汶川大地震和昆仑山大地震“震前扰动”影响的分析[J].地球物理学报,2009,5(7):1363-1375.
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