广东阳江4.9级地震序列尾波Qc值变化特征研究
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摘要
采用Aki的单次散射模型计算了广东阳江地区2003年10月至2007年5月尾波Qc值,流逝时间为24~27 s、28~31 s、38~44 s的Qc值平均值分别为95、115和124。2004年9月17日阳江4.9级地震前后,流逝时间较短的两个Qc值变化较为同步,Qc值出现"低值—回弹—发震—低值"演化过程,而流逝时间38~44 s的Qc值在整个研究时段内未出现显著异常过程。研究表明,Qc值对地震序列发展的监测是有效的,前兆异常信息的获取与流逝时间的选取具有较大的相关性,对于广东阳江地区,作为前兆监测手段的Qc值,其流逝时间在24~31 s较为合适。
In this paper,based on the single scatter model(Aki),Coda Q_c was calculated from May 2003 to May 2007 in Yangjiang area,Guangdong Province,using vertical digital seismic wave recorded by Yangjiang earthquake station whose epicenter distance between 7 to 30 km.The average of Q_c with 24~27 s of elapsed time windows was 95,and 28~31 s is 115,and 34~44 s is 124.The M4.9 Yangjiang earthquake occurred on September 17,2004.The temporal characteristics of Q_c between 24~27 s and 28~31 s of elapsed time windows show rough agreements from Feb.2004 to Dec.2004.Q_c would trend to decrease at first about half a year before the main shock occurred,then increased,a short time after the main shock occurred,Q_c would trend to decrease to the normal value 2~3 months after the main shock occurred.Q_c with 38~44 s of elapsed time windows didn′t appear anomalous change.Q_c is an effective mean to observe the evolvement of earthquake sequence and predict the main shock,but the key point is how to select the length of the elapsed time windows.As an observational mean for seismic precursor,the elapsed time windows of Q_c should be about 24~31 s for Yangjiang areas.
In this paper,based on the single scatter model(Aki),Coda Q_c was calculated from May 2003 to May 2007 in Yangjiang area,Guangdong Province,using vertical digital seismic wave recorded by Yangjiang earthquake station whose epicenter distance between 7 to 30 km.The average of Q_c with 24~27 s of elapsed time windows was 95,and 28~31 s is 115,and 34~44 s is 124.The M4.9 Yangjiang earthquake occurred on September 17,2004.The temporal characteristics of Q_c between 24~27 s and 28~31 s of elapsed time windows show rough agreements from Feb.2004 to Dec.2004.Q_c would trend to decrease at first about half a year before the main shock occurred,then increased,a short time after the main shock occurred,Q_c would trend to decrease to the normal value 2~3 months after the main shock occurred.Q_c with 38~44 s of elapsed time windows didn′t appear anomalous change.Q_c is an effective mean to observe the evolvement of earthquake sequence and predict the main shock,but the key point is how to select the length of the elapsed time windows.As an observational mean for seismic precursor,the elapsed time windows of Q_c should be about 24~31 s for Yangjiang areas.
引文
[1]Aki K,Chouet B.Origin of coda waves,attenuation and scattering effects[J].J Geophys Res,1975,80:3 322-3 342.
[2]张天中,马云生,张焕生,等.震源谱的尾波多台多震综合求解方法[J].地球物理学报,1997,40(5):702-709.
[3]梅世蓉,冯德益,等.中国地震预报概论[M].北京:地震出版社,1993.86-91.
[4]Sato H.Temporal changes in scattering and attenuation associated with the scattering approximation[J].J Phys Earth,1988,25:27-41.
[5]朱新运.影响尾波Q值数据结果的算法因素分析[J].东北地震研究,2006,22(3):8-13.
[6]Aki K.Summary of discussion on coda waves at the Istanbul,IASPEI meeting.Phys.Earth Planet.Inter.1991,67:1-3.
[7]Jin A,Aki K,Liu Z,et al.Seismological evidence for the brittle-ductile interaction hypothesis onearthquake loading[J].Earth Planets Space,2004,56:823-830.
[8]吕坚,朱新运,高建华,等.江西九江-瑞昌震区的尾波衰减特征初探[J].地震,2006,26(4):15-21.
[9]马云生,张天中,张焕生.北京及其周围地区尾波Q值分布特征的研究[J].地震学报,1995,17(4):448-458.
[10]王伟君,刘杰.云南4个地震序列Q值变化特征对比研究[J].地震,2006,26(1):19-25.
[11]马宏生,刘杰,张国民,等.尾波Qc值随时间变化在地震预测中应用的研究[J].地震,2005,25(4):39-48.
[12]Felher M,Sato H.Coda[J].Pure Appl Geophys,2003,160:541-554.
[13]啜永清,张淑亮,苏燕,等.大同地震序列的尾波Q值变化特征研究.地震,2004,24(2):66-71.
[14]马宏生,刘杰,张国民,等.云南地区尾波Qc值的分布特征及其初步解释[J].地震,2006,26(3):37-43.
[15]康英,杨选,吕金水,等.2004年阳江MS4.9地震震源参数分析[J].地震,2005,25(3):109-114.
[2]张天中,马云生,张焕生,等.震源谱的尾波多台多震综合求解方法[J].地球物理学报,1997,40(5):702-709.
[3]梅世蓉,冯德益,等.中国地震预报概论[M].北京:地震出版社,1993.86-91.
[4]Sato H.Temporal changes in scattering and attenuation associated with the scattering approximation[J].J Phys Earth,1988,25:27-41.
[5]朱新运.影响尾波Q值数据结果的算法因素分析[J].东北地震研究,2006,22(3):8-13.
[6]Aki K.Summary of discussion on coda waves at the Istanbul,IASPEI meeting.Phys.Earth Planet.Inter.1991,67:1-3.
[7]Jin A,Aki K,Liu Z,et al.Seismological evidence for the brittle-ductile interaction hypothesis onearthquake loading[J].Earth Planets Space,2004,56:823-830.
[8]吕坚,朱新运,高建华,等.江西九江-瑞昌震区的尾波衰减特征初探[J].地震,2006,26(4):15-21.
[9]马云生,张天中,张焕生.北京及其周围地区尾波Q值分布特征的研究[J].地震学报,1995,17(4):448-458.
[10]王伟君,刘杰.云南4个地震序列Q值变化特征对比研究[J].地震,2006,26(1):19-25.
[11]马宏生,刘杰,张国民,等.尾波Qc值随时间变化在地震预测中应用的研究[J].地震,2005,25(4):39-48.
[12]Felher M,Sato H.Coda[J].Pure Appl Geophys,2003,160:541-554.
[13]啜永清,张淑亮,苏燕,等.大同地震序列的尾波Q值变化特征研究.地震,2004,24(2):66-71.
[14]马宏生,刘杰,张国民,等.云南地区尾波Qc值的分布特征及其初步解释[J].地震,2006,26(3):37-43.
[15]康英,杨选,吕金水,等.2004年阳江MS4.9地震震源参数分析[J].地震,2005,25(3):109-114.
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