利用FOCMEC方法计算震源机制解的影响因素分析——以九江-瑞昌MS5.7地震为例
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摘要
应用Snoke最新发展的利用P波、SV波和SH波的初动和振幅比联合计算震源机制解的方法(FOCMEC),以2005年11月26日九江-瑞昌MS5.7地震为例,分析速度结构模型、震源定位误差、初动与振幅比资料和台站分布等对计算震源机制解的影响。结果表明,FOCMEC方法应采用研究区内的精细速度结构模型,各层速度误差在5%内时,对计算结果影响较小;2类精度内的震中定位误差对计算结果影响较小;造成入射角变化不大的震源深度的误差对计算结果影响较小;在初动和台站数量较少时也能准确确定震源机制解。因此FOCMEC方法是一种稳定、可靠的计算中小地震震源机制解的方法。
Based on polarities of P,SV and SH waves combining with their amplitude ratios,using the Focal Mechanism Determining Method of FOCMEC,taking JiuJiang-RuiChang MS5.7 earthquake on Nov 26 2005 as an example,the influencing factors such as velocity structure model,focal positioning error,data of the first motion and amplitude ratios,distribution of stations and so on are analyzed.The result shows that fine velocity structure model in the study area is necessary in this method;the velocity error of each layer within 5% is negligible.Within the type 2 accuracy of the epicenter location error and the change of focal depth resulting in little change in incidence angle are of little impact on the focal mechanism solutions.Focal mechanism solutions can also be accurately obtained when the number of polarities and stations is relatively less.Therefore,FOCMEC is a stable and reliable method for determining the focal mechanisms of moderate-small earthquakes.
Based on polarities of P,SV and SH waves combining with their amplitude ratios,using the Focal Mechanism Determining Method of FOCMEC,taking JiuJiang-RuiChang MS5.7 earthquake on Nov 26 2005 as an example,the influencing factors such as velocity structure model,focal positioning error,data of the first motion and amplitude ratios,distribution of stations and so on are analyzed.The result shows that fine velocity structure model in the study area is necessary in this method;the velocity error of each layer within 5% is negligible.Within the type 2 accuracy of the epicenter location error and the change of focal depth resulting in little change in incidence angle are of little impact on the focal mechanism solutions.Focal mechanism solutions can also be accurately obtained when the number of polarities and stations is relatively less.Therefore,FOCMEC is a stable and reliable method for determining the focal mechanisms of moderate-small earthquakes.
引文
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[10]http://www.iris.edu/software/downloads/processing/
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[14]刘丽芳,毛慧玲,苏有锦,等.利用P波、S波初动和振幅比计算2000年姚安Ms6.5地震序列震源机制解[J].地震研究,2009,32(1):26-30.
[15]笠原庆一.地震力学[M].北京:地震出版社,1984:28-49.
[16]吕坚,倪四道,沈小七,等.九江-瑞昌地震的精确定位及其发震构造初探[J].中国地震,2007,23(2):166-174.
[17]吕坚,郑勇,倪四道,等.2005年11月26日九江-瑞昌Ms5.7、Ms4.8地震的震源机制介于发震构造研究[J].地球物理学报,2008,51(1):158-164.
[18]刘斌.地震学原理与应用[M].合肥:中国科学技术大学出版社,2009,33-43.
[19]王椿镛,张先康,陈步云,等.大别造山带地壳结构研究[J].中国科学(D辑),1997,27(3):221-226.
[2]国家地震局监测预防司.测震学分析预报方法[M].北京:地震出版社,1997:121-151.
[3]中国地震局监测预报司.地震参数[M].北京:地震出版社,2003:21-22.
[4]Kisslinger C,Bowman J R,and Koch K.Procedures for computing focal mechanisms fromlocal(SV/P)z data[J].Bull.Seism.Soc.Am.,1981,71(6):1719-1730.
[5]梁尚鸿,李幼铭,束沛镒,等.利用区域地震台网P、S振幅比资料测定小震震源参数[J].地球物理学报,1984,27(3):249-256.
[6]郑先进,刘东旺,刘泽民,等.安徽地区应力场分区特征及中强震前震源机制的一致性研究[J].华北地震科学,2010,(1):16-20.
[7]吴大铭,王培德,陈运泰.用SH波和P波振幅比确定震源机制解[J].地震学报,1989,11(3):275-278.
[8]Snoke J A,Munsey J W,Teague A G,et al.Aprogramfor focal mechanismdetermination by combined use of polarity and SV-P ampli-tude ratio data[J].Earthquake Notes,1984,55(3):15-20.
[9]Snoke J A.Earthquake mechanism[A].James D E.Encyclopedia of Geophysics[C].New York:Van Nostrand Reinhold Company,1989,239-245.
[10]http://www.iris.edu/software/downloads/processing/
[11]刘杰,郑斯华,康英,等.利用P波和S波的初动和振幅比计算中小地震的震源机制解[J].地震,2004,24(1):19-26.
[12]兰从欣,邢成起,苗春兰,等.近年首都圈地区中小地震震源机制解及其特征分析[J].华北地震科学,2005,23(4):21-25.
[13]屠泓为,王海涛,赵翠萍.用P波、S波的初动和振幅比计算新疆伽师两次强地震震源机制解[J].内陆地震,2006,20(2):131-138.
[14]刘丽芳,毛慧玲,苏有锦,等.利用P波、S波初动和振幅比计算2000年姚安Ms6.5地震序列震源机制解[J].地震研究,2009,32(1):26-30.
[15]笠原庆一.地震力学[M].北京:地震出版社,1984:28-49.
[16]吕坚,倪四道,沈小七,等.九江-瑞昌地震的精确定位及其发震构造初探[J].中国地震,2007,23(2):166-174.
[17]吕坚,郑勇,倪四道,等.2005年11月26日九江-瑞昌Ms5.7、Ms4.8地震的震源机制介于发震构造研究[J].地球物理学报,2008,51(1):158-164.
[18]刘斌.地震学原理与应用[M].合肥:中国科学技术大学出版社,2009,33-43.
[19]王椿镛,张先康,陈步云,等.大别造山带地壳结构研究[J].中国科学(D辑),1997,27(3):221-226.
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