新疆4次中强地震前小震震源机制变化特征
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摘要
采用点源位错模型、层状介质速度结构,利用地震波垂直向记录的直达P珔、S珔波最大振幅,计算小地震震源机制。通过系统聚类,利用矢量合成方法,计算得到各类解的平均震源机制解。采用上述方法,针对2003年以来新疆北天山西段和中天山地区4次中强地震前,震源区周围中小地震震源断错性质和P轴方位的变化进行分析。结果显示,中强地震前2～3年中小地震震源机制解类型随机分布,震前1年表现出明显的优势分布特点,主压应力P轴方位发生较明显的偏转变化。
With maximum amplitude of direct 、 recorded by the vertical direction,the article applied the point-source dislocation model and layer medium velocity structure to calculate focal mechanism solutions of small earthquakes.With the vector resultant and hierarchial clustering method,we got mean focal mechanism solutions of different classification.With above method,we analyzed the source dislocation character and P axis azimuth of moderate and small earthquakes around the hypocentral region before 4 mid-strong earthquakes in the central Tianshan area in Xinjiang since 2003.The result shows that focal mechanism solution type of small earthquakes in 2~3 years before these mid-strong earthquakes is stochastic,and the type appears preponderant one year before these mid-strong earthquakes and P axis azimuth exists obvious deflection change.
With maximum amplitude of direct 、 recorded by the vertical direction,the article applied the point-source dislocation model and layer medium velocity structure to calculate focal mechanism solutions of small earthquakes.With the vector resultant and hierarchial clustering method,we got mean focal mechanism solutions of different classification.With above method,we analyzed the source dislocation character and P axis azimuth of moderate and small earthquakes around the hypocentral region before 4 mid-strong earthquakes in the central Tianshan area in Xinjiang since 2003.The result shows that focal mechanism solution type of small earthquakes in 2~3 years before these mid-strong earthquakes is stochastic,and the type appears preponderant one year before these mid-strong earthquakes and P axis azimuth exists obvious deflection change.
引文
[1]高国英,王海涛,聂晓红,等.新疆伽师及周围构造应力场区域特征探讨[J].地震地质,2007,29(1):77-87.
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[5]刁桂苓,于利民,李钦祖.震源机制解的系统聚类分析[J].中国地震,1992,8(3):86-92.
[6]梁尚鸿,李幼铭,束沛镒.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):249-257.
[7]孙加林,武慧聪,阎海滨.关于强震前中小地震平均主压应力方向和初动符号矛盾比变化问题的研究[C]//国家地震局科技监测司.地震预报方法实用化研究文集——地震学专辑.北京:学术书刊出版社,1989:460-472.
[8]华祥文.震前应力变化与震后应力过程的研究[C]//国家地震局科技监测司,地震预报方法实用化研究文集——地震学专辑.北京:学术书刊出版社,1989:448-459.
[2]马瑾,李钦祖,刁桂苓,等.小震震源机制类型的地震预报作用及其力学意义[J].地震,1994,15(增刊):25-32.
[3]高国英,王海涛,温和平,等.帕米尔东北侧中强地震前应力场动态变化特征分析[J].西北地震学报,2001,23(4):389-394.
[4]刁桂苓,高国英,聂晓红,等.伽师序列中小地震震源机制分析[J].国际地震动态,2007,(12):1-9.
[5]刁桂苓,于利民,李钦祖.震源机制解的系统聚类分析[J].中国地震,1992,8(3):86-92.
[6]梁尚鸿,李幼铭,束沛镒.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):249-257.
[7]孙加林,武慧聪,阎海滨.关于强震前中小地震平均主压应力方向和初动符号矛盾比变化问题的研究[C]//国家地震局科技监测司.地震预报方法实用化研究文集——地震学专辑.北京:学术书刊出版社,1989:460-472.
[8]华祥文.震前应力变化与震后应力过程的研究[C]//国家地震局科技监测司,地震预报方法实用化研究文集——地震学专辑.北京:学术书刊出版社,1989:448-459.
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