用P波、S波初动和振幅比计算中小地震震源机制在云南地区的应用
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摘要
利用云南数字地震台网记录的区域波形资料,用P、S波初动和P、S波的振幅比联合计算了发生在云南省内的91次中小地震的震源机制。通过与矩心矩张量法和P波初动法的结果对比分析,认为用P、S波初动和振幅比求解震源机制的方法是可行可靠的,用这种方法不仅可以得到5级以上地震的震源机制,也可以计算台网分布较好地区的3~4级地震的震源机制。另外,用91个地震的震源机制资料得到了云南地区震源机制类型、主压应力轴的平面分布及其统计图,结果表明云南地区以走滑型地震为主,主压应力轴优势分布方向为NNE向,这些结果与利用哈佛得到的结果是一致的。
In this paper,focal mechanisms of 91 moderate-small earthquakes occurred in Yunnan are calculated using digital seismic wave data from Yunnan digital seismic network based on the program of focal mechanism determinations combing the first motion of P,SV and SH waves with their amplitude ratio.Compared with the results using centroid-moment-tensor and first motion of P wave,our result is more reasonable.The method can not only be used to calculate focal mechanisms of earthquakes bigger than ML5.0,but also can be used to calculate focal mechanisms of moderate-small earthquakes.Additionally,the focal mechanisms types、horizontal distribution and statistical diagram of maximum stress orientations in Yunnan has been calculated using focal mechanisms of 91 moderate-small earthquakes,the results show that the focal mechanisms are mainly slip faulting and orientations of maximum stress mostly are in the NNE direction in Yunnan,which are accordant with the results using Harvard data.
In this paper,focal mechanisms of 91 moderate-small earthquakes occurred in Yunnan are calculated using digital seismic wave data from Yunnan digital seismic network based on the program of focal mechanism determinations combing the first motion of P,SV and SH waves with their amplitude ratio.Compared with the results using centroid-moment-tensor and first motion of P wave,our result is more reasonable.The method can not only be used to calculate focal mechanisms of earthquakes bigger than ML5.0,but also can be used to calculate focal mechanisms of moderate-small earthquakes.Additionally,the focal mechanisms types、horizontal distribution and statistical diagram of maximum stress orientations in Yunnan has been calculated using focal mechanisms of 91 moderate-small earthquakes,the results show that the focal mechanisms are mainly slip faulting and orientations of maximum stress mostly are in the NNE direction in Yunnan,which are accordant with the results using Harvard data.
引文
[1]苏有锦,刘祖荫,蔡民军,等.云南地区强震分布的深部地球介质背景[J].地震学报,1999,21(3):313-322.
[2]秦嘉政,皇甫岗,钱晓东.云南强震活动与预测方法研究[M].云南:云南科技出版社,2006.
[3]周云好.地震矩张量反演和震源破裂过程反演[D].北京:中国地震局地球物理所,2002.
[4]于海英,朱元清,郭育.使用SV/P_SH/P和SV/SH振幅比确定震源机制解[J].地震研究,2003,26(4):355-360.
[5]Snoke J A,Munsey JW,Teague A G,et al.A program for focalm echan ism determ ination by comb ined use of polarity and SV2Pamplitude ratio data[J].Earthquake Notes,1984,55(3):15-22.
[6]Snoke J A.Earthquake m echan ism//Jam es D E.Encycloped ia of Geophysics[C].New York:Van Nostrand Reinhold Compa-ny,1989:239-245.
[7]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.
[8]屠泓为,王海涛,赵翠萍.用P波S波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.
[9]陈天长,堀内茂木,郑斯华.利用P波初动和短周期P、S波振幅测定川滇地区地震震源机制解和应力场[J].地震学报,2001,23(4):436-440.
[10]赵小艳,苏有锦,付虹,等.欧亚地震带现代构造应力场及其分区特征[J].地震研究,2007,30(2):146-151.
[11]吴建平,明跃红,王椿镛.云南地区中小地震震源机制及构造应力场研究[J].地震学报,2004,26(5):457-465.
[12]程万正,刁桂苓,吕弋培,等.川滇地块的震源力学机制、运动速率和活动方式[J].地震地质,2003,(1):71-87.
[13]胡新亮,刁桂苓,马瑾,等.利用数字地震记录的P、S振幅比资料测定小震震源机制解的可靠性分析[J].地震地质,2004,26(2):347-354.
[2]秦嘉政,皇甫岗,钱晓东.云南强震活动与预测方法研究[M].云南:云南科技出版社,2006.
[3]周云好.地震矩张量反演和震源破裂过程反演[D].北京:中国地震局地球物理所,2002.
[4]于海英,朱元清,郭育.使用SV/P_SH/P和SV/SH振幅比确定震源机制解[J].地震研究,2003,26(4):355-360.
[5]Snoke J A,Munsey JW,Teague A G,et al.A program for focalm echan ism determ ination by comb ined use of polarity and SV2Pamplitude ratio data[J].Earthquake Notes,1984,55(3):15-22.
[6]Snoke J A.Earthquake m echan ism//Jam es D E.Encycloped ia of Geophysics[C].New York:Van Nostrand Reinhold Compa-ny,1989:239-245.
[7]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.
[8]屠泓为,王海涛,赵翠萍.用P波S波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.
[9]陈天长,堀内茂木,郑斯华.利用P波初动和短周期P、S波振幅测定川滇地区地震震源机制解和应力场[J].地震学报,2001,23(4):436-440.
[10]赵小艳,苏有锦,付虹,等.欧亚地震带现代构造应力场及其分区特征[J].地震研究,2007,30(2):146-151.
[11]吴建平,明跃红,王椿镛.云南地区中小地震震源机制及构造应力场研究[J].地震学报,2004,26(5):457-465.
[12]程万正,刁桂苓,吕弋培,等.川滇地块的震源力学机制、运动速率和活动方式[J].地震地质,2003,(1):71-87.
[13]胡新亮,刁桂苓,马瑾,等.利用数字地震记录的P、S振幅比资料测定小震震源机制解的可靠性分析[J].地震地质,2004,26(2):347-354.
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