珊溪水库地震小震震源机制解特征研究
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摘要
利用P波初动和直达P、S波最大速度振幅比联合求解小震震源机制的方法求出珊溪水库ML2.0以上地震的震源机制,得到了珊溪水库震源机制各参数时空特征如下:主压应力为SN向,主张应力为EW向,应力主要为水平应力,发震断层倾角较大且多为走滑断层。在个别4级左右地震前P轴方位都有偏离再恢复的现象。在北纬27.65°～27.69°间,P轴方位集中在0°±30°或者180°±30°,节面走向集中在45°±15°或者135°±15°。震源深度大于4km的地震倾角多集中在70°～90°度之间。
Using P wave first motions and the maximum velocity amplitude ratio of Pg and Sg waves,the focal mechanism solutions of the Shanxi reservoir earthquakes above ML 2.0were calculated.The time and space characteristics of the focal mechanism solutions parameters were obtained as follow:most of the main press stresses are North-south oriented,most of the main tensile stresses are East-west oriented,the stresses are almost horizontal,most of the slips of the planes are above 60°,and most of the faults are strike-slip type.Both of the azimuths of the Paxis have the trend of first deviation and then recovery before some MS 4.0 earthquakes.In the range from 27.66°to 27.69°N,focal mechanism solutions parameters have a good consistency. Most of the azimuths of the P-axis are 0±30° and 180±30°,and most of strikes of the plane are 45±15°and 135±15°.Most of the slips with focal depths deeper than 4km are between 70° and 90°.
Using P wave first motions and the maximum velocity amplitude ratio of Pg and Sg waves,the focal mechanism solutions of the Shanxi reservoir earthquakes above ML 2.0were calculated.The time and space characteristics of the focal mechanism solutions parameters were obtained as follow:most of the main press stresses are North-south oriented,most of the main tensile stresses are East-west oriented,the stresses are almost horizontal,most of the slips of the planes are above 60°,and most of the faults are strike-slip type.Both of the azimuths of the Paxis have the trend of first deviation and then recovery before some MS 4.0 earthquakes.In the range from 27.66°to 27.69°N,focal mechanism solutions parameters have a good consistency. Most of the azimuths of the P-axis are 0±30° and 180±30°,and most of strikes of the plane are 45±15°and 135±15°.Most of the slips with focal depths deeper than 4km are between 70° and 90°.
引文
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[5]张辉,王熠熙.2012年5月3日金塔-阿拉善盟5.4级地震震源机制解[J].西北地震学报,2012,34(2):205-206.ZHANG Hui,WANG Yi-xi.Focal Mechanism of the JintanAlashanmeng M5.4Earthquake on May 3,2012[J].North-western Seismological Journal,2012,34(2):205-206.(in Chinese)
[6]张辉,2012年5月11日甘肃肃南MS4 .9地震震源机制解[J].西北地震学报,2012,34(2):207-208.ZHANG Hui.Focal Mechanism of the Sunan MS4 .9Earthquake in Gansu Province on May 11,2012[J].Northwestern Seismological Journal,2012,34(2):207-208.(in Chinese)
[7]刘薇,张晓清,石玉成,等.利用格林函数库计算2008年青海大柴旦6.4级地震的余震震源机制[J].地震,2006,26(1):26 -34.LIU Wei,ZHANG Xiao-qing,SHI Yu-cheng,et al.Using Green Function Database and Quick Moment tensor Inversion Calculating the Focal Mechanism Solution of Aftershocks of Dachaidan MS6 .4Earthquake in 2008in Qinghai Province[J].Earthquake,2006,26(1):26-34.(in Chinese)
[8]张永久,程万正.用P、S波速度振幅比求小震机制解的可行性研究[J].中国地震,2007,23(4):366-374.Zhang Yong-jiu,Cheng Wan-zheng.Feasibility Study on Determining Focal Mechanism of Small Earthquakes Using Amplitude Ratio of P and S Waves[J].Earthquake Research in China,2007,23(4):366-374.(in Chinese)
[9]梁尚鸿,李幼铭,等.利用区域地震台网P、S波振幅比资料测定小震震源参数[J].地球物理学报,1984,27(3):247-257.[M].LIANG Shang-hong,LI You-ming,et al.On the Determining of Source Parameters of Small Earthquakes by Using Amplitude Ratios of P and S from Regional Network Observations[J].Chinese Journal of Geophysics,1984,27(3):247-257.(in Chinese)
[11]朱新运,张帆,于俊宜.浙江珊溪水库地震精细定位及构造研究[J].中国地震,2010,26(4):380-390.ZHU Xin-yun,ZHANG Fan,YU Jun-yi.Study on Precise Positioning and Structure of the Shanxi Reservoir Earthquake,Zhejiang Province[J].Earthquake Research in China,2010,26(4):380-390.(in Chinese)
[2]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.LIU Jie,ZHENG Si-hua,KANG Ying,et al.The Focal Mechanism Determinations of Moderate-small Earthquakes Using the First Motion and Amplitude Ratio of P and S Wave[J].Earthquake,2004,24(1):19-26.(in Chinese)
[3]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 .TU Hong-wei,WANG Hai-tao,ZHAO Cui-ping.Calculating Focal Mechanism Solutions of Two Jiashi Strong Earthquakes in Xinjiang with the First Motion and Amplitude Ratio of P and S Wave[J].Inland Earthquake,2006,20(2):131-138.(in Chinese)
[4]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):25-30.LIU Li-fang,MAO Hui-ling,SU You-jin,et al.Determining Focal Mechanism Solution of the 2000Yao'an MS6 .5Earthquake Sequence Using the First Motion and Amplitude Ratio of P and S Wave[J].Journal of Seismological Research,2009,32 (1):25-30.(in Chinese)
[5]张辉,王熠熙.2012年5月3日金塔-阿拉善盟5.4级地震震源机制解[J].西北地震学报,2012,34(2):205-206.ZHANG Hui,WANG Yi-xi.Focal Mechanism of the JintanAlashanmeng M5.4Earthquake on May 3,2012[J].North-western Seismological Journal,2012,34(2):205-206.(in Chinese)
[6]张辉,2012年5月11日甘肃肃南MS4 .9地震震源机制解[J].西北地震学报,2012,34(2):207-208.ZHANG Hui.Focal Mechanism of the Sunan MS4 .9Earthquake in Gansu Province on May 11,2012[J].Northwestern Seismological Journal,2012,34(2):207-208.(in Chinese)
[7]刘薇,张晓清,石玉成,等.利用格林函数库计算2008年青海大柴旦6.4级地震的余震震源机制[J].地震,2006,26(1):26 -34.LIU Wei,ZHANG Xiao-qing,SHI Yu-cheng,et al.Using Green Function Database and Quick Moment tensor Inversion Calculating the Focal Mechanism Solution of Aftershocks of Dachaidan MS6 .4Earthquake in 2008in Qinghai Province[J].Earthquake,2006,26(1):26-34.(in Chinese)
[8]张永久,程万正.用P、S波速度振幅比求小震机制解的可行性研究[J].中国地震,2007,23(4):366-374.Zhang Yong-jiu,Cheng Wan-zheng.Feasibility Study on Determining Focal Mechanism of Small Earthquakes Using Amplitude Ratio of P and S Waves[J].Earthquake Research in China,2007,23(4):366-374.(in Chinese)
[9]梁尚鸿,李幼铭,等.利用区域地震台网P、S波振幅比资料测定小震震源参数[J].地球物理学报,1984,27(3):247-257.[M].LIANG Shang-hong,LI You-ming,et al.On the Determining of Source Parameters of Small Earthquakes by Using Amplitude Ratios of P and S from Regional Network Observations[J].Chinese Journal of Geophysics,1984,27(3):247-257.(in Chinese)
[11]朱新运,张帆,于俊宜.浙江珊溪水库地震精细定位及构造研究[J].中国地震,2010,26(4):380-390.ZHU Xin-yun,ZHANG Fan,YU Jun-yi.Study on Precise Positioning and Structure of the Shanxi Reservoir Earthquake,Zhejiang Province[J].Earthquake Research in China,2010,26(4):380-390.(in Chinese)
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