小江断裂带及邻区应力降特征分析
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摘要
在对S波观测记录位移谱进行传播路径、场地响应和仪器响应等校正的基础上,根据Brune圆盘震源模型,利用遗传算法估算了小江断裂带及邻区335次ML2.0～5.3地震的应力降,分析了应力降的时空特征。结果表明:Δσ≥10.0MPa的高应力降地震主要分布在小江断裂带的东川、巧家及其以北地区和元谋、武定一带。小江断裂带北段、中段、南段Δσ≥10.0MPa的地震所占比例分别为10.2%、10.9%和1.6%,据此结合地震活动性分析了该断裂带不同段的强震危险性。结合震源位置和速度结构联合反演方法得到的震源位置精确定位结果,分析了应力降和震源深度变化情况及其所反映的断层深部延伸和分布情况。
Doing the propagation path correction,site effect correction,and instrument response correction,etc.for the observational S-wave data,we obtained source spectra for the small-and moderate-earthquakes.Using Brune Source Model and by means of generalized inversion technique,we calculated the stress drop of 335 earthquakes(MS2.0～5.3)in Xiaojiang Fault Zone and its adjacent areas.The temporal and spatial features of the stress drop showed that earthquakes with higher stress drop(Δσ≥10.0 MPa)mainly distribute in Dongchuan,Qiaojia and the areas in the north of Qiaojia,Yuanmou,and Wuding region.The earthquakes with Δσ≥10.0 MPa account separately for 10.2%,10.9% and 1.6% of the total in the northern,middle and southern segment of the Xiaojiang Fault Zone.According to the seismicity in the Zone,we analyzed the strong earthquake risk in different segments of the Zone.On the basis of the precisely-relocated results from the simultaneous inversion of location and velocity structure,we also analyzed the variation of stress drop and focal depth,and the extension and distribution of the Zone in the deep Earth.
Doing the propagation path correction,site effect correction,and instrument response correction,etc.for the observational S-wave data,we obtained source spectra for the small-and moderate-earthquakes.Using Brune Source Model and by means of generalized inversion technique,we calculated the stress drop of 335 earthquakes(MS2.0～5.3)in Xiaojiang Fault Zone and its adjacent areas.The temporal and spatial features of the stress drop showed that earthquakes with higher stress drop(Δσ≥10.0 MPa)mainly distribute in Dongchuan,Qiaojia and the areas in the north of Qiaojia,Yuanmou,and Wuding region.The earthquakes with Δσ≥10.0 MPa account separately for 10.2%,10.9% and 1.6% of the total in the northern,middle and southern segment of the Xiaojiang Fault Zone.According to the seismicity in the Zone,we analyzed the strong earthquake risk in different segments of the Zone.On the basis of the precisely-relocated results from the simultaneous inversion of location and velocity structure,we also analyzed the variation of stress drop and focal depth,and the extension and distribution of the Zone in the deep Earth.
引文
[1]闻学泽,杜方,易桂喜,等.2010.红河断裂带以北的云南地区大地震危险背景的讨论[R]//云南新一轮强震活跃期强震危险性研讨会报告.
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黄玉龙,郑斯华,刘杰,等.2003.广东地区地震动衰减和场地响应的研究[J].地球物理学报,46(1):54-61.
皇甫岗,陈颙,秦嘉政,等.2010.云南地震活动性[M].昆明:云南科技出版社.
刘福田.1984.震源位置和速度结构的联合反演(I)——理论和方法[J].地球物理学报,27(2):167-175.
刘杰,郑斯华,黄玉龙.2003.利用遗传算法反演非弹性衰减系数、震源参数和场地响应[J].地震学报,25(2):211-218.
刘丽芳,苏有锦,刘杰,等.2007.用Moya方法反演云南数字地震台站场地响应[J].地震研究,30(1):39-42.
马宏生.2007.川滇地区强震孕育的深部动力学环境研究[D].北京:中国地震局地球物理研究所.
毛玉平,韩新民.2003.云南地区强震(M≥6)研究[M].昆明:云南科技出版社.
钱晓东,秦嘉政.2008.小江断裂带及周边地区强震危险性分析[J].地震研究,31(4):354-361.
钱晓东.2010.破裂时间法在云南小江断裂带强震预测中的应用[J].地震研究,33(2):138-146.
秦嘉政,钱晓东,叶建庆.2005.2001年施甸MS5.9地震序列的震源参数研究[J].地震学报,27(3):250-259.
苏有锦,刘杰,郑斯华,等.2006.云南地区S波非弹性衰减Q值研究[J].地震学报,28(2):206-212.
闻学泽.1993.小江断裂带的破裂分段与地震潜势概率估计[J].地震学报,15(3):323-330.
易桂喜,闻学泽,苏有锦.2008.川滇活动地块东边界强震危险性研究[J].地球物理学报,51(6):1719-1725.
张世民,谢富仁.2001.鲜水河—小江断裂带7级以上强震构造区的划分及其构造地貌特征[J].地震学报,23(1):36-44.
张天中,马云生,黄蓉良,等.2000.1995年陡河地震前后小震震源参数及其相互关系[J].地震学报,22(3):233-240.
周龙泉,刘杰,马宏生,等.2009.2003年大姚6.2级、6.1级地震序列震源位置及震源区速度结构的联合反演[J].地震,29(2):12-29.
Andrews D J.1989.Mechannics of fault junctions[J].JGR,94(B7):9389-9397.
Atkinson G M,Mereu R F.1992.The shape of ground motion attenuation curves in southeastern Canada[J].BSSA,82(5):2014-2031.
Brune J N.1970.Tectonic stress and the spectra of seismic shear waves from earthquake[J].JGR,75(26):4997-5009.
Brune J N.1971.Correction[J].JGR,76(20):5002.
Crosson R S.1976.Crustal structure modeling of earthquake data,1,Sim-ultaneous least squares estimation of hypocenter and velocity parame-ters[J].JGR,81(B17):3036-3046.
Jones L E,Helmberger D V.1998.Earthquake source parameters and fault kinematic in the eastern California shear zone[J].BSSA,88(6):1337-1352.
Kissling E,Ellsworth W L,Eberhard-Phillips D,et al.1994.Initial refer-ence models in local earthquake tomography[J].JGR,99(B10):19635-19646.
Michael A J.1988.Effects of three-dimensional velocity structure on the seismicity of the1984Morgan Hill,California,aftershock sequence[J].BSSA,78(3):1199-1221.
Moya C A,Aguirre J,Irikura K.2000.Inversion of source parameters and site effects from strong ground motion records using genetic algo-rithms[J].BSSA,90(4):977-992.
Pavlis G L.1986.Appraising earthquake hypocenter location errors:a complete,practical approach for single-event locations[J].BSSA,76(6),1699-1710.
Pavlis L G,Booker J R.1980.The mixed discrete-continuous inverse problem:application to the simultaneous determination of earthquake hypocenters and velocity structure[J].JGR,85(B9):4801-4810.
Spencer C,Gubbins D.1980.Travel time inversion for simultaneous earth-quake location and velocity structure determination in laterally var-ying media[J].Geophys J R Astron Soc,63(1):95-116.
Thurber C H.1983.Earthquake locations and three-dimensional crustal structure in the Coyote late area,Central California[J].JGR,88(B10):8226-8236.
[2]刘丽芳,周龙泉.2010.西南地区震源位置及区域速度结构的联合反演[R]//地震行业科研专项“全国地震活动状态动态评价系统的研制”(200708020)分项研究报告.
黄玉龙,郑斯华,刘杰,等.2003.广东地区地震动衰减和场地响应的研究[J].地球物理学报,46(1):54-61.
皇甫岗,陈颙,秦嘉政,等.2010.云南地震活动性[M].昆明:云南科技出版社.
刘福田.1984.震源位置和速度结构的联合反演(I)——理论和方法[J].地球物理学报,27(2):167-175.
刘杰,郑斯华,黄玉龙.2003.利用遗传算法反演非弹性衰减系数、震源参数和场地响应[J].地震学报,25(2):211-218.
刘丽芳,苏有锦,刘杰,等.2007.用Moya方法反演云南数字地震台站场地响应[J].地震研究,30(1):39-42.
马宏生.2007.川滇地区强震孕育的深部动力学环境研究[D].北京:中国地震局地球物理研究所.
毛玉平,韩新民.2003.云南地区强震(M≥6)研究[M].昆明:云南科技出版社.
钱晓东,秦嘉政.2008.小江断裂带及周边地区强震危险性分析[J].地震研究,31(4):354-361.
钱晓东.2010.破裂时间法在云南小江断裂带强震预测中的应用[J].地震研究,33(2):138-146.
秦嘉政,钱晓东,叶建庆.2005.2001年施甸MS5.9地震序列的震源参数研究[J].地震学报,27(3):250-259.
苏有锦,刘杰,郑斯华,等.2006.云南地区S波非弹性衰减Q值研究[J].地震学报,28(2):206-212.
闻学泽.1993.小江断裂带的破裂分段与地震潜势概率估计[J].地震学报,15(3):323-330.
易桂喜,闻学泽,苏有锦.2008.川滇活动地块东边界强震危险性研究[J].地球物理学报,51(6):1719-1725.
张世民,谢富仁.2001.鲜水河—小江断裂带7级以上强震构造区的划分及其构造地貌特征[J].地震学报,23(1):36-44.
张天中,马云生,黄蓉良,等.2000.1995年陡河地震前后小震震源参数及其相互关系[J].地震学报,22(3):233-240.
周龙泉,刘杰,马宏生,等.2009.2003年大姚6.2级、6.1级地震序列震源位置及震源区速度结构的联合反演[J].地震,29(2):12-29.
Andrews D J.1989.Mechannics of fault junctions[J].JGR,94(B7):9389-9397.
Atkinson G M,Mereu R F.1992.The shape of ground motion attenuation curves in southeastern Canada[J].BSSA,82(5):2014-2031.
Brune J N.1970.Tectonic stress and the spectra of seismic shear waves from earthquake[J].JGR,75(26):4997-5009.
Brune J N.1971.Correction[J].JGR,76(20):5002.
Crosson R S.1976.Crustal structure modeling of earthquake data,1,Sim-ultaneous least squares estimation of hypocenter and velocity parame-ters[J].JGR,81(B17):3036-3046.
Jones L E,Helmberger D V.1998.Earthquake source parameters and fault kinematic in the eastern California shear zone[J].BSSA,88(6):1337-1352.
Kissling E,Ellsworth W L,Eberhard-Phillips D,et al.1994.Initial refer-ence models in local earthquake tomography[J].JGR,99(B10):19635-19646.
Michael A J.1988.Effects of three-dimensional velocity structure on the seismicity of the1984Morgan Hill,California,aftershock sequence[J].BSSA,78(3):1199-1221.
Moya C A,Aguirre J,Irikura K.2000.Inversion of source parameters and site effects from strong ground motion records using genetic algo-rithms[J].BSSA,90(4):977-992.
Pavlis G L.1986.Appraising earthquake hypocenter location errors:a complete,practical approach for single-event locations[J].BSSA,76(6),1699-1710.
Pavlis L G,Booker J R.1980.The mixed discrete-continuous inverse problem:application to the simultaneous determination of earthquake hypocenters and velocity structure[J].JGR,85(B9):4801-4810.
Spencer C,Gubbins D.1980.Travel time inversion for simultaneous earth-quake location and velocity structure determination in laterally var-ying media[J].Geophys J R Astron Soc,63(1):95-116.
Thurber C H.1983.Earthquake locations and three-dimensional crustal structure in the Coyote late area,Central California[J].JGR,88(B10):8226-8236.
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