1995年河北沙城M_L4.1地震发震断层参数测定
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摘要
在一维单侧有限移动震源模式下, 根据拐角频率的方位变化, 利用最小二乘法研究了1995 年7月20日河北沙城ML4.1地震的发震断层面参数。结果表明, 这次地震的断层面破裂方向为224°, 与余震分布和震源机制的NE向节面一致。地震马赫数v/c约为1.85, 即平均破裂速度大于S波速度, 为一次超速破裂。若取横波速度为3.5 km/s, 则破裂长度约为1 km。因此, 这次地震破裂以超S波速的速度从北东向西南方向传播了约1 km。
By considering 1D finite moving source model propagating unilaterally, the corner frequency is employed to determine the azimuth of rupture propagation direction and source parameters of the July 20, 1995 M_L4.1 Shacheng Earthquake, Hebei Province, such as rupture direction, rupture velocity and fault length, by means of a least-squares approach. The results show that the azimuth angle of the fault plane for this event is about 224°, consistent with aftershock distribution and the NE nodal plane of focal mechanism solution. The seismic Mach number v/c is about 1.85, which means that the average rupture velocity is greater than that of S-wave. Given the velocity of S wave 3.5 km/s, the fault length is about 1.0 km. So the rupture propagated about a length of 1.0 km along the direction from NE to SW at a super velocity of S wave.
By considering 1D finite moving source model propagating unilaterally, the corner frequency is employed to determine the azimuth of rupture propagation direction and source parameters of the July 20, 1995 M_L4.1 Shacheng Earthquake, Hebei Province, such as rupture direction, rupture velocity and fault length, by means of a least-squares approach. The results show that the azimuth angle of the fault plane for this event is about 224°, consistent with aftershock distribution and the NE nodal plane of focal mechanism solution. The seismic Mach number v/c is about 1.85, which means that the average rupture velocity is greater than that of S-wave. Given the velocity of S wave 3.5 km/s, the fault length is about 1.0 km. So the rupture propagated about a length of 1.0 km along the direction from NE to SW at a super velocity of S wave.
引文
[1] 卓钰如,李文香.用多普勒效应研究中小地震的破裂面和破裂传播速度[J].地震学报,1982,4(1):1426.
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[4] LiY,DollC,ToksozM N.Source characterization and fault plane determinations forMblg=1.2 to4.4 earthquakes in theCharlevoix seismic zone,Quebec,Canada[J].BullSeismSocAm,1995,85:16041621.
[5] MoriJ,HartzellS.Source inversion of the1988Upland,California, earthquake: determination of afault plane for a small event[J].BullSeismSocAm,1990,80:507518.
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[7] 许向彤,陈运泰,王培德.1995年7月20日怀来盆地ML=4.1地震的破裂过程[J].地震学报,1999,21(6):570582.
[8] 许向彤,陈运泰,王培德.1995年7月20日怀来盆地ML=4.1地震序列震源参数的精确测定[J].地震学报,2001,23(3):225238.
[9] BadawyA,AbdelFattahA K.Source parameters and fault plane determinations of the28thDec.,1999NorthernCairo earthquake[J].Tectonophysics,2001,334(12):6377.
[10] AbdelFattahA K.An approach to investigate earthquake rupture processes[J].ActaGeophysicaPolonica,2003,51(3):257269.
[11] AbdelFattahA K,BadawyA.Source characteristics and tectonic implications of moderate earth quake, northeasternCairo prefecture[J].ActaGeophysicaPolonica,2004,52(1):2943.
[12] AndrewsD J.Objective determination of source parameters and similarity of earthquakes of differentsize[A].In:DasS,BoatwrightJ,ScholzC H.EarthquakeSourceMechanics[C].WashingtonDC:AGU,1986.259267.
[13] 徐果明,周惠兰.地震学原理[M].北京:科学出版社,1982.397400.
[14] BenMenhaemA.Radiation of seismic body waves from a finite moving source in theEarth[J].JGeophysRes,1962,67:345350.
[2] FrankelA,FletcherJ,VernonF, et al.Rupture characteristics and tomographic source imaging ofML3 earthquakes nearAnza, southernCalifornia[J].J GeophysRes,1986,91:1263312650.
[3] LiY,ThurberC H.Source properties of two microearthquakes atKilauea volcano,Hawaii[J].BullSeismSocAm,1988,78:11231132.
[4] LiY,DollC,ToksozM N.Source characterization and fault plane determinations forMblg=1.2 to4.4 earthquakes in theCharlevoix seismic zone,Quebec,Canada[J].BullSeismSocAm,1995,85:16041621.
[5] MoriJ,HartzellS.Source inversion of the1988Upland,California, earthquake: determination of afault plane for a small event[J].BullSeismSocAm,1990,80:507518.
[6] MoriJ.Fault plane determinations for small three small earthquakes alongSanJacinto faultCalifor nia: search for cross faults[J].J GeophysRes,1993,98:1771117722.
[7] 许向彤,陈运泰,王培德.1995年7月20日怀来盆地ML=4.1地震的破裂过程[J].地震学报,1999,21(6):570582.
[8] 许向彤,陈运泰,王培德.1995年7月20日怀来盆地ML=4.1地震序列震源参数的精确测定[J].地震学报,2001,23(3):225238.
[9] BadawyA,AbdelFattahA K.Source parameters and fault plane determinations of the28thDec.,1999NorthernCairo earthquake[J].Tectonophysics,2001,334(12):6377.
[10] AbdelFattahA K.An approach to investigate earthquake rupture processes[J].ActaGeophysicaPolonica,2003,51(3):257269.
[11] AbdelFattahA K,BadawyA.Source characteristics and tectonic implications of moderate earth quake, northeasternCairo prefecture[J].ActaGeophysicaPolonica,2004,52(1):2943.
[12] AndrewsD J.Objective determination of source parameters and similarity of earthquakes of differentsize[A].In:DasS,BoatwrightJ,ScholzC H.EarthquakeSourceMechanics[C].WashingtonDC:AGU,1986.259267.
[13] 徐果明,周惠兰.地震学原理[M].北京:科学出版社,1982.397400.
[14] BenMenhaemA.Radiation of seismic body waves from a finite moving source in theEarth[J].JGeophysRes,1962,67:345350.
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