利用点源叠加合成有限尺度运动源的理论地震图
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摘要
在点源格林函数解析解的基础上,根据动力学的独立性原理,把运动的有限尺度破裂源看做是多个动态的点源的叠加。文中的叠加包含有两重意思,一是震源大小的叠加,二是运动过程的叠加。利用这个想法给出了不同传播模式下有限源的面元划分方法和时间延迟的计算方法,并以Bouchon模型为例,验证了点源叠加方法的正确性和合理性。系统分析了在用点源叠加方法合成有限面源理论地震图中,单元划分的精细程度对合成理论地震图精度的影响。结果表明在保证一定合成理论地震图精度的前题下,因震源破裂传播速度、震源时间函数的频率特征及接收点位置等参数的不同,对面源离散的精细程度要求也不同。在强地面运动模拟计算和利用近场记录反演震源破裂过程等研究中,都需要将断层面离散成一系列子破裂单元,研究结果对离散过程中尺度的选定具有重要参考价值。
The kinematical finite source is considered as stacking of dynamic point sources based on the dynamic independent principle.The stacking has two means,the stacking of the area of sources and the stacking of the kinematical process.Following this idea,the authors showe different discretizing method and rise time for different propagating models of the finite source.The stacking method is validated by comparing with analytical results.The relationship between the critical value and rise time,special distribution of stations,crack propagating velocity for a strike-slip fault in a two-layer earth model are further discussed.The analysis shows that to keep the precision of the synthetic seismograms,the critical areas vary with the rupture speed,frequency of the source time function and the position of the stations.The results can be a valuable reference for discritizing the planar element in strong ground motion simulation and near source inversion.
The kinematical finite source is considered as stacking of dynamic point sources based on the dynamic independent principle.The stacking has two means,the stacking of the area of sources and the stacking of the kinematical process.Following this idea,the authors showe different discretizing method and rise time for different propagating models of the finite source.The stacking method is validated by comparing with analytical results.The relationship between the critical value and rise time,special distribution of stations,crack propagating velocity for a strike-slip fault in a two-layer earth model are further discussed.The analysis shows that to keep the precision of the synthetic seismograms,the critical areas vary with the rupture speed,frequency of the source time function and the position of the stations.The results can be a valuable reference for discritizing the planar element in strong ground motion simulation and near source inversion.
引文
[1]Robinson R,Benites R.Upgrading a synthetic seismicitymodel for more realistic fault ruptures.Geophy Res Letters,2001,28(9):1843-1846
[2]Bouchon M.The compete synthesis of seismic crustal phaseat regional distance.J Geophys Res,1982,87(1):735-741
[3]Kennett B L N.Seismic Wave Propagation in StratifiedMedia.New York:Cambridge University Press,1982
[4]Chen X F.Seismogram synthesis in multi-layered half-space.Earthquake Research in China,1999,13(2):149-174
[5]Chen X F,Zhang H M.An efficient method for computingGreen’s functions for a layered half-space at large epicentraldistances.Bull Seis Soc Am,2001,91:858-869
[6]Yao Z X,Harkrider D G.A generalized reflection-transmission coefficient matrix and discrete wavenumbermethod for synthetic seismograms.Bull Seis Soc Amer,1983,73:1685-1699
[7]Bouchon M,Aki K.Discrete wave-number representation ofseismic-source wave fields.Bull Seism Soc Am,1977,67:259-277
[8]Bouchon M.Discrete wavenumber representation of elasticwave fields in three-dimentions space.J Geophys Res,1979,84:3609-3614
[9]Olson A H,Apsel R J.Finite faults and inverse theory withapplications to the 1979 Imperial Valley earthquake.BullSeism Soc Am,1982,72:1969-2001
[10]Aki K,Richards P G.Quantitative Seismology:Theory andMethods.San Francisco:W.H.Freeman,1980
[2]Bouchon M.The compete synthesis of seismic crustal phaseat regional distance.J Geophys Res,1982,87(1):735-741
[3]Kennett B L N.Seismic Wave Propagation in StratifiedMedia.New York:Cambridge University Press,1982
[4]Chen X F.Seismogram synthesis in multi-layered half-space.Earthquake Research in China,1999,13(2):149-174
[5]Chen X F,Zhang H M.An efficient method for computingGreen’s functions for a layered half-space at large epicentraldistances.Bull Seis Soc Am,2001,91:858-869
[6]Yao Z X,Harkrider D G.A generalized reflection-transmission coefficient matrix and discrete wavenumbermethod for synthetic seismograms.Bull Seis Soc Amer,1983,73:1685-1699
[7]Bouchon M,Aki K.Discrete wave-number representation ofseismic-source wave fields.Bull Seism Soc Am,1977,67:259-277
[8]Bouchon M.Discrete wavenumber representation of elasticwave fields in three-dimentions space.J Geophys Res,1979,84:3609-3614
[9]Olson A H,Apsel R J.Finite faults and inverse theory withapplications to the 1979 Imperial Valley earthquake.BullSeism Soc Am,1982,72:1969-2001
[10]Aki K,Richards P G.Quantitative Seismology:Theory andMethods.San Francisco:W.H.Freeman,1980
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