利用点源叠加合成有限尺度运动源的理论地震图

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。研究结果对诸如强地面运动的模拟计算及用近场记录反演震源破裂过程等相关研究中所涉及的选定适当的尺度将断层面离散成系列子破裂单元有重要参考价值。

Point Source Stacking Method to Compute Synthetic Seismogram of Finite Moving Planar Source

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 showed 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 could be the valuable reference for the discritizing the planar element in strong ground motion simulation and near source inversion.