Accurate modeling of basin structures and quantitative analysis of basin amplification effects are critical for seismologists and engineers. The Indirect Boundary Element Method (IBEM), developed from the Boundary Element Method (BEM), is particularly well-suited for these tasks due to its capability to manage layers with lateral inhomogeneities. However, current IBEM studies mostly focus on wavefields generated by plane wave incidence or point sources emitting pure spherical P or S waves, which often fail to capture the complex behavior of real seismic events. To address this limitation, we propose an updated IBEM scheme that simulates wavefields from dip-slip sources using the displacement-stress discontinuity vector. We validate this updated IBEM through degenerated models and sources, confirming its robustness in handling dip-slip sources. Further numerical tests reveal several features of basin amplification effects from dip-slip sources: (1) Sources with varying dips cause substantial differences in-basin peak numbers and amplitudes compared to simplified sources. For the surface responses, the ratio of maximum amplitudes (in-basin to out-of-basin) can exceed 10 with asymmetric distributed peaks. (2) The basin amplification effect for dip-slip sources shows similar frequency and velocity contrast dependencies compared to other simplified sources. Our study shows the IBEM scheme is effective and advantageous in basin amplification effect analysis, especially for different source configurations under the same model, with great potential for further applications for seismology, earthquake engineering, and hazard control.

中文翻译：

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使用间接边界元法 （IBEM） 对倾滑源的流域响应进行数值分析


盆地结构的准确建模和盆地放大效应的定量分析对于地震学家和工程师来说至关重要。间接边界元法 （IBEM） 是从边界元法 （BEM） 发展而来的，由于它能够管理具有横向不均匀性的层，因此特别适合这些任务。然而，目前的 IBEM 研究主要集中在平面波入射或发射纯球面 P 或 S 波的点源产生的波场上，这些波场往往无法捕捉到真实地震事件的复杂行为。为了解决这一限制，我们提出了一种更新的 IBEM 方案，该方案使用位移-应力不连续向量模拟来自倾滑源的波场。我们通过退化模型和来源验证了这个更新的 IBEM，证实了它在处理 Dip-slip 来源方面的稳健性。进一步的数值测试揭示了倾滑源盆地放大效应的几个特征：（1） 与简化源相比，具有不同倾角的源会导致盆地峰值数和振幅存在很大差异。对于表面响应，最大振幅（盆内与盆外）的比率可以超过 10，并且分布的峰值不对称。（2） 与其他简化源相比，倾滑源的盆地放大效应显示出相似的频率和速度对比依赖性。研究表明，IBEM 方案在盆地放大效应分析中具有有效和优势，特别是对于同一模型下的不同震源配置，在地震学、地震工程和灾害控制方面的进一步应用具有很大的潜力。