发表机构
University of Hamburg（汉堡大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究扩展SPECFEM3D谱元法，直接模拟旋转地震动，引入PGRR图，验证于解析解，并揭示低速沉积盆地显著放大旋转地震动，为地震工程提供新工具。
AI 中文摘要
对地震诱发地面运动的完整表征需要三个平动分量和三个转动分量，以及应变张量的六个分量。尽管旋转地震动具有重要性，但其特征尚未被完全认识。有限的观测数据库以及在真实地质介质中模拟它们的挑战，主要制约了该领域的研究。在本研究中，我们开发了谱元软件包SPECFEM3D的一个扩展，该扩展在数值求解过程中，直接根据Gauss-Lobatto-Legendre积分点处位移的空间梯度来评估旋转地震动。该实现针对均匀弹性介质的解析解进行了验证，在到达时间、振幅、波形特征和空间传播方面表现出良好的一致性。为了分析旋转地震动的传播模式，我们引入了峰值地面旋转速率（PGRR）图，类似于峰值地面速度（PGV）图。PGRR和PGV图的比较表明，平动和转动的关键位置并不重合。随后，在层状介质中针对两种地震震源机制模拟了旋转地震动，展示了不同震源特征下PGRR图的变化。最后，开发了印度-恒河盆地的三维（3D）模型，以表明低速沉积物会显著放大并重新分布旋转地震动。盆地中PGRR的空间分布相对于相应的通用层状介质发生了显著变化。所开发的框架为在复杂地质环境中研究旋转地震动以及评估其与传感器部署策略、地震危险性和地震工程的潜在相关性提供了基础。
英文摘要
A complete characterization of earthquake induced ground motions require three translational and three rotational components, together with the six components of the strain tensor. Despite the importance of rotational ground motions, their characteristics are not yet completely recognized. Limited observational database and challenges of simulating them in realistic geological media has primarily constrained the research in this domain. In the present study, we develop an extension of the spectral-element package SPECFEM3D that directly evaluates rotational ground motion from spatial gradients of displacements at the Gauss-Lobatto-Legendre integration points during the numerical solution. The implementation is validated against analytical solutions for a homogeneous elastic medium, showing good agreement in arrival times, amplitudes, waveform characteristics, and spatial propagation. For analyzing the propagation patterns of rotational ground motions, we introduce Peak Ground Rotation Rate (PGRR) maps, analogous to Peak Ground Velocity (PGV) maps. Comparison of PGRR and PGV maps revealed that the critical locations of translations and rotations do not coincide. Rotational ground motions are subsequently simulated in a layered medium for two earthquake source mechanisms, demonstrating the variation in PGRR maps for different source characteristics. Finally, a three-dimensional (3D) model of the Indo-Gangetic Basin is developed to show that low-velocity sedimentary deposits substantially amplify and redistribute rotational ground motions. The spatial distribution of PGRRs in the basin changes significantly relative to the corresponding generic layered medium. The developed framework provides a basis for investigating rotational ground motions in complex geological environments and assessing its potential relevance to sensor deployment strategies, seismic hazard and earthquake engineering.
