...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Pure and Applied Geophysics >Topography-Dependent Eikonal Traveltime Tomography for Upper Crustal Structure Beneath an Irregular Surface
【24h】

Topography-Dependent Eikonal Traveltime Tomography for Upper Crustal Structure Beneath an Irregular Surface

机译：不规则表面下上地壳结构的地形相关的真实旅行时间断层扫描

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Seismic modeling of the crust with nonflat topography can be made by first-arrival traveltime tomography, which faces the challenge of an irregular free surface. A feasible way to deal with this problem consists of expanding the physical space by overlapping a low velocity layer above the irregular surface in order to have a flat topography, besides using the classical eikonal equation solver for traveltime computation. However, the undesirable consequences of this method include seismic ray deviations due to the transition from an irregular surface that is the free boundary to an inner discontinuity lying in the expanded computational space. An alternative solution, called irregular surface flattening, which involves the transformation between curvilinear and Cartesian coordinate systems, has been recently proposed through the formulation of the topography-dependent eikonal equation (TDEE) and a new solver for forward modeling of traveltimes. Based on the solution of this equation, we present topography-dependent eikonal traveltime tomography (hereafter TDETT) for seismic modeling of the upper crust. First-arrival traveltimes are calculated using the TDEE solver and the raypaths with the minimum traveltime that can be found by following the steepest traveltime gradient from the receiver to the source. By solving an algebraic equation system that connects the slowness perturbations with the already determined traveltimes, these variables can be obtained making use of the back-projection algorithm. This working scheme is evaluated through three numerical examples with different topographic complexities that are conducted from synthetic data and a fourth example with somewhat more complicated topography and real data acquired in northeastern Tibet. The comparison of the results obtained by both methods, i.e., physical space expansion above the irregular surface and irregular surface flattening, fully validates the tomography scheme that is proposed to construct seismic velocity models with nonflat topography.
机译：具有非平坦地形的地壳的地震建模可以通过首次到达的旅行时间层析成像来完成，这需要面对不规则的自由表面。解决此问题的可行方法包括，除了使用经典的Eikonal方程求解器进行行程时间计算外，还可以通过在不规则表面上方重叠低速层来扩展物理空间，从而获得平坦的地形。但是，此方法的不良后果包括由于从作为自由边界的不规则表面过渡到位于扩展计算空间中的内部不连续性而导致的地震射线偏差。最近，通过制定依赖于地形的电子方程（TDEE）和用于行进时间正向建模的新求解器，提出了另一种解决方案，称为不规则表面平坦化，涉及曲线和笛卡尔坐标系之间的转换。基于该方程的解，我们提出了与地形有关的真实旅行时间断层扫描（以下简称TDETT），用于上地壳的地震建模。使用TDEE求解器和具有最小传播时间的射线路径来计算首次到达的传播时间，可以通过遵循从接收器到源的最陡的传播时间梯度来找到。通过求解将慢度扰动与已经确定的行进时间联系起来的代数方程组，可以利用反投影算法获得这些变量。通过从合成数据中进行的三个具有不同地形复杂性的数值示例对这​​个工作方案进行了评估，而第四个示例是在西藏东北部获得的地形和实际数据稍微复杂一些的示例。通过比较两种方法获得的结果，即不规则表面上方的物理空间扩展和不规则表面平坦化，可以充分验证提出的构造非平面地形地震速度模型的层析成像方案。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号