Deriving Sensitivity Kernels of Coda-Wave Travel Times to Velocity Changes Based on the Three-Dimensional Single Isotropic Scattering Model
Deriving Sensitivity Kernels of Coda-Wave Travel Times to Velocity Changes Based on the Three-Dimensional Single Isotropic Scattering Model
复制标题
基于三维单一各向同性散射模型推导尾波传播时间对速度变化的灵敏度核
DOI：
10.1007/s00024-016-1358-0
复制
发表时间：
2017
影响因子：
2
通讯作者：
Nakahara H. and K. Emoto
中科院分区：
文献类型：
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作者：
吉本和生;Nakahara H. and K. Emoto
近年来，尾波干涉测量法已被用于监测地下结构的时间变化。用尾波干涉测量法可以探测到与大地震和火山爆发有关的地震速度变化。为了约束速度变化的空间范围，通常假定空间均匀性。然而，正确定位速度变化的区域以了解引起速度变化的物理机制是很重要的。本文研究了尾波传播时间对速度变化的敏感性核。在以往的研究中，已经建立了二维单次散射和多次散射、三维多次散射和扩散的灵敏度核。本文给出并推导了三维单散射情况下的灵敏度核的解析表达式。这些灵敏度核在源和接收位置均显示两个峰值，这与先前使用不同散射模型的研究相似。随着时间的推移，这两个峰更加明显。我们通过与声波传播的有限差分模拟进行比较来验证我们的公式。我们的公式使我们能够分析地评估灵敏度核，这对于分析来自较深地震的体波特别有用。
Recently, coda-wave interferometry has been used to monitor temporal changes in subsurface structures. Seismic velocity changes have been detected by coda-wave interferometry in association with large earthquakes and volcanic eruptions. To constrain the spatial extent of the velocity changes, spatial homogeneity is often assumed. However, it is important to locate the region of the velocity changes correctly to understand physical mechanisms causing them. In this paper, we are concerned with the sensitivity kernels relating travel times of coda waves to velocity changes. In previous studies, sensitivity kernels have been formulated for two-dimensional single scattering and multiple scattering, three-dimensional multiple scattering, and diffusion. In this paper, we formulate and derive analytical expressions of the sensitivity kernels for three-dimensional single-scattering case. These sensitivity kernels show two peaks at both source and receiver locations, which is similar to the previous studies using different scattering models. The two peaks are more pronounced for later lapse time. We validate our formulation by comparing it with finite-difference simulations of acoustic wave propagation. Our formulation enables us to evaluate the sensitivity kernels analytically, which is particularly useful for the analysis of body waves from deeper earthquakes.