On the sensitivity of teleseismic full-waveform inversion to earth parametrization, initial model and acquisition design
On the sensitivity of teleseismic full-waveform inversion to earth parametrization, initial model and acquisition design
复制标题
远震全波形反演对地球参数化、初始模型和采集设计的敏感性
DOI：
--
复制
发表时间：
2018
期刊：
影响因子：
--
通讯作者：
G. Nolet
中科院分区：
文献类型：
--
作者：
S. Beller;V. Monteiller;L. Combe;S. Operto;G. Nolet
摘要 全波形反演（FWI）还不是一种成熟的远震数据岩石圈成像技术。因此，需要根据远震实验的规范更准确地评估其前景和缺陷。三个重要问题涉及（1）用于优化和可视化的岩石圈参数化的选择，（2）初始模型和（3）采集设计，特别是在接收器扩展和采样方面。这三个问题是通过受西阿尔卑斯山 CIFALPS 实验启发的现实综合示例进行研究的。各向同性弹性 FWI 采用伴随状态形式实现，旨在通过最小化经典的基于最小二乘差的失配函数来更新三个参数类别。首先根据辐射方向图讨论三种不同的地下参数化，将密度 (ρ) 与 P 和 S 波速度（Vp 和 Vs）、P 和 S 阻抗（Ip 和 Is）或弹性模量（λ 和 μ）相结合，然后再通过 FWI 进行评估。我们得出的结论是，在将 (ρ, λ, μ) 优化参数后验重新组合为 Ip 和 Is 后，(ρ, λ, μ) 参数化提供了与真实模型最相关的 FWI 模型。由于远震数据的低频内容，PREM 等一维参考全局模型在平滑后为 FWI 提供了足够准确的初始模型，这是消除分层印记所必需的。评估了两种站点部署：粗略的平面几何形状与密集的线性几何形状。我们明确地得出结论，应该青睐粗糙的面几何形状，因为它可以显着增加成像深度的穿透力以及水平分辨率。这是因为与线性部署相比，面几何形状通过更广泛的散射和倾角采样，显着增加了局部波数覆盖范围。
S U M M A R Y Full-waveform inversion (FWI) is not yet a mature imaging technology for lithospheric imaging from teleseismic data. Therefore, its promise and pitfalls need to be assessed more accurately according to the specifications of teleseismic experiments. Three important issues are related to (1) the choice of the lithospheric parametrization for optimization and visualization, (2) the initial model and (3) the acquisition design, in particular in terms of receiver spread and sampling. These three issues are investigated with a realistic synthetic example inspired by the CIFALPS experiment in the Western Alps. Isotropic elastic FWI is implemented with an adjoint-state formalism and aims to update three parameter classes by minimization of a classical least-squares difference-based misfit function. Three different subsurface parametrizations, combining density (ρ) with P and S wave speeds (Vp and Vs) , P and S impedances (Ip and Is), or elastic moduli (λ and μ) are first discussed based on their radiation patterns before their assessment by FWI. We conclude that the (ρ, λ, μ) parametrization provides the FWI models that best correlate with the true ones after recombining a posteriori the (ρ, λ, μ) optimization parameters into Ip and Is. Owing to the low frequency content of teleseismic data, 1-D reference global models as PREM provide sufficiently accurate initial models for FWI after smoothing that is necessary to remove the imprint of the layering. Two kinds of station deployments are assessed: coarse areal geometry versus dense linear one. We unambiguously conclude that a coarse areal geometry should be favoured as it dramatically increases the penetration in depth of the imaging as well as the horizontal resolution. This results because the areal geometry significantly increases local wavenumber coverage, through a broader sampling of the scattering and dip angles, compared to a linear deployment.
影响因子：
2.8
作者：
Bozdag, Ebru;Peter, Daniel;Pugmire, David
通讯作者：
Pugmire, David