ISSN 1004-4140
CN 11-3017/P

多频段组合菲涅尔带走时层析成像方法研究

Fresnel Zone Travel-time Tomography Based on Multi-band Frequencies' Combination

  • 摘要: 针对传统射线层析存在的种种局限性,菲涅尔带走时层析成像摒弃了传统的数学射线,考虑到地震信号具有一定的频带宽度,中央射线附近的介质对地震波的传播产生不同程度的影响。本文提出了多频段组合菲涅尔带走时层析成像方法。该方法以频率域波动方程Born和Rytov近似为基础,推导出建立在带限地震波理论基础上的波动方程Rytov近似走时敏感核函数,实现第一菲涅尔带约束下的波动方程走时层析反演方法。同时由于多个频段的引入,充分利用低频段和高频段的特有优势,从而兼顾菲涅尔带层析的计算效率与分辨率。模型试算结果证明了本方法的有效性和稳定性。

     

    Abstract: To resolve the problems of tomography based on ray theory, Fresnel tomography discards the concept of zero-width geometric ray. Taking into account the seismic signal has a certain bandwidth, high-frequency radiation path not only on the nature of the medium will affect the propagation of seismic waves, rays near the same media features will affect the propagation of seismic waves. We propose the Fresnel zone travel-time tomography based on multi-band frequencies' combination. This paper starts from the Born and Rytov approximation of frequency-domain wave equation to derive the travel-time sensitivity kernels of wave equation on the band-limited wave-field and the travel-time residual can be obtained based on the Rytov approximation at the same time. Meanwhile, we enhance the resolution and precision by combining multiple frequencies during different stages of iteration. The inverted result proves that our method has a higher resolution and accuracy

     

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