二阶Born近似有限频率走时敏感核

发布时间：2018-06-01 09:20

本文选题：二阶Born近似 + 有限频理论　；参考：《地球物理学报》2016年03期

【摘要】：有限频率层析成像考虑了非均匀介质中波的散射、衍射、波前愈合等物理性质,使得其对速度异常体的分辨能力远大于射线层析成像.推导和计算有限频率敏感核是进行有限频率层析成像的关键,当前推导有限频率敏感核多借助一阶Born近似,但这只适用于弱散射介质的情况.本文基于二阶Born近似并利用傅里叶变换推导了三维均匀介质情况下有限频率敏感核的解析表达式,并将其推广到非均匀介质中得到了三维非均匀介质中有限频率敏感核.研究表明:当介质中速度扰动小于2%时,基于二阶Born近似的有限频率敏感核与基于一阶Born近似的有限频率敏感核差别很小,可近似认为相同;当介质中速度扰动大于5%时,基于二阶Born近似的有限频率敏感核与基于一阶Born近似的有限频率敏感核有较大不同,表明此时已不能忽略二次散射.
[Abstract]:The finite frequency tomography takes into account the physical properties of wave scattering, diffraction and wave front healing in inhomogeneous media, which makes the resolution of velocity anomalies much larger than that of X-ray tomography. The derivation and calculation of finite frequency sensitive kernels is the key of finite frequency tomography. At present, most of the finite frequency sensitive nuclei are derived by first-order Born approximation, but this is only suitable for weak scattering media. Based on the second-order Born approximation and Fourier transform, the analytical expressions of finite frequency sensitive kernels in three-dimensional homogeneous media are derived, and the finite frequency sensitive kernels in three-dimensional inhomogeneous media are obtained. The results show that when the velocity perturbation in the medium is less than 2, the difference between the finite frequency sensitive kernel based on the second order Born approximation and the finite frequency sensitive kernel based on the first order Born approximation is very small and can be approximately considered the same, and when the velocity perturbation in the medium is greater than 5, The finite frequency sensitive kernel based on the second order Born approximation is different from the finite frequency sensitive kernel based on the first order Born approximation, which indicates that the secondary scattering can not be ignored at this time.
【作者单位】：中国科学院地质与地球物理研究所;中国科学院大学;
【基金】：中国科学院地质与地球物理研究所自选课题(31531180)
【分类号】：P315.31

【参考文献】