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

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