Early-arrival waveform inversion for near-surface velocity and anisotropic parameters: modeling and sensitivity kernel analysis

Early-arrival waveform inversion for near-surface velocity and anisotropic parameters: modeling and sensitivity kernel analysis

Xukai Shen

Abstract:

Understanding the relationships between vertical velocity, anisotropic parameters $\epsilon$ , $\delta$ and traveltime is important both for parametrization of waveform inversion and proper interpretation of waveform inversion results. Forward modeling indicates that traveltime is more sensitive to vertical velocity and $\epsilon$ than to $\delta$ . This suggests that $\delta$ may be fixed during an inversion for vertical velocity and $\epsilon$ . When vertical velocity and $\epsilon$ are directly parametrized, $\epsilon$ changes little during the inversion. A more balanced sensitivity kernel can be obtained by using different parametrizations, such as the vertical and horizontal velocities, or the logarithms of slowness and $\epsilon$ .