A search algorithm for first break traveltime in 2D TTI medium

A search algorithm presented in this paper is directly based on the exact relations of phase velocity with phase angle, group angle with phase angle, and group velocity with phase velocity given by Thomsen (1986). By combining nonlinear interpolation of traveltime and inverse interpolation from group angle to phase angle, the local search of traveltime is realized. After total search of traveltime, calculations of first breaks of seismic waves in TTI medium is completed. Model tests show that the algorithm is suitable for both weak and strong anisotropic TTI medium with arbitrary slanting symmetry axis and obtain first break traveltime with high precision.