A New Approach to Derive NMO Velocity and Moveout for Seismic Waves in HTI Media

We have derived anisotropic moveouts of seismic waves in HTI media by a new approach. In this approach, we use the idea of rotating VTI media into HTI media to study the behavior of the velocity and moveout of seismic waves in HTI media. This is achieved by developing a relationship between the incident angle and azimuth angel in HTI media and the angle to the symmetry axis in VTI media. In this approach, we firstly derive two general definitions which easily define the NMO velocity and the quadratic parameter in VTI media. Based on these definitions and the relationship between the angles of VTI and HTI media, we derived the exact formula of NMO velocities and anisotropy parameters of P, SV and SH waves in HTI media. The NMO velocities in HTI media obtained in this approach are exactly elliptical for any strength anisotropy. Based on the NMO velocity and anisotropy parameters, we also derived the exact format of moveout for P and SV waves. For weak HTI media, a unified moveout for P and SV waves is obtained.