In Chapter , I introduce the concept of tau (vertical travel-time) tomography and derive the operator relating changes in slowness to moveout errors in tau space. I show how tau tomography is less sensitive to the initial guess at reflector position and slowness estimate. Figure 8 shows the model of Figure 4 with the correct and initial reflector positions in depth (left) and tau (right).
On a synthetic I show how performing tomography in tau rather than depth better constrains the slowness changes. I show that the tau tomography problem converges faster to a more reasonable result than its depth counterpart. The resulting migration is better focused and the reflectors are better positioned by doing tau rather than depth tomography.