Summary of the algorithm

The tomographic velocity analysis method with planewave synthesis imaging presented in this chapter can be summarized as follows:

• Define an initial model w.
• Begin Loop

  1.

  Event picking:

  • Perform surface-oriented planewave synthesis imaging.
  • Pick dominant reflectors in the stacked image.

  2.

  Measuring the traveltime error:

  • Perform reflector-oriented planewave synthesis imaging for each reflector.
  • Do RMO velocity analysis for each reflector picked.
  • Select $\gamma$ based on semblance value.
  • Convert $\gamma$ to $\Delta t$.

  3.

  Calculating the slowness error from the traveltime error:

  • Calculate $\Delta w$ by inverting $\Delta t$ using conjugate gradient.
  • Update $w = w + \Delta w$.

  4.

  Convergence test: If $\Delta w$ is small, exit from the loop.

• END Loop