Wavepath Tomography for Model Building and Hazard Detection

In complex velocity models, such as below rugose salt bodies, wavefield continuation migration is usually superior to Kirchhoff methods because of multi-pathing, sharp velocity contrasts and the bandlimited nature of seismic wave propagation. Wavepath tomography offers a way to build the velocity model in a way that is consistent with the migration operator: instead of tracing rays to backproject residual velocities, a "wavepath" is constructed using the actual wavefield continuation operator to represent the wave propagation between surface source/receiver pairs and subsurface reflection points by multiplication of impulse responses downgoing from the surface location and upgoing from the reflection point. The size of the inversion is kept manageable by restricting the wavepath to the first Fresnel zone. We demonstrate the applicability and superiority of this approach for building complex velocity models in areas of salt tectonics and for hazard detection.