Velocity tomography based on turning waves and finite-frequency sensitivity kernels

Abstract

We present a velocity tomography method, which is based on finite-frequency sensitivity kernels and applied to turning waves in models with generally positive velocity gradient. The finite-frequency sensitivity kernels are calculated using the one-way propagator. They replace the ray tracing to create links between the velocity model errors and the observed travel time residuals. The new approach is a wave-equation based method and wave phenomena are naturally incorporated. To demonstrate the inversion process, numerical examples are presented. For 2D velocity models with 10% to 30% velocity errors, we generate the synthetic data set. The travel time differences between seismograms from the true velocity model and those from the initial (intermediate) model are used as input data. The inversion is solved in an iterative way and the velocity models can be successfully updated.