Model regularization for seismic traveltime tomography with an edge-preserving smoothing operator

The solutions of the seismic first-arrival traveltime tomography are generally non-unique, and the Tikhonov model regularization for the inversion is commonly used to stabilize the inversion. However, the Tikhonov regularization for traveltime tomography often produces a low-resolution velocity model. To sharpen the velocity edges for the traveltime tomographic results and fit data at the same time, we should apply the edge-preserving concepts to regularize the inversion. In this study, we develop a new model regularization method by introducing an edge-preserving smoothing operator to detect the model edges in traveltime tomography. This edge-preserving smoothing operator is previously used in processing seismic images for enhancing resolution. We design three synthetic velocity models with sharp interfaces and with or without velocity gradients to study the performance of the regularization method with the edge-preserving smoothing operator. The new edge-preserving regularization not only sharpens the model edges but also maintains the smoothness of the velocity gradient in the layer.