Minimum travel time tree algorithm for seismic ray tracing: improvement in efficiency

The computational efficiency of the basic minimum travel time tree (MTTT) algorithm for seismic ray tracing is improved by means of dynamically adjusting the pre-defined propagation area of secondary waves according to the spread of seismic waves. The improvement on the MTTT algorithm is achieved explicitly by limiting the calculation of seismic rays and travel times to a small pre-defined propagation area of secondary waves and to the secondary waves from the points around the straight elongation of the incoming ray. Numerical examples verify that a good approximation of travel times and ray paths can be obtained with the improved algorithm using a small pre-defined propagation area of secondary waves even for complex models. Furthermore, the denser a grid coverage a model has, the greater the improvement in computational efficiency the new algorithm makes. The computational efficiency is more obvious for a 3D model than for a 2D one.