f 2D Modelling of thin layers

Forward modelling of seismic response of thin layers is not perforrned satisfactorily by conventional techniques. Finite-Difference methods stumble upon small grids, Ray-Tracing becomes cumbersome with conversions, multiples and post critical effects, and Reflectivity works only with horizontal layers. Hybrid schemes that join ray methods with reflectivity might offer a useful low-cost alternative [1,2]. Our scheme uses rays to transport the reflectivity of thin-layered small-scale discontinuities across large scale homogeneities. Conversely transmissivity - that takes into account interbed reverberation and conversions - correctly energizes transmitted rays, even in post critical situations.