Computation of Synthetic Seismograms with the Reflectivity Method and Comparison with Observations

The reflectivity method for the computation of synthetic seismograms, as devised by Fuchs, is extended to include the elastic transmission losses and time shifts due to a stack of layers on top of the reflecting medium. Numerical details of this method are described, and a comparison with the ray-theoretical method, as devised by Müller, is given. The results of both methods agree well if the models are not too complicated. The field of application of these methods is the comparison with observed seismograms obtained from refraction studies of the Earth's crust and upper mantle. The reflectivity method is applied to the interpretation of observations along a profile in Central Europe. The compressional velocity of the lower crust beneath this profile increases gradually without showing a pronounced structure. At the Mohorovčić discontinuity whose depth is about 27 km the velocity increases from 6.8 to 8.0 km s−1. The zone immediately below the Moho is homogeneous, followed by an increase in velocity to 8.15 km s−1 at a depth of about 35 km.