Spectral ratio of the horizontal and vertical Rayleigh wave components andits application to some problems of seismology

According to the theory of surface wave propagation in weakly heterogeneous media, the kinematic and amplitude wave characteristics should be the same as in a laterally homogeneous medium. Consequently, one may expect that th e spectral ratio of the radial and vertical components of Rayleigh waves re corded at any station should be controlled by the velocity structure under the station. However, the analysis of the amplitude ratio of the radial and vertical components recorded at the Obninsk station indicates that its fre quency dependence is not the same for different earthquakes and significant ly varies with the station-to-epicenter azimuth. This can be attributed to the fact that the real structure of the crust and upper mantle is inconsist ent with assumptions about the weak lateral heterogeneity of the medium. As suming that averaging over different azimuths can suppress the path effects , a model consistent with the average ratio of spectra is constructed for t he lithosphere under the Obninsk station. The ratio of spectra obtained fro m observations can be used for calculating the radial component of the Rayl eigh wave from records of the vertical component, thereby enabling the elim ination of the Rayleigh wave from the radial component of a record. Hence, the azimuthal anomaly of the Love wave can be determined from records of th e tangential and radial components (the latter with the removed Rayleigh wa ve).