caa a22 4500 477047092 CHVBK 20180405111333.0 cr unu---uuuuu 170330e19960301xx s 000 0 eng 10.1007/BF00882060 doi (NATIONALLICENCE)springer-10.1007/BF00882060 Radiation patterns of point sources situated close to structural interfaces and to the earth's surface [Elektronische Daten] [Pert Jílek, Vlastislav Červený] The seismic wave field is considerably influenced by local structures close to the source and to the receiver. This applies to sources and receivers situated close to localized inhomogeneities, to structural interfaces, to the earth's surface, etc. In this paper we concentrate our attention mainly to the ray-theoretical radiation patterns of point sources situated close to the structural interfaces and to the earth's surface. In numerical modeling of high-frequency seismic wave fields by the ray method, the interaction of the source with the earth's surface has not usually been taken into account. The proposed procedure of the computation of the radiation patterns of point sources situated directly on structural interfaces and on the earth's surface is based on the zero-order approximation of the ray method, assuming that the length of the ray between the source and the receiver is long. The derived equations are extended to point sources located close to structural interface, to the earth's surface and to thin transition layers using the hybrid ray-reflectivity method, seeČervený (1989). The thin layer need not be homogeneous; it may include an arbitrary inner layering (transition layers, laminas, etc.) The only requirement is for the layer to be thin. Roughly speaking, we require its thickness to be less than one quarter of the prevailing wavelength. The hybrid ray-reflectivity method describes well even certain non-ray effects (tunneling.S * waves, etc.). Explicit analytical expressions for radiation patterns for all above listed point sources are found. These expression have a local character and may be easily implemented into computer codes designed for the routine computation of ray amplitudes and synthetic ray seismograms in 2-D and 3-D, laterally varying isotropic layered and block structures by the ray method. Numerical examples of radiation patterns ofP andS waves of point sources situated close to the earth's surface and to a thin low-velocity surface layer are presented and discussed. The explosive point source (center of dilatation) and the vertical and horizontal single force point sources are considered. It has been ascertained that the radiation patterns of point sources depend drastically on the depth of the source below the surface even if the depths vary within one quarter of the prevailing wavelength. Birkhäuser Verlag, 1996 Ray-theoretical radiation pattern of point sources nationallicence sources close to structural interfaces nationallicence sources close to the earth's surface nationallicence explosive sources nationallicence single force point sources nationallicence S * waves nationallicence Jílek Pert Department of Geophysics, Charles University, Ke Karlovu 3, 121 16, Praha 2, Czech Republic aut Červený Vlastislav Department of Geophysics, Charles University, Ke Karlovu 3, 121 16, Praha 2, Czech Republic aut pure and applied geophysics Birkhäuser-Verlag 148/1-2(1996-03-01), 175-225 0033-4553 148:1-2<175 1996 148 24 https://doi.org/10.1007/BF00882060 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00882060 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Jílek Pert Department of Geophysics, Charles University, Ke Karlovu 3, 121 16, Praha 2, Czech Republic aut NATIONALLICENCE 700 1- Červený Vlastislav Department of Geophysics, Charles University, Ke Karlovu 3, 121 16, Praha 2, Czech Republic aut NATIONALLICENCE 773 0- pure and applied geophysics Birkhäuser-Verlag 148/1-2(1996-03-01), 175-225 0033-4553 148:1-2<175 1996 148 24 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer