PROPAGATION OF ELASTIC WAVES IN LAYERED MEDIA BY ...

390 BULLETIN OF THE SEISMOLOGICAL SOCIETY OF AMERICAand PiPtP2, are indicated on the theoretical seismograms for purposes of comparison.(5) Interface Wave Series. Figures 17 and 18 show a series of theoretical seismogramsat a fixed observation point located on the interface between two semi-infinitemedia. A point source of compressional waves emitting a pulse of width 4A = .8 islocated in the upper medium. The observation point is located on the interface at adistance equal to four times the height of the source above the interface. This16,0A×RRECEIVER ON SURFACE IAT DISTANCE 2h / /8.O I I< ,.o z'.o t,,~,/a/AxR28.0 RECEIVER ON SURFACE / I /~,.o 2.o 3.0 ~ 4"~.o ~/"-~.c t%/a8.0~,~P, ,Ps, P,/~,P~S,i P, ss, he' P'P, /I16.0 / / AxR2HRECEIVER ON SURFACE ~ [~x AT D,STANCE 4h I 18.0e,s,-- fvsl/,:I,.o ~.o ~.o ~ \\//~.oy-8.0 P,~ P, ~s, ~s~ P, ,~,P,s,.s,FIG. 15. Horizontal and vertical displacements on the surface of a layered half-space (continuationof Figure 14). The three curves are for observation points located at distances of two-,three- and four-layer thicknesses from the epicenter.