INVESTIGATIONS ON THE NONELASTIC BEHAVIOR OF THE UPPER MANTLE
Quarterly narrative progress rept. no. 6, 1 Nov 1966-31 Jan 1967
TECHNISCHE HOCHSCHULE KARLSRUHE (GERMANY F R) GEOPHYSIKALISCHES INST
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The spectrum of seismic body phases radiated from sources within the earths crust is distorted by multiple reflections in the crustal layers. To estimate the crustal distortion crustal transfer functions for P-waves have been computed for sources having a simple radiation pattern in the infinite medium the buried explosive point source standing for an underground explosion, and the vertical point source acting at the free surface of the crust and standing for an atmospheric explosion. The crustal model is taken from Finland. Radiation patterns have been computed for P-waves in the frequency range from 0 to 0.5 cps. An attempt has been made to separate the effect of the free surface from that of the layered crust in case of the explosive source. The latter effect starts to be noticeable at frequencies above 0.3 cps. Using the model for the upper mantle model in Europe Lehmann, 1959 the radiation patterns have been transformed into amplitude-distance functions. Implications for the interpretation of experimental amplitude-distance curves of P-waves are discussed.