Radiation Patterns of Seismic Surface Waves from Buried Dipolar Point Sources in a Flat Stratified Earth

Explicit compact expressions were obtained for the far displacement field of Rayleigh and Love waves generated by force configurations which served to simulate sheartype faults with arbitrary dip and slip. The medium transfer functions for dipolar sources were computed for a Gutenberg fiat continental earth model with 23 layers. These were then used to obtain universal radiation pattern charts for coupleand double-couple-type sources at various depths over the period range 50 to 350 sec. It was demonstrated by means of few typical examples that the radiation patterns of Rayleigh waves may depend strongly on the depth of the source, and unlike the fundamental Love mode may be rather sensitive to small variations in frequency. For a given source and frequency the radiation pattern may differ considerably from one mode to another.