Further model study of the radiation of elastic waves from a dipole source

Earthquake-generated compressional and shear waves have been used extensively in recent years for studying the mechanism at the focus? In general the procedure is to compare the radiation pattern of these waves with the theoretical pattern derived from simple sources such as singlets, dipoles, quadrupoles, etc. The importance of these investigations to our understanding of tectonic processes makes it desirable to examine the methods with a view toward placing them on a firm theoretical and experimental foundation. One approach is to use the methods of ultrasonic-model seismology to determine whether or not the radiation pattern postulated for certain sources is actually observed. The effects of various perturbations such as finite fault length and elastic heterogeneity near the focus can be conveniently examined.