Model Seismology on Characteristics of Surface Waves Generated from a Sinusoidal Source of a Finite Duration

\Ve cannot always define group velocity by dw/d~, because this value some-times becomes zero or negative. Indeed various wave groups may be supposed, but anyone of them will be important which can have considerable amplitudes. Sometimes a wave group will predominate in practice when dw/d ~ coincides with x/t, but sometimes it will not. In the latter case, none or another wave group may be observed. Surface waves were generated from a pulse and from sinusoidal waves of a finite duration in the same two dimentional model. Characteristics, namely group velocity and relative amplitude, of them have been coincided with each other. The group velocity defined by xlt in practice has been found to coincide also with a part of the calculated curve giving dw/d~. On the part, condition dw/d~=x/t must be satisfied. However, the other part of dispersion curves calculated leaves some questions in future. 1. Conception of group velocit