Point source in a layer overlying a semi-infinite solid with special reference to diffracted waves - a periodic source

Abstract

The author has discussed the problem of a point source of dilatational waves in a homogeneous, isotropic, perfectly elastic layer overlying a homogeneous, isotropic, perfectly elastic halfspace in a previous paper. There it is supposed that the disturbance is harmonic with respect to time. In the present paper the work is extended to the Lamb pulse and surface displacements at great epicentral distances are obtained. Theoretical seismograms, showing relative magnitude and times of arrival of different pulses, are obtained for two values of the source depth. As for the harmonic source it has been found that the contribution due to the diffracted waves is small as compared to that due to the minimum-time-path waves, the main contributor to the response curve being the direct and the reflected waves.