The history of events occurring near the source following a small explosion has been deduced from the Rayleigh waves recorded at two distances. The Fourier analysis method developed by Sato, and Lamb’s solution for the displacement on a half-space have been employed in two distinct approaches to this problem. The displacement history from the first approach shows an essentially rectilinear vibration of the earth partiele, following the initial compression. The second technique yields the vertical point force equivalent to the explosion. The vertical acceleration at the source from the first method agrees fairly well in general form with the force found in the second.
Information about the phase velocities and the initial phases of the constituent frequency components is a valuable by product of the Fourier analysis technique.