An experimental study of the seismic ringing of the moon

Abstract

The seismic records obtained from the seismic station ALSEP (Apollo Lunar Surface Experiments Package) on the moon, due to the impact of the LM (Lunar Module) of the Apollo XII and the S-IVB rocket state of the Apollo XIII moon missions show the seismic signals decaying in amplitude slowly with time. The observed ringing phenomenon on these records along with the fact that the disturbances lasted for a long period were unexpected. Laboratory experiments on homogeneous spheres have produced this ‘ringing’. The physical explanation of this may be complicated, and it is quite possible that this observed ringing is due to the combined effect of the filtering, reflections and scattering of energy due to the curvature of the homogeneous (in the seismic sense) sphere. The explanation of the ‘ringing’ of the moon may very well lie in such a study.