Short‐period oceanic surface waves of the rayleigh and first shear modes

Abstract

Waves corresponding to the short‐period segment of the Rayleigh mode and to the first shear mode are identified for paths traversing the deep ocean, apparently for the first time. It appears that the reason for the presence of the waves in this case and their conspicuous absence in all other cases is that (a) the shock which excited these waves is the atomic explosion of Operation Wigwam, deep in the Pacific Ocean; (b) earthquake sources are generally too deep to excite short‐period surface waves efficiently. The new data strongly support the normal mode explanation for the dispersion of Rayleigh waves crossing the Pacific Ocean and furnish supporting evidence for the crustal structures previously deduced from surface wave dispersion and from refraction shooting. The unusual characteristics of the body phases and the T phase may probably be explained, as well, by assuming the source was within the water layer.