The Transmission of Rayleigh Waves across an Ocean Floor with Two Surface Layers, Part II: Numerical

Abstract

Summary This investigation obtains values of the wave velocity and group velocity of waves of Rayleigh type, following ocean paths corresponding to the structures indicated by experimental investigations using explosions at sea. Eight different models have been considered, with ocean depths 4 or 6 km, a sedimentary layer of depth 1 or 2 km, underlain by basic rocks of thickness 5 or 7 km; in all cases these structures were supposed to rest on ultrabasic rocks of great thickness. The wave velocity was found for a series of values of the wavenumber by solving an eleven-row determinantal equation; the computations were performed by the use of the SEAC electronic computer of the U. S. National Bureau of Standards, and from these values the corresponding values of the group velocity were obtained by numerical differentiation. The general agreement of these dispersion curves with observed values indicates that they should be useful in determining the ray track and time of passage of a train of Rayleigh waves crossing an ocean floor whose structure and depth are varying from place to place.