Propagation of Rayleigh and Scholte waves along edge of quarter-space

Abstract

A surprisingly large leaky Rayleigh wave component has been observed propagating along the edge of a laboratory nonsaline-ice quarter-space in water with both source and receiver positioned along the edge of one of the two surfaces of the quarter-space. Studies on different solids (aluminum, Plexiglas, limestone) indicate that all surface and interface edge waves travel slower than their corresponding waves on a solid half-space. The measured ratio of the edge Rayleigh wave velocity to the half-space Rayleigh wave velocity is 0.9617 for aluminum 6061, 0.9665 for Plexiglas, and 0.9954 for limestone. Ultrasonic experimental results are presented on edge Rayleigh waves, and on edge leaky Rayleigh waves and Scholte waves for the liquid/solid case. The edge wave has no geometrical spreading and dominates the received signal when the receiver is moved slightly away from the water loaded edge of the quarter space. The Rayleigh waves along the horizontal and vertical faces at the edge are out of phase influencing the radiation of the leaky Rayleigh wave for the water-loaded case. Near the edge it is observed that a decrease in the Scholte wave signal is accompanied by an increase in the leaky Rayleigh wave signal. The leaky Rayleigh wave velocity for the water/ice is slightly smaller than the shear wave velocity at the onset of the signal. [Work supported by DREP and ONR.]