Experimental results on bulk waves and Rayleigh waves in slate

Abstract

This paper describes experimental results on velocity measurements of bulk and Rayleigh waves in a highly anisotropic natural medium (slate). Bulk waves velocities are measured using a standard ultrasonic pulse transmission setup. The Rayleigh waves are excited using the wedge technique and recorded by an interferometer which detects both the in-plane and out-of-plane components of the displacement they produce in a point of a sample surface. The experiments constitute part of a study of the propagation of surface seismic waves in anisotropic geological structures using scaled-down models. The elastic behavior of a block of slate whose faces are traversed by these surface waves is studied, and it is verified that this rock shows a good fit to a physical model of a solid with an axis of symmetry of revolution.