In this paper, we report experiments on the scattering of surface-elastic waves by a periodic array of cylindrical holes. The experiments were performed in a marble quarry by drilling cylindrical holes in two different configurations: honeycomb and triangular lattices. The attenuation spectra of the surface waves show the existence of absolute band gaps for elastic waves in these semi-infinite two-dimensional crystals. Results are compared with theoretical calculations based on a scalar-wave approach. The scaling property of the underlying theory has led us to explore the possible application of the results obtained to the attenuation of surface waves in seismic movements.

This work was partially supported by the Comisión Interministerial de Ciencia y Tecnología of Spain, Contract No. MAT97-0698-C04. We also thank the Consejo Superior de Investigaciones Científicas for the special funding to perform this experiment.

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