ON THE RESONANCE OF A 2-DIMENSIONAL ALLUVIAL VALLEY

This paper describes a study of the resonance phenomenon of a 2-D allu vial valley embedded in a half-space and subjected to an incident plan e SH wave. The scattered wave and refracted wave are expressed as a se ries of basis functions, and both the scattered and refracted coeffici ents can be related to the incident wave by the so-called T-matrix met hod. By using singular-value decomposition and solving the eigenvalue problem, one can decouple the effects of all resonance modes. Therefor e, the amplification factor of each partial eigenwave can be found, an d used to determine the resonance frequencies of each normal mode and its overtones. The motion of the ground subjected to the incident plan e SH wave and the mode shape of each single normal mode are determined and discussed for semicircular and semi-elliptical alluvial valleys.