Phase velocity of surface waves in the transition zone of continental margins: 1. Love waves

Abstract

The phase velocity of surface waves in the transition zone of a thickening layer is found to be severely influenced by back reflections from the structure beyond the seismic observatory. This feature is more important in producing phase shifts than is the shift in the eigen-value due to the inclined geometry. The effect of an inclined upper surface and an inclined Moho on the phase velocities of Love waves in a single layer are computed. For surface waves traveling from the thinner to the thicker layer, the upper surface produces no calculable effect. For both directions of propagation for an inclined Moho and for propagation from the thicker to the thinner layer for an inclined upper surface, the effect is a maximum in the period range 25 to 45 sec and has a phase shift whose sign is undeterminable in the absence of precise information about the geometry.