abstract

A finite element technique is developed to study the propagation of Love waves across nonhorizontally-layered structures. A half-space is approximated by a rigid base at great depth. Previous results of other authors are confirmed. Detailed models of a continental boundary and of a structure including a slab of lithosphere dipping downard at an angle of 45° are analyzed. For incident fundamental Love-mode motion, at a period of 25 sec, on either side of the model of a continental boundary, the total energy in all of the reflected modes is found to be less than 0.1 per cent of the incident energy, while the energy in the transmitted higher modes is 48 per cent of the incident energy. These results are strikingly different from the results for previous models of a continental boundary. For incident fundamental Love-mode motion, at a period of 25 sec, on the “oceanic” side of the model including the dipping slab, the total energy in the reflected modes is found to be approximately 1 per cent of the incident energy, and that in the transmitted higher modes, 36 per cent of the incident energy. For incident fundamental Love-mode motion, at a period of 25 sec, on the “shallow sea” side of the model including the dipping slab, the total energy in the reflected modes is found to be approximately 3 per cent of the incident energy, and that in the transmitted higher modes, 34 per cent of the incident energy.

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