1. Elsasser, W. M., The Application of Modern Physics to the Earth and Planetary Interiors, NATO Institute, Newcastle (in the press, 1969).
2. Isacks, B., Oliver, J., and Sykes, L. R., J. Geophys. Res., 73, 5855 (1968).
3. Isacks, B., Sykes, L. R., and Oliver, J., Bull. Geol. Soc. Amer., 80 (in the press).
4. Burridge, R., and Knopoff, L., Bull. Seis. Soc. Amer., 54, 1875 (1964).
5. Savage, J. C., Bull. Seis. Soc. Amer., 55, 263 (1965).