1. The following common abbreviations have been used:
2. AGU -American Geophysical Union Transactions.
3. BSSA -Bulletin of the Seismological Society of America.
4. A. B. ANDREWS , 1957 , "Frequency Dependence of Seismic Wave Attenuation " Unpublished Ph. D. Thesis , Penn. State Univ., Abstract in Geophysics, v. 23 , p1075 .