Distance-Amplitude Relationships for Long-Period P, S, and LR from Measurements on Recordings of the Long-Period Experimental Stations

Measurements on long-period P, S, and LR phases were extracted from an eight-month data base for nine stations of the Long Period Experimental network. Amplitude-distance curves were plotted for P and S from shallow-focus events these curves generally agreed with the commonly-used Gutenberg-Richter B factors. The amplitude-distance curve for LR was different in slope than the commonly-used correction curve for M sub S however, this difference would not be sufficient to affect routine network M sub S estimates by more than roughly . 1 magnitude unit. The Q for 20-second LR implied by this new data is roughly 700, in contrast to the 300 implied by the accepted amplitude-distance curve.