where a is in cm∕s2, a1= 1.31, a2= -0.92 and a3= 1.455 (σ is not given).
Uses data from former USSR, former Yugoslavia, Portugal, Italy, Iran, Greece and Pakistan.
Peak ground accelerations have either been taken from true-to-scale accelerograms or have been supplied
by local networks. Records have not been high- or low-pass filtered because it was found not to work with
Believes body-wave or local magnitude are the appropriate magnitude scales because interested in the
high-frequency range of spectra, which are seen and sampled by strong-motion instruments, and most
engineering structures have high natural frequencies.
Most of the magnitudes were recalculated using P-waves of periods of not more than 1.2s because it was
found that the magnitude was dependent on the period of the P-waves used for its determination.
Groups data into intervals of 0.5 magnitude units by 10km in which the mean and standard deviations of
the PGAs is calculated. This grouping minimises distance and magnitude-dependent effects. Notes that
the number of observations is barely sufficient to allow a statistical treatment of the data and hence only
test general trend. Notes that scatter is significant and decreases with increasing magnitude.