- Ground-motion model is:
where A

_{e}is in cm∕s2, for A_{e}≥ 160cm∕s2 a_{1}= 0.28, a_{2}= -0.8 and a_{3}= 1.70 and for A_{e}< 160cm∕s2 a_{1}= 0.80, a_{2}= -2.3 and a_{3}= 0.80 (σ not given). - As a rule, PGA corresponds to S-wave.
- Use five source mechanism categories (about 70 records, 59 earthquakes from W. N. America including Hawaii,
Guatemala, Nicaragua, Chile, Peru, Argentina, Italy, Greece, Romania, central Asia, India and
Japan):
- 1.
- Contraction faulting (uplift and thrust), about 16 earthquakes.
- 2.
- Contraction faulting with strike-slip component, about 6 earthquakes.
- 3.
- Strike-slip, about 17 earthquakes.
- 4.
- Strike-slip with dip-slip component, about 6 earthquakes.
- 5.
- Dip-slip, about 9 earthquakes.

- Use these approximately 70 records to derive ratios of mean measured, A
_{0}, to predicted PGA, A_{e}, log(A_{0}∕A_{e}), and for ratios of mean horizontal to vertical PGA, log A_{h}∕A_{v}, for each type of faulting. Use every earthquake with equal weight independent of number of records for each earthquake. - Results are:
Category 1 Category 2 Category 3 Category 4 Category 5 log A _{0}∕A_{e}0.35 ± 0.13 (16) 0.11 ± 0.17 (5) 0.22 ± 0.08 (17) 0.06 ± 0.13 (6) -0.06 ± 0.20 (9) log A _{h}∕A_{v}0.32 ± 0.13 (12) 0.32 ± 0.08 (5) 0.27 ± 0.07 (12) 0.18 ± 0.10 (5) 0.17 ± 0.11 (5) where ± gives 0.7 confidence intervals and number in brackets is number of earthquakes used.

- Also calculate mean envelope increasing speed for P-wave amplitudes, A, obtained at teleseismic distances: n = dlnA∕dt, where t is time for P-wave arrival and try to relate to ratios for each type of faulting.