- Ground-motion model is:
where Y is in cm∕s2; α

_{1}= 0.4648, α_{2}= 0.9125, α_{4}= -0.0118 and σ = 0.77 for horizontal PGA; and α_{1}= -0.1276, α_{2}= 0.9384, α_{4}= -0.0111 and σ = 0.75 for vertical PGA. - Data from 56 NEHRP class B (rock) sites.
- Focal depths between 10 and 29km. Do not include this in model based on previous study.
- Use data from 1985 to 2004 from free-field stations. Dataset quite well balance w.r.t. number of records for each event.
- Data reasonably well distributed but data predominantly from M
_{w}≤ 6. - Baseline correct and high-pass filter data (0.05Hz cut-off for M
_{w}> 6.5 and 0.1Hz otherwise). - Use quadratic mean to combine horizontal components because likely to be slightly more conservative than geometric mean.
- Constrain geometric decay coefficient to -0.5 to avoid unrealistic values.
- Examine residuals w.r.t. M
_{w}and R and find no trends.