- Ground-motion model is:
where PGA is in gal, C0 = 0.192, C1 = 0.867, C2 = -0.294, C3 = -0.008, C4 = 0.113 and σ = 0.903.
- Use 2 site classes:
- Class 1 (rock and hard alluvial with V s,30 > 800m∕s) and class 2 (thin soft alluvial with 500 ≤
V s,30 ≤ 700m). S = 0.
- Class 3 (soft gravel and sandy sites with 300 ≤ V s,30leq500m∕s) and class 4 (soft soil with
V s,30 < 300m∕s). S = 1.
- Use data of Zaré and Bard (2002).
- Select records with PGA of any component > 0.05m∕s2.
- Choose functional form because it is simple and hence avoids computational difficulties.
- Use repi rather than rhypo because of uncertainties in focal depth estimates and because almost all
earthquakes have depths ≤ 35km.
- Originally use coefficients for each of the 4 site classes of Zaré and Bard (2002) but find that the order
of predicted PGAs is not as expected (e.g. PGAs on site class 4 are smaller than those on site class 2).
Therefore, combine the original classes 1 and 2 together and classes 3 and 4 together.
- Plot residuals w.r.t. predicted PGA and find no trend.