- Ground-motion model is:
where A is in cm∕s2, c1 = -0.5342, c2 = 2.1380, c3 = 0.4440, c4 = 1.4821 and σ = 0.28 for horizontal
PGA and c1 = -0.5231, c2 = 1.9876, c3 = 0.5502, c4 = 1.4038 and σ = 0.27 for vertical PGA.
- Most stations on rock or firm ground. 4 instruments (from close to coast) installed on sandy or silty-sandy
soils. Not enough data to correct for site effects or derive site coefficients. Check residuals (not shown) for
each station and find no systematic bias.
- Focal depths h between 3.4 and 76.0km (most < 40km). No correlation between h and repi.
- Use data from 12 (5 Etnas and 7 GSR-18s) temporary and 5 permanent strong-motion stations.
- Since data from digital instruments only apply baseline correction.
- Exclude data from 3 events only recorded at 3 stations.
- Relocate earthquakes because of poor locations given by agencies. Recompute ML from accelerograms.
- Inclusion of h leads to less scatter but note need for larger database to better understand effect of h.
- Examine residuals w.r.t. distance and find no trend or bias.