- Ground-motion model is:
where S(0.02) is in gal, a(0.02) = 0.318, b(0.02) = 0.00164 and c(0.02) = 1.597 (Δs(0.02) and σ only given
- Use two site conditions:
q = 0
- Pre-Quaternary: Rock (sandstone, siltstone, shale, granite, mudstone, etc.); thickness of surface soil
overlying rock is less than 10m; shallow soil or thin alluvium, 160 records. S-wave velocities > 600m∕s.
q = 1
- Quaternary: Soil (alluvium, clay, sand, silt, loam, gravel, etc.), 336 records. S-wave velocities
Exclude records from very soft soil such as bay mud or artificial fill because few such records and ground
motions may be strongly affected by soil nonlinearity.
- Use equivalent hypocentral distance, Xeq, because strong motion in near-source region affected from points
other than nearest point on fault plane.
- Use portion of record after initial S-wave arrival.
- Approximates PGA by spectral acceleration for period of 0.02s and 5% damping.
- Plot the amplitude factors from first stage against Mw; find well represented by linear function.