- Ground-motion model is:
where A is in cm∕s2, a = 7.7, b = 0.49, c = 1.45, d = 0.19, h = 25.0 and σ = 0.46.
- Model soil using its fundamental period of the overburden soil, Ts. Thickness of deposit defined as depth
to rock base, defined either as V s > 800m∕s or when ratio of shear-wave velocity in ith layer to shear-wave
velocity in i-1th layer is greater than 2 (only calculate period to 100m because only have important effect
on structure). For outcropping rock, Ts = 0.05s.
- Eight distance intervals used for weighting, five 10km wide up to 50km, 50–69.9km, 70–99.9km and
100–200km. Within each interval each earthquake received equal weight, inversely proportional to number
of records from that earthquake in interval.
- Use resolve accelerations in direction, θ, which gives largest value. Find scatter is lower than for larger
- Many (27) earthquakes only have one record associated with them and 60 records are from San Fernando.