Costa et al. (2006)

Ground-motion model is: $∘ ------- log10(PGA ) = c0 + c1M + c2M 2 + (c3 + c4M )log( d2 + h2) + cSS$
where PGA is in g, c₀ = -3.879, c₁ = 1.178, c₂ = -0.068, c₃ = -2.063, c₄ = 0.102, c_S = 0.411, h = 7.8 and σ = 0.3448 (for larger horizontal component), c₀ = -3.401, c₁ = 1.140, c₂ = -0.070, c₃ = -2.356, c₄ = 0.150, c_S = 0.415, h = 8.2 and σ = 0.3415 (for horizontal component using vectorial addition), c₀ = -3.464, c₁ = 0.958, c₂ = -0.053, c₃ = -2.224, c₄ = 0.147, c_S = 0.330, h = 6.1 and σ = 0.3137 (for vertical).
Use two site classes (since do not have detailed information on geology at all considered stations):
S = 0
Rock
S = 1
Soil
Use selection criteria: 3.0 ≤ M ≤ 6.5 and 1 ≤ d_e ≤ 100km.
Bandpass filter with cut-offs between 0.1 and 0.25Hz and between 25 and 30Hz.
Compute mean ratio between recorded and predicted motions at some stations of the RAF network. Find large ratios for some stations on soil and for some on rock.