- Ground-motion model is the same as Bindi et al. (2011a) (see Section 2.341) but with different
coefficients. Using 5 site classes (MOD1): a = 3.478, c1 = -1.734, c2 = 0.378, h = 8.119, c3 = -1.08×10-3,
b1 = -0.166, b2 = -0.062, b3 = 0, sA = 0, sB = 0.085, sC = 0.248, sD = 0.240, sE = 0.477, fNF = -0.037,
fSS = 0.099, fTF = -0.062, fUN = 0, τ = 0.172 (inter-event), ϕ = 0.298 (intra-event) and σ = 0.344
(total); and using 6 site classes (MOD2): a = 3.415, c1 = -1.876, c2 = 0.438, h = 10.095, c3 = -9.75×10-4,
b1 = -0.266, b2 = -0.065, b3 = 0, sAA = 0, sA = 0.211, sB = 0.227, sC = 0.386, sD = 0.401, sE = 0.614,
fNF = -0.041, fSS = 0.104, fTF = -0.063, fUN = 0, τ = 0.161 (inter-event), ϕ = 0.299 (intra-event)
and σ = 0.340 (total).
- Reassess the 47 sites currently classified as Eurocode A in Italian strong-motion database (many of sites
originally classified by Bindi et al. (2011a) as Eurocode A had subsequently been reclassified). Use 6
proxies based on geological, topographical and geophysical indicators: 1) V s,30 ≥ 800m∕s, 2) rock conditions
according to surface geology, 3) flat topographic surface, 4) absence of interaction with structures, 5) flat
H/V spectral ratio of noise measurements without directional effects and 6) flat or moderately broadband
H/V response spectral ratio of earthquake waveforms. Require 4 out of 6 criteria to be satisfied for a site
to be classed as reference rock. Class 23 stations as reference rock.
- Derive two models: MOD1) use 5 site classes with coefficient for class A constrained to zero; and MOD2)
use 6 site class, where generic rock sites (A) and reference rock sites (Aref) are separated and coefficient
for Aref is constrained to zero.
- Also derive σ for the rock site classes separately.
- Find significant reduction in predicted ground motions and standard deviations for reference rock sites.