### 2.116 Boore et al. (1994a) & Boore et al. (1997)

• Based on Boore et al. (1993) see Section 2.105
• Ground-motion model is:
where Y is in g, b1 to b5, h and σ are same as for Boore et al. (1993) (see Section 2.105) and for randomly oriented component bV = -0.371 and V A = 1400 and for larger horizontal component bV = -0.364 and V A = 1390.
• Model site effect as a continuous function of average shear-wave velocity to 30m deep, V S.
• Coefficients b1, b2, b3,b4 and b5 from Boore et al. (1993).
• Find no basis for different magnitude scaling at different distances.
• Find evidence for magnitude dependent uncertainty.
• Find evidence for amplitude dependent uncertainty.
• Find marginal statistical significance for a difference between strike-slip (defined as those with a rake angle within 30 of horizontal) and reverse-slip motions but do not model it. Modelled in Boore et al. (1994b) (by replacing b1 by bSSGSS+bRSGRS where GSS = 1 for strike-slip shocks and 0 otherwise and GRS = 1 for reverse-slip shocks and 0 otherwise) and reported in Boore et al. (1997). Coefficients for randomly oriented horizontal component are: bSS = -0.136 and bRS = -0.05111.
• Analysis done using one and two-stage maximum likelihood methods; note that results are very similar.
• Earthquakes with magnitudes below 6.0 are poorly represented.
• Note that few Class A records.
• Note that V S does not model all the effects of site because it does not model effect of the thickness of attenuating material on motion.
• Note that ideally would like to model site in terms of average shear-wave velocity to one-quarter wavelength.
• Note lack measurements from distances greater than 100km so that weak-motion data from seismographic stations maybe should be used.
• Note that use of cutoff distances independent of geology or azimuth may be over strict but it is simple and objective. Note that methods based on data from nontriggered stations or using seismogram data may be better.

11These are taken from Table 8 of Boore et al. (1997) which uses natural logarithms so they were converted into terms of logarithms to base 10.