- Ground-motion model is:
μ(M,r

_{jb},V_{s}) is natural logarithm of ground-motion parameter (e.g. ln(PGA) where PGA is in g), b_{1,ss}= 0.853 ± 0.28, b_{1,rv}= 0.872 ± 0.27, b_{2}= 0.442 ± 0.15, b_{3}= -0.067 ± 0.16, b_{5}= -0.960 ± 0.07, b_{v}= -0.154 ± 0.14, h = 8.90km, V_{a}= 760m∕s, σ = 0.47 ± 0.02 (intra-event) and τ = 0.23 (inter-event). Also gives overall σ = (0.93 - 0.10M_{w})^{0.5}for M_{w}≤ 7.0 and overall σ = 0.48 for M_{w}> 7.0. - Uses six site classes (from Wills et al. (2000)):
- B
- 760 ≤ V
_{s}≤ 1500m∕s. Uses V_{s}= 1000m∕s in regression. 12 records. - BC
- Boundary between B and C. Uses V
_{s}= 760m∕s in regression. 36 records. - C
- 360 ≤ V
_{s}≤ 760m∕s. Uses V_{s}= 560m∕s in regression. 16 records. - CD
- Boundary between C and D. Uses V
_{s}= 360m∕s in regression. 166 records. - D
- 180 ≤ V
_{s}≤ 360m∕s. Uses V_{s}= 270m∕s in regression. 215 records. - DE
- Boundary between D and E. Uses V
_{s}= 180m∕s in regression. 2 records.

- Uses data from the SCEC Phase III strong-motion database.
- Uses three faulting mechanism classes:
- Strike-slip
- Use b
_{1,ss}. 14 earthquakes, 103 records. - Reverse
- Use b
_{1,rv}. 6 earthquakes, 300 records. - Oblique
- Use 0.5(b
_{1,ss}+ b_{1,rv}). 8 earthquakes, 46 records.

- Notes that data is unbalanced in that each earthquake has a different number of records for each site type hence it is important to correct observations for the inter-event terms before examining residuals for site effects.
- Plots average site class residuals w.r.t. BC category and the residuals predicted by equation and finds good match.
- Uses 197 records with basin-depth estimates (depth defined to the 2.5km∕s shear-wave velocity isosurface) to examine dependence of inter-event corrected residuals w.r.t. basin depth. Plots residuals against basin depth and fits linear function. Finds that all slopes are significantly different than zero by more than two sigmas. Finds a significant trend in subset of residuals where basin-depths are known w.r.t. magnitude hence needs to test whether basin-depth effect found is an artifact of something else. Hence derives Ground-motion models (coefficients not reported) using only subset of data for which basin-depth estimates are known and examines residuals w.r.t. basin-depth for this subset. Finds similar trends as before hence concludes found basin effect is truly an effect of the basin. Notes that basin-depth coefficients should be derived simultaneously with other coefficients but because only a subset of sites have a value this could not be done.
- Tests for nonlinearity by plotting residuals for site class D w.r.t. predicted ground motion for BC boundary. Fits linear equation. Finds slope for PGA is significantly different than zero.
- Notes that due to large number of class D sites site nonlinearity could have affected other coefficients in equation leading to less of a trend in residuals. Tests for this by plotting residuals for site classes B and BC combined w.r.t. predicted ground motion for BC boundary. Fits linear equation. Finds non-significant slopes. Notes that nonlinearity may lead to rock ground motions being underestimated by model but not enough data to conclude.
- Investigates inter-event variability estimate through Monte Carlo simulations using 250 synthetic databases because uncertainty estimate of τ was considered unreliable possibly due to limited number of events. Find that there could be a problem with the regression methodology adopted w.r.t. the estimation of τ.
- Plots squared residuals w.r.t. magnitude and fits linear equations. Finds significant trends. Notes that method could be not statistically correct because squared residuals are not Gaussian distributed.
- Plots squared residuals w.r.t. V
_{s}and does not find a significant trend. - Provides magnitude-dependent estimates of overall σ up to M
_{w}7.0 and constant overall σ for larger magnitudes. - Tests normality of residuals using Kolmogorov-Smirnov test and finds that the null hypothesis cannot be rejected. Also examines theoretical quantile-quantile plots and finds nothing notable.