- Ground-motion model is:
^{2}), c_{1}= -2.19617, m_{1}= 0.52375, m_{2}= -0.06094, r_{1}= -3.80190, r_{2}= 0.35508, r_{3}= 11.64156, s_{B}= 0.21070, s_{C}= 0.28251, s_{D}= 0.28288, b_{V }= -0.31007, b_{V 800}= -0.70244, V_{A}= 2319.18598, f_{N}= -0.02411, f_{R}= 0.07246, f_{SS}= -0.05632, ϕ = 0.25892 (intra-event), τ = 0.22145 (inter-event) and σ = 0.34071 (total). - Use three alternative site terms. Mean V
_{s,30}equals 365m∕s. Either use V_{s,30}to characterise sites or four Eurocode 8 site classes:- A
- Rocklike, V
_{s,30}≥ 800m∕s. 7% of data. S_{B}= S_{C}= S_{D}= 0. - B
- Stiff, 360 ≤ V
_{s,30}< 800m∕s. 43% of data. S_{B}= 1, S_{C}= S_{D}= 0. - C
- Soft, 180 ≤ V
_{s,30}< 360m∕s. 40% of data. S_{C}= 1, S_{B}= S_{D}= 0. - D
- Very soft, V
_{s,30}< 180m∕s. 10% of data. S_{D}= 1, S_{B}= S_{C}= 0.

- Use three faulting mechanisms using classification of Boore and Atkinson (2008):
- Normal
- 20 earthquakes. F
_{N}= 1, F_{R}= F_{SS}= 0. - Strike-slip
- 43 earthquakes. F
_{SS}= 1, F_{N}= F_{R}= 0. - Reverse
- 26 earthquakes. F
_{R}= 1, F_{N}= F_{SS}= 0.

- Focal depths ≤ 20km..
- Update of previous models by Cauzzi and Faccioli (2008), Cauzzi (2008), Cauzzi et al. (2008), Faccioli et al. (2010) and Cauzzi et al. (2011).
- All data from digital accelerometers.
- Most data from Japan (K-Net) (1448 records, 49 earthquakes) with some data from Europe and Middle East (Italy, Iceland, Iran, Turkey, Switzerland, Greece) (195 records, 35 earthquakes), western USA (California and Alaska) (79 records, 7 earthquakes), New Zealand (61 records, 5 earthquakes) and China and Taiwan (95 records, 2 earthquakes).
- Only use data from earthquakes with known fault geometries (from which r
_{rup}can be estimated) except for M_{w}≤ 5.7, where comparison of r_{rup}and r_{hypo}shows that statistically indistinguishable. - Use procedure of Paolucci et al. (2008) to avoid filtering records with a probability > 0.9 of long-period disturbance levels being < 15%. High-pass filter remaining records with 20s cut-off.
- Did not check for regional dependency since now largely accepted to merge data from various regions.
- Aim for simple though physically-sound functional form. Prefer a simple magnitude-independent r
_{3}over one that is magnitude-dependent because of stability in regression results and lack of trade-off with other coefficients. Also this choice allows use of two-stage regression thereby yielding a smaller σ. Do not include anelastic term because of negligible impact on predictions for r_{rup}< 150km. - Derive model in four stages. First, undertake regressions to investigate overall variation of coefficients and
to identify trade-offs. Constrain r
_{2}and r_{3}from this step in subsequent steps. Second, undertake two-step maximum-likelihood regression to find r_{1}, s_{B}, s_{C}, s_{D}, c_{1}, m_{1}and m_{2}. Smooth m_{2}(T) for T < 1s by fitting a high-order polynomial to the raw coefficients. Next repeat regression holding m_{2}fixed. This had a positive effect on stability of c_{1}and m_{1}. Third, find b_{V }, b_{V 800}and V_{A}by two-stage weighted maximum-likelihood regression. Fourth, find f_{N}, f_{R}and f_{SS}by two-step maximum-likelihood regression. - Examine predicted magnitude-scaling and observations from r
_{rup}< 10km adjusted to rock-like conditions. Find evidence for over-saturation at large magnitudes but note that there is large uncertainty because of limited data for M_{w}> 7.2. Model predicts oversaturation for short-periods and large magnitudes, which is retained. Provide equations to remove oversaturation from model. - Examine residuals w.r.t. predicted PGA on rock and grouped by EC8 site class to seek nonlinear site amplification. Fit lines to residuals and find trends, which could interpret as nonlinearity but given scatter in results believe evidence for soil nonlinearity is weak.
- Find inclusion of faulting mechanism terms slightly reduces σ for T < 0.3s.
- Believe that because model developed independently of other recent models and using an independent dataset that it can contribute to capturing epistemic uncertainty in ground-motion prediction.
- Note that one limitation of model is the use of V
_{s,30}but cannot add terms to account for 2D or 3D basin-type effects because of lack of require information for most records. - Note that there is still a lack of data from rock-like sites.