- Ground-motion model is
^{46}: - Use V
_{s,30}to characterise sites. V_{s,30}ranges from 100 to 2000m∕s. Most sites with V_{s,30}≤ 500m∕s. - Consider 3 styles of faulting based on rake angle:
- 1.
- Reverse. About 1700 records.
- 2.
- Normal. About 100 records.
- 3.
- Strike-slip. About 600 records.

But this effect is not included in final model.

- Use the Pacific Earthquake Engineering Research Center database.
- Use the M5’ model tree approach, which is a soft computing method. M5’ searches for best model using tree building, tree pruning and smoothing steps. Choose best model based on: simplest structure and minimum rules; models providing best predictions for training set; and minimum number of instances in each class or leaf should be larger than 100 (to avoid over-fitting). M5’ only proposes linear equations, which note is a limitation.
- Randomly split 2815 records into part for training (2252 records) and part for testing (563 records).
- Most data from M
_{w}≤ 6.6. - Use mean absolute error, root mean square error, correlation coefficient and discrepancy ratio to evaluate model both using training and testing sets. Find good fits.
- Undertake sensitivity analysis by developing models leaving out each of the input parameters in turn. Find
r
_{rup}is the most important parameter and then M_{w}.

^{46}Because the functional form and classes are decided by an automatic algorithm the coefficients have been included in the
equations directly.